# Natural Antispasmodics: Source, Stereochemical Configuration, and Biological Activity

Authors: Edith Fabiola Martínez-Pérez; Zaida N. Juárez; Luis R. Hernández; Horacio Bach
Journal: BioMed Research International
 (2018)

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## Abstract

Natural products with antispasmodic activity have been used in traditional medicine to alleviate different illnesses since the remote past. We searched the literature and compiled the antispasmodic activity of 248 natural compounds isolated from terrestrial plants. In this review, we summarized all the natural products reported with antispasmodic activity until the end of 2017. We also provided chemical information about their extraction as well as the model used to test their activities. Results showed that members of the Lamiaceae and Asteraceae families had the highest number of isolated compounds with antispasmodic activity. Moreover, monoterpenoids, flavonoids, triterpenes, and alkaloids were the chemical groups with the highest number of antispasmodic compounds. Lastly, a structural comparison of natural versus synthetic compounds was discussed.


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## Body

## 1. Introduction

Antispasmodic compounds are currently used to reduce anxiety, emotional and musculoskeletal tension, and irritability. Although most of the available antispasmodic compounds are synthetic or semisynthetic, traditional uses of this group of compounds are still popular.We collected information about natural compounds with antispasmodic activity isolated from terrestrial plants. We searched the databases of Google Scholar, PubMed, and SciFinder and compiled the information about 248 compounds published until December 2017. This review focuses on the antispasmodic activity of isolated compounds and activities from extracts without further purification are not discussed.


## 2. The Neurons

Nerve cells or neurons are responsible for receiving, conducting, and transmitting signals. A neuron consists of a nucleated body, a long thin extension called an axon, and several dendrites or prolongations extended from the cell body. Axons conduct signals from the nucleated body towards distant targets, while dendrites provide an enlarged surface area to receive signals from the axons of other neurons.Signal transmission through axons is driven by a change in the electrical potential across the plasma membrane of neurons. This plasma membrane contains voltage-gated cation channels, which are responsible for generation of action potentials. An action potential is triggered by a depolarization of the plasma membrane or a shift to a less negative value.In nerve and skeletal muscle cells, a stimulus can cause sufficient depolarization to open voltage-gated Na+ channels allowing the entrance of Na+ into the cell. This influx of Na+ depolarizes the membrane further causing the opening of more Na+ channels. To avoid a permanent influx, Na+ channels are able to reclose rapidly even when the membrane is still depolarized. This function is based on the presence of voltage-gated K+ channels, which are responsible for K+ efflux equilibrating the membrane potential even before the total inactivation of Na+ channels. In some cases, the action potential in some muscles depends on voltage-gated Ca2+ channels.


### 2.1. Transmission of Signals

The transmission of signals occurs mainly between neurons or from neurons to skeletal muscles, which are the final acceptors of electrical signals, causing a muscular contraction.


#### 2.1.1. Signal Transmission between Neurons

Neuronal signals are transmitted between neurons at specialized sites of contact known as synapses. Neurons are separated by a synaptic cleft where a release of a neurotransmitter occurs. This neurotransmitter is stored in vesicles and is released by exocytosis. Upon triggering, the neurotransmitter is released into the cleft provoking an electrical change in the postsynaptic cell by binding to the transmitter-gated ion channels. To avoid a continuous electrical change and to ensure both spatial and temporal precision of signal transmission, the neurotransmitter is rapidly removed from the cleft either by specific enzymes in the synaptic cleft or by reuptake mediated by neurotransmitter carrier proteins [1].Neurotransmitters can also open cation channels causing an influx of Na+ and then called excitatory neurotransmitters (e.g., acetylcholine, glutamate, and serotonin) or produce an opening of Cl- channels and then inhibiting the signal transmission by maintaining the postsynaptic membrane polarization [e.g., γ-aminobutyric acid (GABA) and glycine].


#### 2.1.2. Neuromuscular Signal Transmission

The transmission of electrical signals to muscles involves five sequential and orchestrated steps: (i) nerve electric signal reaches the nerve terminal, (ii) it depolarizes the plasma membrane of the terminal, (iii) voltage-gated Ca2+ channels opens causing an increase in Ca2+ concentration in the neuron cytosol, and (iv) release of acetylcholine into the synaptic cleft is triggered. Acetylcholine binds to acetylcholine receptors in the muscle plasma membrane opening Na+ channels and provoking a membrane depolarization. This depolarization enhances the opening of more Na+ channels causing a self-propagating depolarization. The generalized depolarization of the muscle plasma membrane activates Ca2+ channels in specialized regions on the membrane causing Ca2+ release from the sarcoplasmic reticulum (Ca2+ storage) into the cytosol.As a consequence of an increase in the Ca2+ concentration, myofibrils in the muscle cell contract. The increase of Ca2+ in the cytosol is transient because Ca2+ is rapidly pumped back into the sarcoplasmic reticulum causing a relaxation of the myofibrils. This process is very fast and Ca2+ concentration at resting levels is restored within 30 milliseconds [2].


## 2.1. Transmission of Signals

The transmission of signals occurs mainly between neurons or from neurons to skeletal muscles, which are the final acceptors of electrical signals, causing a muscular contraction.


### 2.1.1. Signal Transmission between Neurons

Neuronal signals are transmitted between neurons at specialized sites of contact known as synapses. Neurons are separated by a synaptic cleft where a release of a neurotransmitter occurs. This neurotransmitter is stored in vesicles and is released by exocytosis. Upon triggering, the neurotransmitter is released into the cleft provoking an electrical change in the postsynaptic cell by binding to the transmitter-gated ion channels. To avoid a continuous electrical change and to ensure both spatial and temporal precision of signal transmission, the neurotransmitter is rapidly removed from the cleft either by specific enzymes in the synaptic cleft or by reuptake mediated by neurotransmitter carrier proteins [1].Neurotransmitters can also open cation channels causing an influx of Na+ and then called excitatory neurotransmitters (e.g., acetylcholine, glutamate, and serotonin) or produce an opening of Cl- channels and then inhibiting the signal transmission by maintaining the postsynaptic membrane polarization [e.g., γ-aminobutyric acid (GABA) and glycine].


### 2.1.2. Neuromuscular Signal Transmission

The transmission of electrical signals to muscles involves five sequential and orchestrated steps: (i) nerve electric signal reaches the nerve terminal, (ii) it depolarizes the plasma membrane of the terminal, (iii) voltage-gated Ca2+ channels opens causing an increase in Ca2+ concentration in the neuron cytosol, and (iv) release of acetylcholine into the synaptic cleft is triggered. Acetylcholine binds to acetylcholine receptors in the muscle plasma membrane opening Na+ channels and provoking a membrane depolarization. This depolarization enhances the opening of more Na+ channels causing a self-propagating depolarization. The generalized depolarization of the muscle plasma membrane activates Ca2+ channels in specialized regions on the membrane causing Ca2+ release from the sarcoplasmic reticulum (Ca2+ storage) into the cytosol.As a consequence of an increase in the Ca2+ concentration, myofibrils in the muscle cell contract. The increase of Ca2+ in the cytosol is transient because Ca2+ is rapidly pumped back into the sarcoplasmic reticulum causing a relaxation of the myofibrils. This process is very fast and Ca2+ concentration at resting levels is restored within 30 milliseconds [2].


## 2.1.1. Signal Transmission between Neurons

Neuronal signals are transmitted between neurons at specialized sites of contact known as synapses. Neurons are separated by a synaptic cleft where a release of a neurotransmitter occurs. This neurotransmitter is stored in vesicles and is released by exocytosis. Upon triggering, the neurotransmitter is released into the cleft provoking an electrical change in the postsynaptic cell by binding to the transmitter-gated ion channels. To avoid a continuous electrical change and to ensure both spatial and temporal precision of signal transmission, the neurotransmitter is rapidly removed from the cleft either by specific enzymes in the synaptic cleft or by reuptake mediated by neurotransmitter carrier proteins [1].Neurotransmitters can also open cation channels causing an influx of Na+ and then called excitatory neurotransmitters (e.g., acetylcholine, glutamate, and serotonin) or produce an opening of Cl- channels and then inhibiting the signal transmission by maintaining the postsynaptic membrane polarization [e.g., γ-aminobutyric acid (GABA) and glycine].


## 2.1.2. Neuromuscular Signal Transmission

The transmission of electrical signals to muscles involves five sequential and orchestrated steps: (i) nerve electric signal reaches the nerve terminal, (ii) it depolarizes the plasma membrane of the terminal, (iii) voltage-gated Ca2+ channels opens causing an increase in Ca2+ concentration in the neuron cytosol, and (iv) release of acetylcholine into the synaptic cleft is triggered. Acetylcholine binds to acetylcholine receptors in the muscle plasma membrane opening Na+ channels and provoking a membrane depolarization. This depolarization enhances the opening of more Na+ channels causing a self-propagating depolarization. The generalized depolarization of the muscle plasma membrane activates Ca2+ channels in specialized regions on the membrane causing Ca2+ release from the sarcoplasmic reticulum (Ca2+ storage) into the cytosol.As a consequence of an increase in the Ca2+ concentration, myofibrils in the muscle cell contract. The increase of Ca2+ in the cytosol is transient because Ca2+ is rapidly pumped back into the sarcoplasmic reticulum causing a relaxation of the myofibrils. This process is very fast and Ca2+ concentration at resting levels is restored within 30 milliseconds [2].


## 3. Receptors

The autonomic nerve system controls and monitors the internal environment of the body. The input of its activity is provided by neurons that are associated with specific sensory receptors located in the blood vessels, muscles, and visceral organs (Table1). According to the neurotransmitter secreted, these neurons are classified as adrenergic or cholinergic. The adrenergic neurons secrete the neurotransmitter noradrenalin termed also norepinephrine. Adrenergic receptors include the types α and β, which are further categorized as α1, α2, β1, β2, and β3. On the other hand, cholinergic neurons secrete acetylcholine, which induces a postsynaptic event. There are two types of cholinergic receptors, the nicotinic receptor (abundant at the neuromuscular junction) and the muscarinic receptor (abundant on smooth and cardiac muscles and glands).Table 1
Receptors targeted by neurotransmitters in the body.
Receptor Targeted by Adrenergic Epinephrine (adrenaline) Norepinephrine (noradrenaline) Dopaminergic Dopamine Cholinergic Acetylcholine GABAergic GABA Glutaminergic Glutamate Histaminergic Histamine Serotonergic Serotonin Glycinergic Glycine Opioid Dynorphin Enkephalin Endorphin Endomorphin NociceptinThere are several agonists (neurotransmitters, hormones, and others) able to bind to specific receptors and activate the contraction of smooth muscle. Upon binding the agonist to the receptor, the mechanism of contraction is based on an increase of phospholipase C. This enzyme hydrolyzes phosphatidylinositol 4,5-bisphosphate located on the membrane, producing two powerful secondary messengers termed diacylglycerol (DG) and inositol 1,4,5 triphosphate (IP3). IP3 binds to specific receptors in the sarcoplasmic reticulum, causing release of Ca2+ within the muscle. DG together with Ca2+ activates the protein kinase C (PKC), which phosphorylates specific proteins. In most smooth muscles, the contraction process commences when PKC phosphorylates Ca2+ channels or other proteins that regulate the cyclic process. For instance, Ca2+ binds to calmodulin (a multifunctional intermediate calcium-binding messenger protein), triggering the activation of the myosin light chain (MLC) kinase, which phosphorylates the light chain of myosin and together with actin carries out the process of initiating the shortening of the smooth muscle cell [147]. However, the elevation of the intracellular concentration of Ca2+ is transient, and the contractile response is maintained by a mechanism sensitized by Ca2+ modulated by the inhibition of myosin phosphatase activity by Rho kinase. This mechanism sensitized to Ca2+ is initiated at the same time that phospholipase C is activated and involves the activation of the small RhoA protein bound to guanosine triphosphate (GTP). Above activation, RhoA increases the activity of Rho kinase, leading to the inhibition of myosin phosphatase. This promotes the contractile state, since the myosin light chain cannot be dephosphorylated [147].Relaxation of smooth muscle occurs as a result of either removing the contractile stimuli or by the direct action of a substance that stimulates the inhibition of the contractile mechanism. In any circumstance, the relaxation process requires a decrease in the intracellular Ca2+ concentration and an increase in the activity of the MLC phosphatase. The sarcoplasmic reticulum and plasma membrane remove Ca2+ from the cytosol. Na+/Ca2+ channels are located on the plasma membrane and help to reduce the intracellular concentration of Ca2+. During relaxation, other contributors that restrict the Ca2+ entry into the cell are the voltage-operated channels and Ca2+ receptors in the plasma membrane, which remain closed [147].


## 4. Spasmodic Compounds

The historical antecedents date from the year 1504 when South American natives inhabiting the basins of the high Amazon and the Orinoco prepared a mixture of alkaloids termed curare. This substance was placed in the tips of arrows in order to hunt (prey paralyzing) and fight in wars. Curare produces muscle weakness, paralysis, respiratory failure, and death [148]. In 1800, Alexander von Humboldt, identified that curare was made from the extracts of the speciesChondrodendron tomentosum andStrychnos toxifera.In 1935, the French physiologist Claude Bernard managed to isolate the alkaloid d-tubocurarine from the curare [149]; and one year later, it was elucidated that this compound had the ability to inhibit acetylcholine, blocking the transmission of nerve impulses to the muscles [150]. Lastly, new benzylisoquinoline alkaloids were isolated from curare by Galeffi et al. in 1977 [151, 152].In 1822, the pharmacist Rudolph Brandes obtained an impure alkaloid fromAtropa belladonna (Solanaceae), which after purification was named atropine. Interestingly, atropine was not produced as a natural compound from the plant and it was a derivative generated from the alkaloid hyoscyamine during the process of purification [153]. It is important to note that atropine has been naturally found in small quantities in other members of the Solanaceae family such asDatura stramonium,Duboisia myoporoides, andScopolia japonica [154–156].The use of the plantPapaver somniferum (opium poppy) (Papaveraceae) dates back to about 4000 BC. At present the plant is only used to extract a base material for the manufacture of other alkaloids, such as noscapine and codeine, both discovered by the French pharmacist Pierre-Jean Robiquet in 1831 and 1832, respectively [157]. In 1848, papaverine was another substance extracted from the same plant by the German chemist Georg Merck [158], which is rarely used today because of the high doses needed (approximately 6 to 12 mg). However, it is still used as a control in experimental models with the purpose of studying antispasmodic activity of plant extracts.In the20th century, extracts and powders derived fromA. belladonna were widely used as antispasmodics, but from the 1950s these preparations were displaced by synthetic and semisynthetic anticholinergic compounds in order to obtain a better response [159], such as the case of methocarbamol and guaifenesin. On the other hand, a series of compounds such as dantrolene, glutethimide, methaqualone, chlormezanone, metiprilone, and ethchlorvynol were introduced to replace the meprobamate, which had to be withdrawn from the market in 1960 due to problems resulting from use such as abstinence, addictions, and overdoses.In 1962, the Swiss chemist Heinrich Keberle synthesized baclofen, which can be obtained by reacting glutarimide with an alkaline solution [160]. Glutarimide can also be found in plants such asCroton cuneatus andC. membranaceus (Euphorbiaceae) [161, 162].The arrival of the quaternary compounds of nitrogen reinforce their peripheral anticholinergic activity offering also the advantages of being poorly absorbed in the gastrointestinal tract, producing a more powerful and longer lasting sedative effect unlike atropine [1]. For example, ipratropium bromide was developed by the German company Boehringer Ingelheim in 1976 and used to treat asthma. This compound was obtained by reacting atropine with isopropyl bromide [163]. Another quaternary compound was the n-butylhyoscine bromide, which is possible to obtain by the organic synthesis of scopolamine and the cimetropium bromide found in theA. belladonna [164]. Although at present the preparations of plant mixtures are no longer used for therapeutic purposes, these compounds formed a part of and served as the basis for modern pharmacology for their applicability as antispasmodics and anesthetics.Spasms are involuntary contractions of the muscles, which are normally accompanied by pain and interfere with the free and effective muscular voluntary activity. Muscle spasm can originate from multiple medical conditions and is often associated with spinal injury, multiple sclerosis, and stroke.Spasticity and rigidity are caused by a disinhibition of spinal motor mechanisms. There are several scenarios where a muscle can produce a spasm: (i) unstable depolarization of motor axons; (ii) muscular contractions persist even if the innervation of muscle is normal and despite attempts of relaxation (myotonia); (iii) after one or a series of contractions, the muscle can decontract slowly, as occurring in hypothyroidism; and (iv) muscles lack the energy to relax.


### 4.1. Distribution of Spasmodic Compound in Nature

Spasmodic compounds are widely distributed in nature (Table2). Frequently, these compounds are found in animals that paralyze their preys or used for defense. Some examples include the venom of the black widow and tarantula spiders [11, 165] and the venom of snakes [166]. Plants also produce spasmodic metabolites, such as strychnine, an alkaloid obtained from the treeStrychnos nux-vomica (Loganiaceae). Furthermore, microorganisms synthesize spasmodic compounds such as the neurotoxins tetanospasmin and botulinum toxin from the Gram-positive bacteriaClostridium tetaniandC. botulinum, respectively. These toxins produce a toxic disorder, which is characterized by persistent spasms of skeletal muscles on spinal neurons similar to strychnine.Table 2
Representative organisms producing spasmodic compounds.
Compound Organism Symptoms Mechanism Reference Bacterial Botulinum toxin Clostridium botulinum Muscular relaxation Secretion of acetylcholine into synapses is blocked [3] Tetanospasmin Clostridium tetani Muscular spasm Inhibits the binding of GABA and glycine [4]  Marine Nematocyst venom extract Sea anemones Nausea, vomiting, muscle cramp, severe pain, paralysis Delay in the voltage-dependent Na+ channels inactivation [5] Nematocyst venom extract Chironex fleckeri (Cnidaria) Contraction of arterial smooth muscle Increase of cytosolic Ca2+ concentration [6] Ciguatoxin Gambierdiscus toxicus (Dinoflagellate) Nausea, vomiting, abdominal pain, intestinal spasm Interact with voltage-gated increasing the Na+ permeability and Ca2+ homeostasis [7] Chordata Plotosus lineatus (Catfish) Violent pain, shock, spasm Increase of the vascular permeability in peritoneum [8]  Terrestrial Ergotamine Claviceps purpurea(fungus) Seizure, spasms psychosis, nausea, vomiting Agonist of several neurotransmitter receptors [9] α-Latrotoxin Latrodectus tredecimguttatus (black widow spider) Facial flushing, hypertension, muscle spasm, tachycardia Causes Ca2+-dependent and -independent release of neurotransmitters [10] Vanillo-toxin, hanatoxin, huwentoxin Tarantula species Severe pain, cramps, erythema, swelling, tachycardia Unrevealed [11–14] β-Neurotoxin Mesobuthus martensii(scorpion) Increases muscular contraction, spasm, convulsion Modulates Ca2+ channels [15] Crotoxin Crotalus durissus terrificus(rattlesnake) Severe pain, drooping eyelids, low blood pressure, muscle weakness Blocks the cholinergic post-synaptic response [16]


### 4.2. Mechanisms of Antispasmodic Activity of Natural Products

Antispasmodic compounds exert their activity in different ways, such as antispasmodic activity through inhibition of the response to the neurotransmitters 5-hydroxytryptamine (5-HT) or serotonin and acetylcholine. However, other authors attribute the antispasmodic effect to (i) capsaicin-sensitive neurons, (ii) the participation of vanilloid receptors [167], (iii) the activation of K+ ATP channels, (iv) the blockade of Na+ channels and muscarinic receptors, (v) the reduction of extracellular Ca2+, or (vi) the blockade of Ca2+ channels [22, 168, 169]. The above is merely a reflection of the ambiguity of the studies showing the mechanisms of action of the antispasmodic compounds [36]. For example, the hydroalcoholic extract ofMarrubium vulgare showed antispasmodic effect, having the ability to inhibit the neurotransmitters acetylcholine, bradykinin, prostaglandin E2, histamine, and oxytocin [170], whereas a dual effect of antidiarrheal and laxative activities was reported inFumaria parviflora [171].


## 4.1. Distribution of Spasmodic Compound in Nature

Spasmodic compounds are widely distributed in nature (Table2). Frequently, these compounds are found in animals that paralyze their preys or used for defense. Some examples include the venom of the black widow and tarantula spiders [11, 165] and the venom of snakes [166]. Plants also produce spasmodic metabolites, such as strychnine, an alkaloid obtained from the treeStrychnos nux-vomica (Loganiaceae). Furthermore, microorganisms synthesize spasmodic compounds such as the neurotoxins tetanospasmin and botulinum toxin from the Gram-positive bacteriaClostridium tetaniandC. botulinum, respectively. These toxins produce a toxic disorder, which is characterized by persistent spasms of skeletal muscles on spinal neurons similar to strychnine.Table 2
Representative organisms producing spasmodic compounds.
Compound Organism Symptoms Mechanism Reference Bacterial Botulinum toxin Clostridium botulinum Muscular relaxation Secretion of acetylcholine into synapses is blocked [3] Tetanospasmin Clostridium tetani Muscular spasm Inhibits the binding of GABA and glycine [4]  Marine Nematocyst venom extract Sea anemones Nausea, vomiting, muscle cramp, severe pain, paralysis Delay in the voltage-dependent Na+ channels inactivation [5] Nematocyst venom extract Chironex fleckeri (Cnidaria) Contraction of arterial smooth muscle Increase of cytosolic Ca2+ concentration [6] Ciguatoxin Gambierdiscus toxicus (Dinoflagellate) Nausea, vomiting, abdominal pain, intestinal spasm Interact with voltage-gated increasing the Na+ permeability and Ca2+ homeostasis [7] Chordata Plotosus lineatus (Catfish) Violent pain, shock, spasm Increase of the vascular permeability in peritoneum [8]  Terrestrial Ergotamine Claviceps purpurea(fungus) Seizure, spasms psychosis, nausea, vomiting Agonist of several neurotransmitter receptors [9] α-Latrotoxin Latrodectus tredecimguttatus (black widow spider) Facial flushing, hypertension, muscle spasm, tachycardia Causes Ca2+-dependent and -independent release of neurotransmitters [10] Vanillo-toxin, hanatoxin, huwentoxin Tarantula species Severe pain, cramps, erythema, swelling, tachycardia Unrevealed [11–14] β-Neurotoxin Mesobuthus martensii(scorpion) Increases muscular contraction, spasm, convulsion Modulates Ca2+ channels [15] Crotoxin Crotalus durissus terrificus(rattlesnake) Severe pain, drooping eyelids, low blood pressure, muscle weakness Blocks the cholinergic post-synaptic response [16]


## 4.2. Mechanisms of Antispasmodic Activity of Natural Products

Antispasmodic compounds exert their activity in different ways, such as antispasmodic activity through inhibition of the response to the neurotransmitters 5-hydroxytryptamine (5-HT) or serotonin and acetylcholine. However, other authors attribute the antispasmodic effect to (i) capsaicin-sensitive neurons, (ii) the participation of vanilloid receptors [167], (iii) the activation of K+ ATP channels, (iv) the blockade of Na+ channels and muscarinic receptors, (v) the reduction of extracellular Ca2+, or (vi) the blockade of Ca2+ channels [22, 168, 169]. The above is merely a reflection of the ambiguity of the studies showing the mechanisms of action of the antispasmodic compounds [36]. For example, the hydroalcoholic extract ofMarrubium vulgare showed antispasmodic effect, having the ability to inhibit the neurotransmitters acetylcholine, bradykinin, prostaglandin E2, histamine, and oxytocin [170], whereas a dual effect of antidiarrheal and laxative activities was reported inFumaria parviflora [171].


## 5. Methods Used to Evaluate Antispasmodic Compounds

### 5.1. Gastrointestinal Model

The small intestine is characterized by its large surface area as a result of its circular folds, villi, and microvilli. It is the longest part of the GI system (approximately 5 meters) and comprises about 5% of its initial length, which corresponds to the duodenum (characterized by the absence of the mesentery) and then the jejunum (around 40% of the intestinal length), ending with the ileum. It is the organ of absorption of nutrients and digestion in organisms. These functions are carried out mainly in the duodenum and jejunum.The main types of bowel movement are the segmentation and peristaltism. The segmentation is most frequent in the small intestine and consists of contractions of the circular muscle layer in very close areas. Contractions last for 11-12 and 8-9 contractions per min in the duodenum and ileum, respectively. When this segmentation is rhythmic, the contractions are alternated with relaxation. This type of movement results in a mixed effect of the chyme (acidic fluid that passes from the stomach to the small intestine) with the digestive secretions, allowing an optimal contact with the intestinal mucosa. In the case of peristalsis, contractions of successive sections of the circular smooth muscle cause the movement of the intestinal contents in anterograde form. The short peristaltic movement also takes place in the small intestine, but less frequently than the segmentation movements. Peristaltic waves rarely cross more than 10 cm of intestine and, due to the low frequency of propulsion of the chyme, it is in this zone where digestion and absorption are preferably carried out. Peristalsis is regulated mainly by the nervous action of the myenteric plexus (major nerve supply to the gastrointestinal tract that controls GI tract motility) in the intestinal wall.The diversity of experimental models used for the testing of antispasmodic compounds is large. These models mainly use isolated organs or live animals. Once the organ is extracted from the animal, the intestinal motility is assessed with the administration of a substance. The use of extracted organs can be sustained for hours when placed in a physiological solution, such as Ringer, Jalon, Tyrode, and Krebs [172].The most used organs to perform the studies are guinea pig ileum, duodenum, heart, trachea, and jejunum. The same organs can be also extracted from rabbit, mouse, rat, and hamster (Table3). The preparation of ileum is preferred because it evaluates the spasmolytic activity. However, although the jejunum contracts spontaneously, it allows evaluating the spasmolytic activity directly and without the use of an agonist [173].Table 3
Natural products with antispasmodic activity isolated from terrestrial plants.
Compound name Species (Family) Preparation (Solvent) Model tested Source Reference Monoterpenoids 1 Myrcene, β-myrcene Plectranthus barbatus (Lamiaceae) Leaf (MeOH) ACh, BaCl2, KCl in guinea pig ileum EO [17] 2 Citral B, β-citral, Neral Aloysia triphylla (Verbenaceae) Leaf (Hexane) Carbachol, KCl, O, PGF (2α) in rat uterus IC [18] Cymbopogon citratus (Poaceae) Leaf (MeOH 70%) ACh, KCl in rabbit ileum IC [19] Melissa officinalis (Lamiaceae) Aerial part (EtOH 70%) ACh, KCl in rat ileum EO [20] 3 Geranyl formate Anthemis mauritiana (Compositae) Flower (Distillation) Ca2+, carbachol, KCl in rabbit and rat jejunum EO [21] 4 Geranyl acetate Nepeta cataria (Lamiaceae) Leaf (Aqueous) Carbachol, KCl in guinea pig trachea and rabbit jejunum EO [22] 5 Geraniol Rosa damascene (Rosaceae) Flower (hydrodistillation) ACh, KCl, electrical field stimulation in rat ileum IC [23] 6 Citronellol Rosa damascene (Rosaceae) Flower (hydrodistillation) ACh, KCl, electrical field stimulation in rat ileum IC [23] 7 (±)-α-Phellandrene Zingiber officinale (Zingiberaceae) Rhizome (MeOH) Serotonin in rat ileum EO [24] 8 (±)-β-Phellandrene Croton sonderianus (Euphorbiaceae) Leaf (Distillation) ACh, KCl in rat tracheal smooth muscle EO [25] 9 Terpinolene Zingiber officinale (Zingiberaceae) Rhizome (MeOH) Serotonin in rat ileum EO [24] 10 D-(+)-Limonene Zingiber roseum (Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] Dracocephalum kotschyi(Lamiaceae) Aerial part (Hydrodistillation) ACh, electrical field stimulation, KCl in rat ileum EO [28] 11  γ-Terpinene Acalypha phleoides (Euphorbiaceae) Aerial part infusion MeOH-CHCl3 (1:1) ACh, BaCl2, H, S in guinea pig ileum and rabbit jejunum IC [29] 12 Thymoquinone Nigella sativa (Ranunculaceae) Seed infusion (Aqueous) BaCl2, carbachol, leukotriene in rat trachea IC [30] 13 (R)-(+)-Pulegone Calamintha glandulosa (Lamiaceae) Aerial parts infusion (Diethyl ether) KCl in rat ileum IC [31] Mentha x villosa (Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 14 (-)-Menthol Mentha piperita(Lamiaceae) Leaf and flower infusion (EtOH) S in rat ileum IC [32]  15 dl-α-Terpineol Casimiroa pringlei(Rutaceae) Aerial part infusion (Ethylic ether) KCl in rat uterine smooth muscle IC [33] Zingiber roseum(Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] Dracocephalum kotschyi(Lamiaceae) Aerial part (Hydrodistillation) ACh, electrical field stimulation, KCl in rat ileum EO [28] 16 (-)-Piperitone Casimiroa pringlei(Rutaceae) Aerial part infusion (Ethylic ether) KCl in rat uterine smooth muscle IC [33] 17 (+)-Rotundifolone Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 18 (R)-(-)-Carvone Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 19 (R,R,R)-Carvone-1,2-oxide) Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 20 (S)-(+)-Carvone Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 21 1,8-Cineole Ocimum gratissimum(Lamiaceae) Leaf infusion (MeOH) ACh, KCl in guinea pig ileum IC [34] Nepeta cataria(Lamiaceae) Leaf infusion (Aqueous) Carbachol, KCl in guinea pig trachea and rabbit jejunum EO [22] Casimiroa pringlei(Rutaceae) Aerial part infusion (Ethylic ether) KCl in rat uterine smooth muscle IC [33] 22  p-Cymene Lippia graveolens (Verbenaceae) Leaf infusion (Distillation) Carbachol, H in guinea pig ileum IC [35] Zingiber roseum(Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] Poliomintha longiflora (Lamiaceae) Leaves stem infusion (Distillation) Carbachol, H in guinea pig ileum IC [35] 23 Carvacrol Origanum acutidens (Lamiaceae) Leaf, stem and flower infusion (MeOH) Spontaneous contraction in rat ileum EO [36] Thymus vulgaris (Lamiaceae) Whole plants (Ethanol) ACh, BaCl2, KCl in rat trachea and ileum IC [37] 24 Thymol Acalypha phleoides (Euphorbiaceae) Aerial part infusion [MeOH-CHCl3 (1:1)] ACh, BaCl2, H, KCl, S in guinea pig ileum and rabbit jejunum IC [29] Thymus vulgaris (Lamiaceae) Whole plants (Ethanol) ACh, BaCl2, KCl in rat trachea and ileum IC [37] 25 Thujane or Sabinane Anthemis mauritiana (Asteraceae) Flower infusion (Aqueous) Carbachol, KCl in rabbit jejunal smooth muscle EO [21]  26 (±)-Camphor Acalypha phleoides (Euphorbiaceae) Aerial part infusion [MeOH-CHCl3 (1:1)] ACh, BaCl2, H, KCl, S in guinea pig ileum and rabbit jejunum IC [29] Lippia dulcis(Verbenaceae) Leaf infusion (Steam distillation) Carbachol, H in porcine bronchi EO [38] 27 (+)-α-Pinene Anthemis mauritiana (Asteraceae) Flower infusion (Aqueous) Carbachol, KCl in rabbit jejunal smooth muscle EO [21] Nepeta cataria (Lamiaceae) Leaf infusion (Aqueous) Carbachol, KCl in guinea pig trachea and rabbit jejunum EO [22] Plectranthus barbatus (Lamiaceae) Leaf infusion (MeOH) ACh, BaCl2, H, KCl in guinea pig ileum EO [17] 28 (-)-α-Pinene Dissotis rotundifolia (Melastomataceae) Leaf infusion (EtOH) Carbachol in mouse intestinal motility E [39] Eucalyptus tereticornis (Myrtaceae) Commercial ACh, KCl in rat trachea EO [40] Zingiber roseum(Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] 29 (+)-β-Pinene Ferula gummosa (Apiaceae) Resin infusion (Hydroalcoholic, ether, MeOH) ACh, KCl in rat ileum IC [41] Zingiber officinale (Zingiberaceae) Rhizome infusion (MeOH) S in rat ileum EO [24] Zingiber roseum (Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] 30 Cantleyine Strychnos trinervis (Loganiaceae) Root bark (EtOAc) Carbachol, H, KCl in guinea pig trachea IC [42] 31 Penstemonoside Parentucellia latifolia (Scrophulariaceae) Whole plant infusion (Butanol) ACh, CaCl2, KCl in rat uterus IC [43] 32 Aucubine or aucuboside Parentucellia latifolia (Scrophulariaceae) Whole plant infusion (Butanol) ACh, CaCl2, KCl in rat uterus IC [43] 33 2′-O-Acetyldihydropenstemide Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 34 2′-O-trans-p-Coumaroyl-dihydropenstemide Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 35 2′-O-Acetylpatrinoside Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 36 Patrinoside Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 37 Valtriate or Valepotriate Valeriana procera(Valerianeaceae) Root infusion (EtOH) BaCl2, carbachol, KCl in guinea pig ileum and stomach IC [45]  38 Isovaltrate or Isovaltratum Valeriana procera(Valerianeaceae) Root infusion (EtOH) BaCl2, carbachol, KCl in guinea pig ileum and stomach IC [45] 39 Epoxygaertneroside Morinda morindoides(Rubiaceae) Leaf infusion (Aqueous) ACh, KCl in guinea pig ileum IC [46] 40 Gaertneroside Morinda morindoides(Rubiaceae) Leaf infusion (Aqueous) ACh, KCl in guinea pig ileum IC [46] 41 Catalpinoside or Catapol Parentucellia latifolia (Scrophulariaceae) Whole plant infusion (Butanol) ACh, CaCl2, KCl in rat uterus IC [43]  Sesquiterpenes 43 (±)-Hernandulcin Lippia dulcis(Verbenaceae) Leaf infusion (Steam distillation) Carbachol, H in porcine bronchi EO [38] 43 Humulene or α-Caryophyllene Nepeta cataria (Lamiaceae) Leaf infusion (Aqueous) Carbachol, KCl, in guinea pig trachea and rabbit jejunum EO [22] 44 β-Caryophyllene epoxide Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] 45 β-Caryophyllene Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] Plectranthus barbatus(Lamiaceae) Leaf infusion (MeOH) ACh, BaCl2, H, KCl in guinea pig ileum EO [17] Pterodon polygalaeflorus (Fabaceae) Seed (Steam distillation) ACh, KCl in rat ileum smooth muscle IC [48] 46 Bicyclogermacrene or Lepidozene Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] 47 (+)-Capsidiol Nicotiana silvestri(Solanaceae) Leaf infusion (EtOAc) ACh, BaCl2, bradykinin, carbachol in guinea pig ileum and trachea IC [49] 48 S-Petasin Petasites formosanus (Compositae) Aerial parts (EtOH) CaCl2, carbachol, H, KCl in guinea pig trachea IC [50] 49 (+)-Isopetasin Petasites formosanus (Compositae) Aerial parts (EtOH) CaCl2, carbachol, H, KCl in guinea pig trachea IC [50] 50 Valeranone o Jatamansone Valeriana procera(Valerianeaceae) Root infusion (EtOH) BaCl2, carbachol, KCl in guinea pig ileum and stomach IC [45] 51 Chamazulene Matricaria recutita(Asteraceae) Plant infusion (Aqueous) Human platelet E [51] 52 Spathulenol Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52]  53 Cynaropicrin Cynara scolymus(Asteraceae) Leaf and flower infusion (MeOH 70%) ACh in guinea pig ileum IC [53] 54 Cedrenol Anthemis mauritiana(Asteraceae) Flower infusion (Aqueous) Carbachol, KCl in rabbit jejunal smooth muscle EO [21] 55 (+)-Bakkenolide A Hertia cheirifolia (Asteraceae) Aerial parts (MeOH) ACh, BaCl2 in rat duodenum IC [54] 56 Himachalol Cedrus deodara (Pinaceae) Wood infusion ACh, BaCl2, H, nicotine, S in guinea pig ileum and seminal vesicle, rabbit jejunum and rat uterus IC [55] 57 (E)-Damascenone Ipomoea pes-caprae (Convolvulaceae) Leaf infusion (Aqueous) H in guinea pig ileal smooth muscle IC [56] 58 (-)-Isogermacrene D Artemisia vulgaris (Compositae) Stem and leaf infusion (Aqueous) guinea pig ileum  [57] 59 Ezoalantonin Artemisia vulgaris(Compositae) Leaf (CHCl3) H, PMA, S in guinea pig ileum and trachea IC [57] 60Costunolide Radix aucklandiae(Asteraceae) Rhizome (MeOH) ACh, KCl, S in rat jejunum IC [58] 61Dehydrocostuslactone Radix aucklandiae(Asteraceae) Rhizome (MeOH) ACh, KCl, S in rat jejunum IC [58]  Diterpenes 62E-Phytol Ipomoea pes-caprae (Convolvulaceae) Leaf infusion (Aqueous) H in guinea pig ileal smooth muscle IC [56] 633α-Angeloyloxy-2α-hydroxy-13,14Z-dehydrocativic acid Brickellia paniculata (Compositae) Leaf infusion (MeOH) KCl in rat myometrial tissue IC [59] 6415-Epicyllenin A Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 65Cyllenin A Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 66Marrulibacetal Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 67(13R)-9α,13α-epoxylabda-6β(19),16(15)-diol dilactone Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 68Marrubin Marrubium vulgare(Lamiaceae) Aerial parts (Aqueous) KCl in rat aorta IC [61] 69Marrubenol or Marrubiol Marrubium vulgare(Lamiaceae) Aerial parts (Aqueous) KCl in rat aorta IC [61]  70Marrulanic acid Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 71Marrulactone Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 72(+)-Dehydroabietic acid Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52] 739β-Hydroxydehydroabietyl alcohol Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52] 749α,13α-Epidioxyabiet-8(14)-en-18-oic acid methyl ester Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52] 754-epi-Hyalic acid Croton argyrophylloides(Euphorbiaceae) Bark infusion (MeOH) ACh, KCl in rat tracheal smooth muscle IC [62] 76Pimaradienoic acid or Continentalic acid Viguiera arenaria (Asteraceae) Root infusion (CH2Cl2) ACh, KCl in rat carotid artery IC [63] 778(14),15-Sandaracopimaradiene-7α,18-diol Tetradenia riparia (Lamiaceae) Leaf infusion (CHCl3) BaCl2, H, methacholine in guinea pig ileum IC [64] 783,4-Secoisopimara-4(18),7,15-triene-3-oic acid Salvia cinnabarina(Lamiaceae) Aerial parts (EtOH) ACh, BaCl2, H in guinea pig ileum IC [65] 79ent-Kaurenoic acid Viguiera arenaria (Asteraceae) Root infusion (CH2Cl2) ACh, KCl in rat carotid artery IC [63] Viguiera hypargyrea (Asteraceae) Root infusion (Hexane) Spontaneous contraction in guinea pig ileum IC [66] 80Beyerenic acid or Monogynoic acid Viguiera hypargyrea (Asteraceae) Root infusion (Hexane) Spontaneous contraction in guinea pig ileum IC [66] 81ent-7α-Acetoxytrachyloban-18-oic acid Xylopia langsdorfiana(Annonaceae) Stem infusion (EtOH 95%) BaCl2, H, KCl in guinea pig ileum IC [67] 82ent-7α -hydroxytrachyloban-18-oic acid Xylopia langsdorfiana(Annonaceae) Stem infusion (EtOH 95%) BaCl2, H, KCl in guinea pig ileum IC [67] 83Phorbol 12-acetate-13-tiglate Crotonis tiglium (Euphorbiaceae) Fruit (MeOH) Spontaneous contraction in rabbit jejunum E [68] 843,7,10,14,15-pentaacetyl-5-butanoyl-13,17-epoxy-8-myrsinene Pycnocycla spinosa (Umbelliferae) Aerial parts (MeOH) KCl in rat illeum IC [69]  Triterpenoids 85Agapanthagenin 3-O-β-D-glucopyranoside Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 86Agapanthagenin Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 87 β-sitosterol Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [71]  88β-sitosterol 3-O-β-D-glucopyranoside Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [71] 89α-Spinasteryl β-D-glucoside Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 90Tropeoside B1 and B2 Allium cepa(Alliaceae) Bulbs [CHCl3:MeOH (9:1)] ACh, H in guinea pig ileum IC [72] 91Tropeoside A1 and A2 Allium cepa(Alliaceae) Bulbs [CHCl3:MeOH (9:1)] ACh, H in guinea pig ileum IC [72] 92Elburzensoside A1 and A2 Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 93Elburzensoside C1 and C2 Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 94Galphimin A Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 95Galphimin B Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 96Galphimin C Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 97Galphimin E Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 98Galphimin F Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 99Handianol Herissanthia tiubae (Malvaceae) Leaf infusion (EtOH) Carbachol, H, KCl in guinea pig ileum and trachea, and rat aorta IC [74] 100Cycloartanol Herissanthia tiubae (Malvaceae) Leaf infusion (EtOH) Carbachol, H, KCl in guinea-pig ileum, trachea and rat aorta IC [74] 101Taraxasteryl acetate Brickellia veronicifolia (Asteraceae) Aerial parts [CH2Cl2:MeOH (1:1)] Gastrointestinal motility test in mouse E [75] 102Pomolic acid or Benthamic acid or Randialic acid A Licania pittieri (Rosaceae) Leaf infusion (EtOH) Carbachol, KCl in rat aorta IC [76] 103Ursolic acid Agastache mexicana(Lamiaceae) Aerial part (MeOH) ACh, KCl in guinea pig ileum IC [77] 104Ehretiolide Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 105Ehretiolide acetate Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 106Camaldulin Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [71] 107Zygophyloside N Zygophyllum gaetulum(Zygophyllaceae) Root infusion (MeOH) Electrically-induced contractions of isolated guinea pig ileum E [79]  108Erythrodiol Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 1093-β-tridecanoyloxy-28-hydroxyolean-12-ene Conyza filaginoides(Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 1103-β-Hydroxyolean-9(11),12-dien-28-oic acid Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 1114-epi-Hederagenin Hedera helix(Araliaceae) Leaf infusion (EtOH) ACh in guinea pig ileum IC [80] 112Hederacoside C Hedera helix(Araliaceae) Leaf infusion (EtOH) ACh in guinea pig ileum IC [80] 113Betulinic acid Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 114α-Amyrin acetate Tylophora hirsuta (Asclepiadaceae) Aerial parts (MeOH) KCl in rabbit jejunum IC [81]  Phloroglucinol derivatives 115Hyperforin Hypericum perforatum (Hypericaceae) Aerial parts (EtOH 70%) KCl in rabbit jejunum IC [82] 116Hypericin Hypericum perforatum (Hypericaceae) Aerial parts (EtOH 70%) KCl in rabbit jejunum IC [82]  Coumarins 117Scopoletin Brunfelsia hopeana (Solanaceae) Root infusion (EtOH) Phenylephrine, KCl, PGF2, serotonin in rat aorta IC [83] 118Todannone Toddalia asiaticavar. floribunda (Rutaceae) Aerial parts (EtOH 95%) ACh, BaCl2, H, nicotine in guinea pig ileum IC [84] 119(2S∗,3R∗)-2-[(3E)-4,8-dimethylnona-3,7-dien-1-yl]-2,3-dihydro-7-hydroxy-2,3-dimethylfuro[3,2c] coumarin Ferula heuffelii (Apiaceae) Underground part (CHCl3) ACh, KCl in rat ileum IC [85] 120Osthole Prangos ferulacea (Apiaceae) Root (Acetone) ACh, KCl, electric field stimulation in rat ileum IC [86] 121Angelicin Heracleum thomsoni (Apiaceae) Aerial part infusion (EtOH) ACh, BaCl2, H, S in cat ureter, guinea pig bile duct and trachea, monkey gall bladder, rabbit jejunum, and rat uterus IC [87] 122Glycycoumarin Glycyrrhizae radix (Leguminosae) Root infusion (Aqueous) A23187, BaCl2, carbachol, KCl in mouse jejunum IC [88] Glycyrrhiza ularensis(Leguminosae) Root infusion (Aqueous) Carbachol in mouse jejunum E [89]   Chalcones 123Davidigenin Mascarenhasia arborescens (Apocynaceae) Leaf and stem infusion (MeOH) ACh, H in guinea pig and rat duodenum IC [90] 124Isoliquiritigenin Glycyrrhiza glabra(Leguminosae) Root infusion (Aqueous) ACh, KCl, O, spontaneous contraction in rat uterus IC [91] Glycyrrhiza ularensis(Leguminosae) Root infusion (Aqueous) (Aqueous) BaCl2, carbachol, KCl in mouse jejunum,ileum and rectum IC [92] 125Licochalcone A Glycyrrhiza inflata (Leguminosae) Root infusion (Aqueous) A23187, BaCl2, carbachol, KCl in mouse jejunum IC [93]  Flavonoids 126(-)-Pinostrobin Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 127(-)-(S)-Sakuranetin Dodonaea viscosa (Sapindaceae) Leaf infusion [CHCl3:MeOH (1:1)] ACh, BaCl2, H in rat uterus IC [94] 128(±)-Sternbin Artemisia monosperma (Compositae) Aerial part (EtOH) ACh, O in rat ileum, pulmonary artery, urinary bladder, trachea, and uterus IC [95] 129Ouratea catechin Maytenus rigida (Celastraceae) Stem bark (EtOH) BaCl2, carbachol, KCl, H in guinea pig ileum IC [96] 130Apegenin Achillea millefolium (Asteraceae) Whole plant infusion (MeOH 40%) ACh, CaCl2, H, PE, S in rat ileum IC [97] 131Buddleoflavonol or Linarigenin Agastache mexicana(Lamiaceae) Aerial part (MeOH) ACh, KCl in guinea pig ileum IC [77] 132Luteolin Achillea millefolium (Asteraceae) Whole plant infusion (MeOH 40%) ACh, CaCl2, H, PE, S in rat ileum IC [97] Artemisia copa (Compositae) Aerial parts (Aqueous) KCl, PE, S in rat aorta E [98] Plantago lanceolata (Plantaginaceae) Aerial part (EtOH) ACh, BaCl2, H, KCl in guinea pig ileum and trachea IC [99] Thymus vulgaris(Lamiaceae) Leaf and flower (EtOH) ACh, BaCl2, carbachol, H in guinea pig ileum and trachea, and rat vas deferens IC [100] 133Scutellarein 6-β-D-glucoside (isovitexin) Aloysia citridora (Verbenaceae) Leaf infusion (Aqueous) ACh, CaCl2, KCl in rat duodenum IC [101]  134Vitexin Aloysia citridora (Verbenaceae) Leaf infusion (Aqueous) ACh, CaCl2, KCl in rat duodenum IC [101] Aspalathus linearis(Fabaceae) Commercial (Aqueous) KCl in rabbit jejunum IC [102] 135Xanthomycrol Brickellia paniculata (Compositae) Leaf infusion (MeOH) KCl, O in rat uterus IC [59] 136Demethoxycentaureidin Piptadenia stipulacea (Leguminosae) Aerial parts, (CHCl3) Carbachol, H, O, in guinea pig ileum and trachea, rat aorta and uterus IC [103] 137Gnaphaliin B Gnaphalium liebmannii (Asteraceae) Aerial parts (Hexane) ACh, carbachol in guinea pig trachea IC [104] 138Kaempferol or Kaempherol Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 139Gnaphaliin A Gnaphalium liebmannii (Asteraceae) Aerial parts (Hexane) ACh, carbachol in guinea pig trachea IC [104] 140Quercetin Achillea millefolium (Asteraceae) Whole plant infusion (MeOH 40%) ACh, CaCl2, H, PE, serotonin in rat ileum IC [97] Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] Drosera madascariensis (Droseraceae) Leaf extract (EtOH 70%) Carbachol, H, PGF2 in guinea pig ileum and trachea IC [106] Drosera rotundifolia(Droseraceae) Aerial parts (EtOH 70%) Carbachol in guine pig ileum IC [107] Morinda morindoides(Rubiaceae) Leaf extract (Aqueous) Ac, KCl in guinea pig ileum IC [46] 1413-O-Methylquercetin Rhamnus nakaharai (Rhamnaceae) Stem bark (not reported) Carbachol, H, KCl in guinea pig trachea IC [108] 1423,4′-Dimethylquercetin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 1433,7-Dimethylquercetin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 144Isoquercetin Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] Drosera rotundifolia(Droseraceae) Aerial parts (EtOH 70%) Carbachol in guinea pig ileum IC [107] Drosera madascariensis(Droseraceae) Leaf extract (EtOH 70%) Carbachol, H, PGF2 in guinea pig ileum and trachea IC [106] Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105]  145Quercetin 3-α-rhamnoside or Quercitroside Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] Morinda morindoides(Rubiaceae) Leaf extract (Aqueous) ACh, KCl in guinea pig ileum IC [46] 146Quercetin 3-O-β-L-arabinoside Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] 147Quercetin 3-O-β-D-galactoside Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] Drosera madascariensis(Droseraceae) Leaf extract (EtOH 70%) Carbachol, H, PGF2 in guinea pig ileum and trachea IC [106] 148Quercetin 3-O-β-gentiobioside 3-O-β-D- Morinda morindoides(Rubiaceae) Leaf extract (Aqueous) ACh, KCl in guinea pig ileum IC [46] Glucopyranosylquercetin Drosera rotundifolia(Droseraceae) Aerial parts (EtOH 70%) Carbachol in guinea pig ileum EO [107] 149Centaureidin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 150Casticin or Vitexicarpin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 151Prunetol or Sophoricol Genista tridentata (Papilionaceae) Not reported AC, electric field stimulation, 6-oxo PGE1 in guinea pig ileum IC [110] 152Boeravinone E Boerhaavia diffusa (Nyctaginaceae) Root infusion (MeOH) ACh in guinea pig ileum IC [111] 1534,6,11-trihydroxy-9-methoxy-10-methyl-6,12-dihydro-5,7-dioxatetraphen-12-one Boerhaavia diffusa (Nyctaginaceae) Root infusion (MeOH) ACh in guinea pig ileum IC [111] 154Boeravinone G Boerhaavia diffusa (Nyctaginaceae) Root infusion (MeOH) ACh in guinea pig ileum IC [111] 155(2R,3S,2”R,3”R)-Manniflavonone Garcinia buchananii (Clusiaceae) Stem bark (EtOH 70%) Bay K 8644 in mouse ileum IC [112] 156Hyperoside Hypericum perforatum (Hypericaceae) Aerial parts (EtOH 70%) KCl in rabbit jejunum IC [82] 157Chrysoeriol Artemisia copa(Compositae) Aerial parts (Aqueous) KCl, PE, S in rat aorta E [98] Aspalathus linearis(Fabaceae) Commercial (Aqueous) KCl in rabbit jejunum IC [102] 158Spinacetin Artemisia copa(Compositae) Aerial parts (Aqueous) KCl, PE, S in rat aorta E [98] 159Vicenin 2 Perilla frutescens(Lamiaceae) Commercial (Aqueous) ACh, BaCl2 i rat ileum IC [113] 160Orientin Aspalathus linearis(Fabaceae) Commercial (Aqueous) KCl in rabbit jejunum IC [102]   Phenylmetanoids 161Salicylic acid methyl ether Brickellia veronicifolia (Asteraceae) Aerial parts [CH2Cl2:MeOH (1:1)] Gastrointestinal motility test in mouse E [75] 162 O-Anisic acid or 6-Methoxysalicylic acid Brickellia veronicifolia (Asteraceae) Aerial parts [CH2Cl2:MeOH (1:1)] Gastrointestinal motility test in mouse E [75] 163Protocatechuic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 164Benzyl 2,5-dimethoxybenzoate Brickellia veronicifolia(Asteraceae) Aerial parts [CH2Cl2-MeOH (1:1)] Gastrointestinal motility test in mouse E [75]  Phenylethanoids 165O-Methylbalsamide Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 166(-)-Tembamide Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 167O-Methyltembamide Zanthoxylum hyemale (Rutaceae) Steam bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114]  Phenylpropanoids 168Eugenol Ocimum gratissimum(Lamiaceae) Not reported ACh, KCl in guinea pig ileum EO [34] 169Rosemaric acid or Rosemary acid or trans-Rosmarinic acid Thymus vulgaris (Lamiaceae) Commercial KCl in rat trachea IC [100] 170 trans-Chlorogenic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 171 cis-Chlorogenic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 1723,5-Dicaffeoylquininic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 173Verbascoside Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 174Isoacteoside or Isoverbascoside Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 175Plantamajoside or Plantamoside or Purpureaside A Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 176Lavandulifolioside Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 177Echinacoside Cistanche tubulosa(Orobanchaceae) No reported (EtOH) KCl, PE in rat aorta IC [115] 178Schisandrin A or Wuweizisu A Schisandra chinensis(Schisandraceae) Academic Spontaneous contractions in rat colon IC [116]  179Schisandrin B or Wuweizisu B Schisandra chinensis(Schisandraceae) Fruit decoction (Aqueous) ACh, KCl, S in guinea pig ileum IC [117] 180Schisandrol B Schisandra chinensis(Schisandraceae) Fruit decoction (Aqueous) ACh, KCl, S in guinea pig ileum IC [117]  Stilbenoids 181Aloifol II or Dendrophenol or Moscatilin Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH 1:1)] Spontaneous contraction in guinea pig ileum IC [118] 182Batatasin III Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH 1:1)] Spontaneous contraction in guinea pig ileum IC [118] Scaphyglottis livida (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 1834-[2-(3-hydroxy-5-methoxyphenyl)ethyl]-2-methoxyphenol Scaphyglottis livida (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 184Gigantol Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] Spontaneous contraction in guinea pig ileum IC [118] 185Coelonin Scaphyglottis livida (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 186 Erianthridin Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 187 Ephemeranthoquinone Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] Spontaneous contraction in guinea pig ileum IC [118] 188 Nudol Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 189 3,4- dimethoxyphenanthrene-2,5-diol Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 190 Denthyrsinin Scaphyglottis livida(Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 191 Gymnopusin Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 192 Fimbriol A Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120]  Curcuminoid 193 (1E,5S,6E)-5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadien-3-one Curcuma longa(Zingiberaceae) Macerated rhizome (EtOH 70%) ACh, BaCl2, CaCl2, H, KCl, O in guinea pig Ileum and rat uterus IC [121]  Benzofurans and Related 194 (+)-Vitisin C Vitis spp. (Vitaceae) Stem infusion (MeOH) PE in rabbit aorta IC [122] 195 Butylphthalide Ligusticum wallichii (Umbelliferae) Rhizome (hydrodistillation) CaCl2, KCl in rat aorta EO [123] 196 cis-Butylidenephthalide Ligusticum wallichii (Umbelliferae) Rhizome (hydrodistillation) CaCl2, KCl in rat aorta EO [123]  197 Ligustilide A or cis-Ligustilide Ligusticum wallichii (Umbelliferae) Rhizome (hydrodistillation) CaCl2, KCl in rat aorta EO [123] 198 12-acetoxytremetone Helichrysum italicumssp.italicum(Asteraceae) Flowers (EtOH) ACh, BaCl2 in mouse ileum IC [124] 199 1-[(2R)-2-(3-hydroxyprop-1-en-2-yl)-2,3-dihydro-1-benzofuran-5-yl]ethan-1-one Helichrysum italicumssp.italicum(Asteraceae) Flowers (EtOH) ACh, BaCl2 in mouse ileum IC [124]  Alkaloids 200 Indicaxanthin Opuntia ficus indica (Cactaceae) Fruit pulp infusion (Aqueous) Carbachol, KCl in mouse ileum IC [125] 201 Papaverine Daucus carota(Apiaceae) Seed infusion (MeOH 90%) ACh, BaCl2, H, KCl, S, O in dog trachea, guinea pig, rabbit, rat ilea, rat uterus IC [126] 202 Higenamine Nandina domestica (Berberidaceae) Fruit (Aqueous) ACh, H, KCl in guinea pig trachea IC [127] 203 Atherosperminine Fissistigma glaucescens(Annonaceae) Bark (MeOH) Carbachol, KCl, LTC4, PGF2α, U46619 in guinea pig trachea IC [128] 204 (+)-Domestine or (+)-Nantenine Platycapnos spicata (Fumariaceae) Academic supplier BaCl2, CaCl2, KCl, PE, S in rat aorta and atria IC [129] 205 10-Methylacridone Citrus deliciosa(Rutaceae) Root juice (MeOH) Rabbit ileum IC [130] 206 Spermatheridine or liriodenin Fissistigma glaucescens (Annonaceae) Leaf infusion (MeOH) Carbachol in canine trachea IC [131] 207 Citpressine I Citrus deliciosa(Rutaceae) Root juice (MeOH) Rabbit ileum IC [130] 208 Jatrorhizine or Neprotine Berberis aristata (Berberidaceae) Institutional supplier ACh, S, spontaneous contractions in rat ileum IC [132] Coptis chinensis(Ranunculaceae) Rhizoma (EtOH 70%) ACh in guinea pig ileum IC [133] 209 Coptisine Coptis chinensis(Ranunculaceae) Rhizoma (EtOH 70%) ACh in guinea pig ileum IC [133] 210 Escholine or Thalictrine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 211 (+)-Isothebaine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 212 (+)-Corytuberine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 213 (+)-Isocorydine or Luteanine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 214 (+)-Chelidonine or Stylophorine Chelidonium majus (Papaveraceae) Commercial supplier BaCl2, carbachol in guinea pig ileum IC [135]  215 (-)-8 beta-(4′-hydroxybenzyl)-2,3-dimethoxyberbin-10-ol Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 216 3-O-methylconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 217 3,5-di-O-methylconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 2185,6-dihydro-3,5-di-O-methylconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 219 5,6-dihydroconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 220 Constrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 221 Isojuripidine Solanum asterophorum (Solanaceae) Leaf infusion (MeOH) ACh, CaCl2, H in guinea pig ileum IC [137] 222 Sarcodine Sarcocca saligna (Buxaceae) Whole plant (MeOH) ACh, KCl in guinea pig ileum, rat stomach fundus, rabbit jejunum IC [138] 223 Saracorine or Sarcorine Sarcococca saligna (Buxaceae) Whole plant infusion (MeOH) ACh, KCl in rabbit jejunum IC [139] 224 Saracocine Sarcocca saligna (Buxaceae) Whole plant (MeOH) ACh, KCl in guinea pig ileum, rat stomach fundus, rabbit jejunum IC [138] 225 Alkaloid C Sarcocca saligna(Buxaceae) Whole plant (MeOH) ACh, KCl in guinea pig ileum, rat stomach fundus, rabbit jejunum IC [138] 226 (-)-Pachyaximine A Sarcococca saligna (Buxaceae) Whole plant infusion (MeOH) ACh, KCl in rabbit jejunum, KCl IC [139] 227 (-)-(R)-Geibalansine or (-)-R-Geilbalansine Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 228 Hyemaline Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 229 Theophylline Fissistigma glaucescens (Annonaceae) Leaf infusion (MeOH) Carbachol in canine trachea IC [131] 230Carboxyscotangamine A Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 231Scotanamine A Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 232Piperine Piper nigrum (Piperaceae) Fruit (EtOH) Ileum loop in mice IC [141]  Amines 233Scotanamine B Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [123]  234Scotanamine C Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 235Scotanamine D Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 236N1-Caffeoyl-N3-dihydrocaffeoylspermidine Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 237N1, N10-Bis(dihydrocaffeoyl)spermidine Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 238Caffeoylputrescine Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140]  Isothiocyanates 239 Redskin or Senfoel Cruciferous vegetables (Brassicaceae) Commercial source ACh, electrical contraction in mouse ileum IC [142]  Alcohols 240 (3E)-4-(3,4-dimethoxyphenyl)but-3-en-1-ol Zingiber cassumunar (Zingiberaceae) Chemically synthesized O in rat uterus IC [143]  Ketones 241 2-Decanone Ruta chalepensis(Rutaceae) Leaf (EtOH 70%) KCl in rat ileum E [144] 242 2-Undecanone Ruta chalepensis(Rutaceae) Leaf (EtOH 70%) KCl in rat ileum E [144] 243 2-Tridecanone Ruta chalepensis(Rutaceae) Leaf (EtOH 70%) KCl in rat ileum E [144] 244 Latifolone Ferula heuffelii (Apiaceae) Underground part (CHCl3) ACh, KCl in rat ileum IC [85] 245Dshamirone Ferula heuffelii (Apiaceae) Underground part (CHCl3) ACh, KCl in rat ileum IC [85]  Phenolic compounds 246 6-(4-hydroxy-3-methoxyphenyl)-hexanonic acid (HMPHA) Pycnocycla spinosa(Umbelliferae) Aerial parts (MeOH) KCl in rat ileum IC [145] 247 Isovanillin Pycnocycla spinosa(Umbelliferae) Aerial parts (MeOH) KCl in rat ileum IC [146] 248 Iso-acetovanillon Pycnocycla spinosa(Umbelliferae) Aerial parts (MeOH) KCl in rat ileum IC [146] IC = isolated compound, E = extract, EO = essential oil, ACh = acetylcholine, O = oxytocin, PMA =β-Phenylethyl amsine, PGF = Prostaglandin F2α, H = histamine, S = serotonin.Some advantages of performingex vivo experiments are as follows: (i) different substances can be evaluated in fresh tissues without absorption factors, metabolic excretion or interference due to nerve reflexes; (ii) it is possible to quantify the effect produced by a precisely determined drug; and (iii) it is easier to obtain dose-effect curves, such as the smooth muscle where the contraction obtained under the influence of a spasm or in tissue homogenates is measured by determination of the enzyme activities [172, 174].


### 5.2. Guinea Pig Ileum and Rat Stomach

The ileum is removed and cut in strips of approximately 2 cm long and then placed in a bath filled with an isotonic solution as mentioned earlier. Electrophysiological studies are performed by graphically recording the contractions with the aid of a transducer, which is calibrated 30 min before the treatment begins. A range of 0.01 to 0.03μM is generally used to determine dose response curves of the antispasmodic substance [175].In rats, the stomach is removed and the corpus and fundus are cut in strips of approximately 5 mm x 15 mm and placed on a prewarmed warm solution as mentioned before.


### 5.3. Compounds Used to Elicit a Spasmodic Activity

The main compounds used are acetylcholine, atropine, BaCl2, carbachol, histamine, KCl, and serotonin.Acetylcholine is a postganglionic neurotransmitter in the parasympathetic neurons that innervate the intestine. The response to acetylcholine is regulated by activation of the two types of muscarinic receptors: M2 and M3 [176]. The activation of these receptors causes contractions by increasing the intracellular concentration of Ca2+ via IP3 [176]. Atropine is a competitive reversible antagonist of muscarinic acetylcholine receptors M1, M2, M3, M4, and M5.Different substances are used to produce contractions. For example, BaCl2 induces contractions by mobilizing membrane-bound Ca2+ [177], carbachol is a cholinomimetic drug (cholinergic agonist) that binds and activates acetylcholine receptors [178], histamine acts by either accelerating the release of acetylcholine or interacting supra-additively with the acetylcholine at the smooth muscle [179], whereas KCl increases the voltage-operated Ca2+ channel activity by increasing intracellular free Ca2+ in smooth muscle [180]. Serotonin is also an important neurotransmitter mainly stored in the digestive tract, affecting the secretory and motor activities. At high concentrations, it acts as a vasoconstrictor by contracting endothelial smooth muscle directly or by potentiating the effects of other vasoconstrictors [181, 182].


## 5.1. Gastrointestinal Model

The small intestine is characterized by its large surface area as a result of its circular folds, villi, and microvilli. It is the longest part of the GI system (approximately 5 meters) and comprises about 5% of its initial length, which corresponds to the duodenum (characterized by the absence of the mesentery) and then the jejunum (around 40% of the intestinal length), ending with the ileum. It is the organ of absorption of nutrients and digestion in organisms. These functions are carried out mainly in the duodenum and jejunum.The main types of bowel movement are the segmentation and peristaltism. The segmentation is most frequent in the small intestine and consists of contractions of the circular muscle layer in very close areas. Contractions last for 11-12 and 8-9 contractions per min in the duodenum and ileum, respectively. When this segmentation is rhythmic, the contractions are alternated with relaxation. This type of movement results in a mixed effect of the chyme (acidic fluid that passes from the stomach to the small intestine) with the digestive secretions, allowing an optimal contact with the intestinal mucosa. In the case of peristalsis, contractions of successive sections of the circular smooth muscle cause the movement of the intestinal contents in anterograde form. The short peristaltic movement also takes place in the small intestine, but less frequently than the segmentation movements. Peristaltic waves rarely cross more than 10 cm of intestine and, due to the low frequency of propulsion of the chyme, it is in this zone where digestion and absorption are preferably carried out. Peristalsis is regulated mainly by the nervous action of the myenteric plexus (major nerve supply to the gastrointestinal tract that controls GI tract motility) in the intestinal wall.The diversity of experimental models used for the testing of antispasmodic compounds is large. These models mainly use isolated organs or live animals. Once the organ is extracted from the animal, the intestinal motility is assessed with the administration of a substance. The use of extracted organs can be sustained for hours when placed in a physiological solution, such as Ringer, Jalon, Tyrode, and Krebs [172].The most used organs to perform the studies are guinea pig ileum, duodenum, heart, trachea, and jejunum. The same organs can be also extracted from rabbit, mouse, rat, and hamster (Table3). The preparation of ileum is preferred because it evaluates the spasmolytic activity. However, although the jejunum contracts spontaneously, it allows evaluating the spasmolytic activity directly and without the use of an agonist [173].Table 3
Natural products with antispasmodic activity isolated from terrestrial plants.
Compound name Species (Family) Preparation (Solvent) Model tested Source Reference Monoterpenoids 1 Myrcene, β-myrcene Plectranthus barbatus (Lamiaceae) Leaf (MeOH) ACh, BaCl2, KCl in guinea pig ileum EO [17] 2 Citral B, β-citral, Neral Aloysia triphylla (Verbenaceae) Leaf (Hexane) Carbachol, KCl, O, PGF (2α) in rat uterus IC [18] Cymbopogon citratus (Poaceae) Leaf (MeOH 70%) ACh, KCl in rabbit ileum IC [19] Melissa officinalis (Lamiaceae) Aerial part (EtOH 70%) ACh, KCl in rat ileum EO [20] 3 Geranyl formate Anthemis mauritiana (Compositae) Flower (Distillation) Ca2+, carbachol, KCl in rabbit and rat jejunum EO [21] 4 Geranyl acetate Nepeta cataria (Lamiaceae) Leaf (Aqueous) Carbachol, KCl in guinea pig trachea and rabbit jejunum EO [22] 5 Geraniol Rosa damascene (Rosaceae) Flower (hydrodistillation) ACh, KCl, electrical field stimulation in rat ileum IC [23] 6 Citronellol Rosa damascene (Rosaceae) Flower (hydrodistillation) ACh, KCl, electrical field stimulation in rat ileum IC [23] 7 (±)-α-Phellandrene Zingiber officinale (Zingiberaceae) Rhizome (MeOH) Serotonin in rat ileum EO [24] 8 (±)-β-Phellandrene Croton sonderianus (Euphorbiaceae) Leaf (Distillation) ACh, KCl in rat tracheal smooth muscle EO [25] 9 Terpinolene Zingiber officinale (Zingiberaceae) Rhizome (MeOH) Serotonin in rat ileum EO [24] 10 D-(+)-Limonene Zingiber roseum (Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] Dracocephalum kotschyi(Lamiaceae) Aerial part (Hydrodistillation) ACh, electrical field stimulation, KCl in rat ileum EO [28] 11  γ-Terpinene Acalypha phleoides (Euphorbiaceae) Aerial part infusion MeOH-CHCl3 (1:1) ACh, BaCl2, H, S in guinea pig ileum and rabbit jejunum IC [29] 12 Thymoquinone Nigella sativa (Ranunculaceae) Seed infusion (Aqueous) BaCl2, carbachol, leukotriene in rat trachea IC [30] 13 (R)-(+)-Pulegone Calamintha glandulosa (Lamiaceae) Aerial parts infusion (Diethyl ether) KCl in rat ileum IC [31] Mentha x villosa (Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 14 (-)-Menthol Mentha piperita(Lamiaceae) Leaf and flower infusion (EtOH) S in rat ileum IC [32]  15 dl-α-Terpineol Casimiroa pringlei(Rutaceae) Aerial part infusion (Ethylic ether) KCl in rat uterine smooth muscle IC [33] Zingiber roseum(Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] Dracocephalum kotschyi(Lamiaceae) Aerial part (Hydrodistillation) ACh, electrical field stimulation, KCl in rat ileum EO [28] 16 (-)-Piperitone Casimiroa pringlei(Rutaceae) Aerial part infusion (Ethylic ether) KCl in rat uterine smooth muscle IC [33] 17 (+)-Rotundifolone Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 18 (R)-(-)-Carvone Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 19 (R,R,R)-Carvone-1,2-oxide) Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 20 (S)-(+)-Carvone Mentha x villosa(Lamiaceae) Leaf infusion (MeOH) KCl in guinea pig ileum IC [27] 21 1,8-Cineole Ocimum gratissimum(Lamiaceae) Leaf infusion (MeOH) ACh, KCl in guinea pig ileum IC [34] Nepeta cataria(Lamiaceae) Leaf infusion (Aqueous) Carbachol, KCl in guinea pig trachea and rabbit jejunum EO [22] Casimiroa pringlei(Rutaceae) Aerial part infusion (Ethylic ether) KCl in rat uterine smooth muscle IC [33] 22  p-Cymene Lippia graveolens (Verbenaceae) Leaf infusion (Distillation) Carbachol, H in guinea pig ileum IC [35] Zingiber roseum(Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] Poliomintha longiflora (Lamiaceae) Leaves stem infusion (Distillation) Carbachol, H in guinea pig ileum IC [35] 23 Carvacrol Origanum acutidens (Lamiaceae) Leaf, stem and flower infusion (MeOH) Spontaneous contraction in rat ileum EO [36] Thymus vulgaris (Lamiaceae) Whole plants (Ethanol) ACh, BaCl2, KCl in rat trachea and ileum IC [37] 24 Thymol Acalypha phleoides (Euphorbiaceae) Aerial part infusion [MeOH-CHCl3 (1:1)] ACh, BaCl2, H, KCl, S in guinea pig ileum and rabbit jejunum IC [29] Thymus vulgaris (Lamiaceae) Whole plants (Ethanol) ACh, BaCl2, KCl in rat trachea and ileum IC [37] 25 Thujane or Sabinane Anthemis mauritiana (Asteraceae) Flower infusion (Aqueous) Carbachol, KCl in rabbit jejunal smooth muscle EO [21]  26 (±)-Camphor Acalypha phleoides (Euphorbiaceae) Aerial part infusion [MeOH-CHCl3 (1:1)] ACh, BaCl2, H, KCl, S in guinea pig ileum and rabbit jejunum IC [29] Lippia dulcis(Verbenaceae) Leaf infusion (Steam distillation) Carbachol, H in porcine bronchi EO [38] 27 (+)-α-Pinene Anthemis mauritiana (Asteraceae) Flower infusion (Aqueous) Carbachol, KCl in rabbit jejunal smooth muscle EO [21] Nepeta cataria (Lamiaceae) Leaf infusion (Aqueous) Carbachol, KCl in guinea pig trachea and rabbit jejunum EO [22] Plectranthus barbatus (Lamiaceae) Leaf infusion (MeOH) ACh, BaCl2, H, KCl in guinea pig ileum EO [17] 28 (-)-α-Pinene Dissotis rotundifolia (Melastomataceae) Leaf infusion (EtOH) Carbachol in mouse intestinal motility E [39] Eucalyptus tereticornis (Myrtaceae) Commercial ACh, KCl in rat trachea EO [40] Zingiber roseum(Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] 29 (+)-β-Pinene Ferula gummosa (Apiaceae) Resin infusion (Hydroalcoholic, ether, MeOH) ACh, KCl in rat ileum IC [41] Zingiber officinale (Zingiberaceae) Rhizome infusion (MeOH) S in rat ileum EO [24] Zingiber roseum (Zingiberaceae) Fresh seeds (Hydrodistilled with diethyl ether) Carbachol, KCl in rat duodenal smooth muscle EO [26] 30 Cantleyine Strychnos trinervis (Loganiaceae) Root bark (EtOAc) Carbachol, H, KCl in guinea pig trachea IC [42] 31 Penstemonoside Parentucellia latifolia (Scrophulariaceae) Whole plant infusion (Butanol) ACh, CaCl2, KCl in rat uterus IC [43] 32 Aucubine or aucuboside Parentucellia latifolia (Scrophulariaceae) Whole plant infusion (Butanol) ACh, CaCl2, KCl in rat uterus IC [43] 33 2′-O-Acetyldihydropenstemide Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 34 2′-O-trans-p-Coumaroyl-dihydropenstemide Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 35 2′-O-Acetylpatrinoside Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 36 Patrinoside Viburnum prunifolium (Caprifoliaceae) Root and stem bark infusion (MeOH) Carbachol in rabbit jejunum and guinea pig trachea E [44] 37 Valtriate or Valepotriate Valeriana procera(Valerianeaceae) Root infusion (EtOH) BaCl2, carbachol, KCl in guinea pig ileum and stomach IC [45]  38 Isovaltrate or Isovaltratum Valeriana procera(Valerianeaceae) Root infusion (EtOH) BaCl2, carbachol, KCl in guinea pig ileum and stomach IC [45] 39 Epoxygaertneroside Morinda morindoides(Rubiaceae) Leaf infusion (Aqueous) ACh, KCl in guinea pig ileum IC [46] 40 Gaertneroside Morinda morindoides(Rubiaceae) Leaf infusion (Aqueous) ACh, KCl in guinea pig ileum IC [46] 41 Catalpinoside or Catapol Parentucellia latifolia (Scrophulariaceae) Whole plant infusion (Butanol) ACh, CaCl2, KCl in rat uterus IC [43]  Sesquiterpenes 43 (±)-Hernandulcin Lippia dulcis(Verbenaceae) Leaf infusion (Steam distillation) Carbachol, H in porcine bronchi EO [38] 43 Humulene or α-Caryophyllene Nepeta cataria (Lamiaceae) Leaf infusion (Aqueous) Carbachol, KCl, in guinea pig trachea and rabbit jejunum EO [22] 44 β-Caryophyllene epoxide Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] 45 β-Caryophyllene Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] Plectranthus barbatus(Lamiaceae) Leaf infusion (MeOH) ACh, BaCl2, H, KCl in guinea pig ileum EO [17] Pterodon polygalaeflorus (Fabaceae) Seed (Steam distillation) ACh, KCl in rat ileum smooth muscle IC [48] 46 Bicyclogermacrene or Lepidozene Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] 47 (+)-Capsidiol Nicotiana silvestri(Solanaceae) Leaf infusion (EtOAc) ACh, BaCl2, bradykinin, carbachol in guinea pig ileum and trachea IC [49] 48 S-Petasin Petasites formosanus (Compositae) Aerial parts (EtOH) CaCl2, carbachol, H, KCl in guinea pig trachea IC [50] 49 (+)-Isopetasin Petasites formosanus (Compositae) Aerial parts (EtOH) CaCl2, carbachol, H, KCl in guinea pig trachea IC [50] 50 Valeranone o Jatamansone Valeriana procera(Valerianeaceae) Root infusion (EtOH) BaCl2, carbachol, KCl in guinea pig ileum and stomach IC [45] 51 Chamazulene Matricaria recutita(Asteraceae) Plant infusion (Aqueous) Human platelet E [51] 52 Spathulenol Croton sonderianus(Euphorbiaceae) Leaf infusion (Steam distillation) ACh, KCl in rat tracheal smooth muscle EO [25] Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52]  53 Cynaropicrin Cynara scolymus(Asteraceae) Leaf and flower infusion (MeOH 70%) ACh in guinea pig ileum IC [53] 54 Cedrenol Anthemis mauritiana(Asteraceae) Flower infusion (Aqueous) Carbachol, KCl in rabbit jejunal smooth muscle EO [21] 55 (+)-Bakkenolide A Hertia cheirifolia (Asteraceae) Aerial parts (MeOH) ACh, BaCl2 in rat duodenum IC [54] 56 Himachalol Cedrus deodara (Pinaceae) Wood infusion ACh, BaCl2, H, nicotine, S in guinea pig ileum and seminal vesicle, rabbit jejunum and rat uterus IC [55] 57 (E)-Damascenone Ipomoea pes-caprae (Convolvulaceae) Leaf infusion (Aqueous) H in guinea pig ileal smooth muscle IC [56] 58 (-)-Isogermacrene D Artemisia vulgaris (Compositae) Stem and leaf infusion (Aqueous) guinea pig ileum  [57] 59 Ezoalantonin Artemisia vulgaris(Compositae) Leaf (CHCl3) H, PMA, S in guinea pig ileum and trachea IC [57] 60Costunolide Radix aucklandiae(Asteraceae) Rhizome (MeOH) ACh, KCl, S in rat jejunum IC [58] 61Dehydrocostuslactone Radix aucklandiae(Asteraceae) Rhizome (MeOH) ACh, KCl, S in rat jejunum IC [58]  Diterpenes 62E-Phytol Ipomoea pes-caprae (Convolvulaceae) Leaf infusion (Aqueous) H in guinea pig ileal smooth muscle IC [56] 633α-Angeloyloxy-2α-hydroxy-13,14Z-dehydrocativic acid Brickellia paniculata (Compositae) Leaf infusion (MeOH) KCl in rat myometrial tissue IC [59] 6415-Epicyllenin A Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 65Cyllenin A Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 66Marrulibacetal Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 67(13R)-9α,13α-epoxylabda-6β(19),16(15)-diol dilactone Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 68Marrubin Marrubium vulgare(Lamiaceae) Aerial parts (Aqueous) KCl in rat aorta IC [61] 69Marrubenol or Marrubiol Marrubium vulgare(Lamiaceae) Aerial parts (Aqueous) KCl in rat aorta IC [61]  70Marrulanic acid Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 71Marrulactone Marrubium globosumssp. libanoticum(Lamiaceae) Aerial part infusion (MeOH) ACh in mouse ileum IC [60] 72(+)-Dehydroabietic acid Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52] 739β-Hydroxydehydroabietyl alcohol Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52] 749α,13α-Epidioxyabiet-8(14)-en-18-oic acid methyl ester Lepechinia caulescens (Lamiaceae) Leaf infusion (Hexane) KCl in rat uterus IC [52] 754-epi-Hyalic acid Croton argyrophylloides(Euphorbiaceae) Bark infusion (MeOH) ACh, KCl in rat tracheal smooth muscle IC [62] 76Pimaradienoic acid or Continentalic acid Viguiera arenaria (Asteraceae) Root infusion (CH2Cl2) ACh, KCl in rat carotid artery IC [63] 778(14),15-Sandaracopimaradiene-7α,18-diol Tetradenia riparia (Lamiaceae) Leaf infusion (CHCl3) BaCl2, H, methacholine in guinea pig ileum IC [64] 783,4-Secoisopimara-4(18),7,15-triene-3-oic acid Salvia cinnabarina(Lamiaceae) Aerial parts (EtOH) ACh, BaCl2, H in guinea pig ileum IC [65] 79ent-Kaurenoic acid Viguiera arenaria (Asteraceae) Root infusion (CH2Cl2) ACh, KCl in rat carotid artery IC [63] Viguiera hypargyrea (Asteraceae) Root infusion (Hexane) Spontaneous contraction in guinea pig ileum IC [66] 80Beyerenic acid or Monogynoic acid Viguiera hypargyrea (Asteraceae) Root infusion (Hexane) Spontaneous contraction in guinea pig ileum IC [66] 81ent-7α-Acetoxytrachyloban-18-oic acid Xylopia langsdorfiana(Annonaceae) Stem infusion (EtOH 95%) BaCl2, H, KCl in guinea pig ileum IC [67] 82ent-7α -hydroxytrachyloban-18-oic acid Xylopia langsdorfiana(Annonaceae) Stem infusion (EtOH 95%) BaCl2, H, KCl in guinea pig ileum IC [67] 83Phorbol 12-acetate-13-tiglate Crotonis tiglium (Euphorbiaceae) Fruit (MeOH) Spontaneous contraction in rabbit jejunum E [68] 843,7,10,14,15-pentaacetyl-5-butanoyl-13,17-epoxy-8-myrsinene Pycnocycla spinosa (Umbelliferae) Aerial parts (MeOH) KCl in rat illeum IC [69]  Triterpenoids 85Agapanthagenin 3-O-β-D-glucopyranoside Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 86Agapanthagenin Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 87 β-sitosterol Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [71]  88β-sitosterol 3-O-β-D-glucopyranoside Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [71] 89α-Spinasteryl β-D-glucoside Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 90Tropeoside B1 and B2 Allium cepa(Alliaceae) Bulbs [CHCl3:MeOH (9:1)] ACh, H in guinea pig ileum IC [72] 91Tropeoside A1 and A2 Allium cepa(Alliaceae) Bulbs [CHCl3:MeOH (9:1)] ACh, H in guinea pig ileum IC [72] 92Elburzensoside A1 and A2 Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 93Elburzensoside C1 and C2 Allium elburzense(Alliaceae) Flower and bulb infusion (Hexane) H in guinea pig ileum IC [70] 94Galphimin A Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 95Galphimin B Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 96Galphimin C Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 97Galphimin E Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 98Galphimin F Galphimia glauca (Malpighiaceae) Leaf infusion (MeOH) Electrical-induced contraction in guinea pig ileum IC [73] 99Handianol Herissanthia tiubae (Malvaceae) Leaf infusion (EtOH) Carbachol, H, KCl in guinea pig ileum and trachea, and rat aorta IC [74] 100Cycloartanol Herissanthia tiubae (Malvaceae) Leaf infusion (EtOH) Carbachol, H, KCl in guinea-pig ileum, trachea and rat aorta IC [74] 101Taraxasteryl acetate Brickellia veronicifolia (Asteraceae) Aerial parts [CH2Cl2:MeOH (1:1)] Gastrointestinal motility test in mouse E [75] 102Pomolic acid or Benthamic acid or Randialic acid A Licania pittieri (Rosaceae) Leaf infusion (EtOH) Carbachol, KCl in rat aorta IC [76] 103Ursolic acid Agastache mexicana(Lamiaceae) Aerial part (MeOH) ACh, KCl in guinea pig ileum IC [77] 104Ehretiolide Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 105Ehretiolide acetate Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 106Camaldulin Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [71] 107Zygophyloside N Zygophyllum gaetulum(Zygophyllaceae) Root infusion (MeOH) Electrically-induced contractions of isolated guinea pig ileum E [79]  108Erythrodiol Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 1093-β-tridecanoyloxy-28-hydroxyolean-12-ene Conyza filaginoides(Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 1103-β-Hydroxyolean-9(11),12-dien-28-oic acid Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 1114-epi-Hederagenin Hedera helix(Araliaceae) Leaf infusion (EtOH) ACh in guinea pig ileum IC [80] 112Hederacoside C Hedera helix(Araliaceae) Leaf infusion (EtOH) ACh in guinea pig ileum IC [80] 113Betulinic acid Eucalyptus camaldulensis (Myrtaceae) Leaf infusion (EtOAc) KCl, spontaneous contraction in rabbit jejunum IC [78] 114α-Amyrin acetate Tylophora hirsuta (Asclepiadaceae) Aerial parts (MeOH) KCl in rabbit jejunum IC [81]  Phloroglucinol derivatives 115Hyperforin Hypericum perforatum (Hypericaceae) Aerial parts (EtOH 70%) KCl in rabbit jejunum IC [82] 116Hypericin Hypericum perforatum (Hypericaceae) Aerial parts (EtOH 70%) KCl in rabbit jejunum IC [82]  Coumarins 117Scopoletin Brunfelsia hopeana (Solanaceae) Root infusion (EtOH) Phenylephrine, KCl, PGF2, serotonin in rat aorta IC [83] 118Todannone Toddalia asiaticavar. floribunda (Rutaceae) Aerial parts (EtOH 95%) ACh, BaCl2, H, nicotine in guinea pig ileum IC [84] 119(2S∗,3R∗)-2-[(3E)-4,8-dimethylnona-3,7-dien-1-yl]-2,3-dihydro-7-hydroxy-2,3-dimethylfuro[3,2c] coumarin Ferula heuffelii (Apiaceae) Underground part (CHCl3) ACh, KCl in rat ileum IC [85] 120Osthole Prangos ferulacea (Apiaceae) Root (Acetone) ACh, KCl, electric field stimulation in rat ileum IC [86] 121Angelicin Heracleum thomsoni (Apiaceae) Aerial part infusion (EtOH) ACh, BaCl2, H, S in cat ureter, guinea pig bile duct and trachea, monkey gall bladder, rabbit jejunum, and rat uterus IC [87] 122Glycycoumarin Glycyrrhizae radix (Leguminosae) Root infusion (Aqueous) A23187, BaCl2, carbachol, KCl in mouse jejunum IC [88] Glycyrrhiza ularensis(Leguminosae) Root infusion (Aqueous) Carbachol in mouse jejunum E [89]   Chalcones 123Davidigenin Mascarenhasia arborescens (Apocynaceae) Leaf and stem infusion (MeOH) ACh, H in guinea pig and rat duodenum IC [90] 124Isoliquiritigenin Glycyrrhiza glabra(Leguminosae) Root infusion (Aqueous) ACh, KCl, O, spontaneous contraction in rat uterus IC [91] Glycyrrhiza ularensis(Leguminosae) Root infusion (Aqueous) (Aqueous) BaCl2, carbachol, KCl in mouse jejunum,ileum and rectum IC [92] 125Licochalcone A Glycyrrhiza inflata (Leguminosae) Root infusion (Aqueous) A23187, BaCl2, carbachol, KCl in mouse jejunum IC [93]  Flavonoids 126(-)-Pinostrobin Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] 127(-)-(S)-Sakuranetin Dodonaea viscosa (Sapindaceae) Leaf infusion [CHCl3:MeOH (1:1)] ACh, BaCl2, H in rat uterus IC [94] 128(±)-Sternbin Artemisia monosperma (Compositae) Aerial part (EtOH) ACh, O in rat ileum, pulmonary artery, urinary bladder, trachea, and uterus IC [95] 129Ouratea catechin Maytenus rigida (Celastraceae) Stem bark (EtOH) BaCl2, carbachol, KCl, H in guinea pig ileum IC [96] 130Apegenin Achillea millefolium (Asteraceae) Whole plant infusion (MeOH 40%) ACh, CaCl2, H, PE, S in rat ileum IC [97] 131Buddleoflavonol or Linarigenin Agastache mexicana(Lamiaceae) Aerial part (MeOH) ACh, KCl in guinea pig ileum IC [77] 132Luteolin Achillea millefolium (Asteraceae) Whole plant infusion (MeOH 40%) ACh, CaCl2, H, PE, S in rat ileum IC [97] Artemisia copa (Compositae) Aerial parts (Aqueous) KCl, PE, S in rat aorta E [98] Plantago lanceolata (Plantaginaceae) Aerial part (EtOH) ACh, BaCl2, H, KCl in guinea pig ileum and trachea IC [99] Thymus vulgaris(Lamiaceae) Leaf and flower (EtOH) ACh, BaCl2, carbachol, H in guinea pig ileum and trachea, and rat vas deferens IC [100] 133Scutellarein 6-β-D-glucoside (isovitexin) Aloysia citridora (Verbenaceae) Leaf infusion (Aqueous) ACh, CaCl2, KCl in rat duodenum IC [101]  134Vitexin Aloysia citridora (Verbenaceae) Leaf infusion (Aqueous) ACh, CaCl2, KCl in rat duodenum IC [101] Aspalathus linearis(Fabaceae) Commercial (Aqueous) KCl in rabbit jejunum IC [102] 135Xanthomycrol Brickellia paniculata (Compositae) Leaf infusion (MeOH) KCl, O in rat uterus IC [59] 136Demethoxycentaureidin Piptadenia stipulacea (Leguminosae) Aerial parts, (CHCl3) Carbachol, H, O, in guinea pig ileum and trachea, rat aorta and uterus IC [103] 137Gnaphaliin B Gnaphalium liebmannii (Asteraceae) Aerial parts (Hexane) ACh, carbachol in guinea pig trachea IC [104] 138Kaempferol or Kaempherol Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 139Gnaphaliin A Gnaphalium liebmannii (Asteraceae) Aerial parts (Hexane) ACh, carbachol in guinea pig trachea IC [104] 140Quercetin Achillea millefolium (Asteraceae) Whole plant infusion (MeOH 40%) ACh, CaCl2, H, PE, serotonin in rat ileum IC [97] Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] Drosera madascariensis (Droseraceae) Leaf extract (EtOH 70%) Carbachol, H, PGF2 in guinea pig ileum and trachea IC [106] Drosera rotundifolia(Droseraceae) Aerial parts (EtOH 70%) Carbachol in guine pig ileum IC [107] Morinda morindoides(Rubiaceae) Leaf extract (Aqueous) Ac, KCl in guinea pig ileum IC [46] 1413-O-Methylquercetin Rhamnus nakaharai (Rhamnaceae) Stem bark (not reported) Carbachol, H, KCl in guinea pig trachea IC [108] 1423,4′-Dimethylquercetin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 1433,7-Dimethylquercetin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 144Isoquercetin Conyza filaginoides (Asteraceae) Leaf infusion [CHCl3:MeOH (1:1)] Spontaneous contraction in rat ileum IC [47] Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] Drosera rotundifolia(Droseraceae) Aerial parts (EtOH 70%) Carbachol in guinea pig ileum IC [107] Drosera madascariensis(Droseraceae) Leaf extract (EtOH 70%) Carbachol, H, PGF2 in guinea pig ileum and trachea IC [106] Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105]  145Quercetin 3-α-rhamnoside or Quercitroside Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] Morinda morindoides(Rubiaceae) Leaf extract (Aqueous) ACh, KCl in guinea pig ileum IC [46] 146Quercetin 3-O-β-L-arabinoside Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] 147Quercetin 3-O-β-D-galactoside Psidium guajava(Myrtaceae) Leaf extract (MeOH) Peristalsis in guinea pig ileum IC [105] Drosera madascariensis(Droseraceae) Leaf extract (EtOH 70%) Carbachol, H, PGF2 in guinea pig ileum and trachea IC [106] 148Quercetin 3-O-β-gentiobioside 3-O-β-D- Morinda morindoides(Rubiaceae) Leaf extract (Aqueous) ACh, KCl in guinea pig ileum IC [46] Glucopyranosylquercetin Drosera rotundifolia(Droseraceae) Aerial parts (EtOH 70%) Carbachol in guinea pig ileum EO [107] 149Centaureidin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 150Casticin or Vitexicarpin Artemisia abrotanum (Asteraceae) Aerial part (MeOH 67%) Carbachol in guinea pig trachea IC [109] 151Prunetol or Sophoricol Genista tridentata (Papilionaceae) Not reported AC, electric field stimulation, 6-oxo PGE1 in guinea pig ileum IC [110] 152Boeravinone E Boerhaavia diffusa (Nyctaginaceae) Root infusion (MeOH) ACh in guinea pig ileum IC [111] 1534,6,11-trihydroxy-9-methoxy-10-methyl-6,12-dihydro-5,7-dioxatetraphen-12-one Boerhaavia diffusa (Nyctaginaceae) Root infusion (MeOH) ACh in guinea pig ileum IC [111] 154Boeravinone G Boerhaavia diffusa (Nyctaginaceae) Root infusion (MeOH) ACh in guinea pig ileum IC [111] 155(2R,3S,2”R,3”R)-Manniflavonone Garcinia buchananii (Clusiaceae) Stem bark (EtOH 70%) Bay K 8644 in mouse ileum IC [112] 156Hyperoside Hypericum perforatum (Hypericaceae) Aerial parts (EtOH 70%) KCl in rabbit jejunum IC [82] 157Chrysoeriol Artemisia copa(Compositae) Aerial parts (Aqueous) KCl, PE, S in rat aorta E [98] Aspalathus linearis(Fabaceae) Commercial (Aqueous) KCl in rabbit jejunum IC [102] 158Spinacetin Artemisia copa(Compositae) Aerial parts (Aqueous) KCl, PE, S in rat aorta E [98] 159Vicenin 2 Perilla frutescens(Lamiaceae) Commercial (Aqueous) ACh, BaCl2 i rat ileum IC [113] 160Orientin Aspalathus linearis(Fabaceae) Commercial (Aqueous) KCl in rabbit jejunum IC [102]   Phenylmetanoids 161Salicylic acid methyl ether Brickellia veronicifolia (Asteraceae) Aerial parts [CH2Cl2:MeOH (1:1)] Gastrointestinal motility test in mouse E [75] 162 O-Anisic acid or 6-Methoxysalicylic acid Brickellia veronicifolia (Asteraceae) Aerial parts [CH2Cl2:MeOH (1:1)] Gastrointestinal motility test in mouse E [75] 163Protocatechuic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 164Benzyl 2,5-dimethoxybenzoate Brickellia veronicifolia(Asteraceae) Aerial parts [CH2Cl2-MeOH (1:1)] Gastrointestinal motility test in mouse E [75]  Phenylethanoids 165O-Methylbalsamide Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 166(-)-Tembamide Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 167O-Methyltembamide Zanthoxylum hyemale (Rutaceae) Steam bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114]  Phenylpropanoids 168Eugenol Ocimum gratissimum(Lamiaceae) Not reported ACh, KCl in guinea pig ileum EO [34] 169Rosemaric acid or Rosemary acid or trans-Rosmarinic acid Thymus vulgaris (Lamiaceae) Commercial KCl in rat trachea IC [100] 170 trans-Chlorogenic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 171 cis-Chlorogenic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 1723,5-Dicaffeoylquininic acid Hedera helix(Araliaceae) Aerial parts (EtOH 30%) ACh in guinea pig ileum IC [80] 173Verbascoside Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 174Isoacteoside or Isoverbascoside Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 175Plantamajoside or Plantamoside or Purpureaside A Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 176Lavandulifolioside Plantago lanceolata (Plantaginaceae) Aerial part infusion (EtOH 20%) ACh, BaCl2, H, KCl in guinea pig ileum and trachea E [99] 177Echinacoside Cistanche tubulosa(Orobanchaceae) No reported (EtOH) KCl, PE in rat aorta IC [115] 178Schisandrin A or Wuweizisu A Schisandra chinensis(Schisandraceae) Academic Spontaneous contractions in rat colon IC [116]  179Schisandrin B or Wuweizisu B Schisandra chinensis(Schisandraceae) Fruit decoction (Aqueous) ACh, KCl, S in guinea pig ileum IC [117] 180Schisandrol B Schisandra chinensis(Schisandraceae) Fruit decoction (Aqueous) ACh, KCl, S in guinea pig ileum IC [117]  Stilbenoids 181Aloifol II or Dendrophenol or Moscatilin Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH 1:1)] Spontaneous contraction in guinea pig ileum IC [118] 182Batatasin III Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH 1:1)] Spontaneous contraction in guinea pig ileum IC [118] Scaphyglottis livida (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 1834-[2-(3-hydroxy-5-methoxyphenyl)ethyl]-2-methoxyphenol Scaphyglottis livida (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 184Gigantol Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] Spontaneous contraction in guinea pig ileum IC [118] 185Coelonin Scaphyglottis livida (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 186 Erianthridin Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 187 Ephemeranthoquinone Nidema boothii (Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] Spontaneous contraction in guinea pig ileum IC [118] 188 Nudol Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 189 3,4- dimethoxyphenanthrene-2,5-diol Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 190 Denthyrsinin Scaphyglottis livida(Orchidaceae) Whole plant infusion [CH2Cl2-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [119] 191 Gymnopusin Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120] 192 Fimbriol A Maxillaria densa(Orchidaceae) Whole plant infusion [CHCl3-MeOH (1:1)] ACh, BaCl2, H in rat ileum IC [120]  Curcuminoid 193 (1E,5S,6E)-5-hydroxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadien-3-one Curcuma longa(Zingiberaceae) Macerated rhizome (EtOH 70%) ACh, BaCl2, CaCl2, H, KCl, O in guinea pig Ileum and rat uterus IC [121]  Benzofurans and Related 194 (+)-Vitisin C Vitis spp. (Vitaceae) Stem infusion (MeOH) PE in rabbit aorta IC [122] 195 Butylphthalide Ligusticum wallichii (Umbelliferae) Rhizome (hydrodistillation) CaCl2, KCl in rat aorta EO [123] 196 cis-Butylidenephthalide Ligusticum wallichii (Umbelliferae) Rhizome (hydrodistillation) CaCl2, KCl in rat aorta EO [123]  197 Ligustilide A or cis-Ligustilide Ligusticum wallichii (Umbelliferae) Rhizome (hydrodistillation) CaCl2, KCl in rat aorta EO [123] 198 12-acetoxytremetone Helichrysum italicumssp.italicum(Asteraceae) Flowers (EtOH) ACh, BaCl2 in mouse ileum IC [124] 199 1-[(2R)-2-(3-hydroxyprop-1-en-2-yl)-2,3-dihydro-1-benzofuran-5-yl]ethan-1-one Helichrysum italicumssp.italicum(Asteraceae) Flowers (EtOH) ACh, BaCl2 in mouse ileum IC [124]  Alkaloids 200 Indicaxanthin Opuntia ficus indica (Cactaceae) Fruit pulp infusion (Aqueous) Carbachol, KCl in mouse ileum IC [125] 201 Papaverine Daucus carota(Apiaceae) Seed infusion (MeOH 90%) ACh, BaCl2, H, KCl, S, O in dog trachea, guinea pig, rabbit, rat ilea, rat uterus IC [126] 202 Higenamine Nandina domestica (Berberidaceae) Fruit (Aqueous) ACh, H, KCl in guinea pig trachea IC [127] 203 Atherosperminine Fissistigma glaucescens(Annonaceae) Bark (MeOH) Carbachol, KCl, LTC4, PGF2α, U46619 in guinea pig trachea IC [128] 204 (+)-Domestine or (+)-Nantenine Platycapnos spicata (Fumariaceae) Academic supplier BaCl2, CaCl2, KCl, PE, S in rat aorta and atria IC [129] 205 10-Methylacridone Citrus deliciosa(Rutaceae) Root juice (MeOH) Rabbit ileum IC [130] 206 Spermatheridine or liriodenin Fissistigma glaucescens (Annonaceae) Leaf infusion (MeOH) Carbachol in canine trachea IC [131] 207 Citpressine I Citrus deliciosa(Rutaceae) Root juice (MeOH) Rabbit ileum IC [130] 208 Jatrorhizine or Neprotine Berberis aristata (Berberidaceae) Institutional supplier ACh, S, spontaneous contractions in rat ileum IC [132] Coptis chinensis(Ranunculaceae) Rhizoma (EtOH 70%) ACh in guinea pig ileum IC [133] 209 Coptisine Coptis chinensis(Ranunculaceae) Rhizoma (EtOH 70%) ACh in guinea pig ileum IC [133] 210 Escholine or Thalictrine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 211 (+)-Isothebaine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 212 (+)-Corytuberine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 213 (+)-Isocorydine or Luteanine Mahonia aquifolium (Berberidaceas) Cortex and fruit infusion KCl, PE in rat aorta IC [134] 214 (+)-Chelidonine or Stylophorine Chelidonium majus (Papaveraceae) Commercial supplier BaCl2, carbachol in guinea pig ileum IC [135]  215 (-)-8 beta-(4′-hydroxybenzyl)-2,3-dimethoxyberbin-10-ol Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 216 3-O-methylconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 217 3,5-di-O-methylconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 2185,6-dihydro-3,5-di-O-methylconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 219 5,6-dihydroconstrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 220 Constrictosine Aristolochia constricta (Aristolochiaceae) Aerial part infusion (MeOH) ACh, electrical contraction, H in guinea pig ileum IC [136] 221 Isojuripidine Solanum asterophorum (Solanaceae) Leaf infusion (MeOH) ACh, CaCl2, H in guinea pig ileum IC [137] 222 Sarcodine Sarcocca saligna (Buxaceae) Whole plant (MeOH) ACh, KCl in guinea pig ileum, rat stomach fundus, rabbit jejunum IC [138] 223 Saracorine or Sarcorine Sarcococca saligna (Buxaceae) Whole plant infusion (MeOH) ACh, KCl in rabbit jejunum IC [139] 224 Saracocine Sarcocca saligna (Buxaceae) Whole plant (MeOH) ACh, KCl in guinea pig ileum, rat stomach fundus, rabbit jejunum IC [138] 225 Alkaloid C Sarcocca saligna(Buxaceae) Whole plant (MeOH) ACh, KCl in guinea pig ileum, rat stomach fundus, rabbit jejunum IC [138] 226 (-)-Pachyaximine A Sarcococca saligna (Buxaceae) Whole plant infusion (MeOH) ACh, KCl in rabbit jejunum, KCl IC [139] 227 (-)-(R)-Geibalansine or (-)-R-Geilbalansine Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 228 Hyemaline Zanthoxylum hyemale (Rutaceae) Stem bark infusion (EtOH) ACh, BaCl2 in rat ileum IC [114] 229 Theophylline Fissistigma glaucescens (Annonaceae) Leaf infusion (MeOH) Carbachol in canine trachea IC [131] 230Carboxyscotangamine A Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 231Scotanamine A Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 232Piperine Piper nigrum (Piperaceae) Fruit (EtOH) Ileum loop in mice IC [141]  Amines 233Scotanamine B Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [123]  234Scotanamine C Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 235Scotanamine D Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 236N1-Caffeoyl-N3-dihydrocaffeoylspermidine Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 237N1, N10-Bis(dihydrocaffeoyl)spermidine Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140] 238Caffeoylputrescine Scopolia tangutica (Solanaceae) Root (95% EtOH) Carbachol in Chinese hamster ovarian cell IC [140]  Isothiocyanates 239 Redskin or Senfoel Cruciferous vegetables (Brassicaceae) Commercial source ACh, electrical contraction in mouse ileum IC [142]  Alcohols 240 (3E)-4-(3,4-dimethoxyphenyl)but-3-en-1-ol Zingiber cassumunar (Zingiberaceae) Chemically synthesized O in rat uterus IC [143]  Ketones 241 2-Decanone Ruta chalepensis(Rutaceae) Leaf (EtOH 70%) KCl in rat ileum E [144] 242 2-Undecanone Ruta chalepensis(Rutaceae) Leaf (EtOH 70%) KCl in rat ileum E [144] 243 2-Tridecanone Ruta chalepensis(Rutaceae) Leaf (EtOH 70%) KCl in rat ileum E [144] 244 Latifolone Ferula heuffelii (Apiaceae) Underground part (CHCl3) ACh, KCl in rat ileum IC [85] 245Dshamirone Ferula heuffelii (Apiaceae) Underground part (CHCl3) ACh, KCl in rat ileum IC [85]  Phenolic compounds 246 6-(4-hydroxy-3-methoxyphenyl)-hexanonic acid (HMPHA) Pycnocycla spinosa(Umbelliferae) Aerial parts (MeOH) KCl in rat ileum IC [145] 247 Isovanillin Pycnocycla spinosa(Umbelliferae) Aerial parts (MeOH) KCl in rat ileum IC [146] 248 Iso-acetovanillon Pycnocycla spinosa(Umbelliferae) Aerial parts (MeOH) KCl in rat ileum IC [146] IC = isolated compound, E = extract, EO = essential oil, ACh = acetylcholine, O = oxytocin, PMA =β-Phenylethyl amsine, PGF = Prostaglandin F2α, H = histamine, S = serotonin.Some advantages of performingex vivo experiments are as follows: (i) different substances can be evaluated in fresh tissues without absorption factors, metabolic excretion or interference due to nerve reflexes; (ii) it is possible to quantify the effect produced by a precisely determined drug; and (iii) it is easier to obtain dose-effect curves, such as the smooth muscle where the contraction obtained under the influence of a spasm or in tissue homogenates is measured by determination of the enzyme activities [172, 174].


## 5.2. Guinea Pig Ileum and Rat Stomach

The ileum is removed and cut in strips of approximately 2 cm long and then placed in a bath filled with an isotonic solution as mentioned earlier. Electrophysiological studies are performed by graphically recording the contractions with the aid of a transducer, which is calibrated 30 min before the treatment begins. A range of 0.01 to 0.03μM is generally used to determine dose response curves of the antispasmodic substance [175].In rats, the stomach is removed and the corpus and fundus are cut in strips of approximately 5 mm x 15 mm and placed on a prewarmed warm solution as mentioned before.


## 5.3. Compounds Used to Elicit a Spasmodic Activity

The main compounds used are acetylcholine, atropine, BaCl2, carbachol, histamine, KCl, and serotonin.Acetylcholine is a postganglionic neurotransmitter in the parasympathetic neurons that innervate the intestine. The response to acetylcholine is regulated by activation of the two types of muscarinic receptors: M2 and M3 [176]. The activation of these receptors causes contractions by increasing the intracellular concentration of Ca2+ via IP3 [176]. Atropine is a competitive reversible antagonist of muscarinic acetylcholine receptors M1, M2, M3, M4, and M5.Different substances are used to produce contractions. For example, BaCl2 induces contractions by mobilizing membrane-bound Ca2+ [177], carbachol is a cholinomimetic drug (cholinergic agonist) that binds and activates acetylcholine receptors [178], histamine acts by either accelerating the release of acetylcholine or interacting supra-additively with the acetylcholine at the smooth muscle [179], whereas KCl increases the voltage-operated Ca2+ channel activity by increasing intracellular free Ca2+ in smooth muscle [180]. Serotonin is also an important neurotransmitter mainly stored in the digestive tract, affecting the secretory and motor activities. At high concentrations, it acts as a vasoconstrictor by contracting endothelial smooth muscle directly or by potentiating the effects of other vasoconstrictors [181, 182].


## 6. Antispasmodic Activity of Natural Compounds

Compounds isolated from terrestrial plants have shown the ability to function as antispasmodic compounds. The chemical group with the highest number of members of antispasmodic compounds is the monoterpenoid group (41 compounds) followed by flavonoids (35 compounds), alkaloids (with 33 compounds), and triterpenes with 31 (Figure1). Although we summarize in Table 3 248 compounds, in most of the cases the mechanism behind their activity has not been elucidated.Figure 1
Number of isolated compounds with antispasmodic activity. The total number was obtained from Table 3. “Others” is the sum of the compounds belonging to alcohols, amines, benzofurans, chalcones, coumarins, curcuminoids, isothiocyanates, ketones, phenolic, phenylmethanoids, phenylethanoids, glucinols, and phloroglucinols.


## 7. Mutagenicity

Studies related to the mutagenicity of antispasmodics are very scarce. This topic has been underestimated when testing the bioactivities of ethnomedicinal plants. Probably the most useful method to determine the mutagenicity of natural products or plant extracts is the Ames method [183]. This test is based on the rate of mutations detected in genetically modified strains ofSalmonella typhimurium.Moreover, this test has also been developed to detect mutagenicity of metabolized compounds in the liver. In this situation, a mixture of liver enzymes (S9 microsomal fraction) is used to mimic the metabolites that will be produced in the liver [184].Few studies have been performed to determine the mutagenicity of natural products with antispasmodic activity. For example, the flavonoids quercetin and luteolin were tested using the Ames method and the appearance of point mutations in four of the tested bacterial strains was shown [185]. In another study, the extracts of the plantsBrickellia veronicaefolia,Gnaphalium sp.,Poliomintha longiflora, andValeriana procera were studied. Compounds isolated from these plants are listed as antispasmodic compounds (Table 3). Results of the mutagenicity test indicated thatGnaphalium sp.,Poliomintha longiflora (used in the Mexican cuisine and as a traditional medicine), andValeriana procera induced mutagenesis in the tested bacterial strain [186].


## 8. Chemical Similarities between Natural and Synthetic Antispasmodic Compounds

To determine whether or not there is an analogy between synthetic (Table4) and natural antispasmodic compounds, the structures of both groups were compared. Results showed that no similarities were found except for alkaloids, amines, and amino acids.Table 4
Synthetic antispasmodic compounds used in medicine.
Synthetic compound Receptor targeted Main use Alkaloids Chlorzoxazone Prevents release of histamine Muscular spasm Pancuronium Nicotinic acetylcholine Muscle relaxant Riluzole Sodium channels Amyotrophic lateral sclerosis Rocuronium Antagonist of neuromuscular junction Muscle relaxant and anaesthesia Tizanidine α2 adrenergic agonist Muscle relaxant Vecuronium Nicotinic acetylcholine Muscle relaxant and anaesthesia  Curcuminoids Atracurium Nicotinic acetylcholine Muscle relaxant and anaesthesia Cisatracurium Nicotinic acetylcholine Muscle relaxant and anaesthesia Mivacurium Nicotinic acetylcholine Muscle relaxant and anaesthesia  Methylpropanoid Diazepam G A B A A Anxiety, alcohol withdrawal syndrome, muscle spasms, seizures, and restless legs syndrome Prograbide G A B A A + B Epilepsy Orphenadrine  Skeletal muscle relaxant that is used for the treatment of acute muscle aches, pain, or spasms.  Phenylpropanoids Baclofen G A B A B Spinal cord injury, cerebral palsy, and multiple sclerosis Idrocilamide Prevents release of intracellular Ca2+ Skeletal muscle relaxant and muscular painOne of the main differences is that commercial alkaloids are methylated in their nitrogen to make them positive, increasing their solubilities because of salt formation. In contrast, natural products have no positive nitrogen, rendering the molecule neutral and pH dependent. Thus, the compound may or may not be protonated, resulting in a change in its solubility and consequently a change on the targeting tissues.The comparison can perhaps be focused on the distribution of charges rather than by functional groups or families of compounds, emphasizing the electron distribution. For example, a physical characterization such as the heat of formation, the surface electrostatic potential, the molecular weight, the surface tension, the refractive index, the lipophilicity, and others has been used to characterize the structure-activity relationship of alkaloids extracted from the Amaryllidaceae family [187]. These alkaloids were selected because of their ability to inhibit the effect of the acetylcholinesterase enzyme.Of special interest is the natural compound salvinorin A isolated from the Mexican hallucinogenicSalvia divinorum(Lamiaceae) used in the traditional medicine as an antidiarrheal. It has been reported that this compound inhibited the intestinal motility through the activation of other receptors such as κ-opioid receptors (KORs). Upon inflammation of the gut, the cannabinoid C, B1, and KOR receptors are upregulated. It appears that salvinorin A interacts in the cross-talk between these receptors with a reduction of the inflammation as demonstrated in murine and guinea pig models [188, 189].Analysis of the similarities between synthetic and natural antispasmodic structures is depicted in Table5.Table 5
Similarities between natural and synthetic compounds.
Synthetic Natural


## 9. Conclusions

A large number of natural products with antispasmodic activities have been reported. Although the use of plants in traditional medicine is still relevant, it is necessary to perform new studies to elucidate the mechanism of action of antispasmodics. Moreover, more information about cytotoxicity and mutagenesis should be explored to ensure that these compounds are safe for consumption. The findings of this study corroborated the need for safety studies on plants extensively used for primary health care in countries such as Mexico. Such studies must be carried out before continuing with the widespread use of some species, which may provoke long-term and irreversible damage.



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