# Recent Progress on Chemical Constituents and Pharmacological Effects of the GenusNigella

Authors: Yun Niu; Li Zhou; Lijun Meng; Sitan Chen; Changyang Ma; Zhenhua Liu; Wenyi Kang
Journal: Evidence-Based Complementary and Alternative Medicine
 (2020)

---

## Abstract

Seeds of the genusNigella plants as folk medicine are often used to prevent and treat asthma, diarrhea, dyslipidemia, and other diseases around the world. Pharmacological researches showed that seed extract and seed oil have antibacterial, antioxidant, hypoglycemic, and hepatoprotective effects which attributed to their bioactive constituents such as alkaloids, saponins, flavones, and phenols. This paper has covered recent progresses on chemical and pharmacological researches on these plants, including their compounds and pharmacological effects. It was found that the chemical component researches were focused on the seed oil. Therefore, more attention should be paid to the profile of the whole constituents in the seeds.


---

## Body

## 1. Introduction

Plants of the genusNigella originate from family Ranunculaceae, which contain about twenty species, mainly distributed in the Mediterranean area. Two species are cultivated in China, Nigella damascena L. and Nigella glandulifera Freyn et Sint. N. damascena originates in southern Europe and is cultivated as ornamental plants in China. N. glandulifera is mainly found in Xinjiang and Tibet [1]. In addition, N. sativa, known as “black cumin,” is distributed in Southern Europe, southwest Asia, North Africa, and mainly in Pakistan and Egypt [2].Owing to the large quantities of nutritional and medicinal constituents, seeds of genusNigella plants are widely used in food preparations and medicine [2]. N. glandulifera seeds are a common Uyghur medicine, which have galactagogue, diuretics, bronchodilator, and analgesic activities and cure bronchial asthma, edema, and urinary calculus [3]. N. sativa seeds have a long history in usage as the wind dispelling agent, diuretics, and insect repellent [4]. N. damascena seeds are widely used as aromatic agent in bread and cheese, and it is also used in folk medicine to treat menstrual disorders [5]. In view of sufficient literatures on Nigella seeds, here we have summarized the active constituents and their pharmacological activities to provide theoretical elucidation for further utilization.


## 2. Chemical Constituents

Due to the pharmacological activities ofNigella seeds, phytochemical studies were conducted to find all kinds of natural compounds. Over the past few decades, the chemical composition investigations were mainly focused on oils. However, literatures have revealed that the seeds of Nigella genus contained many secondary metabolites such as steroids, flavones, saponins, alkaloids, and phenols. All compounds from the genus Nigella and their references are listed in Table 1.Table 1
Chemical constituents ofNigella genus.
CompoundNameSourceReferenceAlkaloids1–381NigeglanineI[6, 7]24-O-MethylnigeglanineI[6]3NigellicineI[7, 8]4NigellimineI[9]5NigellimineN-oxideI[9]6NigellidineI[6–8]74-O-methylnigellidineI[6]817-O-(β-D-glcp)-4-O-MethylnigellidineI[6]9NigelanoidI[6]10NigeglapineII[10]11NigeglaquineII[10]12Nigellidine-4-O-sulfiteII[7]13NigellaquinomineII[11]14Nigelladine AII[11]15Nigelladine BII[11]16Nigelladine CII[11]17Nigellamine A1I[12]18Nigellamine A2I[12]19Nigellamine A3I[13]20Nigellamine A4I[13]21Nigellamine A5I[13]22Nigellamine DI[14]23Nigellamines B1I[12]24Nigellamine B2I[12]25Nigellamine CI[13]26Nigellamine B3I[14]27MagnoflorineI[15]28FuzitineII[16]29HigenamineII[17]30Nigegladine AII[18]31Nigegladine BII[18]32Nigegladine CII[18]334, 8-Dimethoxy-1-vinyl-β-carbolineII[19]347H-Benzo[c]carbazoleII[19]35Indolyl-3-carboxylic acidII[19]36BerberineII[19]37DamascenineIII[20]38DamascinineIII[20]Flavonols39–5539QuercetinII[21]40KaempferolII[21]41RutinII[21]42Kaempferol-3-O-β-D-glcp-(1⟶2)-β-D-glcp(1⟶2)-D-glucopyranosideII[21][22]43Nigeglanoside [kaempferol-3-O-β-D-galp-(1⟶3)-β-D-glcp-(1⟶3)-β-D-glucopyranoside]II[23]44Kaempferol-3-O-β-D-glcp-(1⟶2)-β-D-galp-(1⟶2)-glcpII[24]45Quercetin-3-O-β-D-glcp-(1⟶2)-β-D-galp-(1⟶2)-glcpI[25]46Quercetin-3-O-(6-O)-feroyl-β-D-glcp-(1⟶2)-β-D-galp-(1⟶2)-glucopyranosideI[25]47NigellosideII[17]48Kaempferol-3-O-α-L-rhap-(1⟶6)-β-D-glcp(1⟶2)-β-D-galp-(1⟶2)-β-D-glucopyranosideII[24]49Nigelflflavonoside AII[26]50Nigelflflavonoside BII[26]51Nigelflflavonoside CII[26]52Nigelflflavonoside DII[26]53Nigelflflavonoside EII[26]54Nigelflflavonoside FII[26]55Kaempferol-3-O-β-D-glucopyranosideIII[20]Triterpenoids56–6756α-HederinII[24]573-O-[α-L-rhap-(1⟶2)-α-L-arap]-28-O-[β-D-glcp]-HederageninII[24]583-O-[α-L-rhap-(1⟶2)-α-L-arap]-28-O-[β-D-glcp-(1⟶6)-β-D-glcp]-HederageninII[24]593-O-[α-L-rhap(1⟶2)-α-L-arap]-28-O-[α-L-rhap(1⟶4)-β-glcp(1⟶6)-β-D-glcp]-HederageninII[24]603-O-[β-D-xylp-(1⟶3)-α-L-rhap-(1⟶2)-α-L-arap]-HederageninII[24]613-O-[β-D-xylp-(1⟶3)-α-L-rhap-(1⟶2)-α-L-arap]-28-O-[β-D-glcp]-HederageninII[24]623-O-[β-D-xylp(1⟶3)-α-L-rhap-(1⟶2)-α-L-arap]-28-O-[α-L-rhap-(1⟶4)-β-D-glcp-L-(1⟶6)-β-D-glcp]-HederageninII[27]63HederageninII[28]64Eleutheroside KII[29]6511-Methoxy-16-hydroxy-17-acetoxy-3-O-[β-D-xylp(1⟶3)-α-L-rhap(1⟶4)-β-D-glcp]-hederageninI[30]66LanosterolI[31]67CyclolaudenolII[23]Steroids 68–7368β-SitosterolI II[23]69StigmasterolI[32]II[31]70CamphoralI[31]71CholesterolI[31]72ErgosterolI[31]73DaucosterolII[33]Phenolics 74–8774p-Hydroxybenzoic acidI[25]752-Methyl-5-isopropyl-p-diphenolII[32]762,4-Dihydroxyphenylacetic acidIII[5]773,4-Dihydroxy-phenylethanolIII[5]78Methyl-2, 4-dihydroxyphenylacetateIII[5]795,7-Dihydroxy-isobenzofuranoneII[34]805,7-Dihydroxy-6-(3-methyl-2-enyl)-isobenzofuranoneII[28]811-O-(2, 4-Dihydroxyphenylacetyl) glycerolIII[35]82Nigephenol AII[36]83Nigephenol BII[36]84Nigephenol CII[36]85Salfredin B11II[36]86p-Coumaric acidIII[20]87Caffeic acidIII[20]Monoterpenoids88–94886-Methoxythymol-3-O-β-D-glucopyranosideII[37]89[β-D-glcp-(6⟶1)-β-D-glcp]-2-Methyl-5-isopropyl-p-pairphenolic glycosideII[24]90trans-Sabinene hydrate methyl etherI[38]91Cis-Sabinene hydrate methyl etherI[38]921,2-Epoxy-menth-4(8)-eneI[38]931,2-Epoxy-menth-4-eneI[38]94Thymoquinone (TQ)I[39]Lipids95–9795Methyl nonadeca-15, 17-dienoateI[40]96Pentyl hexadec-12-enoateI[40]97Pentyl pentadec-11-enoateI[40]Saccharides98 & 9998NigellamoseII[33]99SaccharoseII[33]I:N. sativa seeds; II: N. glandulifera seeds; III: N. damascene seeds.


### 2.1. Alkaloids

Thirty-eight alkaloids (1–38) (Figure 1) were derived from seeds of Nigella genus plants. Natural alkaloids including the indazole ring are infrequent and hitherto identified only ten analogs. Compound 3, first natural alkaloid with an indazole ring, was isolated and identified by Rahman in 1985 [3]. Compound 8 was the first natural alkaloidal glycoside. Containing a highly cross-ring conjugated system, compound 13 was classified as pyrroloquinoline alkaloid, and compounds 14–16 were classified as norditerpenoid alkaloids according to their unique skeletons. The configuration at C-8a for compounds 14 and 15 was S, which was established by comparison of their experimental electronic circular dichroism (ECD) spectra with quantum chemical ECD calculation. Compounds 14–16 was separated and purified by pH-zone-refining countercurrent chromatography, and compound 13 was isolated by high-speed countercurrent chromatography [11]. Novel dolabellane-type diterpene alkaloids 17–26 were also rare in nature [12–14]. In addition, compounds 30–32 with unprecedented skeletons could be speculated to derive from the dimerization of thymoquinone (TQ) [18]. Notably, to date, natural indazole-type alkaloids have only been obtained from species of the genus Nigella and therefore considered as possible taxonomic markers in Nigella genus plants.Figure 1
Akaloids isolated fromNigella genus.


### 2.2. Flavonols

Seventeen flavonols (39–55) (Figure 2) have been obtained from the seeds of Nigella genus plants, which are mainly derived from N. glandulifera and N. sativa. The localizations and classes of the glycosyl or acetyl groups are shown as follows.Figure 2
Flavonols and sugar residues isolated fromNigella genus.


### 2.3. Triterpenoids

The seeds of this genus are rich in triterpenoid components, mostly with hederagenin as the basic skeleton. There are ten compounds (56–65) with hederagenin as their mother nucleus from genus Nigella. The linkage pattern and locations of glycosyl moieties are shown in Figure 3.Figure 3
Triterpenoids and sugar residues isolated from Nigella genus.


### 2.4. Steroids

There are six steroids (68–73) (Figure 4) isolated from the seeds of this genus, mostly existing in N. sativa seeds oil.Figure 4
Steroids isolated from theNigella genus.


### 2.5. Phenols

Twelve phenolic compounds (74–87) (Figure 5) were isolated from the seeds of this genus. Compounds 80 and 85 were isobenzofuranone derivatives. Compounds 82–84 contain hydroxymethyl moiety. Compounds 84 and 85 both observed an oxygen bridge between C-8a and C-2, an (Z)-3-methylbutenyl unit of the tetrasubstituted benzene ring.Figure 5
Phenols isolated from theNigella genus.


### 2.6. Others

In addition, other categories compounds were obtained fromN. glandulifera, such as monoterpenoids 88–89 [24, 37] and saccharides 98 and 99 [33]. Compounds 95–97 [40] were identified as novel lipids with long-chain aliphatic nature and unsaturated double bond from N. sativa. And, monoterpenoids 90–94 were derived from the volatile oil of N. sativa [38] (Figure 6).Figure 6
Monoterpenoids, saccharides, and lipids isolated from theNigella genus.The seeds ofNigella plants are affluent in lipids and oil, with the content of lipids at 35%–42% and the volatile oil accounting for 1.5%. As the main active constituent in volatile oil, compound 99 (TQ) was clarified possessing many pharmacological activities [39]. Hao and Ren [41] had identified 10 fatty acids from the seeds of N. glandulifera, among which linoleic acid was the most abundant. In addition, oleic acid, palmitic acid, and three glyceryl hexadecanoate were also found from the seeds of N. glandulifera.Moreover, two polysaccharides were determined inN. sativa seeds. BCWSP with average molecular weight about 800 kDa mainly contained arabinose (5.83%), galactose (5.76%), xylose (3.19%), glucose (3.18%), rhamnose (2.74%), and mannose (2.28%). And, the yield of the polysaccharides was 5.18% [42]. With the molecular weight determined as about 95 kDa, BCPP exhibited the content of rhamnose : arabinose : xylose : galactose : glucose in a ratio of 29 : 42 : 2 : 24 : 3 as main sugar residues and yielded approximately 1.5% [43].


## 2.1. Alkaloids

Thirty-eight alkaloids (1–38) (Figure 1) were derived from seeds of Nigella genus plants. Natural alkaloids including the indazole ring are infrequent and hitherto identified only ten analogs. Compound 3, first natural alkaloid with an indazole ring, was isolated and identified by Rahman in 1985 [3]. Compound 8 was the first natural alkaloidal glycoside. Containing a highly cross-ring conjugated system, compound 13 was classified as pyrroloquinoline alkaloid, and compounds 14–16 were classified as norditerpenoid alkaloids according to their unique skeletons. The configuration at C-8a for compounds 14 and 15 was S, which was established by comparison of their experimental electronic circular dichroism (ECD) spectra with quantum chemical ECD calculation. Compounds 14–16 was separated and purified by pH-zone-refining countercurrent chromatography, and compound 13 was isolated by high-speed countercurrent chromatography [11]. Novel dolabellane-type diterpene alkaloids 17–26 were also rare in nature [12–14]. In addition, compounds 30–32 with unprecedented skeletons could be speculated to derive from the dimerization of thymoquinone (TQ) [18]. Notably, to date, natural indazole-type alkaloids have only been obtained from species of the genus Nigella and therefore considered as possible taxonomic markers in Nigella genus plants.Figure 1
Akaloids isolated fromNigella genus.


## 2.2. Flavonols

Seventeen flavonols (39–55) (Figure 2) have been obtained from the seeds of Nigella genus plants, which are mainly derived from N. glandulifera and N. sativa. The localizations and classes of the glycosyl or acetyl groups are shown as follows.Figure 2
Flavonols and sugar residues isolated fromNigella genus.


## 2.3. Triterpenoids

The seeds of this genus are rich in triterpenoid components, mostly with hederagenin as the basic skeleton. There are ten compounds (56–65) with hederagenin as their mother nucleus from genus Nigella. The linkage pattern and locations of glycosyl moieties are shown in Figure 3.Figure 3
Triterpenoids and sugar residues isolated from Nigella genus.


## 2.4. Steroids

There are six steroids (68–73) (Figure 4) isolated from the seeds of this genus, mostly existing in N. sativa seeds oil.Figure 4
Steroids isolated from theNigella genus.


## 2.5. Phenols

Twelve phenolic compounds (74–87) (Figure 5) were isolated from the seeds of this genus. Compounds 80 and 85 were isobenzofuranone derivatives. Compounds 82–84 contain hydroxymethyl moiety. Compounds 84 and 85 both observed an oxygen bridge between C-8a and C-2, an (Z)-3-methylbutenyl unit of the tetrasubstituted benzene ring.Figure 5
Phenols isolated from theNigella genus.


## 2.6. Others

In addition, other categories compounds were obtained fromN. glandulifera, such as monoterpenoids 88–89 [24, 37] and saccharides 98 and 99 [33]. Compounds 95–97 [40] were identified as novel lipids with long-chain aliphatic nature and unsaturated double bond from N. sativa. And, monoterpenoids 90–94 were derived from the volatile oil of N. sativa [38] (Figure 6).Figure 6
Monoterpenoids, saccharides, and lipids isolated from theNigella genus.The seeds ofNigella plants are affluent in lipids and oil, with the content of lipids at 35%–42% and the volatile oil accounting for 1.5%. As the main active constituent in volatile oil, compound 99 (TQ) was clarified possessing many pharmacological activities [39]. Hao and Ren [41] had identified 10 fatty acids from the seeds of N. glandulifera, among which linoleic acid was the most abundant. In addition, oleic acid, palmitic acid, and three glyceryl hexadecanoate were also found from the seeds of N. glandulifera.Moreover, two polysaccharides were determined inN. sativa seeds. BCWSP with average molecular weight about 800 kDa mainly contained arabinose (5.83%), galactose (5.76%), xylose (3.19%), glucose (3.18%), rhamnose (2.74%), and mannose (2.28%). And, the yield of the polysaccharides was 5.18% [42]. With the molecular weight determined as about 95 kDa, BCPP exhibited the content of rhamnose : arabinose : xylose : galactose : glucose in a ratio of 29 : 42 : 2 : 24 : 3 as main sugar residues and yielded approximately 1.5% [43].


## 3. Pharmacological Effects

Many researches have been carried out, especially during the past two decades, on the effect ofNigella seeds extracts, oils, and isolated compounds in vivo or in vitro owing to their wide range of biological activities. As a most abundant oil constituent, thymoquinone has antioxidant, anti-inflammatory, immunomodulatory, antihistaminic, antimicrobial, and antitumor effects. In addition, many researches have indicated that thymoquinone had various pharmacological activities, proving to be responsible for oil activities. In addition, some clinical trials have been conducted on eligible patients to evaluate the effects of N. sativa seeds on glycemic control, inflammation, oxidative stress, and so on [44]. And, we have summarized the characteristics of several human studies regarding the effect of Nigella sativa seeds in Table 2.Table 2
Characteristics of human studies ofNigella sativa seeds.
AreaAuthor (date)SubjectsInterventionDosageDurationResultsAmelioration of oxidative stressFarhangi et al. [45]Hashimoto’s thyroiditis patients (n = 23 per group)Nigella sativa capsules1 g/day8 weeksSignificant increase in serum TAC, SOD, and reduction in MDA.Glycemic controlHebatallah et al. [46]T2DM patients (n = 21 per group)Nigella sativa capsules1.35 g/day3 monthsAmelioration of IR and significant reduction in alanine aminotransferase (ALT), TC, LDL, HDL, TG, and TAC comparable to metformin.Anti-inflammationHadi et al. [47]Rheumatoid arthritis patients (n = 23 per group)Nigella sativa oil capsules1 g/day8 weeks(1) Significant reduction of serum MDA, NO, and IL-10 compared with that of the placebo group.(2) No significant differences in serum TNF-α, SOD, catalase, and TAC compared with that of the placebo group.Gastric protectionMahvash et al. [48]H. pylori-infected patients (n = 24 per group)Nigella sativa capsules2 g/day8 weeks(1) Significant increase in theH. pylori eradication rate compared with that of the placebo group.(2) Significant decrease in dyspepsia symptoms (postprandial fullness, gastric pain, or burning and bloating).(3) Significant increase in dietary-intake, weight, and body mass index and improvement in physical health.Liver protectionKhonche et al. [49]Nonalcoholic fatty liver disease patients (n = 60 per group)Nigella sativa oil2.5 mL/day3 months(1) Significant improvement in hepatic steatosis compared with that of the placebo group.(2) Significant increase in ALT, AST, LDL, HDL, and TG compared with that of the placebo group.Kidney protectionMohammad et al. [50]Patients with renal stones (n = 27 per group)Nigella sativa capsules1 g/day10 weeksSignificant reduction in the stone size as compared with the placebo.Lung protectionAbdulrahman et al. [51]Asthmatic patients (n = 40 per group)Nigella sativa oil capsules1 g/day4 weeksSignificant improvement in asthma symptoms and pulmonary functions as compared with the placebo.


### 3.1. Antibacterial Activity

Many studies have discussed the antibacterial efficacy ofN. sativa seeds extracts, as well as oil and compounds. Ayeza et al. [52] found that the activity of the ethanolic extract was better than that of the methanolic extract against Escherichia coli, Vibrio parahaemolyticus, and Bacillus cereus (MIC value 0.25 mg/ml), while the methanolic extract was more active against Listeria monocytogenes. Another study indicated that the methanolic extract of N. sativa seeds had a stronger bactericidal activity than antibiotic ciprofloxacin against Corynebacterium, Staphylococcus aureus, and S. viridians by the disc diffusion assay [53]. As the antibiotic resistance is becoming a crucial problem, N. sativa seeds also have been tested against the resistance strains. The methanol extract of N. sativa seeds showed the MIC value in the range of 0.39–1.5 mg/mL (p<0.001) against methicillin-resistant S. aureus (MRSA) strains. Subsequently, in this research, when combined with N. sativa methanolic extract, cefoxitin inhibited MRSA strains at 0.312 μg/mL, which was 64 times lower than that of ceftoxitin alone. Development of this synergism might be a significant way to enhance the activity of ceftoxitin to alleviate the resistance process [54].In addition,N. sativa essential oil exhibited an activity on S. aureus, E. coli, and Pseudomonas aeruginosa with MIC values of 2.5, 8, and 2 μg/mL respectively, while the streptomycin group showed an MIC value in range of 20–100 μg/mL [55]. It was found that thymoquinone (TQ), which is the major constituent of the oil, exhibited positive effect against Clostridium difficile with the MIC at 10–40 μg/mL, while TQ showed activities against other microorganisms (C. perfringens, Bacteroides fragilis, and B. thetaiotaomicron) with the MIC value at 80–160 μg/mL [56]. It was also found that compounds 93 and 94 showed an activity against S. aureus with the zone of inhibition in the range of 9–11 mm by the agar diffusion technique with amphotericin B as the positive control [40].


### 3.2. Antifungal Activity

In addition,N. sativa essential oil was also a good fungal inhibitor, exhibiting activities on Microsporum gypseum (diameter of inhibition zone: 38 mm), Trichophyton rubrum (20 mm), and T. simii (35 mm), compared with ketoconazole (10, 15, and 32 mm, respectively) [57]. Another finding was that N. sativa essential oil could inhibit Candida albicans (MIC value at 2 μg/mL) and Aspergillus fumigatus (5 μg/mL) in comparison with fluconazole (5 μg/mL) [55]. It was also found that thymoquinone exhibited an activity against Trichophyton mentagrophytes, Microsporum canis, and M. gypseum by the disk diffusion method (with inhibition zone diameter >50 mm), while ketoconazole was in the range of 28–31 mm [58]. Owing to their antifungal effect, Nigella sativa oils can be considered for further investigations to develop antifungal agents.


### 3.3. Antiparasitic Activity

N. sativa aqueous extract had an activity against human Blastocystis hominnis, with an equivalent effect of metronidazole at 500 μg/mL [59]. The methanolic extract of N. sativa seeds significantly suppressed the Plasmodium yoelli nigeriensis growth by 94% at a dosage of 1.25 g/kg body weight (p<0.05) in the mice, while chloroquine showed 86% inhibitory rate in comparison with the untreated group. Moreover, P. yoelli infection led to a significant (p<0.05) decline in the activities of catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD). The extract of N. sativa seeds could restore the activities of these parameters to near normal [60]. In a recent study, it was found that thymoquinone could inhibit the growth of piroplasm parasites in vitro with IC50 values of 35.41, 7.35, 0.28, 74.05, and 67.34 μM for Babesia bovis, B. bigemina, B. divergens, Theileria equi, and B. caballi, respectively [61].


### 3.4. Antioxidant Activity

Some recent studies found that volatile oil, polysaccharide, and extracts inNigella plant seeds possessed an antioxidant activity. Antioxidant enzymes including CAT, SOD, GST, glutathione (GSH), and glutathione peroxidase (GSHPx) were the major constituents of the antioxidant system in most cells. And, antioxidant enzymes play a positive role in neutralizing the free radical-induced oxidative injury. It was found that pretreatment with thymoquinone could attenuate the inhibitory effect of H2O2 on the GSH level and superoxide dismutase activity. Moreover, the activation of the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway in H2O2-induced human retinal pigment epithelium (ARPE) cells was enhanced by thymoquinone. The results indicated that thymoquinone could protect ARPE cells from H2O2-induced oxidative stress through the Nrf2/HO-1 pathway [62]. Furthermore, a recent study was conducted on forty patients with Hashimoto's thyroiditis to evaluate the effect of powdered N. sativa seeds (1 g/day for 8 week) on oxidative stress. The result showed that treatment with N. sativa could increase the serum total antioxidant capacity (TAC) and SOD and reduce the MDA concentrations [45].Three terpenes95–97 isolated from N. sativa seeds showed effect to inhibit the oxidative stress in human skin WS-1 fibroblasts, with IC50 of 0.32, 0.005, and 0.43 mM, respectively [38]. A study was conducted on the polysaccharide fraction (named BCWSP) to test the antioxidant effect, and the results showed that the highest DPPH radical-scavenging activity (63.25%) was recorded at 1 mg/mL and the lowest (21.59%) was obtained at 0.2 mg/mL treated with polysaccharide BCWSP. The study revealed polysaccharide BCWSP possessed an antioxidant activity in a concentration-dependent manner [42].


### 3.5. Antidiabetes

Plant-derived medications have become a significant manner to treat the diabetes to reduce the adverse effect. Numerous studies have been conducted on the hypoglycemic activity of alkaloids ofN. glandulifera and oils of N. sativa. It was found that N. sativa seeds oil could downregulate the expression of the insulin receptor gene and upregulate the expression of insulin-like growth factor-1 (IGF-1) and PI3K compared with the control group. In addition, parameters like blood glucose, liposome composition, and tumor necrosis factor-α (TNF-α) were also reduced by N. sativa seed oil. [63]. It was also found that N. sativa seeds oil could inhibit α-glucosidase with IC50 0.55 mg/mL compared with acarbose (0.53 mg/mL) and thymoquinone (0.65 mg/mL) [64]. Another study was made to evaluate the activity of N. sativa seeds oil on type 2 diabetes mellitus (T2DM) patients. Results indicated that N. sativa oil was equivalent to metformin in losing weight. N. sativa seeds oil also demonstrated a reduction comparable with metformin on some lipid profile parameters like high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and insulin resistance (IR) [46].Alkaloids13–16 isolated from N. glandulifera showed protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with no obvious toxicity to A431 cells at 100 μM [11]. Compounds 14–16 could activate the phosphatidylinositide 3-kinase-protein kinase B (PI3K/Akt) phosphorylation and downregulate the expression of PTP1B protein in L6 moytubes. Western blot results also demonstrated that compounds 14–16 could inhibit PTP1B by activating the insulin receptor substrate-1/Akt and promote the glycogen synthesis via Akt-mediated glycogen synthase kinase 3 phosphorylation [65]. These alkaloids could serve as leading compounds for the investigation of antidiabetic medicine.


### 3.6. Anticancer Activity

The intrinsic pathway of apoptosis is under the regulation of proapoptotic (such as Bax) and antiapoptotic (such as Bcl-2) genes. Caspases and survivin are also responsible for the execution of apoptosis. Recently, a report was conducted to test the antiproliferative and apoptotic activities of potentN. sativa (named P1). Results revealed a concentration-dependent inhibition in MCF-7 cells. There was a reduction in the cell count with the raise in the concentration demonstrated by phase-contrast microscopy images. P1 could upregulate BAX and CASPASE-3 together with downregulation in survivin and BCL-2 gene expression [66]. Several preclinical researches indicated that TQ could induce apoptosis and restrain hepatocellular carcinoma (HCC) progression via different pathways. These results suggested potential applications of TQ for HCC treatment in clinical practices [67–71]. TQ was a perspective chemotherapeutic drug on gliomas and glioblastomas as it could cross the blood-brain barrier with selective virulence for glioblastoma cells in comparison with primary astrocytes [72]. Another study also showed that the eukaryotic elongation factor-2 kinase (eEF-2K) was highly expressed in triple-negative breast cancer cells, promoting cell proliferation, migration, and invasion. Results indicated that TQ could inhibit the protein and mRNA expression of eEF-2K. And, TQ could also promote the production of the tumor suppressor miR-603 as well as the inhibition of the NF-κB pathway [73].Flavonoids were the major active components ofN. glandulifera seeds to suppress the proliferation of breast cancer in a concentration-dependent way, by inhibiting the phosphorylation of janus kinase 2 protein in the janus kinase/signal transducer and activators of the transcription (JAK/STAT) signal pathway [74]. Compounds 9 and 33 exhibited cytotoxicity on T98G, U837, U251, and GL261 glioma cancer cell lines at 100 μm with cell viability ranging from 29% to 57% [6, 19]. Compound 56 could suppress tumors in mice in a concentration-dependent way after intraperitoneal injection [75]. Compounds 82–84 (IC50 range from 15.83 to 17.79 μM) showed a stronger activity against HepG2 cells than 85 (IC50 at 36.95 μM) by the MTT assay, owing to their hydroxymethyl moiety. Compound 83 exhibited inhibitory effects against four human tumor cell lines (Bel7402, HepG2, HCT-8, and A549) with IC50 values (7.69, 15.83, 11.39, and 20.06 μM) similar to 5-fluorouracil (10.07, 16.42, 6.30, and 14.15 μM), suggesting that the prenyl group could be responsible for mediating the cytotoxicity [35].


### 3.7. Anti-Inflammatory Analgesic Activity

Administration TQ of lipopolysaccharide/interferonγ- (LPS/IFNγ-) activated BV-2 microglial cells could increase the expression of neuroprotective proteins and decrease the expression inflammatory cytokines and genes of the NF-κB (nuclear factor-kappa B) pathway [76]. TQ suppressed the expression of TNF-α, interleukin-1β (IL-1β), monocyte chemotactic protein 1, and cyclooxygenase (Cox-2) in PDA cells dose- and time-dependently. TQ could also reduce the transport of NF-κB from the endochylema to the nucleus in PDA cells [77]. TQ could significantly decrease the levels of IL-6, IL-1b, TNF-α, and prostaglandin E2 (PGE2) but increase the IL-10 levels [78].In addition, in a study by Hadi et al. on 42 rheumatoid arthritis (RA) patients,N. sativa oil supplementation (1 g/day for 8 weeks) led to a significant reduction in serum malondialdehyde (MDA), NO, and IL-10 compared with the placebo group, indicating that N. sativa oil could improve the inflammation and reducing the oxidative stress in patients with RA [47]. Compounds 8 and 10 inhibited the lipopolysaccharide-induced nitric oxide emergence at 10 μm with inhibition rates 61% and 41%, respectively. Furthermore, compounds 95–98 could inhibit the nitric oxide secretion via lipopolysaccharide-activated RAW 264.7 macrophages [38].


### 3.8. Cardiovascular Activity and Vessel Protection

Compound30 (at 0.01 μM) could increase the cell viability from 50% to 96% in hypoxia/reoxygenation-induced H9c2 cardiomyocyte. The effect was comparable with verapamil, which was known for its protective effect on cardiomyocytes. [18]. A study showed the protective effects of TQ on the cardiac damage in BALB/c mice. The results demonstrated that TQ played a positive role in the treatment of sepsis-induced cardiac damage [79]. TQ pretreatment could repair the dimethylhydrazine-induced erythrocyte oxidative stress, anaemia, leukocytosis, and thrombocytosis [80]. A study demonstrated that thymoquinone possessed the ameliorative effects upon the pulmonary blood vessels damaged by LPS in a rat model [81].


### 3.9. Gastric Protection

Formation of free radicals and reactive oxygen seem to play a significant role in ulcerative and erosive lesions of the gastrointestinal tract. Therefore, treatments with antioxidants and free radicals scavengers could reduce the I/R-induced gastric mucosal damage. It was found thatN. sativa seed oil exhibited an elevation in lactate dehydrogenase and lipid peroxide level and reduced the content of SOD and GSH. Results revealed that N. sativa seed oil possessed a significant gastroprotective effect, which could be attributed to their FR scavenging ability. [82]. It was also found that TQ had novel gastroprotective mechanisms through suppressing the acid secretion, proton pump, and neutrophil infiltration and increasing the secretion of mucin and nitric oxide [83]. The N. sativa aqueous extract could replenish the ethanol-induced decreased gastric mucosal nonprotein sulfhydryl and gastric wall mucus content. It could also increase the gastric acid secretion of pylorus and prevent the formation of necrotic ulcer [84]. In a recent research by Mahvash [48] on 51 Helicobacter pylori infected patients with functional dyspepsia, the N. sativa treatment group (2 g/day for 8 week) significantly increased the H. pylori eradication rate compared with the placebo group. And, N. sativa could ameliorate the dyspepsia symptoms such as postprandial fullness, gastric pain, or burning and bloating. In addition, the results of administration of polysaccharide BCPP at 200 mg/kg b.w. for ten days demonstrated 85% healing of gastric ulcers. The increase in PGE2 extracellular signal-regulated kinase-2 (ERK-2) showed that BCPP could induce the PGE-2 synthesis via activating the ERK-2 mediated COX-2 activity. Upregulating the expression in matrix metalloproteinase-2 (MMP-2) and downregulating in MMP-9 indicated an indispensable process of gastric mucosal remodulation [53].


### 3.10. Liver Protection

Compounds18, 19, 21, 23, and 24 could ameliorate the triglyceride metabolism in high-glucose-pretreated HepG2 cells [14]. Compound 8 could regulate the glucose consumption mediated by the activation of AMPK, which showed more potent ability than metformin [6]. TQ (10 mg/kg) pretreatment could cause amelioration in the lipid peroxidation level and the activity of SOD and improve the histopathological influence induced by paraquate [85]. The therapeutic effect of N. sativa upon the cholestatic liver injury was probably via the attenuation of oxidative stress in the bile duct-ligated rat liver tissues [86]. TQ could reduce the serum bilirubin level in disease conditions leading to amelioration in hyperbilirubinemia and liver toxicity induced by cyclophosphamide [87]. TQ (12.5 mg/kg) pretreatment increased the level of malondialdehyde and nonprotein sulfhydryl (-SH) in the liver induced by CCl4, indicating TQ as a protective agent for chemical liver injury. However, high dose of TQ could contribute to oxidative the stress-induced liver injury with LD50 at 90.3 mg/mg [88]. A study by A. Khonche et al. [49] on 120 nonalcoholic fatty liver disease (NAFLD) patients showed that the treatment with the mixture (2.5 mL sativa seed oil, 1.25 mL honey, and 1.25 mL water/day.) for 3 months could improve liver steatosis and injury and blood levels of TG, LDL, and HDL in the NAFLD patients.


### 3.11. Kidney Protection

Owing to its antioxidant ability, TQ significantly inhibited lipid peroxidation and reduced the activities of SOD, GSHPx, and CAT in the cadmium-treated renal tissue [89]. TQ also played a potential protective role in renal toxicity induced by sodium nitrite, which could be attributed to suppress the oxidative stress and restore the balance between pre- and anti-inflammatory [90]. TQ significantly ameliorated the activities of SOD and GST and parameters levels of TNF-α, IL-6, and NADPH oxidase-4 (NOX-4), indicating a potential responsibility for TQ in the dioxyxylene-induced nephrotoxicity [91]. In a study by Mohammad et al. [50] on sixty patients with renal stones, the results demonstrated that N. sativa (1 g/day for 10 week) could help to prevent kidney stones and to remove early-forming stones.


### 3.12. Lung Protective Activity

Saponins obtained fromN. glandulifera significantly prolonged the incubation period of cough, while it increased the phenol red secretion of trachea to show a therapeutic effect on ammonia-induced cough in mice [74]. In comparison with the control group, flavonoids showed a significant relaxant effect, which was weaker than that of theophylline [92].Furthermore, TQ could attenuate symptoms of asthma mediated by the A2 adenosine receptor [93]. N. sativa oil could play a role as a potential centrally respiratory stimulant and mediate via the secretion of histamine with the activation of muscarinic cholinergic and histaminergic mechanisms [94]. In a research by Abdulrahman et al. [51] on 80 asthmatics, it was revealed that N. sativa oil supplementation (1 g/day) for 4 weeks could improve the asthma symptoms and pulmonary function.


### 3.13. Nervous System Impact

The exploratory behavior and exercise coordination test of the mice indicated that methanolic and aqueous extracts ofN. sativa seeds significantly inhibited the central nervous system [95]. N. sativa oil exerted a psychostimulative effect and regulated the neurotransmission of dopamine and serotonin, which were a great help of treatment of cognitive disorders [96].TQ showed the neuroprotective effects on MPP+ and rotenone toxicities via rescuing 83–100% of THir neurons in comparison with the rotenone-treated cultures [97]. Moreover, TQ had a neuroprotection potential against Aβ1–42 (Alzheimer’s amyloid-β peptide) toxicity in the rat hippocampal and cortical neurons. Therefore, it might be a potential candidate for Alzheimer’s disease treatment [98]. TQ might play an anticonvulsive role in small seizure epilepsy via the opioid receptor-mediated increase of gamma-aminobutyric acid [99].


### 3.14. Diuretics

Administration with the ethanol extract ofN. sativa (100 mg·kg−1) in Wistar Bratislava rats could lead to an increase in the urine volume, which was less than the volume when furosemide was used as a positive drug. The extract of N. sativa showed a better natriuretic effect than kaluretic effect. However, for N. damascena, the diuretic activity was not due to an increase in the kaluretic effect but mostly to a decrease in Na+ excretion [100].


### 3.15. Other Activities

Compounds76–78 from N. damascena showed an estrogenic activity in a dose-dependent manner, suggesting that phenolic compounds contributed to regulate menstruation [5]. Thymoquinone had a positive effect upon postoperative adhesions on an experimental abdominal adhesion model [101].


## 3.1. Antibacterial Activity

Many studies have discussed the antibacterial efficacy ofN. sativa seeds extracts, as well as oil and compounds. Ayeza et al. [52] found that the activity of the ethanolic extract was better than that of the methanolic extract against Escherichia coli, Vibrio parahaemolyticus, and Bacillus cereus (MIC value 0.25 mg/ml), while the methanolic extract was more active against Listeria monocytogenes. Another study indicated that the methanolic extract of N. sativa seeds had a stronger bactericidal activity than antibiotic ciprofloxacin against Corynebacterium, Staphylococcus aureus, and S. viridians by the disc diffusion assay [53]. As the antibiotic resistance is becoming a crucial problem, N. sativa seeds also have been tested against the resistance strains. The methanol extract of N. sativa seeds showed the MIC value in the range of 0.39–1.5 mg/mL (p<0.001) against methicillin-resistant S. aureus (MRSA) strains. Subsequently, in this research, when combined with N. sativa methanolic extract, cefoxitin inhibited MRSA strains at 0.312 μg/mL, which was 64 times lower than that of ceftoxitin alone. Development of this synergism might be a significant way to enhance the activity of ceftoxitin to alleviate the resistance process [54].In addition,N. sativa essential oil exhibited an activity on S. aureus, E. coli, and Pseudomonas aeruginosa with MIC values of 2.5, 8, and 2 μg/mL respectively, while the streptomycin group showed an MIC value in range of 20–100 μg/mL [55]. It was found that thymoquinone (TQ), which is the major constituent of the oil, exhibited positive effect against Clostridium difficile with the MIC at 10–40 μg/mL, while TQ showed activities against other microorganisms (C. perfringens, Bacteroides fragilis, and B. thetaiotaomicron) with the MIC value at 80–160 μg/mL [56]. It was also found that compounds 93 and 94 showed an activity against S. aureus with the zone of inhibition in the range of 9–11 mm by the agar diffusion technique with amphotericin B as the positive control [40].


## 3.2. Antifungal Activity

In addition,N. sativa essential oil was also a good fungal inhibitor, exhibiting activities on Microsporum gypseum (diameter of inhibition zone: 38 mm), Trichophyton rubrum (20 mm), and T. simii (35 mm), compared with ketoconazole (10, 15, and 32 mm, respectively) [57]. Another finding was that N. sativa essential oil could inhibit Candida albicans (MIC value at 2 μg/mL) and Aspergillus fumigatus (5 μg/mL) in comparison with fluconazole (5 μg/mL) [55]. It was also found that thymoquinone exhibited an activity against Trichophyton mentagrophytes, Microsporum canis, and M. gypseum by the disk diffusion method (with inhibition zone diameter >50 mm), while ketoconazole was in the range of 28–31 mm [58]. Owing to their antifungal effect, Nigella sativa oils can be considered for further investigations to develop antifungal agents.


## 3.3. Antiparasitic Activity

N. sativa aqueous extract had an activity against human Blastocystis hominnis, with an equivalent effect of metronidazole at 500 μg/mL [59]. The methanolic extract of N. sativa seeds significantly suppressed the Plasmodium yoelli nigeriensis growth by 94% at a dosage of 1.25 g/kg body weight (p<0.05) in the mice, while chloroquine showed 86% inhibitory rate in comparison with the untreated group. Moreover, P. yoelli infection led to a significant (p<0.05) decline in the activities of catalase (CAT), glutathione-S-transferase (GST) and superoxide dismutase (SOD). The extract of N. sativa seeds could restore the activities of these parameters to near normal [60]. In a recent study, it was found that thymoquinone could inhibit the growth of piroplasm parasites in vitro with IC50 values of 35.41, 7.35, 0.28, 74.05, and 67.34 μM for Babesia bovis, B. bigemina, B. divergens, Theileria equi, and B. caballi, respectively [61].


## 3.4. Antioxidant Activity

Some recent studies found that volatile oil, polysaccharide, and extracts inNigella plant seeds possessed an antioxidant activity. Antioxidant enzymes including CAT, SOD, GST, glutathione (GSH), and glutathione peroxidase (GSHPx) were the major constituents of the antioxidant system in most cells. And, antioxidant enzymes play a positive role in neutralizing the free radical-induced oxidative injury. It was found that pretreatment with thymoquinone could attenuate the inhibitory effect of H2O2 on the GSH level and superoxide dismutase activity. Moreover, the activation of the nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) pathway in H2O2-induced human retinal pigment epithelium (ARPE) cells was enhanced by thymoquinone. The results indicated that thymoquinone could protect ARPE cells from H2O2-induced oxidative stress through the Nrf2/HO-1 pathway [62]. Furthermore, a recent study was conducted on forty patients with Hashimoto's thyroiditis to evaluate the effect of powdered N. sativa seeds (1 g/day for 8 week) on oxidative stress. The result showed that treatment with N. sativa could increase the serum total antioxidant capacity (TAC) and SOD and reduce the MDA concentrations [45].Three terpenes95–97 isolated from N. sativa seeds showed effect to inhibit the oxidative stress in human skin WS-1 fibroblasts, with IC50 of 0.32, 0.005, and 0.43 mM, respectively [38]. A study was conducted on the polysaccharide fraction (named BCWSP) to test the antioxidant effect, and the results showed that the highest DPPH radical-scavenging activity (63.25%) was recorded at 1 mg/mL and the lowest (21.59%) was obtained at 0.2 mg/mL treated with polysaccharide BCWSP. The study revealed polysaccharide BCWSP possessed an antioxidant activity in a concentration-dependent manner [42].


## 3.5. Antidiabetes

Plant-derived medications have become a significant manner to treat the diabetes to reduce the adverse effect. Numerous studies have been conducted on the hypoglycemic activity of alkaloids ofN. glandulifera and oils of N. sativa. It was found that N. sativa seeds oil could downregulate the expression of the insulin receptor gene and upregulate the expression of insulin-like growth factor-1 (IGF-1) and PI3K compared with the control group. In addition, parameters like blood glucose, liposome composition, and tumor necrosis factor-α (TNF-α) were also reduced by N. sativa seed oil. [63]. It was also found that N. sativa seeds oil could inhibit α-glucosidase with IC50 0.55 mg/mL compared with acarbose (0.53 mg/mL) and thymoquinone (0.65 mg/mL) [64]. Another study was made to evaluate the activity of N. sativa seeds oil on type 2 diabetes mellitus (T2DM) patients. Results indicated that N. sativa oil was equivalent to metformin in losing weight. N. sativa seeds oil also demonstrated a reduction comparable with metformin on some lipid profile parameters like high-density lipoprotein (HDL), low-density lipoprotein (LDL), total cholesterol (TC), and insulin resistance (IR) [46].Alkaloids13–16 isolated from N. glandulifera showed protein tyrosine phosphatase 1B (PTP1B) inhibitory activity with no obvious toxicity to A431 cells at 100 μM [11]. Compounds 14–16 could activate the phosphatidylinositide 3-kinase-protein kinase B (PI3K/Akt) phosphorylation and downregulate the expression of PTP1B protein in L6 moytubes. Western blot results also demonstrated that compounds 14–16 could inhibit PTP1B by activating the insulin receptor substrate-1/Akt and promote the glycogen synthesis via Akt-mediated glycogen synthase kinase 3 phosphorylation [65]. These alkaloids could serve as leading compounds for the investigation of antidiabetic medicine.


## 3.6. Anticancer Activity

The intrinsic pathway of apoptosis is under the regulation of proapoptotic (such as Bax) and antiapoptotic (such as Bcl-2) genes. Caspases and survivin are also responsible for the execution of apoptosis. Recently, a report was conducted to test the antiproliferative and apoptotic activities of potentN. sativa (named P1). Results revealed a concentration-dependent inhibition in MCF-7 cells. There was a reduction in the cell count with the raise in the concentration demonstrated by phase-contrast microscopy images. P1 could upregulate BAX and CASPASE-3 together with downregulation in survivin and BCL-2 gene expression [66]. Several preclinical researches indicated that TQ could induce apoptosis and restrain hepatocellular carcinoma (HCC) progression via different pathways. These results suggested potential applications of TQ for HCC treatment in clinical practices [67–71]. TQ was a perspective chemotherapeutic drug on gliomas and glioblastomas as it could cross the blood-brain barrier with selective virulence for glioblastoma cells in comparison with primary astrocytes [72]. Another study also showed that the eukaryotic elongation factor-2 kinase (eEF-2K) was highly expressed in triple-negative breast cancer cells, promoting cell proliferation, migration, and invasion. Results indicated that TQ could inhibit the protein and mRNA expression of eEF-2K. And, TQ could also promote the production of the tumor suppressor miR-603 as well as the inhibition of the NF-κB pathway [73].Flavonoids were the major active components ofN. glandulifera seeds to suppress the proliferation of breast cancer in a concentration-dependent way, by inhibiting the phosphorylation of janus kinase 2 protein in the janus kinase/signal transducer and activators of the transcription (JAK/STAT) signal pathway [74]. Compounds 9 and 33 exhibited cytotoxicity on T98G, U837, U251, and GL261 glioma cancer cell lines at 100 μm with cell viability ranging from 29% to 57% [6, 19]. Compound 56 could suppress tumors in mice in a concentration-dependent way after intraperitoneal injection [75]. Compounds 82–84 (IC50 range from 15.83 to 17.79 μM) showed a stronger activity against HepG2 cells than 85 (IC50 at 36.95 μM) by the MTT assay, owing to their hydroxymethyl moiety. Compound 83 exhibited inhibitory effects against four human tumor cell lines (Bel7402, HepG2, HCT-8, and A549) with IC50 values (7.69, 15.83, 11.39, and 20.06 μM) similar to 5-fluorouracil (10.07, 16.42, 6.30, and 14.15 μM), suggesting that the prenyl group could be responsible for mediating the cytotoxicity [35].


## 3.7. Anti-Inflammatory Analgesic Activity

Administration TQ of lipopolysaccharide/interferonγ- (LPS/IFNγ-) activated BV-2 microglial cells could increase the expression of neuroprotective proteins and decrease the expression inflammatory cytokines and genes of the NF-κB (nuclear factor-kappa B) pathway [76]. TQ suppressed the expression of TNF-α, interleukin-1β (IL-1β), monocyte chemotactic protein 1, and cyclooxygenase (Cox-2) in PDA cells dose- and time-dependently. TQ could also reduce the transport of NF-κB from the endochylema to the nucleus in PDA cells [77]. TQ could significantly decrease the levels of IL-6, IL-1b, TNF-α, and prostaglandin E2 (PGE2) but increase the IL-10 levels [78].In addition, in a study by Hadi et al. on 42 rheumatoid arthritis (RA) patients,N. sativa oil supplementation (1 g/day for 8 weeks) led to a significant reduction in serum malondialdehyde (MDA), NO, and IL-10 compared with the placebo group, indicating that N. sativa oil could improve the inflammation and reducing the oxidative stress in patients with RA [47]. Compounds 8 and 10 inhibited the lipopolysaccharide-induced nitric oxide emergence at 10 μm with inhibition rates 61% and 41%, respectively. Furthermore, compounds 95–98 could inhibit the nitric oxide secretion via lipopolysaccharide-activated RAW 264.7 macrophages [38].


## 3.8. Cardiovascular Activity and Vessel Protection

Compound30 (at 0.01 μM) could increase the cell viability from 50% to 96% in hypoxia/reoxygenation-induced H9c2 cardiomyocyte. The effect was comparable with verapamil, which was known for its protective effect on cardiomyocytes. [18]. A study showed the protective effects of TQ on the cardiac damage in BALB/c mice. The results demonstrated that TQ played a positive role in the treatment of sepsis-induced cardiac damage [79]. TQ pretreatment could repair the dimethylhydrazine-induced erythrocyte oxidative stress, anaemia, leukocytosis, and thrombocytosis [80]. A study demonstrated that thymoquinone possessed the ameliorative effects upon the pulmonary blood vessels damaged by LPS in a rat model [81].


## 3.9. Gastric Protection

Formation of free radicals and reactive oxygen seem to play a significant role in ulcerative and erosive lesions of the gastrointestinal tract. Therefore, treatments with antioxidants and free radicals scavengers could reduce the I/R-induced gastric mucosal damage. It was found thatN. sativa seed oil exhibited an elevation in lactate dehydrogenase and lipid peroxide level and reduced the content of SOD and GSH. Results revealed that N. sativa seed oil possessed a significant gastroprotective effect, which could be attributed to their FR scavenging ability. [82]. It was also found that TQ had novel gastroprotective mechanisms through suppressing the acid secretion, proton pump, and neutrophil infiltration and increasing the secretion of mucin and nitric oxide [83]. The N. sativa aqueous extract could replenish the ethanol-induced decreased gastric mucosal nonprotein sulfhydryl and gastric wall mucus content. It could also increase the gastric acid secretion of pylorus and prevent the formation of necrotic ulcer [84]. In a recent research by Mahvash [48] on 51 Helicobacter pylori infected patients with functional dyspepsia, the N. sativa treatment group (2 g/day for 8 week) significantly increased the H. pylori eradication rate compared with the placebo group. And, N. sativa could ameliorate the dyspepsia symptoms such as postprandial fullness, gastric pain, or burning and bloating. In addition, the results of administration of polysaccharide BCPP at 200 mg/kg b.w. for ten days demonstrated 85% healing of gastric ulcers. The increase in PGE2 extracellular signal-regulated kinase-2 (ERK-2) showed that BCPP could induce the PGE-2 synthesis via activating the ERK-2 mediated COX-2 activity. Upregulating the expression in matrix metalloproteinase-2 (MMP-2) and downregulating in MMP-9 indicated an indispensable process of gastric mucosal remodulation [53].


## 3.10. Liver Protection

Compounds18, 19, 21, 23, and 24 could ameliorate the triglyceride metabolism in high-glucose-pretreated HepG2 cells [14]. Compound 8 could regulate the glucose consumption mediated by the activation of AMPK, which showed more potent ability than metformin [6]. TQ (10 mg/kg) pretreatment could cause amelioration in the lipid peroxidation level and the activity of SOD and improve the histopathological influence induced by paraquate [85]. The therapeutic effect of N. sativa upon the cholestatic liver injury was probably via the attenuation of oxidative stress in the bile duct-ligated rat liver tissues [86]. TQ could reduce the serum bilirubin level in disease conditions leading to amelioration in hyperbilirubinemia and liver toxicity induced by cyclophosphamide [87]. TQ (12.5 mg/kg) pretreatment increased the level of malondialdehyde and nonprotein sulfhydryl (-SH) in the liver induced by CCl4, indicating TQ as a protective agent for chemical liver injury. However, high dose of TQ could contribute to oxidative the stress-induced liver injury with LD50 at 90.3 mg/mg [88]. A study by A. Khonche et al. [49] on 120 nonalcoholic fatty liver disease (NAFLD) patients showed that the treatment with the mixture (2.5 mL sativa seed oil, 1.25 mL honey, and 1.25 mL water/day.) for 3 months could improve liver steatosis and injury and blood levels of TG, LDL, and HDL in the NAFLD patients.


## 3.11. Kidney Protection

Owing to its antioxidant ability, TQ significantly inhibited lipid peroxidation and reduced the activities of SOD, GSHPx, and CAT in the cadmium-treated renal tissue [89]. TQ also played a potential protective role in renal toxicity induced by sodium nitrite, which could be attributed to suppress the oxidative stress and restore the balance between pre- and anti-inflammatory [90]. TQ significantly ameliorated the activities of SOD and GST and parameters levels of TNF-α, IL-6, and NADPH oxidase-4 (NOX-4), indicating a potential responsibility for TQ in the dioxyxylene-induced nephrotoxicity [91]. In a study by Mohammad et al. [50] on sixty patients with renal stones, the results demonstrated that N. sativa (1 g/day for 10 week) could help to prevent kidney stones and to remove early-forming stones.


## 3.12. Lung Protective Activity

Saponins obtained fromN. glandulifera significantly prolonged the incubation period of cough, while it increased the phenol red secretion of trachea to show a therapeutic effect on ammonia-induced cough in mice [74]. In comparison with the control group, flavonoids showed a significant relaxant effect, which was weaker than that of theophylline [92].Furthermore, TQ could attenuate symptoms of asthma mediated by the A2 adenosine receptor [93]. N. sativa oil could play a role as a potential centrally respiratory stimulant and mediate via the secretion of histamine with the activation of muscarinic cholinergic and histaminergic mechanisms [94]. In a research by Abdulrahman et al. [51] on 80 asthmatics, it was revealed that N. sativa oil supplementation (1 g/day) for 4 weeks could improve the asthma symptoms and pulmonary function.


## 3.13. Nervous System Impact

The exploratory behavior and exercise coordination test of the mice indicated that methanolic and aqueous extracts ofN. sativa seeds significantly inhibited the central nervous system [95]. N. sativa oil exerted a psychostimulative effect and regulated the neurotransmission of dopamine and serotonin, which were a great help of treatment of cognitive disorders [96].TQ showed the neuroprotective effects on MPP+ and rotenone toxicities via rescuing 83–100% of THir neurons in comparison with the rotenone-treated cultures [97]. Moreover, TQ had a neuroprotection potential against Aβ1–42 (Alzheimer’s amyloid-β peptide) toxicity in the rat hippocampal and cortical neurons. Therefore, it might be a potential candidate for Alzheimer’s disease treatment [98]. TQ might play an anticonvulsive role in small seizure epilepsy via the opioid receptor-mediated increase of gamma-aminobutyric acid [99].


## 3.14. Diuretics

Administration with the ethanol extract ofN. sativa (100 mg·kg−1) in Wistar Bratislava rats could lead to an increase in the urine volume, which was less than the volume when furosemide was used as a positive drug. The extract of N. sativa showed a better natriuretic effect than kaluretic effect. However, for N. damascena, the diuretic activity was not due to an increase in the kaluretic effect but mostly to a decrease in Na+ excretion [100].


## 3.15. Other Activities

Compounds76–78 from N. damascena showed an estrogenic activity in a dose-dependent manner, suggesting that phenolic compounds contributed to regulate menstruation [5]. Thymoquinone had a positive effect upon postoperative adhesions on an experimental abdominal adhesion model [101].


## 4. Conclusions and Future Prospects

There are more than 20 species ofNigella genus, but only N. glandulifera, N. sativa, and N. damascena have been studied. The bioactivities of N. sativa seeds are mainly attributed to volatile oils, alkaloids, and steroids, while N. glandulifera mostly contains saponins, flavonoid glycosides, and phenolic compounds. Seeds of Nigella plants can be used as dietary nutritional supplements, expelling agents, diuretics, and preservatives, playing a positive role in antibacterial, anti-inflammatory, antioxidant, antitumor, and lipid-lowering activities and liver protection on the basis of various biological active substances such as volatile oil, saponin, flavonoids, and alkaloids.TQ is the major active component in the essential oil ofN. sativa seeds with anti-inflammatory, antioxidant, antidiabetic, cough and asthma, anticancer, liver protection, and neuroprotective functions. The extract’s functions on the basis of single or multiple chemical constituents are ambiguous. Many evidences indicate that TQ should be studied further in the medical treatment. And, further exploration of the pharmacological effect will scientifically explain the traditional application of the seeds of Nigella, providing a theoretical basis for the further development and utilization of Nigella seeds.



---

*Source: 6756835-2020-06-19.xml*