# Remedy/Nutraceuticals

Def. a "nutrient or food believed to have curative properties" or a "food used as a drug" is called a nutraceutical.
Def. "a source of nourishment, such as food, that can be metabolized by an organism to give energy and build tissue" is called a nutrient.
Def. "any [solid] substance [that] can be consumed by living organisms, especially [by eating], [in order to sustain life]" or "anything that nourishes or sustains" is called a food.

## Alpha-lipoic acids

"Alpha-Lipoic Acid is a naturally occurring micronutrient, synthesized in small amounts by plants and animals (including humans), with antioxidant and potential chemopreventive activities. Alpha-lipoic acid acts as a free radical scavenger and assists in repairing oxidative damage and regenerates endogenous antioxidants, including vitamins C and E and glutathione. This agent also promotes glutathione synthesis. In addition, alpha-lipoic acid exerts metal chelating capacities and functions as a cofactor in various mitochondrial enzyme complexes involved in the decarboxylation of alpha-keto acids."

## Cynarines

Artichoke contains the bioactive agents apigenin and luteolin.
Apigenin (4′,5,7-trihydroxyflavone), found in many plants, is a natural product belonging to the flavone class that is the aglycone of several naturally occurring glycosides.
Apigenin is found in many fruits and vegetables, but parsley, celery, celeriac, and chamomile tea are the most common sources. Apigenin is particularly abundant in the flowers of chamomile plants, constituting 68% of total flavonoids. Dried parsley can contain about 45 mg/gram and dried chamomile flower about 3-5 mg/gram apigenin. The apigenin content of fresh parsley is reportedly 215.5 mg/100 grams, which is much higher than the next highest food source, green celery hearts providing 19.1 mg/100 grams.
Luteolin is a flavone, a type of flavonoid, with a yellow crystalline appearance. Luteolin can function as either an antioxidant or a pro-oxidant and plants rich in luteolin have been used in Chinese traditional medicine
Luteolin is most often found in leaves, but it is also seen in rinds, barks, clover blossom, and ragweed pollen. It has also been isolated from the aromatic flowering plant, Salvia tomentosa in the mint family, Lamiaceae.
Dietary sources include celery, broccoli, artichoke, Bell pepper (green pepper), parsley, thyme, dandelion, perilla, chamomile tea, carrots, olive oil, peppermint, rosemary, navel oranges, and oregano. It can also be found in the seeds of the palm Aiphanes aculeata.
The total antioxidant capacity of artichoke flower heads is one of the highest reported for vegetables. Cynarine is a chemical constituent in Cynara. The majority of the cynarine found in artichoke is located in the pulp of the leaves, though dried leaves and stems of artichoke also contain it.
Cynarine is a hydroxycinnamic acid derivative and a biologically active chemical constituent of artichoke (Cynara cardunculus).

## Fatty acids

Def. any "of a class of aliphatic carboxylic acids, of general formula C$_n$H$_{2n+1}$COOH, that occur combined with glycerol as animal or vegetable oils and fats" is called a fatty acid.
"Only those with an even number of carbon atoms are normally found in natural fats"
Usage notes: "The above general formula applies to the saturated fatty acids. Remove 2 hydrogen atoms for an unsaturated fatty acid, and 2 hydrogen atoms for every double bond in a polyunsaturated faty acid."
In biochemistry, a fatty acid is a carboxylic acid with a long aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, from 4 to 28. Fatty acids are a major component of the lipids (up to 70 wt%) in some species such as microalgae but in some other organisms are not found in their standalone form, but instead exist as three main classes of esters: triglycerides, phospholipids, and cholesteryl esters.

### Types of fatty acids

Fatty acids are classified in many ways: by length, by saturation vs unsaturation, by even vs odd carbon content, and by linear vs branched.

### Length of fatty acids

* Short-chain fatty acids (SCFA) are fatty acids with aliphatic tails of five or fewer carbons (e.g. butyric acid).
* Medium-chain fatty acids (MCFA) are fatty acids with aliphatic tails of 6 to 12 carbons, which can form medium-chain triglycerides.
* Long-chain fatty acids (LCFA) are fatty acids with aliphatic tails of 13 to 21 carbons.
* Very long chain fatty acids (VLCFA) are fatty acids with aliphatic tails of 22 or more carbons.

### Saturated fatty acids

Saturated fatty acids have no C=C double bonds. They have the same formula CH$_3$(CH$_2$)$_n$COOH, with variations in "n". An important saturated fatty acid is stearic acid (n = 16), which when neutralized with lye is the most common form of soap.
Examples of saturated fatty acids :
| Common name | Chemical structure | C:D |
| Caprylic acid | CH$_3$(CH$_2$)$_6$COOH | 8:0 |
| Capric acid | CH$_3$(CH$_2$)$_8$COOH | 10:0 |
| Lauric acid | CH$_3$(CH$_2$)$_{10}$COOH | 12:0 |
| Myristic acid | CH$_3$(CH$_2$)$_{12}$COOH | 14:0 |
| Palmitic acid | CH$_3$(CH$_2$)$_{14}$COOH | 16:0 |
| Stearic acid | CH$_3$(CH$_2$)$_{16}$COOH | 18:0 |
| Arachidic acid | CH$_3$(CH$_2$)$_{18}$COOH | 20:0 |
| Behenic acid | CH$_3$(CH$_2$)$_{20}$COOH | 22:0 |
| Lignoceric acid | CH$_3$(CH$_2$)$_{22}$COOH | 24:0 |
| Cerotic acid | CH$_3$(CH$_2$)$_{24}$COOH | 26:0 |

### Unsaturated fatty acids

Unsaturated fatty acids have one or more C=C double bonds. The C=C double bonds can give either cis or trans isomers.

#### cis

    A cis configuration means that the two hydrogen atoms adjacent to the double bond stick out on the same side of the chain. The rigidity of the double bond freezes its conformation and, in the case of the cis isomer, causes the chain to bend and restricts the conformational freedom of the fatty acid. The more double bonds the chain has in the cis configuration, the less flexibility it has. When a chain has many cis bonds, it becomes quite curved in its most accessible conformations. For example, oleic acid, with one double bond, has a "kink" in it, whereas linoleic acid, with two double bonds, has a more pronounced bend. α-Linolenic acid, with three double bonds, favors a hooked shape. The effect of this is that, in restricted environments, such as when fatty acids are part of a phospholipid in a lipid bilayer or triglycerides in lipid droplets, cis bonds limit the ability of fatty acids to be closely packed, and therefore can affect the melting temperature of the membrane or of the fat. Cis unsaturated fatty acids, however, increase cellular membrane fluidity, whereas trans unsaturated fatty acids do not.

#### trans

    A trans configuration, by contrast, means that the adjacent two hydrogen atoms lie on opposite sides of the chain. As a result, they do not cause the chain to bend much, and their shape is similar to straight saturated fatty acids.
In most naturally occurring unsaturated fatty acids, each double bond has three (omega-3 fatty acid (n-3), six (omega-6 fatty acid (n-6), or nine (omega-9 fatty acid n-9) carbon atoms after it, and all double bonds have a cis configuration. Most fatty acids in the trans configuration (trans fats) are not found in nature and are the result of human processing (e.g., hydrogenation). Some trans fatty acids also occur naturally in the milk and meat of ruminants (such as cattle and sheep). They are produced, by fermentation, in the rumen of these animals. They are also found in dairy products from milk of ruminants, and may be also found in breast milk of women who obtained them from their diet.
The geometric differences between the various types of unsaturated fatty acids, as well as between saturated and unsaturated fatty acids, play an important role in biological processes, and in the construction of biological structures (such as cell membranes).
Examples of Unsaturated Fatty Acids :
| Common name | Chemical structure | Δ$^x$ | C:D | IUPAC | n−x |
| Myristoleic acid | CH$_3$(CH$_2$)$_3$CH=CH(CH$_2$)$_7$COOH | cis-Δ$^9$ | 14:1 | 14:1(9) | n−5 |
| Palmitoleic acid | CH$_3$(CH$_2$)$_5$CH=CH(CH$_2$)$_7$COOH | cis-Δ$^9$ | 16:1 | 16:1(9) | n−7 |
| Sapienic acid | CH$_3$(CH$_2$)$_8$CH=CH(CH$_2$)$_4$COOH | cis-Δ$^6$ | 16:1 | 16:1(6) | n−10 |
| Oleic acid | CH$_3$(CH$_2$)$_7$CH=CH(CH$_2$)$_7$COOH | cis-Δ$^9$ | 18:1 | 18:1(9) | omega-9 fatty acid (n−9) |
| Elaidic acid | CH$_3$(CH$_2$)$_7$CH=CH(CH$_2$)$_7$COOH | trans-Δ$^9$ | 18:1 | 18:1(9t) | omega-9 fatty acid (n−9) |
| Vaccenic acid | CH$_3$(CH$_2$)$_5$CH=CH(CH$_2$)$_9$COOH | trans-Δ$^{11}$ | 18:1 | 18:1(11t) | n−7 |
| Linoleic acid | CH$_3$(CH$_2$)$_4$CH=CHCH$_2$CH=CH(CH$_2$)$_7$COOH | cis,cis-Δ$^9$,Δ$^{12}$ | 18:2 | 18:2(9,12) | omega-6 fatty acid (n−6) |
| Linoelaidic acid | CH$_3$(CH$_2$)$_4$CH=CHCH$_2$CH=CH(CH$_2$)$_7$COOH | trans,trans-Δ$^9$,Δ$^{12}$ | 18:2 | 18:2(9t,12t) | omega-6 fatty acid (n−6) |
| α-Linolenic acid | CH$_3$CH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CH(CH$_2$)$_7$COOH | cis,cis,cis-Δ$^9$,Δ$^{12}$,Δ$^{15}$ | 18:3 | 18:3(9,12,15) | omega-3 fatty acid (n−30) |
| Arachidonic acid | CH$_3$(CH$_2$)$_4$CH=CHCH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CH(CH$_2$)$_3$COOH | cis,cis,cis,cis-Δ$^5$Δ$^8$,Δ$^{11}$,Δ$^{14}$ | 20:4 | 20:4(5,8,11,14) | n−6 |
| Eicosapentaenoic acid | CH$_3$CH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CH(CH$_2$)$_3$COOH | cis,cis,cis,cis,cis-Δ$^5$,Δ$^8$,Δ$^{11}$,Δ$^{14}$,Δ$^{17}$ | 20:5 | 20:5(5,8,11,14,17) | omega-3 fatty acid (n−3) |
| Erucic acid | CH$_3$(CH$_2$)$_7$CH=CH(CH$_2$)$_{11}$COOH | cis-Δ$^{13}$ | 22:1 | 22:1(13) | omega-9 fatty acid (n−9) |
| Docosahexaenoic acid | CH$_3$CH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CHCH$_2$CH=CH(CH$_2$)$_2$COOH | cis,cis,cis,cis,cis,cis-Δ$^4$,Δ$^7$,Δ$^{10}$,Δ$^{13}$,Δ$^{16}$,Δ$^{19}$ | 22:6 | 22:6(4,7,10,13,16,19) | omega-3 fatty acid (n−3) |

#### Oleic acid

Oleic acid is the most common fatty acid in nature. The salts and esters of oleic acid are called oleates.
Oleic acid is found in fats (triglycerides), the phospholipids that make membranes, cholesterol esters, and wax esters.
Oleic acid makes up 59–75% of pecan oil, 61% of canola oil, 36–67% of peanut oil, 60% of macadamia oil, 20–80% of sunflower oil, 15–20% of grape seed oil, sea buckthorn oil, 40% of sesame oil, and 14% of poppyseed oil. High oleic variants of plant sources such as sunflower (~80%) and canola oil (70%) also have been developed. It also comprises 22.18% of the fats from the fruit of the durian species, Durio graveolens. Karuka contains 52.39% oleic acid. It is abundantly present in many animal fats, constituting 37 to 56% of chicken and turkey fat, and 44 to 47% of lard.
Oleic acid is the most abundant fatty acid in human adipose tissue, and second in abundance in human tissues overall, following palmitic acid.

### Even- vs odd-chained fatty acids

Most fatty acids are even-chained, e.g. stearic (C18) and oleic (C18), meaning they are composed of an even number of carbon atoms. Some fatty acids have odd numbers of carbon atoms; they are referred to as odd-chained fatty acids (OCFA). The most common OCFA are the saturated C15 and C17 derivatives, pentadecanoic acid and heptadecanoic acid respectively, which are found in dairy products. On a molecular level, OCFAs are biosynthesized and metabolized slightly differently from the even-chained relatives.

### Carbon atom numbering

Most naturally occurring fatty acids have an unbranched chain of carbon atoms, with a carboxyl group (–COOH) at one end, and a methyl group (–CH$_3$) at the other end.
The position of the carbon atoms in the backbone of a fatty acid are usually indicated by counting from 1 at the −COOH end. Carbon number x is often abbreviated C-x (or sometimes Cx), with x=1, 2, 3, etc. This is the numbering scheme recommended by the IUPAC.
Another convention uses letters of the Greek alphabet in sequence, starting with the first carbon after the carboxyl. Thus carbon α (alpha) is C-2, carbon β (beta) is C-3, and so forth.
Although fatty acids can be of diverse lengths, in this second convention the last carbon in the chain is always labelled as ω (omega), which is the last letter in the Greek alphabet. A third numbering convention counts the carbons from that end, using the labels "ω", "ω−1", "ω−2". Alternatively, the label "ω−x" is written "n−x", where the "n" is meant to represent the number of carbons in the chain.
In either numbering scheme, the position of a double bond in a fatty acid chain is always specified by giving the label of the carbon closest to the carboxyl end. Thus, in an 18 carbon fatty acid, a double bond between C-12 (or ω−6) and C-13 (or ω−5) is said to be "at" position C-12 or ω−6. The IUPAC naming of the acid, such as "octadec-12-enoic acid" (or the more pronounceable variant "12-octadecanoic acid") is always based on the "C" numbering.
The notation Δ$^{x,y,...}$ is traditionally used to specify a fatty acid with double bonds at positions x,y,.... (The capital Greek letter "Δ" (delta) corresponds to Roman "D", for Double bond). Thus, for example, the 20-carbon arachidonic acid is Δ$^{5,8,11,14}$, meaning that it has double bonds between carbons 5 and 6, 8 and 9, 11 and 12, and 14 and 15.
In the context of human diet and fat metabolism, unsaturated fatty acids are often classified by the position of the double bond closest to the ω carbon (only), even in the case of polyunsaturated fatty acid multiple double bonds such as the essential fatty acids. Thus linoleic acid (18 carbons, Δ$^{9,12}$), γ-linolenic acid (18-carbon, Δ$^{6,9,12}$), and arachidonic acid (20-carbon, Δ$^{5,8,11,14}$) are all classified as "ω−6" fatty acids; meaning that their formula ends with –CH=CH–CH $_2$–CH $_2$–CH $_2$–CH $_2$–CH $_3$.
Fatty acids with an odd number of carbon atoms are called odd-chain fatty acids, whereas the rest are even-chain fatty acids. The difference is relevant to gluconeogenesis.

### Naming of fatty acids

The following table describes the most common systems of naming fatty acids.
| Nomenclature | Examples | Explanation |
| Trivial | Palmitoleic acid | Trivial names (or common names) are non-systematic historical names, which are the most frequent naming system used in literature. Most common fatty acids have trivial names in addition to their systematic names (see below). These names frequently do not follow any pattern, but they are concise and often unambiguous. |
| Systematic | Oleic acid cis-9-octadec-9-enoic acid Oleic acid (9Z)-octadec-9-enoic acid | Systematic names (or International Union of Pure and Applied Chemistry (IUPAC) names) derive from the standard IUPAC Rules for the Nomenclature of Organic Chemistry, published in 1979, along with a recommendation published specifically for lipids in 1977. Carbon atom numbering begins from the carboxylic end of the molecule backbone. Double bonds are labelled with cis-/trans- notation or E-Z notation (E)-/E-Z notation (Z)- notation, where appropriate. This notation is generally more verbose than common nomenclature, but has the advantage of being more technically clear and descriptive. |
| Δ$^x$ | Linoleic acid cis-Δ$^9$, cis-Δ$^{12}$ octadecadienoic acid | In Δ$^x$ (or delta-x) nomenclature, each double bond is indicated by Δ$^x$, where the double bond begins at the xth carbon–carbon bond, counting from carboxylic end of the molecule backbone. Each double bond is preceded by a cis- or trans- prefix, indicating the configuration of the molecule around the bond. For example, linoleic acid is designated "cis-Δ$^9$, cis-Δ$^{12}$ octadecadienoic acid". This nomenclature has the advantage of being less verbose than systematic nomenclature, but is no more technically clear or descriptive. |
| n−x (or ω−x) | Omega-3 fatty acid (n−3) (or Omega-3 fatty acid (ω−3) | n−x (n minus x; also ω−x or omega-x) nomenclature both provides names for individual compounds and classifies them by their likely biosynthetic properties in animals. A double bond is located on the xth carbon–carbon bond, counting from the Methyl group (methyl) end of the molecule backbone. For example, α-Linolenic acid is classified as a omega-3 fatty acid (n−3) or (omega-3) fatty acid, and so it is likely to share a biosynthetic pathway with other compounds of this type. The ω−x, omega-x, or "omega" notation is common in popular nutritional literature, but IUPAC nomenclature (IUPAC) has deprecated it in favor of n−x notation in technical documents. The most commonly researched fatty acid biosynthetic pathways are omega-3 fatty acid (n−3) and omega-6 fatty acid (n−6). |
| Lipid numbers | 18:3 Alpha-linolenic acid (18:3n3) Alpha-linolenic acid (18:3, cis,cis,cis-Δ$^9$,Δ$^{12}$,Δ$^{15}$) Alpha-linolenic acid (18:3(9,12,15) | Lipid numbers take the form C:D, where C is the number of carbon atoms in the fatty acid and D is the number of double bonds in the fatty acid. If D is more than one, the double bonds are assumed to be interrupted by methylene bridge CH $_2$ units, i.e., at intervals of 3 carbon atoms along the chain. For instance, α-Linolenic acid is an 18:3 fatty acid and its three double bonds are located at positions Δ$^9$, Δ$^{12}$, and Δ$^{15}$. This notation can be ambiguous, as some different fatty acids can have the same C:D numbers. Consequently, when ambiguity exists this notation is usually paired with either a Δ$^x$ or n−x term. For instance, although α-Linolenic acid and γ-Linolenic acid are both 18:3, they may be unambiguously described as 18:3n3 and 18:3n6 fatty acids, respectively. For the same purpose, IUPAC recommends using a list of double bond positions in parentheses, appended to the C:D notation. For instance, IUPAC recommended notations for α-and γ-Linolenic acid are 18:3(9,12,15) and 18:3(6,9,12), respectively. |

### Free fatty acids

When circulating]] in the plasma (plasma fatty acids), not in their ester, fatty acids are known as non-esterified fatty acids (NEFAs) or free fatty acids (FFAs). FFAs are always bound to a transport protein, such as albumin.

### Coconut oils

The approximate concentration of fatty acids in coconut oil (midpoint of range in source):
Approximate concentration of fatty acids in coconut oil :
| Type of fatty acid | Saturation | Percentage |
| caprylic acid | saturated C8 | 7 |
| capric acid | saturated C10 | 8 |
| lauric acid | saturated C12 | 48 |
| myristic acid | saturated C14 | 16 |
| palmitic acid | saturated C16 | 9.5 |
| oleic acid | monounsaturated C18:1 | 6.5 |
| Other | polyunsaturated | 5 |

## Flavonoids

Def. "any of many compounds that are plant metabolites, being formally derived from flavone; they have antioxidant properties, and sometimes contribute to flavor" is called a flavonoid.

## Flavonolignans

Rhodiolin, a flavonolignan, is the product of the oxidative coupling of coniferyl alcohol with the 7,8-dihydroxy grouping of herbacetin. It can be found in the rhizome of Rhodiola rosea.

## Bioactivity of dietary polyphenols

| Dietary source | Proanthocyanidin (mg/100g) |
| Fruits | |
| Grape seeds | 3532 |
| Blueberries | 332 |
| Apples | 70-141 |
| Pears | 32-42 |
| Nuts | |
| Hazelnuts | 501 |
| Other | |
| Cinnamon bark | 8108 |
| Sorghum grains | 3965 |
| Baking chocolate | 1636 |
| Red wine | 313 |
Grape seeds are rich in unsaturated fatty acids, which helps lowering levels of total cholesterol and LDL cholesterol in the blood.

## Glycosides

Iridoid glycosides :
| Glycosides | Aglycone | Glycone | Plants | Genus species |
| Alcohol glycosides | Alcohol | Glycone | Common name | Genus species |
| Rosavin | cinnamyl alcohol | arabinose | Rhodiola | Rhodiola rosea |
| Salicin | salicyl alcohol | glucose | Willow | Salix |
| Salidrosides | tyrosol | glucose | Rhodiola | Rhodiola rosea |
| Anthraquinone glycosides | Anthraquinone derivative | Glycone | Common name | Genus species |
| Sennosides | reduced anthraquinone | glucose | Legume | Senna |
| Chromone glycosides | Benzo-gamma-pyrone | Glycone | Common name | Genus species |
| 3,5,7-trihydroxylchromone-3-O-alpha-L-arabinopyranoside | chromone | arabinose | Rhododendron | Rhododendron spinuliferum |
| Eucryphin | chromone | rhamnoside | Eucryphia | Eucryphia cordifolia |
| Coumarin glycosides | coumarin | Glycone | Common name | Genus species |
| Aesculin | coumarin | glucose | Horse chestnut | Aesculus hippocastanum |
| Cyanogenic glycosides | Cyanogin | Glycone | Common name | Genus species |
| Amygdalin | cyanohydrin | glucose | Apricot kernels | Prunus armeniaca |
| Flavonoid glycosides | Flavonoid | Glycone | Common name | Genus species |
| Hesperidin | Hesperetin | Rutinose | Bitter Orange | Citrus aurantium |
| Naringin | Naringenin | Neohesperidose | Grapefruit | Citrus × paradisi |
| Rutin | Quercetin | Rutinose | Common rue | Ruta graveolens |
| Quercitrin | Quercetin | Rhamnose | American white oak | Quercus alba |
| Iridoid glycosides | iridoid | Glycone | Common name | Genus species |
| Aucubin | cyclopentan-[C]-pyran | glucose | spotted laurel | Aucuba japonica |
| Phenolic glycosides | Phenol | Glycone | Common name | Genus species |
| Arbutin | Phenol | glucose | Common Bearberry | Arctostaphylos ova-ursi |
| Steroidal glycosides | Steroid | Glycone | Common name | Genus species |
| Digitonin | saraponin | glucose | foxglove | Digitalis purpurea |
| Steviol glycosides | Steviol | Glycone | Common name | Genus species |
| Steviosides | Steviol | isosteviol | candyleaf | Stevia rebaudiana |

## Lagerstroemins

Chemical compounds that have been isolated from the extract include corosolic acid, lager-stroemin, flosin B, and reginin A.
Corosolic acid is a pentacyclic triterpene acid found in Lagerstroemia speciosa, similar in structure to ursolic acid, differing only in the fact that it has a 2-alpha-hydroxy attachment.
In Vietnam the plant's young leaves are consumed as vegetables, and its old leaves and mature fruit are used in traditional medicine for reducing glucose in blood.
Banaba plant, Lagerstroemia speciosa (giant crepe-myrtle, Queen's crepe-myrtle, banabá plant, or pride of India) is a species of Lagerstroemia native to tropical southern Asia.

## Lignans

The lignans are a large group of low molecular weight polyphenols found in plants, particularly seeds, whole grains, and vegetables. The name derives from the Latin word for "wood". Lignans are precursors to phytoestrogens. They may play a role as antifeedants in the defense of seeds and plants against herbivores.
    Structures of some lignans
* Matairesinol, illustrating the debenzylbutyrolactone motif
* Secoisolariciresinol, illustrating the 9,9'-dihydroxydibenzylbutane motif
* Justicidin A, illustrating the arylnaphthalene mofif
* Pinoresinol, illustrating the furanofuran motif
* Steganacin, illustrating the dibenzocyclooctadienelactone motif
* Podophyllotoxin, illustrating the aryltetralin motif
Lignans and lignin differ in their molecular weight, the former being small and soluble in water, the latter being high polymers that are undigestable:
* both are polyphenolic substances derived by oxidative coupling of monolignols
* most lignans feature a C$_{18}$ cores, resulting from the dimerization of C$_9$ precursors
* coupling of the lignols occurs at C8
* classes of lignans: "furofuran, furan, dibenzylbutane, dibenzylbutyrolactone, aryltetralin, arylnaphthalene, dibenzocyclooctadiene, and dibenzylbutyrolactol."
Many lignans are metabolized by mammalian gut microflora, producing enterolignans.
Flax seeds and sesame seeds contain high levels of lignans.
The principal lignan precursor found in flaxseeds is secoisolariciresinol diglucoside.
Other foods containing lignans include cereals (rye, wheat, oat and barley), soybeans, tofu, cruciferous vegetables, such as broccoli and cabbage, and some fruits, particularly apricots and Strawberry|strawberries.
Lignans are not present in seed oil, and their contents in whole or ground seeds may vary according to geographic location, climate, and maturity of the seed crop, and the duration of seed storage.
Secoisolariciresinol and matairesinol were the first plant lignans identified in foods.
Lariciresinol and pinoresinol contribute about 75% to the total lignan intake, whereas secoisolariciresinol and matairesinol contribute only about 25%.
Foods containing lignans:
| Source | Lignan amount |
| Flaxseeds | 85.5 mg per oz (28.35 g) |
| Sesame seeds | 11.2 mg per oz |
| Brassica vegetables | cup (125 ml) |
| Strawberries | 0.2 per half cup |

### Magnolia

The aromatic bark contains magnolol, honokiol, 4-O-methylhonokiol, and obovatol. Magnolol and honokiol activate the nuclear receptor peroxisome proliferator-activated receptor gamma.
Magnolol is an organic compound, classified as lignan, a bioactive compound found in the bark of the Houpu magnolia (Magnolia officinalis) or in Magnolia grandiflora. The compound exists at the level of a few percent in the bark of species of magnolia, the extracts of which have been used in traditional Chinese and Japanese medicine. In addition to magnolol, related lignans occur in the extracts including honokiol, which is an isomer of magnolol.
It is known to act on the GABA$_A$ receptors in rat cells in vitro as well as having antifungal properties. Magnolol has a number of osteoblast-stimulating and osteoclast-inhibiting activities in cell culture and has been suggested as a candidate for screening for anti-osteoporosis activity. It has anti-periodontal disease activity in a rat model. Structural analogues have been studied and found to be strong allosteric modulators of GABA$_A$$_.$
Magnolol is also binding in dimeric mode to PPARγ, acting as an agonist of this nuclear receptor.

### Prickly ash bark

Historically, Zanthoxylum (Prickly ash) bark was used in traditional medicine.
Plants in the genus Zanthoxylum contain the lignan sesamin.

## Terpenoids

While sometimes used interchangeably with "terpenes", terpenoids have additional functional groups, usually containing oxygen. Terpenoids are the largest class of plant secondary metabolites, representing about 60% of known natural products. Many terpenoids have substantial pharmacological bioactivity and are therefore of interest to medicinal chemists. Terpenoids contribute to the scent of eucalyptus, the flavors of cinnamon, cloves, and ginger, the yellow color in sunflowers, and the red color in tomatoes.