Lignan
The lignans are a large group of polyphenols found in plants.[1] Some examples of lignans are enterolignans, enterodiol and enterolactone.[1]
Etymology
From lign- (Latin, "wood") + -an (chemical suffix).
Technical Definition
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Plant lignans are polyphenolic substances derived from phenylalanine via dimerization of substituted cinnamic alcohols (see cinnamic acid), known as monolignols, to a dibenzylbutane skeleton 2. This reaction is catalysed by oxidative enzymes and is often controlled by dirigent proteins.
Structure
![](http://upload.wikimedia.org/wikipedia/commons/thumb/e/e7/Lignan.svg/300px-Lignan.svg.png)
Many natural products, known as phenylpropanoids, are built up of C6C3 units (n-propylbenzene skeleton 1) derived from cinnamyl units just as terpene chemistry builds on isoprene units. Structure 3 is a neolignan, a structure formed by joining the two propylbenzene residues at other than the β-carbon atom of the propyl side chain.
As diet
When a part of the human diet, some plant lignans are metabolized by intestinal bacteria to mammalian lignans enterodiol (1) and enterolactone (2).[2][3][4] Lignans that can be metabolized to mammalian lignans are pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, hydroxymatairesinol, syringaresinol and sesamin. Lignans are one of the major classes of phytoestrogens, which are estrogen-like chemicals and also act as antioxidants. The other classes of phytoestrogens are isoflavones and coumestans.
![](http://upload.wikimedia.org/wikipedia/commons/thumb/7/7e/Enterodiol_and_Enterlactone.svg/250px-Enterodiol_and_Enterlactone.svg.png)
Food sources
Flax seed and sesame seed contain higher levels of lignans than most other foods.[citation needed] The principal lignan precursor found in flaxseed is secoisolariciresinol diglucoside.[citation needed] Other sources of lignans include cereals (rye, wheat, oat and barley - rye being the richest source), soybeans, cruciferous vegetables such as broccoli and cabbage, and some fruit, particularly apricots and strawberries.[1]
Secoisolariciresinol and matairesinol were the first plant lignans identified in foods. Typically, lariciresinol and pinoresinol contribute about 75% to the total lignan intake whereas secoisolariciresinol and matairesinol contribute only about 25%.[1] Lignans are some of the secondary metabolites present in Cannabis sativa.[5]
Sources of lignans:[6]
Source | Amount per 100 g |
---|---|
Flaxseed | 300,000 µg (0.3 g) |
Sesame seed | 29,000 µg (29 mg) |
Brassica vegetables | 185 - 2321 µg |
Grains | 7 - 764 µg |
Red wine | 91 µg |
A 2007 study[7] shows the complexity of mammalian lignan precursors in the diet. In the table below are a few examples of the 22 analyzed species and the 24 lignans identified in this study.
Mammalian lignan precursors as aglycones (µg/100 g). Major compound(s) in bold.
Foodstuff | Pinoresinol | Syringaresinol | Sesamin | Lariciresinol | Secoisolariciresinol | Matairesinol | Hydroxymatairesinol |
---|---|---|---|---|---|---|---|
Flaxseed | 871 | 48 | not detected | 1780 | 165759 | 529 | 35 |
Sesame seed | 47136 | 205 | 62724 | 13060 | 240 | 1137 | 7209 |
Rye bran | 1547 | 3540 | not detected | 1503 | 462 | 729 | 1017 |
Wheat bran | 138 | 882 | not detected | 672 | 868 | 410 | 2787 |
Oat bran | 567 | 297 | not detected | 766 | 90 | 440 | 712 |
Barley bran | 71 | 140 | not detected | 133 | 42 | 42 | 541 |
Pharmacology
Lignans serve an antioxidant role in the plant's defenses against biotic and abiotic factors, and are under basic research for their potential anti-inflammatory or antioxidant activity in laboratory models of human diseases.[8]
See also
References
Footnotes
- ^ a b c d "Lignans". Micronutrient Information Center, Linus Pauling Institute, Oregon State University. 2010. Retrieved 31 July 2017.
- ^ Heinonen, S; Nurmi, T; Liukkonen, K; Poutanen, K; Wähälä, K; Deyama, T; Nishibe, S; Adlercreutz, H (2001). "In vitro metabolism of plant lignans: New precursors of mammalian lignans enterolactone and enterodiol". Journal of Agricultural and Food Chemistry. 49 (7): 3178–86. doi:10.1021/jf010038a. PMID 11453749.
- ^ Axelson, M; Sjövall, J; Gustafsson, B. E.; Setchell, K. D. (1982). "Origin of lignans in mammals and identification of a precursor from plants". Nature. 298 (5875): 659–60. Bibcode:1982Natur.298..659A. doi:10.1038/298659a0. PMID 6285206.
- ^ Borriello, S. P.; Setchell, K. D.; Axelson, M; Lawson, A. M. (1985). "Production and metabolism of lignans by the human faecal flora". The Journal of applied bacteriology. 58 (1): 37–43. doi:10.1111/j.1365-2672.1985.tb01427.x. PMID 2984153.
- ^ Flores-Sanchez, Isvett Josefina; Verpoorte, Robert (2008-10-01). "Secondary metabolism in cannabis". Phytochemistry Reviews. 7 (3): 615–639. doi:10.1007/s11101-008-9094-4. ISSN 1568-7767.
- ^ Milder IE, Arts IC, van de Putte B, Venema DP, Hollman PC (2005). "Lignan contents of Dutch plant foods: a database including lariciresinol, pinoresinol, secoisolariciresinol and matairesinol". Br. J. Nutr. 93 (3): 393–402. doi:10.1079/BJN20051371. PMID 15877880.
- ^ Smeds AI; Eklund, Patrik C.; Sjöholm, Rainer E.; Willför, Stefan M.; Nishibe, Sansei; Deyama, Takeshi; Holmbom, Bjarne R.; et al. (2007). "Quantification of a Broad Spectrum of Lignans in Cereals, Oilseeds, and Nuts". J. Agric. Food Chem. 55 (4): 1337–1346. doi:10.1021/jf0629134. PMID 17261017.
- ^ Korkina, L; Kostyuk, V; De Luca, C; Pastore, S (2011). "Plant phenylpropanoids as emerging anti-inflammatory agents". Mini Reviews in Medicinal Chemistry. 11 (10): 823–35. doi:10.2174/138955711796575489. PMID 21762105.