Lignan

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The lignans are a large group of low molecular weight polyphenols found in plants, particularly seeds, whole grains, and vegetables. [1] The name derives from the Latin word for "wood". [2] Lignans are precursors to phytoestrogens. [1] [3] They may play a role as antifeedants in the defense of seeds and plants against herbivores. [4]

Contents

Biosynthesis and metabolism

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. Thus, most lignans feature a C18 cores, resulting from the dimerization of C9 precursors. The coupling of the lignols occurs at C8. Eight classes of lignans are: "furofuran, furan, dibenzylbutane, dibenzylbutyrolactone, aryltetralin, arylnaphthalene, dibenzocyclooctadiene, and dibenzylbutyrolactol." [5]

Many lignans are metabolized by mammalian gut microflora, producing so-called enterolignans. [6] [7]

Food sources

Flax seeds and sesame seeds contain high levels of lignans. [1] [8] The principal lignan precursor found in flaxseeds is secoisolariciresinol diglucoside. [1] [8] 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 strawberries. [1] 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. [1]

Secoisolariciresinol and matairesinol were the first plant lignans identified in foods. [1] Typically, lariciresinol and pinoresinol contribute about 75% to the total lignan intake, whereas secoisolariciresinol and matairesinol contribute only about 25%. [1]

Foods containing lignans: [1] [9]

SourceLignan amount
Flaxseeds85.5 mg per oz (28.35 g)
Sesame seeds11.2 mg per oz
Brassica vegetables0.3-0.8  mg per half cup (125 ml)
Strawberries0.2 mg per half cup

Prevalence and Health Effects

Lignans are the principal source of dietary phytoestrogens in typical Western diets, even though most research on phytoestrogen-rich diets has focused on soy isoflavones. Lignan's enterolignan products enterodiol and enterolactone have weak estrogenic activity, but they may also exert biological effects through non-estrogenic means. [1]

A 2021 review found that lignans have a positive effect on lipid profiles of patients with dyslipidemia related diseases. [10] As of 2022 there is limited evidence that dietary intake of lignans is associated with a reduced cancer and cardiovascular disease risk. [1]

See also

Related Research Articles

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<span class="mw-page-title-main">Dietary fiber</span> Portion of plant-derived food that cannot be completely digested

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<span class="mw-page-title-main">Nordihydroguaiaretic acid</span> Chemical compound

Nordihydroguaiaretic acid, informally abbreviated NDGA in research articles, is a classic lignan, a phenylpropane dimer linked by a bond between positions C8 and C8′, as opposed to a neolignan. It is a natural compound found in the creosote bush.

<span class="mw-page-title-main">Phytoestrogen</span> Plant-derived xenoestrogen

A phytoestrogen is a plant-derived xenoestrogen not generated within the endocrine system, but consumed by eating plants or manufactured foods. Also called a "dietary estrogen", it is a diverse group of naturally occurring nonsteroidal plant compounds that, because of its structural similarity with estradiol (17-β-estradiol), have the ability to cause estrogenic or antiestrogenic effects. Phytoestrogens are not essential nutrients because their absence from the diet does not cause a disease, nor are they known to participate in any normal biological function. Common foods containing phytoestrogens are soy protein, beans, oats, barley, rice, coffee, apples, carrots.

<span class="mw-page-title-main">Secoisolariciresinol diglucoside</span> Antioxidant phytoestrogen

Secoisolariciresinol diglucoside (SDG) is an antioxidant phytoestrogen present in flax, sunflower, sesame, and pumpkin seeds. In food, it can be found in commercial breads containing flaxseed. It is a precursor of mammal lignans which are produced in the colon from chemicals in foods.

<span class="mw-page-title-main">Equol</span> Isoflavandiol estrogen metabolized from daidzein

Equol (4',7-isoflavandiol) is an isoflavandiol estrogen metabolized from daidzein, a type of isoflavone found in soybeans and other plant sources, by bacterial flora in the intestines. While endogenous estrogenic hormones such as estradiol are steroids, equol is a nonsteroidal estrogen. Only about 30–50% of people have intestinal bacteria that make equol.

<span class="mw-page-title-main">Secoisolariciresinol</span> Chemical compound

Secoisolariciresinol is an organic compound. It is classified as a lignan, i.e., a type of phenylpropanoid. It is present in some cereals, e.g. rye, and together with matairesinol, has attracted much attention for its beneficial nutritional effects.

<span class="mw-page-title-main">Dirigent protein</span>

Dirigent proteins are members of a class of proteins which dictate the stereochemistry of a compound synthesized by other enzymes. The first dirigent protein was discovered in Forsythia intermedia. This protein has been found to direct the stereoselective biosynthesis of (+)-pinoresinol from coniferyl alcohol monomers:

<span class="mw-page-title-main">Matairesinol</span> Chemical compound

Matairesinol is an organic compound. It is classified as a lignan, i.e., a type of phenylpropanoid. It is present in some cereals, e.g. rye, and together with Secoisolariciresinol, has attracted much attention for its beneficial nutritional effects.

<span class="mw-page-title-main">Coumestrol</span> Chemical compound

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<span class="mw-page-title-main">Lariciresinol</span> Chemical compound

Lariciresinol is a lignan, i.e., a type of phenylpropanoids. It is the precursor to enterolignans by the action of gut microflora. Enterolignans are of interest because they are speculated to exhibit beneficial medicinal properties.

<span class="mw-page-title-main">Enterolignan</span> Class of chemical compounds

Enterolignans are organic compounds formed by the action of gut microflora on lignans. They are thus the products of the combined action of both plants and of the animal gut. Prominent enterolignans are enterodiol and enterolactone. Enterolignans are also called "mammalian lignans", although that term is self-contradictory since mammals do not produce lignans.

<span class="mw-page-title-main">Enterolactone</span> Chemical compound

Enterolactone is a organic compound classified as an enterolignan. It is formed by the action of intestinal bacteria on plant lignan precursors present in the diet.

<span class="mw-page-title-main">Enterodiol</span> Lignan formed by the action of intestinal bacteria on lignan precursors found in plants.[1]

Enterodiol is an organic compound with the formula [HOC6H4CH2CH(CH2OH)]2.

<span class="mw-page-title-main">Pinoresinol</span> Chemical compound

Pinoresinol is a tetrahydrofuran lignan found in Styrax sp., Forsythia suspensa, and in Forsythia koreana. It is also found in the caterpillar of the cabbage butterfly, Pieris rapae where it serves as a defence against ants.

<span class="mw-page-title-main">Hydroxymatairesinol</span> Chemical compound

Hydroxymatairesinol (HMR) is a lignan found in Norway spruce. It is an enterolactone precursor with anticancer activities. In rats, HMR decreased the volume of induced tumours and stabilised established tumours, as well as preventing the development of new tumours. It has also shown anti-oxidant properties in vitro.

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References

  1. 1 2 3 4 5 6 7 8 9 10 11 "Lignans". Micronutrient Information Center, Linus Pauling Institute, Oregon State University. 2010. Retrieved 31 July 2017.
  2. ↑ From lign- (Latin, "wood") + -an (chemical suffix).
  3. ↑ 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.
  4. ↑ Saleem, Muhammad; Kim, Hyoung Ja; Ali, Muhammad Shaiq; Lee, Yong Sup (2005). "An update on bioactive plant lignans". Natural Product Reports. 22 (6): 696–716. doi:10.1039/B514045P. PMID   16311631.
  5. ↑ Umezawa, Toshiaki (2003). "Diversity in lignan biosynthesis". Phytochemistry Reviews. 2 (3): 371–90. doi:10.1023/B:PHYT.0000045487.02836.32. S2CID   6276953.
  6. ↑ Adlercreutz, Herman (2007). "Lignans and Human Health". Critical Reviews in Clinical Laboratory Sciences. 44 (5–6): 483–525. doi:10.1080/10408360701612942. PMID   17943494. S2CID   31753060.
  7. ↑ 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.
  8. 1 2 Landete, José (2012). "Plant and mammalian lignans: A review of source, intake, metabolism, intestinal bacteria and health". Food Research International. 46 (1): 410–24. doi:10.1016/j.foodres.2011.12.023.
  9. ↑ 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". British Journal of Nutrition. 93 (3): 393–402. doi: 10.1079/BJN20051371 . PMID   15877880.
  10. ↑ Yang, C., Xia, H., Wan, M. (2021). "Comparisons of the effects of different flaxseed products consumption on lipid profiles, inflammatory cytokines and anthropometric indices in patients with dyslipidemia related diseases: systematic review and a dose–response meta-analysis of randomized controlled trials". Nutrition & Metabolism. 18 (1): 91. doi:10.1186/s12986-021-00619-3. PMC   8504108 . PMID   34635132.{{cite journal}}: CS1 maint: multiple names: authors list (link)
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