Lignans
Lignans are a group of substances that occur as natural substances in plants, e.g. B. in the taiga root, in the valerian root and in various edible plant parts such. B. Flax and sesame seeds, cereal grains, fruits (e.g. in Schisandra ) and vegetables.
Lignans are colorless, crystalline and odorless compounds. The so-called enterolignans are metabolic products that arise in the human intestine through the bacterial breakdown of plant lignans, e.g. B. Enterolactone from the lignan sesamin .
structure
Lignans are characterized by dimeric C 6 C 3 bodies ( phenylpropanoids ), which are connected via the middle (β) -C atom. Different structural variants result from the arrangement and linkage of the C 3 side chains. Many lignans have additional heterocycles, e.g. B. two tetrahydrofuran rings in the sesamine derivatives (diepoxylignans) or one lactone ring in the lignanolides. If two carbons are connected by a CC bond, one speaks of cyclolignans, to which z. B. the podophyllotoxin and the typical lignans from Schisandra count.
In plants, lignans are usually free or glycosidically bound. Polymerization of the C 6 C 3 bodies (= monolignols) creates what is known as lignin , which occurs in the plant cell wall and causes the plant cells to become woody. Lignans and lignin are completely different compounds that should not be confused with one another. Lignin belongs to the group of insoluble fiber.
Tasks and meaning
In the plant, lignans apparently act as defense substances against diseases and infections and also seem to exert a control over plant growth. Some plant lignans are also of interest to humans from a nutritional point of view: Due to their estrogen-like effects and other biochemical properties, they may be of importance for the prevention of cardiovascular diseases and other chronic diseases.
Lignans are also used as herbal sedatives. The sleep-promoting effects have also earned them the name “sleep lignans”.
Some lignans are cytotoxic , including podophyllotoxin , the derivative of which etoposide is used as a cytostatic.
Occurrence in food
Lignans are found mainly in flax seeds and pumpkin seeds .
| Food | Lignans µg / 100 g |
|---|---|
| linseed | 370,000 371,100 384,500 |
| Pumpkin seeds | 20,300 21,400 |
| Strawberries | 1,578 |
| Olives | 1,254 |
| Tea, black | 1,100 |
| cranberry | 1,054 |
| red wine | 1,000 |
| Sunflower seeds | 818 |
| Oat bran | 790 |
| Pumpkin | 695 |
| Wheat bran | 664 |
| Sesame seeds | 661 |
| blackberry | 569 |
| garlic | 520 |
| peanuts | 460 |
| lenses | 457 |
| asparagus | 442 |
| broccoli | 256 437 |
| Wheat , whole grain | 410 |
| Carrots | 381 |
| sweet potato | 336 |
| Apricot , dried | 328 |
| nuts | 96-257 |
| Soybeans | 10-200 |
| rye | 112 |
| barley | 58 |
Individual evidence
- ↑ José L. Peñalvo, Satu-M. Heinonen, Anna-M. Aura, Herman Adlercreutz: Dietary sesamin is converted to enterolactone in humans . In: The Journal of Nutrition . tape 135 , no. 5 , May 2005, pp. 1056-1062 , PMID 15867281 .
- ↑ Peterson et al. 2010. Dietary lignans: Physiology and potential for cardiovascular disease risk reduction. Nutr Rev. 2010 October; 68 (10): 571-603.
- ↑ a b c d Testing for estrogen-like substances with a bio test. In: https://www.laves.niedersachsen.de/ . Lower Saxony State Office for Consumer Protection and Food Safety, 2011, accessed on August 2, 2020 .
- ↑ a b c d e f g h i Dr. oec. troph. Antonie Danz: Phytoestrogens - plant substances with hormonal effects. In: https://www.ugb.de/ . The Association for Independent Health Advice (UGB), 2015, accessed on August 2, 2020 .
- ↑ a b c d e f g h i j k l m n o p q Regina Verena Piller: Phytoestrogens in the diet and their influence on the risk of breast cancer (dissertation). In: http://mediatum.ub.tum.de/ . Technical University of Munich, June 12, 2006, accessed on August 2, 2020 .