Lignan

From Wikipedia, the free encyclopedia

Not to be confused with Lignin.

A lignan is a chemical compound found in plants. Lignans are one of the two major classes of phytoestrogens, which are antioxidants found in a variety of plants which includes flax seeds, pumpkin seeds, sesame seeds, rye, soybeans, broccoli, beans, and some berries. The other class of phytoestrogens is the isoflavones. Plant lignans are polyphenolic substances derived from phenylalanine via dimerization of substituted cinnamic alcohols (see cinnamic acid) to a dibenzylbutane skeleton 2. This reaction is catalysed by oxidative enzymes and is often controlled by dirigent proteins.

Many natural products are built up of C6C3 units (a propylbenzene skeleton 1) derived from cinnamyl units just as terpene chemistry builds on isoprene units. Structure 3 is a neolignan.

When part of the human diet, lignans are converted into the mammalian lignans known as enterodiol (1) and enterolactone (2) by intestinal bacteria.