Lignans in general

In plants and plant foods, lignans occur partly in an esterified form bound to the matrix and glycosidically linked to carbohydrates. They have been isolated from roots, stems, seeds, fruits and leaves of many plants. 

Lignans are represent in a wide variety of plant foods, including seeds, -flax, pumpkin, sunflower, poppy, whole grain- rye, oats, barley, bran – what oat rye and fruits – berries and vegetables. They represent the dimer stage intermediate between the monomeric propylphenol units and lignin.

The lignans form a group of plant phenols whose structure is determined by the union of two cinnamic acid residues or their biogenic equivalents. There are hundreds of different lignans each differing in degree of oxidation, cyclization or derivatization.

The lignans play an important part in the defence mechanism of many plant species, against pathogens and predators. Various roles in chemical defence, such as fungicidal, bactericidal and insecticidal have been reported.

Lignans or plants containing lignans have a long history of use as traditional folk medicines. They are substances that are changed by friendly bacteria in the intestines into compounds that fight cancer. Like phytohormones, they fill estrogen receptors and thus block normal estrogen activity.
Lignans in general