2.1.3. Lignin's: mucilage's (flaxseed)

#### 2.1.3.1. Lignans

Plant lignans are phenolic compounds with a skeleton of 2,3-dibenzylbutane [40]. Flaxseed is the richest food source in the precursors of lignans, secoisolariciresinol diglucoside (SDG), and materesinol, which are phytoestrogens that by action of gastric acid and bacterial glucosidase (facultative aerobics of Clostridia class) of the digestive tract transform into enterolactone and enterodiol, respectively, known as lignans of mammals [41]. These have more antioxidant capacity than their predecessors. Other lignans, such as lariciresinol, hinoquinina, arctigenin, divanillyl tetrahydrofuran nordihydroguaiaretic acid, isolariciresinol, and pinoresinol, are also present in flaxseed but the most abundant is SDG [40]. The health benefits of flaxseed lignans rely in their antioxidant capacity as retainers of hydroxyl radicals, and as estrogenic and antiestrogenic compounds due to their structural similarity to the 17-β-estradiol [37, 41]. The antioxidant activity of flaxseed lignan (SDG) is related to the suppression of the oxidizing conditions of oxygen reactive species [41]. Secoisolariciresinol diglucoside and its aglycone secoisolariciresinol show a high antioxidant capacity and protective effects to the damage of the DNA and liposomes, especially in the epithelial cells of the colon exposed to these compounds, during the metabolism of the colon bacteria that transform them into lignans of mammals [42, 43].
