Isolation and Characterization of Flaxseed (Linum usitatissimum) Constituents

Abstract

During a large-scale isolation of the cancer chemopreventive mammalian lignan precursor secoisolariciresinol diglucoside (SDG, 6) from the defatted meal of flaxseed (Linum usitatissimum L.), a new flavonoid, herbacetin 3,8- O -diglucopynanoside (1) was obtained, along with two known flavonoids, herbacetin 3,7- O- dimethyl ether (3) and kaempferol 3,7- O -diglucopyranoside (4), and the known lignan (-)-pinoresinol diglucoside (5). The structure of herbacetin 3,8- O -ß-D-diglucopynanoside (1) was determined by a combination of NMR techniques. Further, the absolute configuration of the stereogenic center of secoisolariciresinol diglucoside (SDG, 6) was assigned by spectroscopic methods. Herbacetin 3, 7- O- dimethyl ether (3) and herbacetin (2), the aglycone of 1, were shown to mediate antioxidant activity which may contribute to the chemopreventive activity of flaxseed.