The composition, antioxidant and antiproliferative capacities of phenolic compounds extracted from tartary buckwheat bran [Fagopyrum tartaricum (L.) Gaerth]

Tartary buckwheat bran [Fagopyrum tartaricum (L.) Gaerth, FG], a major by-product of tartary buckwheat flour production, may serve as a natural source of phenolic compounds with potential antioxidant activity. In this study, the total content of free phenolic compounds was approximately 4-fold larger than that of bound phenolic compounds. Rutin represented the main phenolic compound existing in both free and bound forms. However, caffeic acid hexose, chlorogenic acid, protocatechuic acid and catechin-glucoside were only detected in the bound phenolic fraction. The biological activity tests indicated that the phenolic extracts (free fraction especially) of tartary buckwheat bran might serve as functional compounds that exert antioxidant activities in vitro (oxygen radical antioxidant capacity, ORAC) and ex-vivo (cellular antioxidant activities, CAA), as well as antiproliferative activity against human liver cancer cells (HepG2) in vitro.