Flavonoids and Antioxidative Activities in Buckwheat

Samples of buckwheat from four cultivars grown at three locations in western Canada for 4 years were used to study the effect of cultivar, location, and growing season on the flavonoid content and antioxidative activities of the seed. Buckwheat contained an average of 387 and 1314 mg/100 g of flavonoid and 47 and 77 mg/100 g of rutin in the seed and hull, respectively. Location was the main source of variation for flavonoid and rutin contents of the seed, while growing season had significant influence on the flavonoid content of the hulls. Variation in antioxidative activities was mainly due to a cultivar × environment effect. Antioxidative activities expressed as AOX (Δ log A 470/min), AA (% inhibition relative to control), and ORR (oxidation rate ratio) ranged from 0.42, 114, and 0.16 to 1.63, 48, and 0.59, respectively. Flavonoid content in buckwheat was strongly correlated with rutin content and weakly associated with antioxidative activities, while rutin content was not related to antioxidative activities. Keywords: Buckwheat; flavonoid; rutin; antioxidant; cultivar effects; seasonal variations; Fagopyrum esculentum