Antioxidant and antiproteinase effects of buckwheat hull extracts

Buckwheat is known not only due to its appropriate nutritional composition but the content of prophylactic compounds, too. These are responsible for buckwheat beneficial impact on human health. Most of them are concentrated in outer layers of buckwheat grain. The subject of this work was to screen hulls of nine common and one tartary buckwheat cultivar for the content of flavonoids and its antioxidant and antiproteinase effects. The highest content of total flavonoids was determined for tartary buckwheat cultivar Madawaska (0.6% of hulls weight). Among common buckwheat cultivars the best values reached samples Bamby (0.23%) and KASHO-2 (0.11%). Antioxidant activity as detected via binding radical ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid)) and monitoring reducing power was the most effective for samples with highest flavonoid content. Buckwheat hulls effectively inhibited pathophysiological proteases thrombin and urokinase, whereas only little effects were seen to trypsin and elastase. In this testing there were again the best samples with highest flavonoid content. Only tartary buckwheat Madawaska effectively inhibited elastase at tested concentrations. No significant correlation was determined between flavonoid content and measured antioxidant or protease inhibitory action. Obtained results allow us to commend tartary buckwheat cultivar Madawaska as well as common buckwheat cultivars Bamby and KASHO-2 for further experiments