Identification of a xanthine oxidase inhibitor in barley tea (Mugi-Cha) and its contribution to the activity

Abstract

As part of our studies on the prevention of lifestyle-related diseases by processed foods, we evaluated the xanthine oxidase (XO) inhibitory activity of barley tea. The activity of the tea (a hot-water extract of roasted barley) was not as potent as that of another roasted beverage coffee. However, the activity of the ethyl acetate-soluble substance from the extract was significantly stronger than that of coffee. Through the purification of the substance, pyrogallol was identified as the most potent compound. After establishing a quantification process for pyrogallol in barley tea, we analyzed correlations between the amount of pyrogallol, color information of grains, and the XO inhibitory capacity of tea using roasted barley grains. The findings suggest that the XO inhibitory activity of barley tea can be evaluated based on the roast degree and chroma b* of barley grains through the content of pyrogallol, although other active compounds may be present in barley tea.