Abstract
Fifty kinds of healthful teas were collected in local markets in the Shikoku area of Japan, to investigate their functions with respect to benefits to human health. Hot water extracts of the teas were examined by assay systems including DPPH radical scavenging, α-glucosidase inhibition, and xanthine oxidase inhibition. The DPPH radical scavenging results revealed that Aioi-Bancha had the most potent radical scavenging activity and was followed by Yamamomo and Urajirokashi-Cha. The α-glucosidase inhibition assay results demonstrated that Yamamomo, Shirakashi-Cha, Aioi-Bancha, Kakinoha-Cha, Urajirokashi-Cha, and Yasou-Cha (kinmizuhiki) were potent inhibitory teas against yeast′s α-glucosidase, whereas Yamaguwanoha and Kuwa-Cha showed potent activity toward α-glucosidase of rat small intestinal powders. Strong xanthine oxidase inhibition was observed in the extracts from three teas made of Labiatae plants (Seisou-Cha, Shiso-Cha, Kakidoushi-Cha). HPLC and LC-MS analyses of the tea extracts clarified that they had very similar constituents and rosmarinic acid was a typically common constituent in the three teas. The contained rosmarinic acid in the extracts is probably responsible for the strong xanthine oxidase inhibition of the three healthful teas.
