Identification and purification of resorcinol, an antioxidant specific to Awa-ban (pickled and anaerobically fermented) tea

Awa-ban tea (Awa, Tokushima prefecture in Japan; ban, "evening" in Japanese) is a type of tea exclusive to the Tokushima area. Awa-ban tea leaves are unique in that they are produced via pickling and anaerobic fermentation. Here, we report the identification and purification of an antioxidant that is specifically present in Awa-ban tea but is absent in green and black tea. The molecule, identified as resorcinol, was found to exhibit radical-scavenging activity in vitro at levels equivalent to those of (-)-epigallocatechin gallate in green tea. Fluorescence microscopy and flow cytometry results further showed that resorcinol decreased the levels of reactive oxygen species in HEK293T cells, human umbilical vein endothelial cells, and Jurkat cells in a concentration-dependent manner. Moreover, the 3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay indicated that treatment with 10. mM resorcinol did not affect cell viability. Our results indicate that Awa-ban tea has properties that are quite distinct from those of green and black tea and is therefore a unique antioxidant beverage. We also suggest that resorcinol is a novel tea-based antioxidant.