Production of Theasinensin A Using Laccase as Antioxidant and Antiaging Agent

Epigallocatechin-3-O-gallate (EGCG), one of the most abundant monomeric catechin compounds in green tea, was oxidized to EGCG dimers through radical oxidative reaction using laccase, a member of the tea polyphenol oxidase family. Electrospray ionization tandem LC-MS (ESI-LC/MS) was applied for the characterization of the dimers, including theacitrin, dehydrotheasinensin, and theasinensin, which were produced by the radical oxidative reaction. Chemical structures of the EGCG dimer were identified using LC/MS/MS and fragmentation patterns of EGCG dimer. The dimers were isomerized by heat treatment at 80°C after oxidation step to mimic heat treatment and drying in the last step of leaf fermentation. As a result of the heat treatment, theasinensin A (TSA) was formed as a major dimer product. After the two steps of Sephadex LH-20 and C18 column chromatography, 27.6 mg of purified TSA was obtained from 485.4 mg of dried reaction mixture. Biological effect of TSA as antioxidant and anti-aging effects were investigated. Purified TSA significantly suppressed the expression of ultraviolet B-induced matrix metalloproteinase-1 in human fibroblast (HS68 cell), indicating the potential use of TSA as antioxidant and anti-aging agent.