Though the instability of polyphenols in cell culture experiment has been investigated previously, underlying mechanism is not completely clear yet. Therefore, this study, stability epigallocatechin gallate (EGCG) medium DMEM was at 4 °C and 37 via UPLC-MS-MS analysis followed by determination antioxidant capacity EGCG. EGCG instable formed various degradation products derived from its dimer wi...