Abstract: Epigallocatechin gallate (EGCG), a polyphenolic flavonoid compound isolated from tea, has many biological functions such as antioxidant, antibacterial, anti-tumor, cholesterol-lowering and anti-obesity properties. However, its instability and low bioavailability lead to limited bioactivities. Recently, biotransformation mediated by microbes may provide an effective way of modifying the structure of EGCG to improve its bioavailability while maintaining and even improving its original bioactivities. This review summarizes the biotransformation of EGCG mediated by different microorganisms and the bioactivities of its resulting breakdown products, mainly focusing on the metabolic pathways, the metabolites, and their bioactivities. It is expected that this review will provides a theoretical basis for further study aiming at the development of EGCG-based value-added products and for in-depth studies on human health promotion triggered by microbial biotransformation of polyphenols.

Key words: epigallocatechin gallate, biotransformation, microorganisms, metabolic pathways, biological activities