Abstract: Crude green tea extract containing epigallocatechin gallate (EGCG) was prepared by ethyl acetate extraction under neutral condition. Inhibitory effect from crude extract against Mycobacterium smegmatis mc²155 was determined by both disk agar diffusion method and growth curve. The changes of structure of cell wall were observed by transmission electron microscopy (TEM). Crude extract showed significant growth inhibition of M. smegmatis mc²155 from both approaches, and the inhibitions were dose-dependent. The changes of cell wall structure were confirmed by TEM. The inhibitory effect of crude tea extract against M. smegmatis mc²155 was detected in this study, and it was postulated that EGCG, a known biologically active compound in green tea, might played a major role against Mycobacterium causing inhibition of biosynthesis of peptidoglycan in the cell wall.

Key words: green tea extraction, EGCG; Mycobacterium smegmatis mc²155, bactriostasis