Inhibitory effect of (-)-epigallocatechin gallate on the growth of Staphylococcus aureus in liquid medium. The inhibitory effect of (-)-epigallocatechin gallate on Staphylococcus aureus is studied in synthetic liquid medium. Addition of the compound is accompanied by a gradual decrease of culture turbidity, which is a clear evidence of the antibacterial effect. The inhibitory effect is concentration-dependent; in particular, at an initial optical density of 0.1 the minimum inhibitory concentration is 0.025 mg/mL. However, the reduction of cell activity cannot be ascribed to a general antibacterial action, since the cells do not lyse. Cell death results from a loss of specific energy. The inhibition of cell respiration by the compound is accompanied by a decrease in the production of endogenous ATP. The latter can be restored by adding nicotinamide adenine dinucleotide (NAD). The addition of the latter to the incubation medium leads to a partial inhibition of the antibacterial activity of (-)-epigallocatechin gallate. In this respect, the inhibitory effect of (-)-epigallocatechin gallate on Staphylococcus aureus seems to be a peculiarity of the organism. In addition, the compound seems to be an effective inhibitor of NADP-dependent alcohol dehydrogenase. A possible explanation of the mode of action of the compound is advanced.