Antimicrobial mechanism of epigallocatechin gallate and gallocatechin gallate: They target 1-deoxy-d-xylulose 5-phosphate reductoisomerase, the key enzyme of the MEP terpenoid biosynthetic pathway.

ABSTRACT

The catechins EGCG and GCG show a variety of pharmacological activities, especially an antibacterial capacity, but their modes of antimicrobial action have not been fully elucidated. 1-Deoxy-d-xylulose 5-phosphate reductoisomerase (DXR), the first key enzyme in the MEP pathway for terpenoid biosynthesis, is a recently validated antimicrobial target. In order to disclose the antibacterial mechanism of EGCG and GCG, the DXR inhibitory activity of them was investigated in this study. The data show that EGCG and GCG both could specifically suppress the activity of DXR, with EGCG exhibiting relatively low effect against DXR (IC50 about 210 µM) and GCG displaying strong activity (IC50 27.5 µM). In addition, studies on inhibition kinetics of the catechins against DXR demonstrate that they are competitive inhibitors of DXR against DXP and uncompetitive inhibitors with respect to NADPH. Meanwhile, the possible interactions between DXR and the catechine, esyth onlols were simulated via docking experiments.