Inhibitory effects of validamycin compounds on the termites trehalase

Trehalase, with the target to control insects, nematodes and fungi, is of increasing interest and has been investigated extensively in recent years. Validamycin compounds, as competitive trehalase inhibitors and lead compounds with broad applications have attracted substantial attention as well. In this study, the characterizations of termites trehalase were investigated and the inhibitory effects of validamycin compounds on the termites trehalase were studied as well. Results showed that the termites trehalase is presumably belonging to the acid trehalase with optimal pH of 3.3 and optimal temperature of 37 degrees C. It was investigated that the concentrations of validoxylamine A (VAA), validoxylamine B (VBB), validamycin A (VA) and validamycin B (VB) required for 50% inhibition IC50 of termites trehalase were calculated to be 14.73 mg l(-1), 20.80 mg l(-1), 3.17 x 10(3) mg l(-1) and 2.24 x 10(3) mg l(-1), respectively. The inhibition kinetic constant K-i values for the above validamycin compounds were 3.2 x 10(-6) mol l(-1), 1.03 x 10(-5) mol l(-1) 4.02 x 10(-4) mol l(-1) and 2.69 x 10(-4) mol l(-1), respectively. Validoxylamine A appeared to be the most potential termites trehalase inhibitor among the four compounds. (C) 2009 Elsevier Inc. All rights reserved.