Fifteen N-(4,5,6-trisubstituted pyrimidin-2-yl)-N’-benzenesulfonylureas and three analogous benzenesulfonylureas without 5-substituent at pyrimidine moiety were studied on a flexing molecular docking method (flexX) according to their biological activity to the active site of acetohydroxyacid synthase (AHAS). The predicted binding affinities of the molecules were found to be linearly relevant to their experimental activities (R＝0.660). Then 27 N-(4,5,6-trisubstituted pyrimidin-2-yl)-N’-benzenesulfonylureas were studied on comparative molecular similarity index analysis. The results showed that the contribution of steric, electrostatic and H-bond donor was 47.3%, 32.8% and 19.9%, respectively. The cross-validated q2 was 0.520. The results indicate that the 3D-QSAR model is significant and has good predictability, providing useful information for designing new good activity AHAS inhibitors prior to their synthesis.

Key words: molecular docking, AHAS, CoMSIA, 3D-QSAR, N-(trisubstituted pyrimidin-2-yl)-N’-benzenesulfonylurea, herbicidal activity