PHARMACOPHORIC CONFORMATIONS OF AZOLE ANTIFUNGALS AND THEIR INTERACTION WITH ACTIVE SITE OF TARGET ENZYME

AIM: To study the interactive mechanism of azole antifungals and functional residues of the active site of lanosterol 14α demethylase of Candida albicans. METHODS: The global minimum-energy conformations of 15 azole antifungals which belong to 4 different structural categories were determined by random conformation search and molecular dynamics simulated annealing. Active analogue approach was empolyed to search for the pharmacophoric conformations of all compounds. The resulting bioactive conformations were docked into the active site of lanosterol 14α demethylase of Candida albicans. RESULTS: All 15 azole antifungals was shown to have similar docking position in the active site. To compare with mammalian enzyme, the structurally selective residues of the active site of fungal lanosterol 14α demethylase were distributed in C terminus of F helix, β6-1 sheet and β6-2 sheet. The common halogenated benzene substructure of azole inhibitors was located deep in the same hydrophobic cavity. The π～π charge transfer complex may exist between halogenated benzene ring of azoles and the hydroxyl benzene side chain of residue Y132 of lanosterol 14α demethylase of Candida albicans. CONCLUSION: The dock results were in accord with SAR analysis. The interactive mode of azole antifungals with active site residues of lanosterol 14α demethylase of Candida albicans was elucidated. The structrual selectivity of the fungal target enzyme to its inhibitors was investigated at the same time.