Synthesis and antimicrobial activities of novel quinazolin-4(3H)-one derivatives containing a 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole moiety

A series of novel quinazolin-4(3H)-one derivatives (6a-6y) containing a 1,2,4-triazolo [3,4-b][1,3,4]thiadiazole moiety were designed and synthesized, and their structures were fully characterized by H-1 NMR, C-13 NMR, HRMS and IR spectra. Among them, the structure of compound 6u was unambiguously confirmed via single crystal X-ray diffraction analysis. The obtained bioassay results showed that compounds 6h, 6k, 6l and 6y had the EC50 (half-maximal effective concentration) values of 34.8, 28.2, 41.5 and 42.5 mu g/mL against the phytopathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo), respectively, which were significantly better than commercial bactericide Bismerthiazol (EC50 = 95.8 mu g/mL). Additionally, compounds 6a and 6b exhibited the strong inhibition activity against the pathogen Xanthomonas axonopodis pv. citri (Xac). (C) 2017 King Saud University. Production and hosting by Elsevier B.V.