Synthesis and biological activities of novel quinazolinone derivatives containing a 1,2,4-triazolylthioether moiety

A series of novel quinazolinone derivatives containing a 1,2,4-triazolylthioether moiety were synthesised and their antimicrobial activities were evaluated. All the target compounds were characterised by H-1 NMR, C-13 NMR, ESI-MS, IR and elemental analyses. The single crystal structure of 3-((5-((2-fluorobenzyl) thio)-4-phenyl-4H-1,2,4-triazol-3-yl) methyl) quinazolin-4(3H)-one (VIIi) was also determined. The preliminary bioassays indicated that some of the target compounds possessed good antimicrobial activities. For example, 3-((4-phenyl-5-((4-(trifluoromethyl) benzyl) thio)-4H-1,2,4-triazol-3-yl) methyl) quinazolin-4(3H)-one (VIIs) exhibited the best inhibitory effect against Xanthomonas oryzae pv. oryzae and Xanthomonas axonopodis pv. citri with the half-effective concentration (EC50) values of 47.6 mu g mL(-1) and 22.1 mu g mL(-1), respectively, which were superior to the commercial bactericide, bismerthiazol. Meanwhile, 3-((5-((4-chlorobenzyl) thio)-4-phenyl-4H1,2,4- triazol-3-yl) methyl) quinazolin-4(3H)-one (VIIh) exhibited better fungicidal activities against Pellicularia sasakii and Colletotrichum capsici at the concentration of 50 mu g mL(-1), in comparison with the commercial fungicide, hymexazol. (C) 2016 Institute of Chemistry, Slovak Academy of Sciences