Synthesis, Crystal Structure, and Agricultural Antimicrobial Evaluation of Novel Quinazoline Thioether Derivatives Incorporating the 1,2,4-Triazolo[4,3-a]pyridine Moiety

Abstract

A total of 22 quinazoline thioether derivatives incorporating a 1,2,4-triazolo­[4,3-a]­pyridine moiety were designed, synthesized, and evaluated as antimicrobial agents in agriculture. Among these compounds, the chemical structure of compound 6l was further confirmed via single-crystal X-ray diffraction analysis. The bioassay results revealed that some of the compounds possessed noticeable in vitro antibacterial activities against the tested phytopathogenic bacteria. For example, compounds 6b and 6g had EC50 values as low as 10.0 and 24.7 μg/mL against Xanthomonas axonopodis pv. citri (Xac), respectively, which were significantly better than that of the commercial agrobactericide bismerthiazol (56.9 μg/mL). Particularly, compound 6b was also found to be capable of suppressing the pathogenic bacterium Xanthomonas oryzae pv. oryzae (Xoo) approximately 12-fold more potent than control bismerthiazol, in terms of their EC50 values (7.2 versus 89.8 μg/mL). Importantly, the most active compound 6b turned out to be one with the highest hydrophilicity and the lowest molecular weight within the series. In vivo bioassays further showed the application prospect of 6b as a promising plant bactericide for controlling Xoo. Additionally, in vitro antifungal activities of these compounds were also evaluated at the concentration of 50 μg/mL. Overall, the present study demonstrated the potential of 1,2,4-triazolo­[4,3-a]­pyridine-bearing quinazoline thioether derivatives as efficient agricultural antibacterial agents for crop protection.

The SYNTHESIS, SCREENING OF NOVEL 1-SUBSTITUTED-3-(4-OXO-2-PHENYLQUINAZOLIN-3(4H)-YL) UREA AND THIOUREA ANALOGUES AS POTENT ANTIBACTERIALS

“…The compounds exhibited comparable antibacterial activity. The reported literature of quinazolinone with substitutions of chloro, methyl, methoxy, hydroxyl, ethers, thioethers,1-chloro-2-(trifluoromethyl) benzene and N-but-3-ene thiourea derivatives exhibited good antibacterial and anticancer activity [23][24][25][26][27][28]. When we compared our synthesized derivatives with them we could find a new target wherein we can structurally modify our derivatives to develop new series of quinazolines with antibacterial as well as anticancer activity.…”

Design, synthesis, and biological activity of novel 1,2,4-oxadiazole derivatives

“…The mycelium growth rate method was utilized to evaluate in vitro antifungal activities of target compounds against R. solani [ 34 ]. The DMSO solution of the test compound was added to a sterilized petri dish containing about 10 mL of molten potato dextrose agar (PDA).…”

An insight on medicinal attributes of 1,2,4-triazoles

“…7 ) possessed significant activities against the tested phytopathogenic bacteria, among which compound 42a was found to be most active and it was 12-fold more potent against Xanthomonas oryzae pv. oryzae with EC 50 value of 7.2 μg/mL than bismerthiazol (EC 50 : 89.8 μg/mL) [ 60 ].…”