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.

中文翻译：

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包含1,2,4-三唑并[4,3- a ]吡啶部分的新型喹唑啉硫醚衍生物的合成，晶体结构和农业抗菌性评价

总共设计，合成和评估了22个结合有1,2,4-三唑并[4,3- a ]吡啶部分的喹唑啉硫醚衍生物，并将其作为农业上的抗菌剂进行了评估。在这些化合物中，通过单晶X射线衍射分析进一步证实了化合物6l的化学结构。生物测定结果表明，某些化合物对被测植物病原菌具有显着的体外抗菌活性。例如，化合物6b和6g的抗轴索黄单胞菌pv的EC ₅₀值低至10.0和24.7μg / mL 。红蜘蛛（西飞），分别比市售农用杀菌剂比美噻唑（56.9μg/ mL）好得多。特别地，还发现化合物6b能够抑制病原细菌米氏黄单胞菌（Xanthomonas oryzae pv）。米曲霉（白叶枯病）约12倍于对照叶枯唑更有效，在其EC方面₅₀的值（7.2对89.8微克/毫升）。重要的是，在该系列中，活性最高的化合物6b证明是具有最高亲水性和最低分子量的化合物。体内生物测定进一步显示了6b作为控制Xoo的有前途的植物杀菌剂的应用前景。。另外，还在50μg/ mL的浓度下评估了这些化合物的体外抗真菌活性。总的来说，本研究证明了带有1,2,4-三唑并[4,3- a ]吡啶的喹唑啉硫醚衍生物作为有效的农业抗菌剂用于农作物保护的潜力。