To discover novel and effective potential agricultural antifungal agents, various kinds of imidazo[1,2-a]quinoxaline derivatives were designed, and synthesized from available and inexpensive reagents. Their antifungal activities were first evaluated against ten typical phytopathogenic fungi. The in vitro antifungal activity showed that some compounds exhibited more obvious broad-spectrum fungicidal activity than the two commercially-available fungicides chlorothalonil and hymexazol. Valsa mali and Botrytis cinerea strains exhibited the highest susceptibility with EC₅₀ values of 1.4–27.0 μg/mL to more than ten compounds. Compounds 5c and 5f showed the most promising inhibitory effects against Valsa mali (EC₅₀ = 5.6 μg/mL) and Fusarium solani (EC₅₀ = 5.1 μg/mL), respectively. Preliminary studies on the mechanism of action indicated that the imidazo[1,2-a]quinoxaline skeleton likely exerted its antifungal effects by disrupting hyphal differentiation, spore germination, and germ tube growth. Moreover, the cell experiment results indicated that these target compounds possessed good safety to BV2 cells. Overall, compounds 5c and 5f can be considered candidate compounds against specific fungi for further detailed research. This study can provide a theoretical basis for the application of imidazo[1,2-a]quinoxaline scaffolds as novel fungicides in agriculture.

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中文翻译：

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咪唑并[1,2-a]喹喔啉衍生物的合成和评价作为潜在的植物病原真菌抗真菌剂

为了发现新型有效的潜在农用抗真菌剂，设计了各种咪唑并[1,2-a]喹喔啉衍生物，并用可用且廉价的试剂合成。首先针对十种典型的植物病原真菌评估了它们的抗真菌活性。体外抗真菌活性表明，部分化合物比两种市售杀菌剂百菌清和恶霉唑表现出更明显的广谱杀菌活性。Valsa mali 和 Botrytis cinerea菌株对 10 多种化合物表现出最高的敏感性，EC _{50值为 1.4–27.0 μg/mL。}化合物5c和5f分别对苹果腐烂病菌(EC ₅₀  = 5.6 μg/mL)和茄病镰刀菌(EC ₅₀ = 5.1 μg/mL)显示出最有希望的抑制作用 。作用机制的初步研究表明，咪唑并[1,2-a]喹喔啉骨架可能通过破坏菌丝分化、孢子萌发和芽管生长来发挥抗真菌作用。此外，细胞实验结果表明这些目标化合物对BV2细胞具有良好的安全性。总体而言，化合物5c和5f可被视为针对特定真菌的候选化合物，以供进一步详细研究。该研究可为咪唑并[1,2-a]喹喔啉支架作为新型杀菌剂在农业中的应用提供理论依据。

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