Natural products (NPs) have attracted increasing attention due to their structural diversity, abundance, and low environmental impact, making them valuable for novel fungicide development. In this study, a series of coumarin-7-N/O acethydrazide derivatives were synthesized by incorporating acetic acid moieties into the coumarin scaffold. The in vitro antifungal activities of these compounds were evaluated against six common plant pathogenic fungi. Compound B13 demonstrated significant antifungal effects, with EC₅₀ values of 3.24, 1.89, 1.70, 0.36, 4.27, and 1.50 μg/mL against Botrytis cinerea, Alternaria solani, Fusarium graminearum, Rhizoctonia solani, Colletotrichum orbiculare and Alternaria alternata, respectively. Notably, the antifungal activity against R. solani was comparable to the commercial fungicide boscalid (EC₅₀ values = 0.31 μg/mL), while the activity against A. solani and A. alternata was significantly higher than that of boscalid (EC₅₀ values = 13.60 and 2.55 μg/mL, respectively), respectively. Furthermore, in vivo assays demonstrated that the protective efficacy of B13 against R. solani at 200 μg/mL (86.9%) was comparable to that of Validamycin (92.1%). The inhibitory effects of B13 against R. solani were further confirmed through scanning electron microscopy and fluorescence microscopy. The influence of the charge distribution of the compound on its antifungal activity was investigated using Density Functional Theory (DFT). Meanwhile, some of the compounds exhibited herbicidal activity against four common field weeds. These results indicate that B13 is a promising candidate for crop protection, exhibiting high efficacy and low toxicity.

中文翻译：

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发现香豆素-7-N/O-乙酰酰肼衍生物作为新型抗真菌和除草剂

天然产物 （NPs） 因其结构多样性、丰富性和低环境影响而引起了越来越多的关注，使其在新型杀菌剂开发中具有价值。在本研究中，通过将乙酸部分掺入香豆素支架中，合成了一系列香豆素-7-N/O 乙酰酰肼衍生物。针对 6 种常见的植物病原真菌评估了这些化合物的体外抗真菌活性。化合物 B13 表现出显著的抗真菌作用，EC₅₀ 值分别为 3.24 、 1.89 、 1.70 、 0.36 、 4.27 和 1.50 μg/mL，分别对灰葡萄孢菌、 链格孢菌 、 禾谷镰刀菌 、 立枯丝核菌 、 链炭疽菌 和 链格孢菌 。 值得注意的是，对立枯菌的抗真菌活性与商业杀菌剂啶酰菌胺相当（EC₅₀ 值 = 0.31 μg/mL），而对茄菌和链取菌的活性分别显著高于啶酰菌胺（EC₅₀ 值 = 13.60 和 2.55 μg/mL）。此外，体内测定表明，B13 在 200 μg/mL （86.9%） 时对茄属 R 的保护效果与 Validamycin （92.1%） 相当。通过扫描电子显微镜和荧光显微镜进一步证实了 B13 对 R. solani 的抑制作用。使用密度泛函理论 （DFT） 研究了化合物的电荷分布对其抗真菌活性的影响。同时，一些化合物对四种常见的田间杂草表现出除草活性。 这些结果表明，B13 是一种很有前途的作物保护候选者，表现出高效和低毒性。