Rice sheath blight, caused by the fungus Rhizoctonia solani, poses a significant threat to rice cultivation globally. This study aimed to investigate the potential mechanisms of action of camphor derivatives against R. solani. Compound 4o exhibited superior fungicidal activities in vitro (EC₅₀ = 6.16 mg/L), and in vivo curative effects (77.5%) at 500 mg/L were significantly (P < 0.01) higher than the positive control validamycin·bacillus (66.1%). Additionally, compound 4o exhibited low cytotoxicity and acute oral toxicity for adult worker honeybees of Apis mellifera L. Mechanistically, compound 4o disrupted mycelial morphology and microstructure, increased cell membrane permeability, and inhibited both PDH and SDH enzyme activities. Molecular docking and molecular dynamics analyses indicated a tight interaction of compound 4o with PDH and SDH active sites. In summary, compound 4o exhibited substantial antifungal efficacy against R. solani, serving as a promising lead compound for further optimization of antifungal agents.

中文翻译：

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樟脑衍生物对立枯丝核菌的抗真菌活性和机制：一种有前景的水稻纹枯病替代抗真菌剂


水稻纹枯病由真菌立枯丝核菌引起，对全球水稻种植构成重大威胁。本研究旨在探讨樟脑衍生物对抗立枯丝核菌的潜在作用机制。化合物4o表现出优异的体外杀菌活性（EC ₅₀ = 6.16 mg/L），500 mg/L的体内疗效（77.5%）显着（P < 0.01）高于阳性对照井冈霉素·芽孢杆菌(66.1%)。此外，化合物4o对Apis mellifera L成年工蜂表现出低细胞毒性和急性口服毒性。从机制上讲，化合物4o破坏菌丝形态和微观结构，增加细胞膜通透性，并抑制PDH和SDH酶活性。分子对接和分子动力学分析表明化合物 4o 与 PDH 和 SDH 活性位点存在紧密的相互作用。总之，化合物 4o 对立枯丝核菌表现出显着的抗真菌功效，可作为进一步优化抗真菌药物的有前景的先导化合物。