Mps1–Targeted Molecular Design of Melatonin for Broad-Spectrum Antifungal Agent Discovery

Melatonin, a multifunctional class of natural products, has demonstrated antifungal activity, making it a promising candidate for developing antifungal agents. The mitogen-activated protein kinase (Mps1) within fungal pathogens has a target inhibitory effect of melatonin in fungi. We use a virtual screening strategy to design melatonin derivatives based on the melatonin-Mps1 targeting model. Of these, a multiflorane-substitution compound <b>M-12</b> emerges as a potent antifungal agent, exhibiting broad-spectrum efficacy against eight phytopathogenic fungal species, and effectively reduces the severity of tomato gray mold, Fusarium head blight in wheat, Sclerotinia stem rot in rape, and peach brown rot. <b>M-12</b> half-maximal effective concentration values (5.50 μM against <i>Botrytis cinerea</i>, 5.21 μM against <i>Fusarium graminearum</i>, 10.6 μM against <i>Rhizoctonia solani</i>, and 9.02 μM against <i>Sclerotinia sclerotiorum</i>) are better than those of commercial broad-spectrum fungicide azoxystrobin (55.0, 23.2, 46.5, and 17.7 μM, respectively). Antifungal activity of enantiomer (<i>S</i>)-<b>M-12</b> (5.02 μM) is significantly greater than its (<i>R</i>)-enantiomer (23.6 μM) against <i>B. cinerea</i>. Molecular docking and transcriptome analysis reveal that <b>M-12</b> achieves its antifungal effects by inhibiting Mps1 kinase, thereby suppressing fungal growth and virulence.