Design, Synthesis, and Antifungal Evaluation of Luotonin A Derivatives against Phytopathogenic Fungi

Abstract

Crop diseases caused by fungi threaten food security and exacerbate the food crisis. Inspired by the application of fungicide candidates from natural products in agrochemical discovery, a series of luotonin A derivatives were designed, synthesized, and evaluated for their antifungal activities against five plant fungi. Most of these compounds exhibited significant fungicidal activity against <i>Botrytis cinerea</i> <i>in vitro</i> with EC₅₀ values less than 1 μg/mL. Among them, compounds <b>w7</b>, <b>w8</b>, <b>w12</b>, and <b>w15</b> showed superior antifungal activity against <i>B. cinerea</i> with EC₅₀ values of 0.036, 0.050, 0.042, and 0.048 μg/mL, respectively, which were more potent than boscalid (EC₅₀ = 1.790 μg/mL). Preliminary mechanism studies revealed that compound <b>w7</b> might pursue its antifungal activity by disrupting the fungal cell membrane and cell wall. Moreover, <i>in vivo</i> bioassay also indicated that compound <b>w7</b> could be effective for the control of <i>B. cinerea</i>. The above results evidenced the potential of luotonin A derivatives as novel and promising candidate fungicides.