Synthesis of Pogostone‐Inspired Dehydroacetic Acid Derivatives and Their Antifungal Activity against Sclerotinia sclerotiorum (Lib.) de Bary

Abstract In an effort to exploit the natural antifungal pogostone, its simplified scaffold dehydroacetic acid (DHA) was used as a lead compound to semi‐synthesize 56 DHA derivatives ( I1 – 48 , II , III , and IV1 – 6 ). Among them, compound IV4 exhibited the most potent antifungal activity with 11.0 μM EC 50 against mycelial growth of Sclerotinia sclerotiorum (Lib.) de Bary whose sclerotia production was also completely suppressed at this concentration. Furthermore, IV4 could completely inhibit infection cushion formation of S. sclerotiorum on rape leaves and achieved a preventive efficacy of 90.2 % at 500 μM, which was on the same level as that of commercial boscalid at 30 μM (88.7 %). The results of physiological and ultrastructural studies indicated that IV4 might disrupt the cell membrane permeability or induce the imbalance of mitochondrial membrane potential homeostasis to exert the antifungal mode of action. Besides, the robust and predicative three‐dimensional quantitative structure‐activity relationship (3D‐QSAR) models were developed and discussed herein.