Natural products as sources of new fungicides (V): Design and synthesis of acetophenone derivatives against phytopathogenic fungi in vitro and in vivo.

A series of acetophenone derivatives (10a-10i, 11, 12a-12g, 13a-13g, 14a-14d and 15a-15l) were designed, synthesized and evaluated for antifungal activities in vitro and in vivo. The antifungal activities of 53 compounds were tested against several plant pathogens, and their structure-activity relationship was summarized. Compounds 10a-10f displayed better antifungal effects than two reference fungicides. Interestingly, the most potent compound 10d exhibited antifungal properties against Cytospora sp., Botrytis cinerea, Magnaporthe grisea, with IC50 values of 6.0-22.6 µg/mL, especially Cytospora sp. (IC50 = 6.0 µg/mL). In the in vivo antifungal assays, 10d displayed the significant protective efficacy of 55.3% to Botrytis cinerea and 73.1% to Cytospora sp. The findings indicated that 10d may act as a potential pesticide lead compound that merits further investigation.