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

Abstract 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 IC 50 values of 6.0–22.6 µg/mL, especially Cytospora sp. (IC 50  = 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.