SYNTHESIS, ANTI-PHYTOPATHOGENIC AND DPPH RADICAL SCAVENGING ACTIVITIES OF C-PRENYLATED ACETOPHENONES AND BENZALDEHYDES

摘要

The syntheses of six prenylated acetophenone and benzaldehyde derivatives and their anti-phytopathogenic and antioxidant activities are reported. These compounds were obtained by electrophilic aromatic substitution (SEAr) of the corresponding arenes and 3-methyl-2-buten-1-ol using ZnCl2 as a Lewis acid catalyst in ethyl acetate. Reasonable to good yields were obtained based on unrecovered aromatic starting material (45-73%). All the synthesized compounds were evaluated against phytopathogenic gram-negative bacteria Agrobacterium tumefaciens, Pseudomonas syringae and Erwinia carotovora and plant fungal pathogens Botrytis cinerea, Phytophthora cinnamomi and Gibberella fujikuroi. The antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity assay and expressed as half maximal inhibitory concentration (IC50) values in μΜ concentrations. The antioxidant activity went from 27.20 μΜ to 100 μΜ. Compound 11 showed statistically significant inhibition of the growth of Botrytis cinerea, and compounds 13 and 15 showed statistically significant inhibition of the growth of Phytophthora cinnamomi, with respect to negative control fungal growth. All six compounds showed bacteriostatic effects against gram-negative plant pathogenic bacteria with IC50 values between 250 and 3.9 μΜ.