Catecholic chalcones control phytopathogenic bacteria in non-toxic concentrations

Evaluate the in vitro and in vivo effects of catecholic chalcones and their derivatives against phytopathogenic bacteria and their in vivo toxicity.

Antibacterial testing was conducted using minimum inhibitory and bactericidal concentrations (MIC/MBC) assays. The fractional inhibitory concentration index was calculated. Inhibition of enzymatic activity was indicated by halos measurement. Toxicity study used Caenorhabditis elegans model and bacterial leaf spot control in tomato was evaluated in vivo. Catecholic chalcones 1 (3-Br), 2 (2-CH3), 3 (3-OH), and 4 (4-OH) presented promising MIC/MBC values varying from 12.5 to 50 µg·mL-1, with bactericidal effect and significant reduction of cellulase, xylanase, amylase, and protease activities. Lethal concentration (LC50) values ranged from 31.25 to 250 µg·mL-1. Catecholic chalcones and streptomycin did not show synergistic activity. Catecholic chalcones 2 and 3 were able to control the bacterial leaf spot in tomato.

These results revealed the promising agrochemical potential of catecholic chalcones and their possible safety application for humans as pesticide.