Antimicrobial substance, 3',4'-dihydroxyacetophenone, in coffee residue

An active antimicrobial substance contained in coffee residue was purified by HPLC. As result of the identification using MS, 1H-, and 13C-NMR, etc., 3',4'-dihydroxyacetophenone was found to be the antimicrobial substance in coffee residue. Comparison of the antimicrobial spectra of 3',4'-dihydroxyacetophenone isomers and catechol suggested that the antimicrobial activity of 3',4'-dihydroxyacetophenone isomers vary depending on the binding sites of hydroxyl groups, and the antimicrobial activity of catechol analogs was inversely proportional to the polarity of groups binding thereto