Antimicrobial activity and stability of tingenone derivatives

Quinone-methide triterpenes of the tingenone series were evaluated for their antimicrobial activity. These compounds were effective against Bacillus cereus, B. subtilis, Sarcina lutea, Staphylococcus aureus, Microsporum gypseum and a Gram-negative bacterium, Klebsiella pneumoniae. Under acidic conditions, the quinone-methide part of these compounds rearranged into the divinyl-phenolic system, and the antimicrobial activity was thus lost.