Antimicrobial Metabolites from Three Serbian Caloplaca.

Abstract

Methanol extracts of three Caloplaca. species showed broad-spectrum antifungal and antibacterial properties against some human and plant pathogens. Fractionation with methylene chloride and isolation of pure anthraquinone derivatives substantially increased the level of antimicrobial activity. Eight anthraquinone derivatives were isolated from the three species. 1-O.-Methylparietin and 8-O.-methylparietin were isolated from lichens for the first time. Minimum inhibitory concentrations for the extracts were found to be 80–320 µg/ml for bacteria and 40–320 µg/ml for fungi, and the pure anthraquinones range from 20 to 320 µg/ml for bacteria and from 20 to 160 µg/ml for fungi.

Keywords:

• Anthraquinones
• antibacterial activity
• antifungal activity
• Caloplaca