Antimicrobial agents from Heterotheca inuloides

Article abstract of DOI:10.1055/s-2006-959462

By bioassay directed fractionation, four sesquiterpenoids 1-4 were isolated as antimicrobial agents from the dried flowers of Heterotheca inuloides, a Mexican medicinal plant locally known as 'arnica'. 7-Hydroxy- 3,4-dihydrocadalin (3) and 7-hydroxycadalin (4) exhibited potent antibacterial activity against Gram-positive bacteria with minimum inhibitory concentrations (MICs) ranging from 6.25 to 12.5 μg/ml. Notably, 7-hydroxy- 3,4-dihydrocadalin showed bactericidal activity against methicillin-resistant Staphylococcus aureus (MRSA) with a minimum bactericidal concentration (MBC) of 12.5 μg/ml.