Flavones and sesquiterpene lactones from Achillea atrata subsp. multifida: antimicrobial activity

Four flavones (1-4) and nine sesquiterpene lactones (5-13), one of them (5) a new compound, were isolated from the aerial parts of Achillea atrata L. subsp. multifida. Although the crude extract demonstrated in vitro inhibitory activity against Candida albicans and Bacillus subtilis, all isolated flavones were active against B. subtilis. Flavones 1, 2, and 3 were also active against C. albicans, while 1 and 3 exhibited activity against E. coli, as well. None of the tested lactones (7, 9, 12, and 13) showed any antimicrobial activity.