New sources and antifungal activity of sesquiterpene lactones

In the search for new sources of sesquiterpene lactones, six Certaurea species have been analyzed. The activity against the fungus Cunninghamella echinulata (+)-cnicin (1) and (+)-salonitenolide (2), isolated from the Centaurea plants, as well as that of(+)-costunolide (3), (-)-dehydrocostuslactone (4), (-)-lychnopholide (5) and(-)-eremantholide C (6), has been evaluated. Compounds 3 and 4 showed noticeable EC50 values, whilst more polar lactones were inactive. These results suggest that a relatively low polarity is one of the molecular requirements for the antifungal activity of sesquiterpene lactones. (C) 2000 Elsevier Science B.V. All rights reserved.