Sesquiterpene lactones from Anthemis melanolepis

From the aerial parts of A. melanolepis, two new sesquiterpene lactones, melanolepin B (= 1 alpha,4 beta,8 alpha-atrihydroxyeudesm-11(13)-en-12,6 alpha-olide; 1) and melanolepin C (= 1 alpha,10 beta-epoxy-8 beta-hydroxygermacra-4(15),11(13)-dien-12,6 alpha-olide; 2), were isolated, together with four known compounds, desacetyllaurenobiolide, dentatin A, taraxasterol, and (3S,5R)-loliolide. Compound 1 was found to have the rare cis-fused eudesmane skeleton. The structures of the isolated compounds were established by means of NMR (H-1, H-1-COSY,H-1,C-13-HSQC, HMBC, NOESY) and MS analyses.