Nine dimeric xanthanolides, pungiolides F-N, and five known analogues, pungiolides A-E, were isolated from fruits of Xanthium chinense. Their structures were elucidated through spectroscopic and electronic circular dichroism (ECD) analyses. Pungiolide F is a xanthanolide dimer with an acyclic linkage. Five of the dimers, pungiolides H, L, A, C and E, exhibited moderate cytotoxicities with IC50 values in the range of 0.90-6.84 μM using taxol as the positive control, which had, by comparison, IC50 values in the range of 0.00118-0.0675 μM. These findings enrich the structural diversity of dimeric sesquiterpene lactones.
Keywords: Compositae; Cytotoxic activity; Dimeric xanthanolides; Xanthium chinense.
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