Cytotoxic pentacyclic triterpenes from Combretum nigricans

A new pentacyclic triterpene, 11α-acetoxy-20,24-epoxy-25-hydroxy-dammar-3-one (1), has been isolated from the African tree Combretum nigricans, together with the known corresponding diol, 20,24-epoxy-11α,25-dihydroxy-dammar-3-one (2). They are responsible, at least in part, for the cytotoxic activity of the methanolic extract of the plant. © 2003 Elsevier Science B.V. All rights reserved.