A new sesquiterpene lactone, named potamopholide, was isolated along with the known triterpene lupeol from the leaves of Vernonia potamophila. The stereochemical structure of the new compound, (3R*,4S*,5E,8S*,10S*)‐3,8‐epoxy‐3,4,13‐trihydroxy‐1‐oxogermacra‐5,7(11)‐dien‐6,12‐olide, was elucidated by mass spectrometric (CIMS, EIMS, HREIMS) and NMR spectroscopic (HMQC, HMBC, NOESY) analyses and by comparison with closely related compounds. The analysis was confirmed by MM+ geometry optimisation of the conformational structure. This 3,8‐O‐bridged 10‐membered ring hemiacetal seems to be related structurally to known 1,4‐O‐bridged compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)

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Following acetylation of a mixture of triterpene glycosides extracted from the root bark of Combretum psidioides eleven oleanane and ursane triterpene type glycosides were isolated. Their structures were established by spectral analysis and by comparison with related compounds; all acetylated derivatives could be correlated with known triterpene glycosides. Attempted acetylation of the sterically hindered 19α-OH group of arjunglucoside I (4) led to introduction of a (3-acetoxy-2-butenoyl) side chain, due to generation of acetylketene as a more reactive acylating agent.