Publications by authors named "W C Kokke"

A novel triterpenoid isolated from the non-saponifiable lipid of the aerial part extract of white bryony (Bryonia dioica) was established to be 3beta-hydroxy-27-norcycloartan-24-one based on spectroscopic methods. Isolation and identification of other known cycloartane triterpenoids and sterols also are described.

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Three novel triterpene alcohols, camelliols A (1), B (3), and C (5), possessing a mono-, bi-, and tricyclic ring system, respectively, have been isolated, along with achilleol A, a known monocyclic triterpene alcohol, from the nonsaponifiable lipids of sasanqua oil (Camellia sasanqua). The structures of these new alcohols were determined on the basis of spectroscopic methods.

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Five triterpenes with a D:C-friedo-oleanane skeleton, D:C-friedo-oleana-7,9(11)-diene-3 beta,29-diol (3-epikarounidiol), 7-oxo-D:C-friedo-olean-8-en-3 beta-ol (7-oxoisomultiflorenol), 7-oxo-8 beta-D:C-friedo-olean-9(11)-ene-3 alpha,29-diol, D:C-friedo-olean-8-ene-3 alpha,29-diol (3-epibryonolol), and D:C-friedo-olean-8-ene-3 beta,29-diol (bryonolol), the first four of which are new naturally occurring compounds, were isolated from the seeds of Trichosanthes kirilowii Maxim. The structures were determined by spectral and chemical methods. 3-Epikarounidiol, 7-oxoisomultiflorenol, and 3-epibryonolol showed marked inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear inflammation in mice.

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The EtOAc extract of the sponge Xestospongia muta collected in Colombus Island, Bahamas, yielded eleven straight-chain unsaturated, polyacetylenic, brominated acids, seven of which were identified on the basis of spectral data, including the unknown acids 2-7. These acetylenic acids are the first known examples that have been shown to inhibit HIV protease, a critical enzyme in the replication of human immunodeficiency virus.

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The structure of 7-oxodihydrokarounidiol [7-oxo-D:C-friedo-olean-8-ene-3 alpha,29-diol], isolates from the seeds of Trichosanthes kirilowii (Cucurbitaceae), was determined by chemical correlation with karounidiol [D:C-friedo-oleana-7,9(11)-diene-3 alpha,29-diol] from the same source. Two other natural products, viz. bryonolic acid (3 beta-hydroxy-D:C-friedo-olean-8-en-29-oic acid) and bryononic acid (3-oxo-D:C-friedo-olean-8-en-29-oic acid), were also correlated with karounidiol.

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