Search

The plant Gymnema sylvestre has been used widely in traditional medicine as a remedy for several diseases, and its leaf extract is known to contain a group of bioactive triterpene saponins belonging to the gymnemic acid class. Gymnemic acid I (1) is one of the main components among this group of secondary metabolites and is endowed with an interesting bioactivity profile. Since there is a lack of information about its specific biological targets, the full interactome of 1 was investigated through a quantitative chemical proteomic approach, based on stable-isotope dimethyl labeling. The ribosome complex was found to be the main partner of compound 1, and a full validation of the proteomics results was achieved by orthogonal approaches. Further biochemical and biological investigations revealed an inhibitory effect of 1 on the ribosome machinery.

Nine ophiuroid species from different geographical areas have been analyzed for their polar steroid content. Six new sulfated polyhydroxysteroids have been isolated, together with six known compounds of this type previously reported from brittle scars. The new steroids possess C-21 and 3 alpha- sulfate groups, which are distinctive features of the steroid sulfates of ophiuroids. Hydroxylation at C-2, C-4, and C-11 and the presence of double bonds at C-5 are further features of the new steroids. The structures of the new compounds were solved by spectroscopic analysis.

Five new amino acid derivs. were isolated from the New Caledonian sponge Jaspis carteri, together with known bengamides A and B. The structures of the new compds. were detd. by interpretation of their spectral data and by comparison with spectral data of known bengamides. Bengamides G (I), and H, I, and J are simply the tridecanoate and pentadecanoate analogs of the original bengamides A and B, whereas bengamide K (II) is a caprolactam formamide deriv. of bengamide B.

Six new cytotoxic isomalabaricane-type triterpenoids and nortriterpenoids with a 3alpha-acetoxy group were isolated, along with the known globostellatic acids B (1) and C (2), from the marine sponge Jaspis sp. collected at Vanuatu Island. The structures were determined by 2D NMR data and by comparison with spectral data of known related compounds.