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Bioassay-guided fractionation of an ethanol extract of Roupellina (Strophanthus) boivinii from the rainforest of Madagascar afforded the six new cardenolide glycosides boivinides 1-6, as well as the four known cardenolide glycosides digitoxigenin 3-O-[beta-D-glucopyrananosyl-(1-->4)-alpha-L-acofriopyranoside], corotoxigenin 3-O-beta-D-boivinoside, 17alpha-corotoxigenin 3-O-beta-D-sarmentoside, and uzarigenin 3-O-alpha-L-rhamnoside. The structures of these compounds were elucidated by various 1D and 2D NMR techniques. All new compounds showed significant antiproliferative activity against the A2780 human ovarian cancer cell line, with boivinide A being the most active at IC50 = 0.17 microM.

Bioassay-guided fractionation of the MeOH and EtOAc fractions of extracts of two lianas collected in Suriname has led to the isolation of five new diterpenoids, humirianthone 1, 1-hydroxy-humirianthone 2, 15R-humirianthol 3, patagonol 4, and patagonal 5, and the five known diterpenoids, humirianthol 7, annonalide 8, acrenol 9, icacinol 10, and the oxidized annonalide 11. All 10 diterpenoids showed cytotoxic activity against the A2780 human ovarian cancer cell line, and compounds 1, 3, 8, and 9 also showed activity against phytopathogenic fungi.

A beta-carboline-, a tryptamine-, and two phenylethylamine-derived alkaloids and three known aromatic compounds were isolated from the aerial parts and roots of Cyathobasis fruticulosa (Bunge) Aellen, and their structures were elucidated by spectroscopic techniques. The one new alkaloid, N-methyl-N-formyl-4-hydroxy-beta-phenylethylamine (1), showed marginal antifungal activity.