New 3,4-Secocycloartane and 3,4-Secodammarane Triterpenes from the Ecuadorian Plant Coussarea macrophylla.

Coussarea macrophylla (Mart.) Müll.Arg. (Rubiaceae) was collected in Ecuador, and the bark was extracted with AcOEt. Chromatographic separation afforded six novel 3,4-secocycloartane and 3,4-secodammarane triterpenes, named macrocoussaric acids A-F, together with the known metabolites secaubryenol and 3,4-secodammara-4(28),20,24-triene-3,26-dioic acid. The structures of the new compounds were determined on the basis of their spectroscopic data. This is the first report of 3,4-secocycloartane and 3,4-secodammarane triterpenes occurring in a Coussarea species. Macrocoussaric acids A and B (2 and 3, resp.) were found to be moderately cytotoxic against five different tumor cell lines.