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

ABSTRACT

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.