The absolute stereostructures of three rare D:B-friedobaccharane skeleton triterpenes from the leaves of Salacia chinensis

Three new D:B-friedobaccharane skeleton triterpenes named foliasalacins D1 (1), D2 (2), and D3 (3) together with the 20 known ones (4-23) were isolated from the leaves of Salacia chinensis Linn., collected in Thailand. The absolute structures of the three new compounds (1-3) possessing the rare D:B-friedobaccharane skeleton were characterized on the basis of chemical and physiochemical evidences.