Melantheraside A–E, five original triterpenes with natural chloride or oxime group from the aerial parts of Melanthera elliptica O. Hoffm

International audience; Five new pentacyclic triterpenoids, Melantheraside A–E (1–5) together with eleven known compounds (6-16) were isolated from the methanol extract of the aerial parts of Melanthera elliptica O. Hoffm. Their structures were established by extensive analysis of 1D- (1H, 13C), 2D- (COSY, ROESY, HSQC and HMBC) NMR data experiments in conjunction with mass spectrometry (TOFESIMS and HR-TOFESIMS) and by comparison with data reported in the literature. The structures of the new compounds were established as: 12α-chloro-3β-hydroxyoleanan-28,13β-olide (1), 3β-acetoxy-12α-hydroxytaraxer-14-en-28-oic acid (2), 3β-hydroxy-12-oximetaraxeran-28,14β-olide (3), 3β-acetoxy-12-oximetaraxeran-28,14β-olide (4) and 2β-carboxyamino-12α-chloro-3-oxo-1-nor-oleanan-28,13β-olide (5). The 3β-acetoxy-12α-chloro-oleanan-28,13β-olide (6) was isolated for the first time as natural product.