Triterpenes possessing an unprecedented skeleton isolated from hydrolyzate of total saponins from Gynostemma pentaphyllum

Five novel triterpenes were isolated from hydrolyzate of total saponins from Gynostemma pentaphyllum and identified as gypensapogenin A (1), gypensapogenin B (2), gypensapogenin C (3), 3-O-β-d-glucopyranosyl-gypensapogenin D (4) and gypensapogenin D (5), two of which (1 and 2) possess unprecedented ring A. The cyclization of the side chains-3 formed five-membered cyclic ketone rings similar to ring E in 1. The 21-oic acid-21, 23-lactone was present in the side chains of 4 and 5. We also proposed the possible formation mechanisms of compounds 1–3. Compounds 1–5 were evaluated for cytotoxic activities in three cell lines including A549, U87 and Hep3B and compound 3 showed significant activities toward A549 and U87 human cancer cells (with IC 50 values at 0.11 and 0.58 μm respectively).

Five novel triterpenes (1–5) were isolated from hydrolyzate of Gynostemma pentaphyllum. Compounds 1 and 2 possess unprecedented ring A and 5-membered cyclic ketone rings in the side chains. Compound 3 showed significant antitumor activities in vitro.Figure optionsDownload as PowerPoint slideHighlights
► Five novel compounds were isolated from the hydrolyzate of Gynostemma pentaphyllum.
► The seven-membered ring A with an oxygen bridge constitutes an unprecedented triterpene skeleton.
► Significant cytotoxicities of 3 against tumor cell lines with IC50 values 0.11 μM and 0.58 μM.