New triterpene saponins from Phryna ortegioides

Abstract

The structures of the new compounds were determined as gypsogenic acid 28-O-beta-D-glucopyranosyl-(1 -> 2)-O-beta-D-glucopyranosyl-(1 -> 6)-O-beta-D-glucopyranosyl ester (1), 3-O-alpha-L-arabinofuranosyl-gypsogenic acid 28-O-beta-D-glucopyranosyl-(1 -> 3)-O-[beta-D-glucopyranosyl-(1 -> 6)]-O-beta-D-glucopyranosyl ester (2), 3-O-alpha-L-arabinofuranosyl-gypsogenic acid 28-O-beta-D-glucopyranosyl-(1 -> 3)-O-[beta-D-glucopyranosyl-(1 -> 2)-O-beta-D-glucopyranosyl-(1 -> 6)-O-]-beta-D-glucopyranosyl ester (3), 3-O-alpha-L-arabinofuranosyl-16 alpha-hydroxyolean-12-en-23,28-dioic acid-28-O-beta-D-glucopyranosyl-(1 -> 3)-O-[beta-D-glucopyranosyl-(1 -> 2)-O-beta-D-glucopyranosyl-(1 -> 6)]-O-beta-D-glucopyranosyl ester (4). Their structures were established by a combination of one-and two-dimensional NMR techniques, and mass spectrometry. Noteworthy, none of isolated compounds possesses as aglycone moiety gypsogenin, considered a marker of Caryophyllaceae family. The cytotoxic activity of the isolated compounds was evaluated against three cancer cell lines including A549 (human lung adenocarcinoma), A375 (human melanoma) and DeFew (human B lymphoma) cells. Only compound 6 showed a weak activity against A375 and DeFew cell lines with IC50 values of 77 and 52 uM, respectively. None of the other tested compounds, in a range of concentrations between 12.5 and 100 uM, caused a significant reduction of the cell number