Four New Pentacyclic Triterpene Glycosides Isolated from the Fruits of Cryptolepis buchananii R.Br. ex Roem. & Schult and Their Inhibition of NO Production in LPS-activated RAW264.7 Cells.

Abstract

From the methanol extract of the Cryptolepis buchananii fruits, four undescribed pentacyclic triterpenene glycosides (1-4) and five known pentacyclic triterpenenes (5-9) were isolated. Their structures were determined to be uncargenin C 28-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl ester (1), 3-O-β-D-glucopyranosyluncargenin C 28-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl ester (2), 3-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl-6β,23-dihydroxyursolic acid 28-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl ester (3), 3-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosylasiatic acid 28-O-α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranosyl ester (4), asiatic acid (5), 2α,3β,23-trihydroxyoleana-11,13(18)-dien-28-oic acid (6), arjunolic acid (7), 6β-hydroxyarjunolic acid (8), and actinidic acid (9) based on analyses of their HR-ESI-MS, 1D and 2D NMR spectra. All the isolates showed significantly NO production inhibition in LPS-activated RAW264.7 cells with the IC50 values ranging from 18.79 to 37.57 μM, compared to that of the positive control compound, dexamethasone, which showed IC50 value of 14.05 μM.