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

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-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-glucopyranosyl ester (1), 3-O-beta-D-glucopyranosyluncargenin C 28-O-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-glucopyranosyl ester (2), 3-O-beta-D-glucopyranosyl-(1 -> 6)-beta-D-glucopyranosyl-6 beta,23-dihydroxyursolic acid 28-O-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-glucopyranosyl ester (3), 3-O-beta-D-glucopyranosyl-(1 -> 2)-beta-D-glucopyranosylasiatic acid 28-O-alpha-L-rhamnopyranosyl-(1 -> 2)-beta-D-glucopyranosyl ester (4), asiatic acid (5), 2 alpha,3 beta,23-trihydroxyoleana-11,13(18)-dien-28-oic acid (6), arjunolic acid (7), 6 beta-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 mu M, compared to that of the positive control compound, dexamethasone, which showed IC50 value of 14.05 mu M.

Automated summary

Four undescribed pentacyclic triterpenene glycosides and five known pentacyclic triterpenenes were isolated from the methanol extract of Cryptolepis buchananii fruits. Their structures were determined through various spectroscopic analyses. These compounds showed significant inhibition of NO production in LPS-activated RAW264.7 cells.