Characterisation of four new triterpenoid saponins with nitric oxide inhibitory activity from aerial parts of Gouania leptostachya

Abstract

Four new triterpenoid saponins (gouaniasides VII-IX [1-3] and joazeiroside C [4]) and one known triterpenoid (5) were isolated from the aerial parts of Gouania leptostachya DC.(Rhamnaceae). Their structures were elucidated via one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization-mass spectrometry, and analyses of hydrolytic cleavage results. The anti-inflammatory potential of compounds 1-3 was evaluated according to their ability to inhibit the production of nitric oxide (NO) by RAW 264.7 macrophages. All compounds at noncytotoxic concentrations significantly inhibited NO production by macrophages in a concentration-dependent manner.

A New Ceanothane-Type Triterpenoid Saponin Isolated from Gouania leptostachya DC. var. tonkinensis Pit. and Its Underlying Anti-Inflammatory Effects

“…Bioassay-guided fractionation of the EtOH extract of G. leptostachya , employing various chromatography separation techniques (silica gel; YMC RP-18, and Sephadex LH-20) resulted in the purification of a new saponin ( 1 ) and 11 known compounds (2-11, Fig. 1 ), namely epigouanic acid A (2)[ 14 ], lupeol (3) [ 15 ], alphitolic acid (4) [ 16 ], ceanothenic acid (5) [ 17 ], daucosterol (6) [ 18 ], and n -butyl- β -D-fructopyranoside (7) [ 19 ], quercitrin (8) [ 20 ], catechin (9) [ 21 ], isoquercitrin (10) [ 22 ], and kaempferol-3- O -(6- O - E -caffeoyl)- β -D-galactopyranosyl-(1→2)- α -L-rhamnopyranosid (11) [ 23 ]. The identified compounds were validated by matching their nuclear magnetic resonance (NMR) data with the relevant literature.…”

“…Previously, we reported four new dammarane triterpenoid saponins (gouaniasines VII–IX) from G. leptostachya . Moreover, their potential nitric oxide inhibitory activity was also evaluated [ 14 ]. However, the underlying mechanisms of inflammation have not yet been discovered.…”