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

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 ionisation-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.