Triterpenoid saponins from Psammosilene tunicoides and their antinociceptive activities.

Herein, five undescribed oleanane-type triterpenoid saponins, namely, psammosaponins A–E, along with nine known compounds, were isolated from the roots of Psammosilene tunicoides. Moreover, part of the ethanolic extract of P. tunicoides was acid-hydrolyzed and three aglycones were isolated from the resulting hydrolysate. The structures of all compounds were established through extensive analysis involving 1D and 2D NMR experiments, HRESIMS measurements, chemical derivatization, and comparison of spectroscopic data with the values reported in the literature. In all, 10 of the isolated saponins and the three aglycones were evaluated in the acetic acid-induced writhing model for their antinociceptive activity. At a dose of 40 mg/kg, these compounds exhibited significant inhibitory effects on the mouse writhing response, with inhibitions ranging from 31.9% to 79.3%. In addition, the structure–activity relationships of the isolates were discussed. Among the isolates, quillaic acid 3- O -glucuronide and 16α-hydroxygypsogenic acid showed better antinociceptive activity with inhibitions of 79.3% and 73.7%, respectively. Both isolates also exhibited antinociceptive activities in hot plate and formalin tests on mice. Their antinociceptive mechanism was explored in lipopolysaccharide–stimulated RAW 264.7 cells. These isolates could significantly inhibit the production of nitric oxide and interleukin-6 and downregulate the expression levels of inducible NO synthase, COX-1, and COX-2. Fourteen oleanane-type triterpenoid saponins including five undescribed triterpenoid saponins, psammosaponins A–E, were isolated from Psammosilene tunicoides , and three aglycones were obtained by hydrolysis of its ethanolic extract. Some of them showed significant antinociceptive activity. [Display omitted] • Five undescribed oleanane-triterpenoid saponins were isolated from Psammosilene tunicoides. • 13 isolated compounds exhibited antinociceptive activity with high inhibitions, up to 79.3%. • Two compounds could effectively inhibit the production of COX-1, iNOS, and IL-6. [ABSTRACT FROM AUTHOR]