Steroidal saponins with anti-inflammatory activity from Tribulus terrestris L.

Abstract

Objective: Tribulus terrestris L. (T. terrestris) is a highly valuable traditional Chinese medicine used to treat stroke, inflammation, pulmonary fibrosis, liver cancer, and urolithiasis. To identify the basic substance responsible for the anti-inflammatory effect of TST (total saponins of Tribulus), its chemical composition was systematically studied, and its effect of inhibiting nitric oxide generation and the expression of related inflammatory factors were determined.
Methods: To separate chemical constituents from T. terrestris by column chromatography. Spectroscopic methods, including 1D and 2D nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) techniques, were used to elucidate the isolated compounds. The anti-inflammatory activities of TST and several compounds were evaluated in vitro.
Results: Fifteen steroidal saponins, including 9 furostanol steroidal saponins (1, 2, 3, 4, 5, 6, 7, 8, and 15) and 6 isospirostanol steroidal saponins (9, 10, 11, 12, 13, and 14), were isolated from T. terrestris. TST significantly decreased the expression of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in RAW 264.7 cells stimulated by lipopolysaccharides. Compounds 13 and 15 evidently reduced TNF-α expression. Compounds 6, 10, 12, 13, and 15 markedly reduced IL-6 expression.
Conclusions: Compounds 1 was a novel furostanol steroidal saponin, named 26-O-β-D-glucopyranosyl-(25R)-5α-furostan-12-carbonyl-20(22)-en-3β, 26-diol-3-O-{β-D-xylopyranosyl-(1→2)-[β-D-xylopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-galactopyranoside}. Compounds 2 was isolated from the family Zygophyllaceae for the first time, and 5 and 6 were isolated from the Tribulus genus. TST and compounds 6, 10, 12, 13, and 15 exerts anti-inflammatory activity.

Keywords

Interleukin-6 / Nitric oxide (NO) inhibition / Steroidal saponins / Tribulus terrestris L. / Tumor necrosis factor-α

Author summay

Miaojie Yang and Mahmood Brobbey Oppong contributed equally to this work.