Tributelosides A-D: Four Undescribed Spirostan Glycosides Isolated from the Branches and Leaves of Tribulus terrestris with Their NO Production Inhibitory Activity in LPS Activated RAW 264.7 Cells.

Four undescribed spirostan glycosides, (25S)-5α-spirostan- 12-one-2α,3β-diol-3-O-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (1), (25S)-5α-spirostan-12-one-2α,3β-diol-3-O-β-D-galatopyranosyl-(1→2)-β-D-glucopyranosyl- (1→4)-β-D-galactopyranoside (2), (25S)-5α-spirostan-12-one-2α,3β-diol-3-O-β-D-glucopyranosyl-(1→2)-[β-D-glucopyranosyl-(1→3)]-β-D-glucopyranosyl-(1→4)-β-D-galactopyranoside (3), and hecogenin 3-O-β-D-glucopyranosyl-(1→3)-[β-D-xylopyranosyl-(1→2)]-β-D-glucopyranosyl-(1→4)-[α-L-rhamnopyranosyl-(1→2)]-β-D-galactopyranoside (4), together with eleven known compounds (5-15) were isolated from the branches and leaves of Tribulus terrestris. Their chemical structures were established through spectroscopic methods, including HR-ESI-MS, 1D-, and 2D-NMR spectra. Preliminary biological evaluation on NO production inhibitory activity in LPS activated RAW 264.7 cells showed that compounds 1-3, 5, and 6 had significant inhibitory effects with IC50 values ranging from 2.4 to 18.3 μM, compared to that of the positive control compound, dexamethazone (IC50 13.6 μM).