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

Abstract

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).