Structure elucidation of secondary metabolites isolated from the leaves of Ixora undulate and their inhibitory activity toward advanced glycation end-products formation.

Three aromatic glycosides (1-3), two sulfur and nitrogen-containing compound glucosides (4, 5), and one flavonoid glycoside (6) were isolated from the leaves of Ixora undulata. Their structures were established by extensive 1D, 2D NMR, and HRESIMS experiments, and structure 4 was further confirmed by single crystal X-ray diffraction analysis. Of the assayed compounds, 7, 11 and 12 showed strong inhibitory activity toward advanced glycation end-products formation with IC50 values of 86.0 μM, 76.6 μM and 98.6 μM, respectively.