Abstract: Previous researches have confirmed that saponins from Tribulus terrestris L. (STT) is effective in controlling serum glucose and lipid levels.The present study investigated the effect of STT on advanced glycation end products (AGEs) formation and AGEs-mediated endothelial cell dysfunction. Fluorescence detection was used to monitor the Maillard reaction. Primary cultured bovine aortic endothelial cells (BAECs) were exposed to 100 μg/mL AGEs for 30 min followed by STT supplementation.Cell viability was detected by MTT assay, whereas cellular nitric oxide (NO) release, enzymatic activity of NO synthase (NOS), and levels of superoxide were monitored by reagent kit. Data showed that STT increased the formation of AGEsat 10 μg/mL. The supplementation of STT also accelerated the decrease in BAECs viability regardless of cell exposure to AGEs. Furthermore, STT elevated the AGEs-induced decline in NO release, as well as increased inducible NOS (iNOS) activities and superoxide levels. Compared with the effects of hecogenin and tigogenin, the negative effect of STT on AGEs-injured BAECs might be ascribed to hecogenin. Our findings suggested that STT was not a suitable candidate for inhibiting nonenzymatic glycation, and it accelerated the AGEs-mediated endothelial cell dysfunction probably by enhancing iNOS activity.

Key words: advanced glycation end products, endothelial cells, saponins;nitric oxide, nitric oxide synthase, superoxide