Protective effects of cyanidin-3- O-glucoside from blackberry extract against peroxynitrite-induced endothelial dysfunction and vascular failure

Abstract

Anthocyanins are a group of naturally occurring phenolic compounds as colorants in several plants, flowers and fruits. These pigments have a great importance as quality indicators, as chemotaxonomic markers and antioxidants. The content of blackberry ( Rubus species) juice was investigated by HPLC/ESI/MS using narrow bore HPLC columns. Using this method we demonstrated that cyanidin-3- O-glucoside represents about 80% of the total anthocyanin contents in blackberry extract. Here we investigated antioxidant activity of the blackberry juice and cyanidin-3-O-glucoside on the endothelial dysfunction in cells and in vascular rings exposed to peroxynitrite. In human umbilical vein endothelial cells (HUVEC) in vitro, peroxynitrite caused a significant suppression of mitochondrial respiration (38 ± 2.1% of control cells), as measured by the mitochondrial-dependent conversion of the dye MTT to formazan. Peroxynitrite caused DNA strand breakage (63 ± 1.9% single strand vs 3 ± 0.9% single strand in control cells), as measured by the alkaline unwinding assay, and caused an activation of PARS, as measured by the incorporation of radiolabeled NAD + to nuclear proteins. Blackberry juice (different dilutions that contained 80 ppm;40 ppm;14.5 ppm of cyanidin-3-O-glucoside) and cyanidin-3- O-glucoside (as chloride) (0.085 μM; 0.028 μM; 0.0085 μM) reduced the peroxynitrite-induced suppression of mitochondrial respiration, DNA damage and PARS activation in HUVECs. Vascular rings exposed to peroxynitrite exhibited reduced endothelium-dependent relaxant responses in response to acetylcholine as well as a vascular contractility dysfunction in response to norepinephrine. The development of this peroxynitrite-induced vascular dysfunction was ameliorated by the blackberry juice (different dilutions that contained 80 ppm;40 ppm;14.5 ppm of cyanidin-3-O-glucoside) and cyanidin-3- O-glucoside (as chloride) (0.085 μM;0.028 μM;0.0085 μM). In conclusion our findings clearly demonstrate that blackberry juice containing cyanidin-3- O-glucoside is a scavenger of peroxynitrite and that exert a protective effect against endothelial dysfunction and vascular failure induced by peroxynitrite.