Anthocyanins Activate Membrane Estrogen Receptors With Nanomolar Potencies to Elicit a Nongenomic Vascular Response Via NO Production

BACKGROUND: The vascular pharmacodynamics of anthocyanins is only partially understood. To examine whether the anthocyanin‐induced vasorelaxation is related to membrane estrogen receptor activity, the role of ERα or GPER antagonism was ascertained on anthocyanins or 17‐β estradiol‐(E2) induced vasodilatations and NO production. METHODS AND RESULTS: The rat arterial mesenteric bed was perfused with either anthocyanins or corresponding 3‐O‐glycosides, or E2, to examine rapid concentration‐dependent vasorelaxations. The luminally accessible fraction of NO in mesenteric perfusates before and after anthocyanins or E2 administration was quantified. Likewise, NO‐DAF signal detected NO production in primary endothelial cells cultures incubated with anthocyanins or E2 in the absence and presence of ERα (ICI 182,780) or GPER (G‐36) selective antagonists. Anthocyanins or corresponding glycosides elicited, within minutes, vasodilation with nanomolar potencies; half maximal anthocyanin response reached 50% to 60% efficacy, in contrast to acetylcholine. The vasorelaxation is of rapid onset and exclusively endothelium‐dependent; NOS inhibition annulled the vasorelaxation. The delphinidin vascular response was not modified by 100 nmol/L atropine but significantly attenuated by joint application of ICI plus G‐36 (52±4.6 versus 8.5±1.5%), revealing the role of membrane estrogen receptors. Moreover, the anthocyanin or E2‐induced NO production was antagonized up to 70% by these antagonists. NO‐DAF signal elicited by anthocyanins was annulled by NOS inhibition or by ICI plus G‐36 addition. CONCLUSIONS: The biomedical effect of anthocyanins or 3‐O‐glycosylates derivatives contained in naturally purple‐colored foods or berries is due to increased NO production, and not to the phytochemical's antioxidant potential, highlighting the nutraceutical role of natural products in cardiovascular diseases.