chlorogenic-acid and 3-nitrotyrosine

Coffee is a rich source of antioxidative polyphenols, but epidemiological studies and interventional trials have failed to demonstrate any clear beneficial effects of coffee consumption on hypertension. The interaction between hydroxyhydroquinone (HHQ) and 5-caffeoylquinic acid (CQA) was examined, in an attempt to understand the controversial effects of coffee on hypertension.. Male Wistar Kyoto (WKY) rats or spontaneously hypertensive rats (SHRs, 14 weeks old) were divided into the following four groups; those on a control diet, 0.005% HHQ diet, 0.5% CQA diet, and HHQ plus CQA diet. The rats were fed the above diets for 8 weeks, and the tail arterial blood pressure was monitored in conscious rats at 2-week intervals. Urinary nitric oxide (NO) metabolites and hydrogen peroxide (H(2)O(2)) excretion were measured 8 weeks after the start of the experiment. Endothelium-dependent and -independent vasorelaxant responses and immunohistochemical staining for nitrotyrosine were examined in aortas.. HHQ inhibited the CQA-induced improvement in hypertension, urinary NO metabolites or H(2)O(2) excretion, endothelial dysfunction, and nitrotyrosine deposits in aortas in SHR. However, the administration of HHQ alone had little effect on either strain.. Based on the content ratio of HHQ and chlorogenic acids in coffee, HHQ interfered with the CQA-induced improvement in blood pressure and endothelial function in SHR. The results explain, at least in part, the conflicting action of coffee drinking on hypertension and vascular reactivity.

Topics: Acetylcholine; Animals; Antihypertensive Agents; Blood Pressure; Body Weight; Chlorogenic Acid; Disease Models, Animal; Endothelium, Vascular; Heart Rate; Hydrogen Peroxide; Hydroquinones; Hypertension; Immunohistochemistry; Male; Nitric Oxide; Nitroprusside; Quinic Acid; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Time Factors; Tyrosine; Vasodilation; Vasodilator Agents

Epidemiologic studies indicate that ingestion of vegetables and fruit inhibits the development of cardiovascular disease. Chlorogenic acids are abundant phenolic compounds contained in vegetables and fruits, but the impact of dietary chlorogenic acids on vascular function in hypertension is not known. We therefore examined the effects of 5-caffeoylquinic acid (CQA), a representative chlorogenic acid, on blood pressure and vascular function in age-matched normotensive Wistar-Kyoto rats and spontaneously hypertensive rats.. A single ingestion of CQA (30-600 mg/kg) reduced blood pressure in spontaneously hypertensive rats, an effect that was blocked by administration of a nitric oxide synthase inhibitor, N(G)-nitro-L-arginine methyl ester. When spontaneously hypertensive rats were fed diets containing 0.5% CQA for 8 weeks (approximately 300 mg/kg per day), the development of hypertension was inhibited compared with the control diet group. CQA ingestion increased urinary excretion of nitric oxide metabolites and decreased urinary excretion of hydrogen peroxide; decreased NADPH-dependent superoxide anion production in the aorta, suggesting that dietary CQA inhibited vascular NADPH oxidase activity; significantly improved acetylcholine-induced endothelium-dependent vasodilation in the aorta; and markedly reduced the degree of immunohistochemical staining for nitrotyrosine and media hypertrophy in aorta sections. In contrast, CQA had no effects in Wistar-Kyoto rats.. Dietary CQA reduces oxidative stress and improves nitric oxide bioavailability by inhibiting excessive production of reactive oxygen species in the vasculature, and leads to the attenuation of endothelial dysfunction, vascular hypertrophy, and hypertension in spontaneously hypertensive rats.

Topics: Animals; Aorta; Blood Pressure; Chlorogenic Acid; Endothelium, Vascular; Hydrogen Peroxide; Immunohistochemistry; In Vitro Techniques; Male; NADP; NADPH Oxidases; Nitrates; Nitric Oxide Synthase Type III; Nitrites; Oxidative Stress; Quinic Acid; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Superoxides; Tyrosine; Vasodilation