Effects of hydroxyhydroquinone-reduced coffee on vasoreactivity and blood pressure

Abstract

Recent studies suggest that chlorogenic acids, which are the main components of the polyphenol class in coffee, decrease blood pressure, and that hydroxyhydroquinone (HHQ), which is generated by roasting coffee beans, inhibits the antihypertensive effect of chlorogenic acids in brewed coffee. Here, we examined the vasoreactivity and antihypertensive effects of HHQ-reduced coffee in mild hypertension. The study design was a double blind, randomized, placebo-controlled intervention study, with a 4-week run-in period, followed by an 8-week test beverage ingestion period. The subjects were Japanese men and women with mild hypertension and vascular failure, who were not taking any antihypertensive drugs. During the test beverage ingestion period, the subjects ingested either active or placebo HHQ-reduced coffee (chlorogenic acids per 184 ml of coffee: active, 300 mg; and placebo, 0 mg) daily. Subjects were randomly divided into two groups: active group (n¼9) and placebo group (n¼12). In the active beverage group, endothelium-dependent, flow-mediated vasodilation impairment was significantly ameliorated and systolic blood pressure was significantly decreased from the baseline, but not in the placebo group. There were no test beverage consumption-related changes in other parameters that may influence blood pressure, such as pulse, cardiac output, body weight or 24-h urine volume. Ingestion of the active beverage significantly decreased urinary isoprostane levels, suggesting a reduced oxidative stress. These findings indicate that HHQ-reduced coffee decreased blood pressure in subjects with mild hypertension. The decreased blood pressure was associated with improved vascular endothelial function.

Antihypertensive effects and mechanisms of chlorogenic acids

“…Following repeated isolation steps using reverse phase high performance liquid chromatography (HPLC), hydroxyhydroquinone (HHQ), a particular fraction, which was derived from CGA and was not seen before high temperature treatment, was discovered in roasted coffee. In both acute and chronic studies, 19,20,31 the administration of HHQ (3 mg kg -1 ) mostly eliminated the anti-hypertension effect of GCEs (containing 300 mg kg -1 of CGA) in SHR. Interestingly, HHQ alone had not been found to exert any effect on blood pressure and vascular function in both WKY and SHR models.…”

“…The current hypothesis for this finding was that the production of HHQ-derived superoxide 31,33,34 neutralized CGA-enhanced nitric oxide (NO) bioactivity, 35 therefore concealing the anti-hypertensive effects of CGA. However, the evidence for HHQ to produce superoxide is rather weak, because acetylcholine-induced vasorelaxation was not attenuated by HHQ in ex vivo experiments.…”

The role of nutrition and nutraceutical supplements in the treatment of hypertension

“…A study of 122 male subjects demonstrated a dose response in SBP and DBP with doses of CGA from 46 mg/d to 185 mg/d. The group that received the 185 mg dose had a significant reduction in BP of 5.6/3.9 mmHg (p < 0.01) over 28 d. Hydroxyhydroquinone is another component of coffee beans which reduces the efficacy of CGAs in a dosedependent manner which partially explains the conflicting results of coffee ingestion on BP [284,286] . Furthermore, there is genetic variation in the enzyme responsible for the metabolism of caffeine modifies the association between coffee intake, amount of coffee ingested and the risk of hypertension, heart rate, MI, arterial stiffness, arterial wave reflections and urinary catecholamine levels [287] .…”

“…Cocoa may also improve insulin resistance and endothelial function [276,279,281] . Polyphenols, chlorogenic acids (CGAs), the ferulic acid metabolite of CGAs and di-hydro-caffeic acids decrease BP in a dose dependent manner, increase eNOS and improve endothelial function in humans [284][285][286] . CGAs in green coffee been extract at doses of 140 mg/d significantly reduced SBP and DBP in 28 subjects in a placebocontrolled randomized clinical trial.…”

Coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone improves postprandial endothelial dysfunction in patients with borderline and stage 1 hypertension

“…It has also been shown that hydroxyhydroquinone increased the production of reactive oxygen species in a dose-dependent manner [30]. Some clinical studies have shown that coffee with a high content of chlorogenic acids and a low content of hydroxyhydroquinone is effective for reducing blood pressure [31,32].…”