Hydroxyhydroquinone interferes with the chlorogenic acid-induced restoration of endothelial function in spontaneously hypertensive rats.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Suzuki
Atsushi
A
Biological Science Laboratories, Kao Corporation, Tochigi, Japan. suzuki.atsushi2@kao.co.jp
Fujii
Akihiko
A
Jokura
Hiroko
H
Tokimitsu
Ichiro
I
Hase
Tadashi
T
Saito
Ikuo
I
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000959:Antihypertensive Agents / Q000097:blood / Q000494:pharmacology* / Q000627:therapeutic use; D001794:Blood Pressure / Q000187:drug effects*; D001835:Body Weight / Q000187:drug effects; D002726:Chlorogenic Acid / Q000097:blood / Q000494:pharmacology* / Q000627:therapeutic use; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D006339:Heart Rate / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000652:urine; D006873:Hydroquinones / Q000494:pharmacology*; D006973:Hypertension / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D007150:Immunohistochemistry; D008297:Male; D009569:Nitric Oxide / Q000652:urine; D009599:Nitroprusside / Q000494:pharmacology; D011801:Quinic Acid / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology / Q000627:therapeutic use; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
D000959:Antihypertensive Agents; D006873:Hydroquinones; D014665:Vasodilator Agents; C472707:caffeoylquinic acid; D011801:Quinic Acid; D009599:Nitroprusside; C013038:hydroxyhydroquinone; D002726:Chlorogenic Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D006861:Hydrogen Peroxide; D000109:Acetylcholine