Vasorelaxant and antioxidant activity of the isoflavone metabolite equol in carotid and cerebral arteries

Jackman, K, Woodman, O, Chrissobolis, S and Sobey, C 2007, 'Vasorelaxant and antioxidant activity of the isoflavone metabolite equol in carotid and cerebral arteries', Brain research, vol. 1141, no. 1, pp. 99-107.


Document type: Journal Article
Collection: Journal Articles

Title Vasorelaxant and antioxidant activity of the isoflavone metabolite equol in carotid and cerebral arteries
Author(s) Jackman, K
Woodman, O
Chrissobolis, S
Sobey, C
Year 2007
Journal name Brain research
Volume number 1141
Issue number 1
Start page 99
End page 107
Total pages 9
Publisher Elsevier BV
Abstract Background and purpose: Equol is the main active intestinal metabolite of the isoflavone daidzein and is postulated to be responsible for the cardiovascular benefits of soy. Cerebral vascular effects of equol are unknown. We compared the vasorelaxant and antioxidant effects of equol and daidzein in carotid and basilar artery of normal and hypertensive rats. Experimental approach: Relaxant responses to equol and daidzein were measured in the isolated carotid artery and in the basilar artery in vivo. Effects of nitric oxide synthase (NOS) inhibition, high extracellular K+, endothelial removal and gender on responses to equol were investigated in carotid arteries. Antioxidant activity was assessed as the reduction of NADPH-induced superoxide levels. Hypertension was induced using angiotensin II (0.7 mg/kg per day for 14 days). Key results: In normotensive rats, equol displayed vasorelaxant activity similar to daidzein. The relaxant effect of equol was independent of an intact endothelium, NOS activity, K+ channels and gender. In the basilar artery, where superoxide levels are higher, equol exerted weak antioxidant effects, whereas effects of daidzein were insignificant. During hypertension, equol-induced vasorelaxation was preserved, whereas relaxant responses to daidzein were impaired. Conclusions and implications: Equol possesses substantial vasodilator and weak antioxidant activity in cerebral arteries, with similar activity to daidzein, whereas in hypertension the vasorelaxant response to equol, but not daidzein, is preserved. However, daidzein possesses comparable direct vascular effects with equol, without the need for intestinal conversion to equol. Nevertheless, equol may represent a more useful therapeutic agent during cerebral vascular disease.
Subject Cognitive Science not elsewhere classified
DOI - identifier 10.1016/j.brainres.2007.01.007
Copyright notice © 2007 Elsevier B.V. All rights reserved.
ISSN 0006-8993
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