Polyphenol-containing azuki bean (Vigna angularis) extract attenuates blood pressure elevation and modulates nitric oxide synthase and caveolin-1 expressions in rats with hypertension

Nutr Metab Cardiovasc Dis. 2009 Sep;19(7):491-7. doi: 10.1016/j.numecd.2008.09.007. Epub 2009 Jan 20.


Background and aims: Azuki beans (Vigna angularis) contain polyphenols such as proanthocyanidins that exhibit potential radical scavenging activities. We herein investigated the effects of polyphenol-containing azuki bean extract (ABE) on elevated blood pressure, nitric oxide (NO) production, and expressions of endothelial NO synthase (eNOS), inducible NOS (iNOS), and caveolin-1 proteins in the aorta and kidney of chronically hypertensive rats.

Methods and results: Spontaneously hypertensive rats (SHRs/Izm) with approximately 200 mm Hg systolic blood pressure (SBP) were randomly divided into 2 groups fed either 0% or 0.9% ABE-containing diet. Age-matched normotensive Wistar-Kyoto rats were used as the control. The content of 24-h urinary nitrate/nitrite (NOx) excretion was measured to evaluate NO production. After 8 weeks of treatment, the eNOS, iNOS, and caveolin-1 protein expressions in the aorta and kidney were analyzed by western blotting. The SBP of the ABE-treated SHR was significantly lower than that of the untreated SHR. The level of 24-h urinary NOx excretion was significantly higher in the ABE-treated SHR than in the untreated SHR. The eNOS and iNOS expressions in the aorta and kidney were remarkably upregulated in the untreated SHR but suppressed in the ABE-treated SHR. The vascular and renal caveolin-1 expressions were upregulated in the ABE-treated SHR.

Conclusions: ABE reduced the elevated blood pressure and increased NO production in long-term treatment. It may be associated with the modulation of eNOS and iNOS protein expressions in the aorta and kidney during the development of hypertension.

MeSH terms

  • Animals
  • Aorta, Thoracic / metabolism
  • Blood Pressure / drug effects*
  • Blotting, Western
  • Caveolin 1 / biosynthesis*
  • Chronic Disease
  • Fabaceae / chemistry*
  • Flavonoids / chemistry
  • Flavonoids / pharmacology*
  • Heart Rate / drug effects
  • Hypertension / pathology
  • Hypertension / physiopathology
  • Hypertension / prevention & control*
  • Kidney / metabolism
  • Kidney / pathology
  • Male
  • Nitric Oxide / urine
  • Nitric Oxide Synthase Type II / metabolism*
  • Nitric Oxide Synthase Type III / metabolism*
  • Phenols / chemistry
  • Phenols / pharmacology*
  • Plant Extracts / pharmacology
  • Polyphenols
  • Rats
  • Rats, Inbred SHR
  • Rats, Inbred WKY


  • Caveolin 1
  • Flavonoids
  • Phenols
  • Plant Extracts
  • Polyphenols
  • Nitric Oxide
  • Nitric Oxide Synthase Type II
  • Nitric Oxide Synthase Type III