Blood pressure-lowering properties of chokeberry (Aronia mitchurinii, var. Viking)

The blood pressure-lowering properties of lyophilized chokeberry juice and polyphenols were monitored using in vitro angiotensin-converting enzyme (ACE) inhibition measurement and a 10 day in vivo study with spontaneously hypertensive rats (SHR). Juice and polyphenols indicated weak ACE-inhibitory activity. The IC50 values for polyphenols and juice were 1.5-2.5 and 4.5 mg dry matter/ml, respectively. In the SHR study the blood pressure-lowering effects of juice and polyphenol extract seemed to be short-term and were generally highest after 3 h from administration (50 mg/kg/day) when mean reductions in systolic blood pressure were 20 +/- 8 and 15 +/- 7 mm Hg, respectively. Corresponding mean decreases in diastolic blood pressure were 23 +/- 6 and 13 +/- 2 mm Hg in juice and polyphenol groups, respectively. It was concluded that both chokeberry juice and polyphenols had blood pressure-lowering effects. We hypothesize that chokeberry polyphenols enhance endothelial nitric oxide production with an ACE-independent mechanism, e.g. by activation of endothelial nitric oxidase enzyme; this is yet to be verified. (C) 2010 Elsevier Ltd. All rights reserved.