Antihypertensive Effect of Blueberry Leaves on Spontaneously Hypertensive Rats

We evaluated the effects of dried blueberry leaves (BL) and its hot-water extract (BLEx) on blood pressure of spontaneously hypertensive rats (SHR). A continuous 3-week administration of BL (3%) and BLEx (1.5%) reduced systolic blood pressure compared to the control group from the 2-week feeding point Additionally, we fractionated BLEx and investigated the compound responsible for the enhanced blood pressure-lowering effect. BLEx were fractionated into 5-fractions using Sephadex LH-20 and Diaion HP20SS chromatography, and assayed for angiotensin-I-converting enzyme (ACE) inhibitory activity in vitro. The fraction composed of proanthocyanidins showed the most potent inhibitory activity (IC50, 0.004 mg/mL) and reduced systolic blood pressure of SHR. These results suggest that BL and BLEx have anti-hypertensive effects and one of the active components has been identified as a proanthocyanidin.