A clinical trial testing the safety and efficacy of a standardized Eucommia ulmoides Oliver bark extract to treat hypertension.

BACKGROUND A tea made from Eucommia ulmoides leaves and bark is part of the Japanese diet. Eucommia is an herbal medicine that, by increasing nitric oxide, reduced blood pressure (BP) in rats and humans in an uncontrolled clinical trial. OBJECTIVE A controlled clinical trial was conducted to evaluate an aqueous bark extract of Eucommia standardized to eight percent pinoresinol di-beta-D-glucoside (PG) for BP reduction in humans. METHODS Study 1: Twenty-four healthy adult subjects with a BP between 120-160/80-100 mmHg were randomized to Eucommia extract 500 mg three times daily for eight weeks. Automatic 24-hour ambulatory blood pressure monitoring (24-h ABPM) was utilized at baseline and after eight weeks. Study 2: The effect of the Eucommia extract on isoproterenol-stimulated lipolysis was evaluated in a human fat cell assay to determine whether Eucommia was a beta-adrenergic blocker. Study 3: Thirty healthy adult subjects with a BP between 120-160/80-100 mmHg were randomized to 1 g Eucommia extract three times daily for two weeks with 24-h ABPM at baseline and after two weeks. RESULTS Study 1: There was no toxicity or any difference in BP between the two groups. Study 2: Eucommia at 0.5% w/v reduced isoproterenol-stimulated lipolysis from 2.67 to 1.4 times the buffer control (P<0.001). Study 3: The Eucommia extract was well-tolerated and reduced BP by an average of 7.5/3.9 mmHg (P<0.008). CONCLUSION The standardized Eucommia extract reduced BP and has beta-adrenergic blocking activity. Eucommia may be an appropriate nutraceutical intervention for prehypertension.