Objective: The purpose of this study was to determine antihypertensive activity of extract and fractions of matoa (Pometia pinnata) leaves.

Methods: Matoa leaves were extracted by reflux, followed by evaporating using rotary evaporator. Hypertension was induced by 50 mg/kg bw. NaCl and 1.5 mg/kg bw. prednisone orally, every day as long as 28 days, then continued over the next 28 days in the therapy period. Male Sprague Dawley rats were divided into 12 groups which were hydrochlorothiazide (0.45 mg/kg bw.), control group hypertensive, control normal, matoa leaves extract (MLE)(with doses of 50 mg/kg bw., 100 mg/kg bw., and 150 mg/kg bw.), ethylacetate fraction (with doses of 4.35 mg/kg bw., 8.71 mg/kg bw., and 13.06 mg/kg bw.), and water fraction (with doses of 10 mg/kg bw., 21.88 mg/kg bw., and 32.82 mg/kg bw.). Measurement of systolic and diastolic blood pressure was done every weeks using direct tail-cuff of noninvasive method. Then histomorphology of muscle heart was performed at the end of this research.

Results: Ethylacetate fraction of matoa leaves 13.08 mg/kg bw. and MLE 150 mg/kg bw. gave significant result in lowering blood pressure (p< 0.05) on the 28th day of therapy and showed an equal profile with hydrochlorothiazide (0.45 mg/kg bw). Histomorphological result of rat’s muscle heart found collagen production was increased in NaCl-prednisone induced rats.

Conclusions: Extract and fractions of P. pinnata leaves could decrease blood pressure of NaCl-prednisone induced hypertension rats, but this effect was not liniear with doses and they did not decrease the collagen production in cardiac myocardium compared to normal group.