Effects of different types of Syzygium Polyanthum leaves extracts on blood pressure of anaesthetized Spontaneously Hypertensive rats

Background: Syzygium polyanthum leaves are used traditionally for treatment of hypertension. Our previous study showed that S. polyanthum leaves decoction caused significant reduction in blood pressure of Spontaneously Hypertensive rats (SHR) but the bioactive compound(s) is yet unknown. Objective: The study aimed to identify the most promising S. polyanthum leaves extract to be subsequently fractionated for the purpose of isolating the bioactive compound(s) responsible for the reduction in blood pressure of SHR. Materials & Methods: SHR rats were anaesthetized using sodium pentobarbital at 60 mg/kg, administered intra-peritonelly. Aqueous (ASP), methanol (MSP), ethyl acetate (EASP) and n-hexane (HSP) extracts of S. polyanthum leaves at increasing doses of 1, 10, 40, and 70 mg/kg were intravenously administered via left jugular vein of SHR (n=6, each group). The changes in hemodynamic parameters including beat-to-beat mean arterial (MAP), systolic (SBP) and diastolic (DBP) blood pressures were recorded through cannulated right main carotid artery using BIOPAC® Recording System. Results: Only EASP, MSP and ASP at doses 40 and 70 mg/kg significantly reduced MAP, SBP and DBP of SHR (P