Department of Pharmacology, School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia; Department of Drug Research, Ethiopian Health and Nutrition Research Institute, Ethiopia
Ayele, Y., Department of Pharmacology, School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia; Urga, K., Department of Drug Research, Ethiopian Health and Nutrition Research Institute, Ethiopia; Engidawork, E., Department of Pharmacology, School of Pharmacy, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia
The aim of this work was to evaluate the antihypertensive activity of the hydroalcohol extract of the leaves of Syzygium guineense (Willd) D.C. (Myrtaceae) in a 1-kidney-1-clip rat model and its vasorelaxant effect on isolated aorta. The extract reduced blood pressure in a dose and time dependent fashion. Following 3 days of treatment, single oral daily doses of 50, 100 and 150 mg/kg caused an overall reduction (p < 0.05) of systolic blood pressure by 6.9, 34.0 and 40.8 mmHg, respectively. The diastolic blood pressure was, however, significantly reduced (p < 0.05) by 100 mg/kg (10.3 mmHg) and 150 mg/kg (18.4 mmHg) doses only. The mean blood pressure was reduced by 5.0, 18.3 and 25.9 mmHg by the respective doses. The extract also caused a dose-dependent relaxation of aorta precontracted with KCl at a concentration of 5-70 mg/mL, with a maximum relaxation of 56.22% achieved at 70 mg/mL concentration. The relaxation mechanism was found to be independent of the endothelium system, muscarinic receptors, histamine receptors, ATP dependent K+ channels, cyclooxygenase enzymes and cGMP/NO pathway. The findings suggest that the extract had an antihypertensive effect most likely caused by dilation of the blood vessels, a confirmation for the folkloric use of the plant. © 2010 John Wiley & Sons, Ltd.
adenosine triphosphate sensitive potassium channel; antihypertensive agent; cyclic GMP; histamine receptor; muscarinic receptor; nitric oxide; plant extract; prostaglandin synthase; Syzygium guineense extract; unclassified drug; vasodilator agent; animal experiment; animal model; animal tissue; antihypertensive activity; aorta; article; blood pressure regulation; diastolic blood pressure; dose response; female; in vitro study; in vivo study; male; mean arterial pressure; Myrtaceae; nonhuman; plant leaf; rat; reticuloendothelial system; systolic blood pressure; Syzygium guineense; vasodilatation; Angiosperms; Animals; Antihypertensive Agents; Aorta; Blood Pressure; Dose-Response Relationship, Drug; Female; Guinea Pigs; Male; Plant Extracts; Plant Leaves; Rats; Rats, Sprague-Dawley; Vasodilation; Vasodilator Agents; Myrtaceae; Rattus; Syzygium guineense