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Biochemistry Research International
Volume 2011, Article ID 159439, 9 pages
http://dx.doi.org/10.1155/2011/159439
Research Article

Evaluation of the Possible Mechanisms of Antihypertensive Activity of Loranthus micranthus: An African Mistletoe

1Department of Biochemistry and Nutrition, Nigerian Institute of Medical Research, PMB 2013, Yaba, Lagos, Nigeria
2Department of Biological Sciences, Boise State University, Boise, ID 83725-1320, USA
3Department of Biochemistry, College of Medicine University of Lagos, PMB 12003, Idi-Araba, Lagos, Nigeria
4Department of Microbiology and Molecular Genetics, University of Pittsburgh, Pittsburgh, PA 15269, USA

Received 3 January 2011; Revised 26 April 2011; Accepted 16 June 2011

Academic Editor: Andrei Surguchov

Copyright © 2011 Bamidele A. Iwalokun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Loranthus micranthus (LM), also called African mistletoe is a major Nigerian Loranthaceae plant used traditionally to treat hypertension. The methanolic leaf extract of the plant (LMME) has been shown to elicit anti-hypertensive activity in rats but mechanism remains unclear. This study was undertaken to study the effect of LM on pressor-induced contraction of rat aorta smooth muscles and serum lipid profiles in mice. The LMME was partitioned to produce n-butanol (NBF-LMME), chloroform (CF-LMME), ethyl acetate (EAF-LMME) and water (WF-LMME) fractions. The median effective concentrations and maximum relaxation of the fractions were determined against epinephrine and KCl pre-contracted rat aorta ring model. Serum lipid profiles and nitric oxide (NO) were determined spectrophotometrically in mice administered per orally 250 mg/kg b.w. of each fraction for 21 days. Data were analyzed statistically. NBF-LMME elicited the highest dose-dependent inhibitory effect on rat aorta pre-contracted with norepinephrine and KCl, followed in decreasing order by WF-LMME > CF-LMME > EAF-LMME. Similar order of activity was observed in the ability of these fractions to inhibit elevation in artherogenic lipids, raise serum nitric oxide and reduce cardiac arginase in mice. We conclude the anti-hypertensive activity of L. micranthus involve anti-artherogenic events, vasorelaxation, cardiac arginase reduction and NO elevation.