World Academy of Science, Engineering and Technology
Published September 28, 2013 | Version 16603
Journal article Open

Effects of a Methanol Fraction of the Leaves of Leonotis leonurus on the Blood Pressure and Heart Rate of Normotensive Male Wistar Rats

Description

Leonotisleonurus a shrub indigenous to Southern
Africa is widely used in traditional medicine to treat a variety of
conditions ranging from skin diseases and cough to epileptic fits and
‘heart problems’. Studies on the aqueous extract of the leaves have
indicated cycloxegenase enzyme inhibitory activity and an
antihypertensive effect.
Five methanol leaf extract fractions (MLEa - MLEe) of L.
leonurus were tested on anaesthetized normotensive male Wistar rats
(AWR) and isolated perfused working rat hearts (IWH). Fraction
MLEc (0.01mg/kg – 0.05mg/kg) induced significant increases in BP
and HR in AWR and positive chronotropic and inotropic effects in
IWH (1.0mg/ml – 5.0mg/ml). Pre-administration of atenolol
(2.0mg/kg) and prazosin (60μg/kg) significantly inhibited MLEc
effect on HR and MAP respectively in vivo, while atenolol
(7.0mg/ml) pre-perfusion significantly inhibited MLEc effect in vitro.
The hypertensive effect of MLEc is probably via β1agonism.
Results also indicate the presence of multiple cardioactive
compounds in L. leonurus.

Files

16603.pdf

Files (149.8 kB)

Name Size
md5:6a1c0b15200220b22d3ba1b0c85ad168
149.8 kB Preview Download

Additional details

References

  • <p>
  • J. Mander, N.W. Quinn, M. Mander, Trade in wildlife medicinals in South Africa. Investigational Report No. 157. Pietermaritzburg: Institute of Natural Resources,1997, pp. 1-3.
  • B. Van Wyk, B. Van Oudtshoorn, N. Gericke, Medicinal plants of South Africa. Cape Town: Briza Publications, 2000, p. 166.
  • J.M. Watt, M.G. Breyer-Brandwijk, Medicinal and poisonous plants of Southern Africa. Edinburgh: E & S Livingstone, 1962, p. 1457.
  • E. Bienvenu, G.J. Amabeoku, P.K. Eagles, G. Scott, E.P. Springfield, "Anticonvulsant activity of aqueous extract of Leonotisleonurus"Phytomedicine, vol. 9, 2002, pp. 217-223.
  • A. K. Jager, A. Hutchings, J. Van Staden, "Screening of Zulu medicinal plants for Prostaglandin - synthesis inhibitors" Journal of Ethnopharmacology, vol. 52(2), 1996, pp. 95-100.
  • J. A. O. Ojewole, "Hypotensive effect of Leonotis leonurus aqueous leaf extract in rats" American Journal of Hypertension, vol. 16(5) Supplement 1, 2003, p. A40.
  • P. Mugabo, A. Njagi, D.L. Dietrich, J. Syce, "Cardiovascular effects of Leonotisleonurus in the normotensive rat" Revista de fitoterapia, vol. 2(1), 2002, p. 163.
  • F. Khan, P. Mugabo, A.P. Burger, D.L.L. Dietrich, "Effects of Leonotisleonurus aqueous exract on the isolated perfused rat heart" ActaPharmacologicaSinica, Supplement 1, 2006, p. 349.
  • K. C. Obikeze, J. M. McKenzie, I. R. Green, P. Mugabo, "Characterization and Cardiovascular Effects of (13S)-9_,13_- epoxylabda-6_(19),15(14)diolDilactone, a diterpenoid Isolated from Leonotis leonurus" South African journal of chemistry, vol. 61, 2008, pp. 119–122. [10] D.E.A. Rivett, "Lingering amongst the Labiatae" South African journal of chemistry, 1984, pp. 368-371. [11] J. A. Duke, Handbook of medicinal herbs. Boca Raton: CRC Press, 2001, p. 276. [12] V.U. Livius, J. Kilo, T. Luscher, M. Gassmann, Circulation. The handbook of experimental animals. The laboratory rat. New York: Georg J Krinke, 2000, p. 1541. [13] F. Sutherland, J. Hearse, "Experimental models for the study of cardiovascular function and disease" Pharmacological Research, vol. 41(6), 2000, pp. 597-603. [14] F. Sutherland, J. Hearse, "The isolated blood and perfusion fluid perfused heart" Pharmacological Research, vol. 41(6), 2000, pp. 613- 647. [15] C. Depre, "Isolated working heart: Description of models relevant to radioisotopic and pharmacological assessments" Nuclear medicine & Biology, vol. 25, 1998, pp. 711-713. [16] P. Mugabo, K.C. Obikeze, A. Njagi, A.P. Burger, I. Green, D.D. Dietrich, "Cardiovascular effects of the alkaloid hippadine on the isolated perfused rat heart" International journal of medicinal and aromatic plants, vol. 2(1), 2012, pp. 172-177. [17] H.B. Chen, M.W. Islam, R. Radhakrishnan, S.A. Wahab, M.A. Naji, "Influence of aqueous extract from Neuradaprocumbens L. on blood pressure of rats" Journal of Ethnopharmacology, vol. 90 (2-3), 2004, pp. 191-194. [18] E.L. McCawley, "Cardioactive alkaloids" in The alkaloids, Chemistry and physiology, R. Manske, Ed. New York: Academic press, 1995, pp. 79-104. [19] D.S. Bhakuni, "Chemical and pharmacological investigation of plants with a biological action on the cardiovascular system", in Advances in medicinal phytochemistry, D. Barton, D.W. Ollis, Eds. London: John Libbery, 1986, pp. 25-35. [20] J.C. Liu, F.L. Hsu, J.C. Tsai, P. Chan, J.Y.H. Liu, G.N. Thomas, B. Tomlinson, M.Y. Lo, J.Y. Lin, "Antihypertensive effects of tannins isolated from traditional Chinese herbs as non-specific inhibitors of angiotensin converting enzyme" Life Science, vol. 73(12), 2003, pp. 1543-1555. [21] B. B. Hoffman, "Adrenoceptor-Activating & other sympathomimetic drugs", in Basic & Clinical pharmacology, 7th ed. B.G. Katzung, Ed. Connecticut: Apnge, 1998, pp. 118-151. [22] Fujitaa, D.L. Roerig, Z. J. Bosnjak, D. F. Stowe, "Effects of vasodilators and perfusion pressure on coronary flow and simultaneous release of nitric oxide from guinea pig isolated hearts" Cardiovascular Research, vol. 38(3), 1998, pp. 655-667.</p>