COMPARATIVE EVALUATION OF THE HYPOTENSIVE EFFECTS OF THE SEED AND LEAF EXTRACTS OF MORINGA OLEIFERA LAM (Moringaceae) IN LABORATORY ANIMALS
COMPARATIVE EVALUATION OF THE HYPOTENSIVE EFFECTS OF THE SEED AND LEAF EXTRACTS OF MORINGA OLEIFERA LAM (Moringaceae) IN LABORATORY ANIMALS
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Date
2015-06
Authors
OSAMEYAN, TIMOTHY AYOWALE
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Abstract
Moringa oleifera is locally used in Nigeria for the management of respiratory disorders,
hypertension and poor blood circulation among other ailments. However, all parts of the
plant are blindly used because the exact part of this plant and / or extractive solvent that
provides the best of its cardiovascular or optimum hypotensive activity has not been
reported. The impetus of this research work therefore is to compare the crude extracts of
the leaf and seed of Moringa oleifera in their two solvent forms respectively, aqueous
and methanol for the leaf; and methanol and pet-ether for the seed, since the seed is very
oily for aqueous extraction. The phytochemical constituents of the leaf and seed extracts
of Moringa oleifera were determined. The effect of Moringa oleifera leaf and seed
extracts on cat blood pressure and guinea pig heart atria were investigated. Intravenous
injection of drugs and test solutions injected through the femoral vein into a cannulated
artery was used to investigate effects of drugs on arterial blood pressure in male cats. The
effects of Moringa oleifera leaf and seed extracts on isolated guinea pig heart atria and
on isoprenaline and Calcium chloride induced contraction, as well as interactions on
specific receptor mediation (Cholinergic, Histaminergic and Adrenergic) as to elucidate
the probable underlying receptor mechanism(s) involved in the actions of the extracts
were also investigated. The aqueous and methanol leaf extracts of M. oleifera contained
alkaloids, tannins, saponins, cardiac glycosides, carbohydrates, flavonoids, steroids and
triterpenes, while anthraquinone was absent. The methanol seed extract of M. oleifera
contained carbohydrates, saponins, alkaloids, tannins and cardiac glycosides with no
flavonoids, steroids and triterpenes, but its pet-ether seed extract had only carbohydrates
and alkaloids. The results revealed that the standard depressor agent, acetylcholine causes
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a fall on blood pressure and both the leaf and seed extracts of Moringa oleifera lowered
the blood pressure of cats in a dose dependent manner, but in varying degree. Both the
aqueous and the methanol leaf extracts demonstrated a higher hypotensive property than
the seed extracts which showed milder hypotensive effect, with its methanol seed extract
causing slightly more relaxation of the arterial system.
The aqueous and methanol extracts of the leaves as well as the methanol seed extract
inhibited adrenaline induced contraction of the cat blood pressure and caused blockade
that was not reversed with higher concentration of adrenaline. Propranolol enhanced the
relaxing effect of all the extracts in a manner that is synergistic including that of the petether
seed extract which was not able to block adrenaline contraction. Mepyramine
(antihistamine,) potentiate the depressor effect of the aqueous and methanol leaf extracts.
The cholinergic antagonist, (atropine), blocked only the aqueous leaf extract and showed
no effect on the methanol leaf and both seed extracts. All the extracts exhibited a
concentration-dependent reduction in both rate and force of the guinea pig atria
spontaneous contraction, except the methanol seed extract which decreased only the rate
of contraction. Similarly, all the extracts of the leaf and seed inhibited isoprenaline and
calcium chloride induced guinea pig atria contraction. In conclusion, the aqueous and
methanol leaf extracts of the plant were found to cause higher depressor effects than the
seed extracts; and the extracts antagonistic actions on adrenaline contraction suggests
adrenergic receptor mediation activity. The in-vitro blockade of calcium chloride-induced
contraction also seemed to suggest the opening of calcium channels as part of the mode
of activity of the extracts in their constrictor actions.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE AWARD
OF A
MASTERS DEGREE IN PHARMACOLOGY
DEPARTMENT OF PHARMACOLOGY AND THERAPEUTICS,
FACULTY OF PHARMACEUTICAL SCIENCES,
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
Keywords
COMPARATIVE EVALUATION,, HYPOTENSIVE EFFECTS,, SEED,, LEAF EXTRACTS,, MORINGA OLEIFERA LAM,, (Moringaceae),, LABORATORY ANIMALS,