EVALUATION OF ETHANOLIC EXTRACTS OF Dichrostachys glomerata and Psidium guajava LEAVES FOR ANTIDIARRHOEAL ACTIVITY
EVALUATION OF ETHANOLIC EXTRACTS OF Dichrostachys glomerata and Psidium guajava LEAVES FOR ANTIDIARRHOEAL ACTIVITY
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Date
2008-01
Authors
OKPARA, JUDE OBI
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Abstract
To appraise some of the ethnomedical uses of Psidium guajava Lineaus (family: Myrtaceae)
and Dichrostachys glomerata Forsskal (family: Leguminosae) the present work was
undertaken to investigate the antidiarrhoeal properties of the ethanolic leaf extracts of these
plants (P. guajava and D. glomerata). The acute oral toxicity studies of the extracts in mice,
phytochemical screening of the extracts for bioactive principle, antibacterial, antiinflammatory
and anthelmintic actions were also studied. The orally determined LD50 values
of the extracts in mice were found to be 1750.0 ± 212.0 mg/kg and 1600.0 ± 283.0 mg/kg for
P. guajava and D. glomerata, respectively. The extracts were, thus, confirmed to be relatively
toxic to mice. The phytochemical screening of the extracts revealed the presence of
flavonoids, tannins, saponins, resins, triterpenoids, carbohydrates and reducing sugars.
The extracts (100, 200 and 400 mg/kg i.p.) caused a dose dependent significant (P<0.05)
decrease of gastro-intestinal distance travelled by the charcoal plug in mice compared to
control (Normal Saline) (5ml/kg i.p.) and markedly protected rats against Castor oil-induced
diarrhoea with loperamide (5mg/kg p.o.) as reference antidiarrhoeal agent. The punch hole
method was used for antibacterial screening of the extracts (50, 100 and 200 mg/ml) using
pure cultures of Staphylococcus aureus, Escherichia coli and Salmonella typhi. The results
were evaluated as zones of inhibition around the hole impregnated with varying
concentrations of the extracts and ampicillin (10 mg/ml) as reference antibacterial drug. The
zone of inhibition ranged between 8.07 – 16.07 mm for P. guajava and 10.12 – 20.00 mm for
D. glomerata leaves extracts. Like indomethacin (10mg/kg p.o.) the extracts (200, 400 and
800 mg/kg p.o.) produced a dose and time related, sustained and significant reduction (P<0.05
– 0.001) in fresh egg albumen (0.5 ml/kg) induced acute inflammation of rat hind paw
oedema. The ethanolic extracts of P. guajava and D. glomerata (200, 400, 800mg/kg p.o.),
like albendazole also, significantly (P<0.05, n = 5) reduced the faecal egg count per gram
(epg) of goats naturally infected with mixed gastro-intestinal nematodes. The percentage
reduction ranged from 38 – 91% in P. guajava and 33 – 81% in D. glomerata treated goats,
respectively. In in vitro studies, the extracts (0.4 – 3.2 mg/ml) significantly (P<0.05, n = 3)
reduced the frequency and the amplitude of spontaneous pendular contractions of rabbit
jejunum and the histamine – induced contraction of guinea pig ileum (a spasmolytic action).
Atropine, an acetylcholine (ACh) blocker at the muscarinic receptors concentrations
dependently reduced and or abolished spasmogenic effects of ACh. The effects of the extracts
were equally compared with those of ACh and histamine (H) whose receptors are found in the
gastro-intestinal tract. The effects of ACh (8.0 x 10-2μg/ml) on the frequency and amplitude of
contraction of the isolated rabbit jejunum and histamine (4.0 x 10-1μg/ml) on isolated guinea
pig ileum decreased (P<0.05) when combined with 3.2 mg/ml of the extracts of P. guajava
and D. glomerata. The results suggested an antagonistic action between ACh and H2 and the
extracts. It is, therefore, postulated that the extracts of P. guajava and D. glomerata may have
caused decrease in gastrointestinal propulsion through either anti-cholinergic effect and or H2
– receptor system antagonism. These findings lend pharmacological support to the traditional
use of P. guajava and D. glomerata leaves extract in the management and/or control of
diarrhoea in man and his animals.
Description
THESIS SUBMITTED TO THE POSTGRADUATE SCHOOL IN
PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE
AWARD OF THE DEGREE OF MASTER OF SCIENCE IN
VETERINARY PHARMACOLOGY
DEPARTMENT OF PHYSIOLOGY AND PHARMACOLOGY
FACULTY OF VETERINARY MEDICINE
AHMADU BELLO UNIVERSITY
ZARIA
NIGERIA.
JANUARY, 2008
Keywords
ETHANOLIC EXTRACTS, Dichrostachys glomerata,, Psidium guajava LEAVES,, ANTIDIARRHOEAL ACTIVITY.