TOXICOLOGICAL AND ANTI-HYPERGLYCAEMIC PROPERTIES OF AQUEOUS LEAF EXTRACT OF PERSEA AMERICANA MILL (LAURECEAE) IN NORMOGLYCAEMIC AND ALLOXAN-INDUCED HYPERGLYCAEMIC WISTAR RATS
TOXICOLOGICAL AND ANTI-HYPERGLYCAEMIC PROPERTIES OF AQUEOUS LEAF EXTRACT OF PERSEA AMERICANA MILL (LAURECEAE) IN NORMOGLYCAEMIC AND ALLOXAN-INDUCED HYPERGLYCAEMIC WISTAR RATS
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Date
2014-12
Authors
OKAFOR, STEPHEN CHIADIKAOBI
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Abstract
Diabetes mellitus has become a global health burden leading to an increase in the
search for herbal anti-hyperglycaemic agents as alternative to synthetic ones. Persea
americana popularly known as avocado pear have been known for its nutritional and
medicinal properties. The leaves of this plant are used in Eastern Nigeria especially in
Anambra state for the management of Diabetes Mellitus. This study was aimed at
evaluating the toxicological and anti-hyperglycaemic properties of aqueous leaf extract
of P. americana Mill. (laureceae) in normoglycaemic and alloxan-induced
hyperglycaemic Wistar rats. Preliminary phytochemical screening, acute toxicity and
sub-chronic toxicity and anti-hyperglycaemic studies of the extract were carried out.
Preliminary phytochemical screening revealed the presence of saponins, steroids,
flavonoids, tannins, alkaloids, cardiac glycosides, triterpenoids and carbohydrates
whereas anthraquinones and cyanogenetic glycosides were absent. The oral median
lethal dose (LD50) of the extract in rats was estimated to be greater than 5000 mg/kg. In
the sub-chronic toxicity study, the extract did not produce significant changes on feed
and water intake, body weights and the relative organ weights of treated rats when
compared with control. P. americana leaf extract significantly (P<0.05) reduced the
blood glucose level in treated normoglycaemic rats compared to normoglycaemic
control. The extract also significantly (P<0.05) decreased only the white blood cell
(WBC) count among the haematological parameters assessed. The extract significantly
(P<0.05) increased AST, urea, creatinine and ALT, while ALP showed no significant
difference when compared with the control. There were no histological changes found
in the heart and spleen tissues of the treated rats. However, dose dependent pathological
changes were observed in the liver, kidney and lung tissues of the treated rats compared
with control. Anti-hyperglycaemic study showed that the extract significantly (P<0.05)
reduced feed and water intake and significantly (P<0.05) decreased the blood glucose
concentration. The body weights of the treated animals increased significantly (P<0.05)
when compared to hyperglycaemic control. There were significant (P<0.05) decrease
observed in the levels of AST, ALT, ALP, urea and creatinine while total protein and
albumin were increased significantly (P<0.05) in treated animals compared to untreated
hyperglycaemic control. No significant changes were observed in all the haematological
parameters of the treated rats when compared to hyperglycaemic control. The extract
also caused significant (P<0.05) decrease in TC, TG, and LDL while HDL was
increased significantly (P<0.05) in the treated rats compared to non-treated
hyperglycaemic control. Histopathological study showed a degenerative effect on the
pancreatic tissue of the hyperglycaemic control for 28 days but revealed restorative
(protective) effect of the extract on pancreatic islet cells of the hyperglycaemic treated
rats. The findings from these studies showed that the aqueous leaf extract of P.
americana is relatively safe on acute administration but revealed possible toxic effects
following sub-chronic daily oral administration in rats at the doses used. The extract
also showed blood glucose lowering activity (both in normogycaemic and
hyperglycaemic rats) alongside anti-hyperlipidaemic activity with reversal of most
alterations observed in hyperglycaemic control. Therefore, the aqueous extract of P.
americana leaf has anti-hyperglycaemic property but toxic on sub-chronic
administration and should be used with caution.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLLMENT OF THE REQUIREMENTS FOR THE AWARD
OF A
MASTER OF SCIENCE DEGREE IN PHARMACOLOGY
DEPARTMENT OF PHARMACOLOGY AND THERAPEUTICS
FACULTY OF PHARMACEUTICAL SCIENCES
AHMADU BELLO UNIVERSITY, ZARIA
NIGERIA
DECEMBER, 2014
Keywords
TOXICOLOGICAL,, ANTI-HYPERGLYCAEMIC,, PROPERTIES,, AQUEOUS,, LEAF, EXTRACT,, PERSEA, AMERICANA, MILL, (LAURECEAE), NORMOGLYCAEMIC, ALLOXAN-INDUCED,, HYPERGLYCAEMIC, WISTAR, RATS.