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

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.

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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