Antidiabetic and antioxidant effects of Annona muricata (Annonaceae), aqueous extract on streptozotocin-induced diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves of Annona muricata are used in Cameroon to manage diabetes and its complications. The aim of this study was to evaluate the antidiabetic, antioxidant activities and the potential toxicity of aqueous extract of Annona muricata in streptozotocin-induced diabetic rats.

MATERIAL AND METHODS: Oral administration of Annona muricata aqueous extract (100mg/kg or 200mg/kg) was studied in normal and streptozotocin-induced diabetic rats. In long term treatment, 2 weeks after streptozotocin-induced diabetic rats, animals received plant extract during 28 consecutive days. For a protective effect, extract was administered 3 days prior to streptozotocin exposure and animals were observed 2 weeks without treatment.

RESULTS: The plant extract was not effective in normal rats. In diabetic rats, single administration of the extract significantly reduced blood glucose levels by 75% and 58.22% respectively at the dose of 100mg/kg and 200mg/kg as compared to the initial value. Treatment of normal rats 3 days prior to diabetes induction showed that, Annona muricata extract has no effect within 72h following STZ injection. However, after 14 days post-treatment, the extract at the dose of 100mg/kg significantly reduced blood glucose levels as compared with initial value and diabetic control rats. Immunohistochemical staining of pancreatic β-cells of diabetic rats treated with the dose of 100mg/kg expressed strong staining for β-cell compared to diabetic control. In a long-term study daily administration of Annona muricata aqueous extract for 28 days to diabetic rats, reduced blood glucose levels, serum creatinine, MDA, AST, ALT activity, and nitrite levels LDL-cholesterol. Total cholesterol, triglycerides, SOD, and CAT activity contents were restored.

CONCLUSION: These different results show that the antidiabetic activity of Annona muricata aqueous extract can be explained by its hypolipidaemic effect, its antioxidant and protective action on pancreatic β-cells, which in turn improve glucose metabolism.