Diabetes mellitus is the fourth killer disease globally. The available management strategies are quite expensive and sometimes unsafe. This necessitates the need for bio-active drugs from medicinal plants. Salvia officinalis (sage) has been in use in herbal medicine for a long time. However, the scientific validation for anti-diabetic effects of various extracts from this plant has been elusive. The present study aimed to determine and compare the anti-hyperglycaemic efficacy of methanolic, hexane, ethyl acetate, and aqueous extracts of Salvia officinalis in alloxan-induced diabetic mice. Dried and powdered leaves were extracted with methanol, hexane, ethyl acetate, and water solvents. Phytochemical screening of the extracts revealed presence of flavanone, sterols, saponins, tannins, alkaloids, and triterpenes. Diabetes was induced in the experimental mice using a single intraperitoneal injection of alloxan monohydrate at a dose of 200 mg/kg bwt. The extracts were subjected to preliminary in vivo bio-assays at dosage levels of 400 mg/kg for 7 days through oral administration. The aqueous extract demonstrated significant hypoglycaemic effect, p˂0.05 hence subjected to further hypoglycaemic studies for 15 days. There was a significant decrease in blood sugar levels of groups treated with aqueous extract at 400 mg/kg and 600 mg/kg doses from 452.00 ± 11.13 mg/dL and 431.00 ± 10.65 mg/dL to 256.33 ± 5.12 mg/dL and 256.67 ± 8.74 mg/dL. Weight gain improved significantly from 28.05 ± 0.39 g and 27.38 ± 0.52 g to 29.32 ± 0.42 g and 28.55 ± 0.38 g respectively compared to controls, p˂0.05. Histopathological studies revealed no significant changes in liver and kidney tissues. Besides, no significant cytotoxic effect was reported. Results from this study indicate that aqueous extract of Salvia officinalis is a potential anti-hyperglycaemic and can be used in modulating blood glucose levels.
Keywords: Diabetes mellitus, Salvia officinalis, Aqueous extract, Hypoglycaemic effect, Phytochemicals.