Antidiabetic efficacies of methanolic and ethyl acetate extracts of Aristolochia ringens (Vahl) roots: in vivo comparative studies

Antidiabetic effects of methanol and ethyl acetate extracts of roots of Aristolochia ringens (Vahl) were comparatively assessed in streptozotocin (STZ)-induced rats. Pulverized root of A. ringens was soaked with methanol, filtered, and concentrated to dryness. The resulting residue was subsequently dissolved in ethyl acetate, filtered, and concentrated to dryness to obtain ethyl acetate extract. Methanol and ethyl acetate extracts of A. ringens root yielded 20.50 g (10.25%) and 16.4 g (8.2%) respectively. Both extracts (150 mg/kg bw) and metformin (14.2 mg/kg bw) used as reference were administered orally to STZ-induced diabetic rats for 7 days. Fasting blood glucose (FBG) level was monitored and percentage reduction in glycemia computed. Hepatic concentrations of glucose and glycogen as well as alpha amylase and glucose-6-phosphate dehydrogenase activities were also evaluated. FBG level persisted in animals that were diabetic but not treated (323.20 ± 1.01 mg/dL), whereas FBG levels in treated rats following administration of metformin, ethyl acetate, and methanol extracts for 7 days were 148.55 ± 1.62, 129.08 ± 2.52, and 181.21 ± 0.44 mg/dL, resulting in percentage reduction of 80.93%, 85.44%, and 69.10% in glycemia respectively. Ethyl acetate extracts from A. ringens root caused higher reduction in hepatic glucose concentration with concomitant increase in glycogen level when compared to the methanol extract. The root extracts also stimulated the activity of glucose-6-phosphate dehydrogenase while inhibiting the activity of α-amylase in the liver of the treated groups compared to the untreated groups. Findings from this study revealed that ethyl acetate extract of Aristolochia ringens displayed strong antidiabetic potential than the methanol extract of the same plant.