Comparative Phytochemical, In-vitro Anti-Hyperglycemic Activities of Napoleona vogelii Hook & Planch Stem Bark and Cassia occidentalis L. Root Extracts

Abstract

This work investigated the comparative phytochemical, proximate and anti-hyperglycemic activities of stem bark of Napoleonaea vogelii and root of Cassia occidentals extracts. Stem bark and N. vogelii root of C. occidentalis were cold extracted with methanol, ethyl acetate, and n-hexane. The extracts were subjected to proximate, phytochemical analyses and anti-hyperglycemic assays. The result of proximate analysis revealed that stem bark of N. vogelii was made up of 40.28 ± 0.49 % crude fibre, 37.05 ± 0.05 % carbohydrates, 7.45 ± 0.45 % protein and more than 6.00 % oil content. whereas 22.33±0.08 % crude fibre, 44.70± 0.93 % carbohydrates, 10.72± 0.05 % protein and 11.00± 0.00 % oil contents in roots of C. occidentalis. Alkaloids and terpenoids were present in all the extracts of N. vogelii and C. occidentalis. Flavonoids were also found in all extracts of N. vogelii, whereas tannins and glycosides were also found in all extracts of C. occidentalis. In vitro antidiabetic screening of the methanol extracts indicated that both plants showed a good concentration-dependent percentage glucose uptake. In all concentrations, extracts of C. occidentalis exhibited better glucose uptake than N. vogelii extracts. comparable to the activity of the standard drug- metronidazole (68.44±0.00 %), From 0.10 – 0.50 mg/mL, the methanol extracts of both plants also showed a dose-dependent α-amylase inhibitory effect.  But the inhibition decreased as the concentration was increased to 1.00 mg/mL. At 0.50 mg/mL, C. occidentalis and N. vogelii showed percentage inhibitory effect of 50.02±0.035 and35.61±0.01. Both plants’ extracts showed good anti-hyperglycemic activity, which may be due to the presence of alkaloids, terpenoids, saponins and tannins in the extracts, validating the folkloric use of both plants in the treatment of diabetes, and thus are good anti-diabetic agents.