Assessment of Phytoconstituents and Antidiabetic Activity of the Crude Extract and Partitioned Fractions of Maytenus senegalensis (Lam.) Exell (Celastraceae) Root Bark

Abstract

Aims: To investigate the antidiabetic activity of the root bark of Maytenus senegalensis ethnomedically used in Nupeland for the management of diabetes and isolate phytoconstiteunts responsible for the pharmacological activities.

Study Design: Air-dried root bark Maytenus senegalensis ground into a fine powder. The pulverized material was macerated in 70% methanol at room temperature for 72h. The extracts were concentrated in vacuo using rotary evaporator at 35ºC. Antidiabetic activity was determined on the crude methanolic extract and partitioned fractions.

Place and Duration of Study: Department of Chemistry and Department of Biochemistry, School of Natural and Applied Sciences, Federal University of Technology, Minna, Nigeria between January, 2012 and July, 2013.

Methodology: The present study reports the phytoconstituents evaluation as well as antidiabetic activity determination of the root bark extract of M. senegalensis on alloxan-induced diabetic rats. Phytoconstituents analysis and characterization of the root bark extract of M. senegalensis were determined using standard phytochemical methods and GC-MS analysis respectively. The crude extract was partitioned using different solvents of varying polarities and the fractions obtained were tested for their phytoconstituents.

Results: The preliminary phytochemical analysis of M. senegalensis root bark indicates the presence of alkaloids, flavonoids, saponins, tannins and steroidal compounds. Anthraquinones was completely absent. The root bark of Maytenus senegalensis was extracted by 70% methanol which was then partitioned using four solvents of different polarities. The crude extract and solvent soluble fractions were used to determine the antidiabetic activity against alloxan induced (150mg/kg body weight) diabetic rats, after oral administration at a dose of 200mg/kg body weight for two weeks. The result revealed reduction in the elevated blood glucose level by 29.75%. Treatment with the known antidiabetic drug, glibenclamide (5mg/kg body weight) lowered blood glucose level by 27.03% indicating significant improvement in activity. Results obtained indicate that 70% methanolic fraction (aqueous methanol soluble fraction) has highest and most effective activity. This aqueous methanol fraction was then subjected to column and thin layer chromatography as well as GC-MS analysis. The GC-MS spectrum reveals the presence of seven different compounds which may have contributed to the ethnomedicinal properties of this plant.

Conclusion: Scientific research has supported the ethnomedicinal claims that M. senegalensis is useful in diabetes management. However, the isolation, purification and characterization as well as mechanism of action of bioactive constituents underlying its curative properties are suggested.