Abstract

This study was conducted to screen the phytochemical constituents and determine the levels of the major and trace elements of three medicinal plants used for the treatment of diabetes mellitus namely; Bridelia ferruginea, Lagerstroemia speciosa and Morus Alba. The air dried leaves of the plants were subjected to soxhlet extraction using ethanol. The crude extracts obtained were subjected to screening for their phytochemical constituents such as alkaloids, tannins, terpenoids, reducing sugars, flavonoids, saponins, anthraquiones, coumarins, emodols, carotenoids and steroids using various standard methods and reagents. Trace metals in the three medicinal plants were also quantitatively analyzed using Flame Atomic Absorption Spectroscopy. A wet digestion procedure involving the use of 4 ml of perchloric acid and 10 ml of aquaregia was adopted to digest the medicinal plants. Anthraquinones, sterols, tannins, terpenoids, flavonoids, alkaloids, saponins, coumarins and reducing sugars were identified in the leaves of all the three plants. However, emodols were absent in all the plants but carotenoids were absent in only B. ferruginea. Elemental concentrations of some of the elements were obtained from the leafy materials in varying quantities. Ten heavy metals (Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni, Zn, and V), two alkali metals (K and Na) and three alkaline earth metals (Ca, Mg and Al) and two halogens (Cl and Br) were quantitatively analysed. The anti-diabetic properties of the plant extracts could be attributed to the presence of steroids, triterpenes and alkaloids. In general, the order of concentration of toxic metals in the medicinal plants was found to follow the order Fe > Mn > Zn > Cu > Ni > V > Pb > Co > Cr > Cd. Sodium content was found to be very high in L. speciosa while chlorine content was found to be very high in B. ferruginea.

Key words: Bridelia ferruginea Benth, Lagerstroemia speciosa Linn., Morus alba L, diabetes.