Abstract
The aim of the present study was to evaluate and compare the relative contributions of different polyphenols to the antioxidants activities of different parts of the plant Terminalia glaucescens. Preliminary phytochemical screening of the crude extracts and solvent fractions of the root, stem and leaves of the plant was carried out using standard procedures. Quantitative determination of the total phenolic and flavonoid contents (TPC and TFC) of the test materials were carried out using Folin Ciocalteu and aluminum chloride colorimetric methods respectively. The in-vitro antioxidant activity was investigated using in-vitro antioxidant model; 1, 1-diphenyl-2-picrylhydrazyl (DPPH) assay. The results showed that the TPC of the methanol fraction of the leaves (96.50±0.25 mg GAE/g extract) were significantly higher than the other fractions. Flavonoids were found more in the leaf than those from other plant parts with the exception of the ethyl acetate fraction from the stem which showed a slightly higher content. Phytochemical screening of T. glaucescens parts revealed the presence of anthraquinones, cardiac glycosides, flavonoids, saponins, phlobatannins and carbohydrates at varying degrees. The IC50 value based on the DPPH of methanol extract of the leaves (2.97±1.0 mg/ml) was the lowest when compared to other plant parts or solvent fractions suggesting potentially better antioxidant properties. A marginally positive correlation was found between TPC and IC50 values for DPPH and TFC. These data therefore revealed that the alcoholic extract of the leaves of Terminalia glaucescens should be preferentially utilized for health conditions where the antioxidant activity of the plant may be desirable.
