Phenolic content distribution and antioxidant activities of Terminalia sericea Burch

Background: Terminalia sericea has been used traditionally for the treatment of diseases associated with oxidative stress. This study was aimed at determining the distribution of phenols in the leaves, stem bark and root bark of Terminalia sericea and their antioxidant activity.Materials and methods: Hot and cold water, methanol/acetone extracts were evaluated for their total phenolic content (TPC), flavone/flavonol content (FFC), flavonone/dihydroflavone content (FDFC), hydroxycinnamic acid derivative content (HCAC) and tannin content (TC). DPPH (2,2-diphenyl-1-picrylhydrazyl) free radicals and reducing power assays were used to assess the antioxidant activity.Results: The leaves had the highest average TPC (440) expressed in milligram Gallic Acid Equivalent (mgCAE) /gram of the extract. The leaves also had the highest average TC (7.14) expressed in milligram Quercetin Equivalent (mgQE) /gram of the extract. The stem had the highest average FDFC (19.23 mgQE/g) while the root had the highest average FFC (74.76 mgQE/g) and HCAC (214.57) expressed in milligram Caffeic Acid Equivalent mgCAE/ gram of the extract. The stem exhibited the highest average DPPH free radical scavenging (9.85 μg/mL) and reducing power (6.01 μg/mL) activities. Water was a better extracting solvent for TPC and FDFC while methanol/acetone was a better extracting solvent for FFC and HCAC. The correlation between TC and reducing power activity (r=0.668) at P < 0.05 suggests that tannins were responsible for the antioxidant activity.Conclusion: This study has shown that the distribution of phenolics differs in the organs of T. sericea, and could affect the quality of medicinal products sold.Key words: Phenolic contents; Terminalia sericea; Antioxidant activity; Distribution studies

Phenolic contents, antioxidant activity and spectroscopic characteristics of <em>Pterocarpus angolensis </em>DC. stem bark fractions

400-406Oxidative stress has been implicated in the damage of biological molecules resulting in aging and diseases such as Alzheimer, cancer, diabetes, cardiovascular disorders. The study aimed at determining the phenolic contents and antioxidant activities of Pterocarpus angolensis crude extract and fractions. The crude extract and fractions of P. angolensis were evaluated for their phenolic contents using Follin-Ciocalteu reagent. The antioxidant activities were evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power assays. Ultraviolet-Visible and Fourier transform infrared spectroscopy were used to assess the spectroscopic characteristics. We obtained 7 fractions from the crude extracts after column chromatography on silica gel 60. The results showed that fraction two (PaF2a) displayed the highest DPPH radical scavenging activity (18.7 &micro;g/ml) but had the lowest phenolic content while fraction three (PaF2b) exhibited the highest reducing power activity (44.28 &micro;g/ml) with high phenolic content. Spectroscopic details showed that PaF2a had maximum absorbance at 287.1 nm while PaF2b displayed maximum absorbance at 288.2 nm. The infra-red spectroscopy presented four main characteristic fingerprinting at 1606, 1518, 1444 and 1064 cm-1 as fingerprints for P. angolensis. There was a difference in the wave number at C==C and C-O vibrations between PaF2a and PaF2b. In conclusion, this study has shown that PaF2a and PaF2b are the antioxidant rich fractions of P. angolensis stem bark and exhibited different spectroscopic characteristics