In vitro antioxidant activity, total phenolic and flavonoid contents of ethanol extract of stem and leaf of Grewia carpinifolia

Free radicals are reactive molecules involved in many physiological processes and have been associated with many diseases, such as cancer, arthritis and liver injury. As a result, there is need to explore substances with free radical scavenging and or antioxidant activity. The present study was designed to evaluate the free radical scavenging activity of ethanol extract of leaf and stem of Grewia carpinifolia using various in vitro models. Ascorbic acid was used as the reference in the study. 1,1-Diphenyl-2-picryl hydroxyl (DPPH) quenching assay, 2,2′-azinobis-3-ethylbenzothiozoline-6-sulfonic acid (ABTS) cation decolorization test, ferric reducing antioxidant power (FRAP) Assay systems were selected for the present experiment. The ability of the extracts to inhibit lipid oxidation was measured using Thiobarbituric Acid Reactive Substances (TBARS) assay. The extracts were used at 0.2, 0.4, 0.6, 0.8 and 1 mg/ml concentrations and radical scavenging activity was determined in terms of inhibition percentage. The IC50 (concentration required for 50% inhibition) was also calculated for each radical. The study revealed that Grewia carpinifolia has a high radical scavenging activity in the various radical systems. The total phenolic content was 19.08 ± 1.21 mg gallic acid equivalent (GAE)/g extract and 14.85 ± 1.09 mg GAE/g extract for the leaf and stem respectively while the flavonoid content was 9.00 ± 0.13 and 13.22 ± 1.53 mg quercetin/g extract. The antioxidant activity of Grewia carpinifolia extract may be due to the high level of flavonoids and phenols in the plant.