Comparative antioxidant capacity of aqueous and ethanol fruit extracts of Tetrapleura tetraptera

Abstract

Background and Objective: Most commonly used synthetic antioxidants have side effects and are carcinogenic according to research reports. Therefore the search for natural antioxidants from plants sources which are presumed to be safe, potent, nutritional and possessing therapeutic value is necessary. The objective of this study was to compare the antioxidant ability of aqueous and ethanol fruit extracts of tetrapleura tetraptera. Materials and Methods: The fruit of Tetrapleura tetraptera was procured, identified, aqueous and ethanol fruit extracts were prepared. The antioxidant activity was evaluated by various in vitro radical scavenging assays, namely, 2, 2’- azino- bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), 2, 2-diphenyl-2- picrylhydrazyl radicals (DPPH), hydroxyl radical, nitric oxide radical, ferric reducing antioxidant potential (FRAP), metal chelating and total antioxidant capacity (TAC). While antioxidant capacity was studied by assessing in vitro inhibition of lipid peroxidation, total phenolic content (TPC), total flavonoid content (TFC) and the reductive potential of the extracts. One-way ANOVA was used for statistical analysis. Results: The results indicated that both fruit extracts of Tetrapleura tetraptera showed strong antioxidant activity and capacity. Aqueous fruit extract, however, produced a higher effect than ethanol in eight assay models namely, Total phenolic content, reductive potential, ABTS, FRAP, DPPH, nitric oxide, anti-lipid peroxidation and metal chelating. The stronger and more potent free radical scavenging and antioxidant activities observed for aqueous extract over ethanol may be due to the high total phenolic content extractable by this solvent. The free radical scavenging and antioxidant activities of this plant suggest that it could be potential natural sources of antioxidants and could have greater importance as therapeutic agents in preventing or slowing oxidative stress-related degenerative diseases. Conclusion: The results of this study showed the potential of Tetrapleura tetraptera to scavenge free radicals. The more potent antioxidant capacity expressed by the aqueous extract implies that water is a better solvent in the extraction of phytonutrients present in this plant and it is therefore recommended for prevention and treatment of oxidative stress relative diseases.