Evaluation and Optimization of Yield and Antioxidant Activity of Moringa oleifera Flower Extract

Abstract

The local population consumes ethanol extracts of Moringa oleifera as antioxidant but without scientific evidence. This work assessed the effect of concentration of ethanol, drying time, and time of harvest of the plant part on its antioxidant activity.  The basic free radicals, 1, 1, diphenyl-2-picryl-hydrazyl (DPPH) and the ferric reducing power (FRAP) assays assessed the antioxidant power of the extracts with the help of ascorbic acid as a standard antioxidant. The response surface design uses reiterated values of the dependent variables, one at a time to assess the dependent variables. Result from the experiments revealed that antioxidant power of the extracts associated positively with   concentration of the extraction solvent. Optimization analysis on the experimental data indicated that 100% solvent showed 7.40% yield, 32.20 amino acid equivalent per gram (AAE/g) of antioxidant capacity, 6.46 mg/100g of total phenolic content, 2.80 mg/100g of total flavonoid content, and desirability of 55.60%. FRAP assay on 59.11% solvent concentration, 43 hours drying time, and a 10:00 a.m. harvest time showed 52.94 g/100g yield, 52.40% oxidation inhibition, 16.42 AAE/g of IC₅₀, 4.94 mg/100g phenolic acid content, and 3.02 mg/100g flavonoid content, at 90% desirability. The values were comparable to ascorbic acid, therefore the ethanol extract Moringa oleifera could serve as a natural antioxidant.