Response Surface Methodology Optimization for Extraction of Antioxidants From Moringa Stenopetala Leaf, Study of Its Phytochemical Screening, and DPPH Antioxidant Assay

Abstract

Moringa stenopetala is a medicinal tree that originated in Africa and Asia. It has been used as a traditional medicine over centuries to treat diseases. Recent studies have shown that Moringa stenopetala is a rich source of antioxidants and other phytochemicals. This study investigated the extraction, phytochemical screening, and DPPH antioxidant assay of Moringa stenopetala leaf (MSL) extract. The study optimizes the process conditions to extract phytochemicals from the MSL. Using Design-Expert software, the experiments were designed and optimized the extract from MSL using the response surface methodology approach. The best optimal parameters for extracting MSL extract were established as the concentration of ethanol: 50%, time: 48 h, and pH 6.5, which resulted in the highest responses: the MSL extract yield (67.95%) and the total phenol content (4.47 mg GAE/mL) with a higher desirability value of 1.0000. The crude extract was then subjected to phytochemical screening to identify the presence of various secondary metabolites. The DPPH antioxidant assay was used to estimate the antioxidant activity of MSL extract. Phytochemical screening results proved that MSL extract contains flavonoids, phenols, saponins, and tannins. DPPH antioxidant assay showed that the 0.15 mg/L of MSL crude extract had a robust antioxidant activity with a maximum percent inhibition of 85.08 ± 0.49. Thus, the results of this study suggested that MSL extract is a better source of antioxidants to use as natural preservatives in food and pharmaceutical industries.