Optimising extraction of antioxidants from roasted Moringa oleifera Lam. leaves using response surface methodology

摘要

Optimal conditions for alcoholic extraction of antioxidants from roasted leaves of Moringa oleifera Lam. were determined using response surface methodology and the phenolic profile of optimised extract determined by HPLC-PDA. The experimental results adequately fitted the second-order polynomial models as indicated by regression coefficient (.90–.95), lack-of-fit >.05, and absolute deviation .01–.04). Using multiple responses optimization and desirability function, the optimal conditions needed to maximize simultaneously antioxidant activity, phenolic content and extract yield were 65%–75% ethanol, 55–65°C and 40 min. The experimental values were not significantly different (p > .05) from those predicted, indicating the suitability of the models in the studied range. HPLC analysis of the extract revealed the presence of quercetin, isoquercetin, caffeic acid, and rutin. Rutin (45 mg/g), a flavonoid, was the major phenolic. The extract exhibited significant antioxidant potential IC50 2,2-diphenyl-2-picryl hydrazyl 1.28 mg/L, ferric reducing antioxidant power 236 mg AAE/g, total phenolic content 176 mg GAE/g and could be used as nutraceuticals.