Application of Response Surface Methodology (RSM) for the Optimization of Ultrasound-Assisted Extraction (UAE) of Moringa oleifera: Extraction Yield, Content of Bioactive Compounds, and Biological Effects In Vitro

This study optimized ultrasound-assisted extraction conditions to maximize the extraction yield, total flavonoid content (TFC), total phenolic content (TPC), and DPP IV enzyme inhibitory activity from Moringa oleifera. The four UAE factors, solvent ratio (A), solvent–solid ratio (B), extraction temperature (C), and extraction time (D), were optimized using response surface methodology (RSM). A Box–Behnken design was used for the experimental design. The optimal conditions were found to be a 50% v/v solvent ratio, a 30% v/w solvent–solid ratio, 35 °C extraction temperature, and 45 min extraction time. The experimental value of extraction yield (R(1)), TFC (R(2)), TPC (R(3)), and DPP IV enzyme inhibitory activity (R(4)) (87.99% w/w, 56.63 mg QE/g extract, 97.26 mg GAE/g extract, and 93.32% inhibition, respectively) agreed with those predicted by RSM models (88.10% w/w, 56.61 mg QE/g extract, 97.16 mg GAE/g extract, and93.38% inhibition, respectively), thus demonstrating the appropriateness of the model used and the ability of the RSM to optimize the extraction conditions. Excellent DPP IV enzyme inhibitory activity was exhibited by M. oleifera compared with the standard, sitagliptin. While the modeled equation fits the data, the t-test is not significant, suggesting that the experimental values agree with those predicted by the RSM–BBD