Optimization ultrasonic–microwave-assisted extraction of phenolic compounds from Clinacanthus nutans using response surface methodology

Clinacanthus nutans (C. nutans) is an edible profitable herb with high phenolic content that recognized herb relieves skin disorder, antityrosinase, and anticancer. Along with these health benefits C. nutans, however, there is no study on the factors that influence the phenolic content of C. nutans extraction by water-based ultrasonic-microwave-assisted extraction (UMAE). The aim of this study evaluates UMAE conditions (ultrasonic power, microwave power, and extraction time) on responses using response surface Box–Behnken design and compared with the hydrothermal extraction. The findings found that the caffeic acid and ferulic acid content decrease with increasing the microwave power and long extraction time (P<0.05). The combination factors significant impact on the phenolic compound are microwave power with a time of extract and ultrasonic with microwave power (P<0.05). The optimization UMAE of C. nutans was ultrasonic power 150 W, microwave power 50 W, and time of extraction 3 min (P < 0.05), and final temperature after extraction should be <60°C. UMAE was a four-fold greater target response and a sixty-fold lower extraction time compared to conventional hydrothermal extraction. The synergistic of ultrasonic and microwave power encourages extraction efficiency, which is advantageous to prepare the high-quality C. nutans extracted raw materials to apply in the nutraceutical, pharmaceutical, and cosmetic industry.