Optimization Protocol for the Microwave-Assisted Extraction of Antioxidant Components from Pinus elliottii Needles Using Response Surface Methodology

Response surface methodology (RSM) based on a Box–Behnken rotatable design was used to determine the optimum conditions for the microwave-assisted extraction of antioxidant compounds from Pinus elliottii needles. Four process variables were evaluated at three levels (29 experimental conditions): ethanol (50, 70, and 90%), solvent:solute ratio (25:1, 20:1, and 15:1), extraction temperature (60, 70, and 80 °C), and ultrasonic power (100, 150, and 200 W). Using RSM, a quadratic polynomial equation was obtained by multiple regression analysis to predict the optimized extraction protocol. The radical scavenging capacity was determined by O2−, ·OH, and DPPH methods. For the microwave-assisted extraction of antioxidant compounds from Pinus elliottii needles, the optimum process used ethanol at 72%, a solvent:solute ratio of 21:1 mL/g, an extraction temperature of 67 °C, and an ultrasonic power of 200 W. The results indicated good correlation between total polyphenols content and O2−, ·OH, and DPPH radical scavenging activities.