Response surface methodology driven ultrasonic-assisted extraction of ellagitannins from pomegranate rind: optimization of parameters and in silico molecular interaction with catalase

The present study deals with the comparative extraction techniques of ellagitannins from pomegranate rind to get higher extraction efficiency for the purpose of waste valorization. Extraction techniques followed the trend high-speed homogenization (2.08%) > ultrasonic-assisted extraction (1.71%) > microwave-assisted extraction (1.40%) > Soxhlet (1.31%) > enzyme-assisted extraction (0.95%) in terms of punicalin equivalent yield. Being green technique, ultrasonic-assisted extraction (UAE) was further optimized by using response surface methodology (RSM). Yield of ellagitanins was maximized to 3.04% in terms of punicalin equivalent yield for UAE using RSM, which is significantly higher than conventional Soxhlet extraction method (1.71%) using optimized conditions. The LC-HRMS analysis found that Punicalin A and B were the major ellagitannins present in the purified extract apart from the hexose sugar of ellagic acid. Ellagitannin-rich extract was evaluated for their antioxidant activity by DPPH, ABTS, and FRAP assays, and the IC 50 values ranged between 4.9–29.2 and 25.4–32.9 for the crude and purified ellagitannin, respectively. In silico analysis revealed good binding capacity of ellagic acid with catalase. Polyphenols from pomegranate rind have strong potential for industrial utilization.