Optimization of ultrasound-assisted extraction of natural antioxidants from Piper betle using response surface methodology

Natural antioxidants are excellent substitute for their synthetic counterparts in dietary supplements. Present study employed three-level Box-Behnken design through RSM to optimize the recovery of natural antioxidants from Piper Bede via ultrasound-assisted extraction (UAE). The influence of three extraction parameters, temperature (50-70 degrees C), ethanol concentration (70-90%) and solute to solvent ratio (1:10-1:30 g/mL) on the extraction yield (EY), total phenolic content (TPC) and antioxidant capacity was investigated. The optimum conditions were determined to be 51.60 degrees C with 78.74% ethanol and ratio of 1:21.85 g/mL. Experimental validation showed a maximum EY of 13.88% with TPC of 311.21 mgGAE/gDW and 97.57% antioxidant capacity that were all within 95% confidence level of predicted values. Additionally, UAE gave significantly better yield (13.71%), TPC (289.05 mgGAE/gDW), total flavonoid content (21.50 mgRE/gDW) and antioxidant activity (94.99%) than maceration which gave lower yield (10.96%), TPC (246.98 mgGAE/gDW), total flavonoid content (13.48 mgRE/gDW) and antioxidant activity (78.12%) respectively. General phytochemical screening exposed the presence of additional saponins and tannins in the UAE extracts. Chemical composition of the optimized extract via GC/MS indicated the presence of four major phenolic compounds, hydroxychavicol, eugenol, isoeugenol and 4-ally1-1,2-diacetoxybenzene with peak areas of 66.55, 11.92, 2.90 and 3.21% respectively.