Characterization of phenolic compounds from Phyllanthus emblica fruits using HPLC-ESI-TOF-MS as affected by an optimized microwave-assisted extraction

摘要

A simple microwave-assisted method for extracting antioxidant phenolic compounds from emblic (Phyllanthus emblica L.) fruits was developed and optimized with response surface methodology (RSM). The influence of process conditions including microwave power, irradiation time, ethanol concentration, and solvent-to-solid ratio on the extraction of total phenolic content was analyzed by using a second-order regression equation. The optimum extraction parameters were as follows: microwave power, 480 W; irradiation time, 29 s; ethanol concentration, 66%; liquid-to-solid ratio, 25 mL/g. Under these conditions, the recovery of total phenolic content was 133.58 ± 15.61 mg gallic acid equivalent/g dry weight (DW). The extracts were also analyzed using HPLC-ESI-TOF-MS to identify eight compounds including hamamelitannin, mucic acid-1,4-lactone-3-O -gallate, ellagic acid, and isocorilagin. To our knowledge, this is the first report of hamamelitannin in emblic fruit. The extracts exhibited strong antioxidant capacities in DPPH and ABTS~(+) radical scavenging assays and showed an excellent inhibition of lipid peroxidation and reducing property. These findings illustrated that the optimized microwave-assisted extraction method was efficient in extracting phenolic compounds with high antioxidant activity from emblic fruits. It was suggested that emblic fruits may be a new potential source as natural antioxidant agents applied in food industry.