Extraction and Antioxidant Activity of Polyphenols from Phyllanthus emblica L.

Polyphenols from Phyllanthus emblica L. were extracted by solvent extraction and their antioxidant activities were studied. The contents of polyphenols was determined by Folin-phenol method,and the extraction rate of polyphenols was taken as the index. Three factor(extraction time,extraction temperature and ethanol concentration)which had great influence on the extraction of polyphenols were determined by single factor experiments. The extraction scheme was further optimized by orthogonal experiment. In vitro experiments were carried out to investigate the scavenging effects of Phyllanthus emblica polyphenols on DPPH free radicals,hydroxyl free radicals,and the inhibition on spontaneous liver lipid oxidation. The results showed that gallic acid had a good linear relationship between 1 and 5 mg/mL,and the linear regression equation was y=0.1431x+0.0791(r=0.9997). The optimum extraction scheme was as follows:Extraction time 135 min,extraction temperature 70 ℃,ethanol concentration 45%,the extraction rate of polyphenols was(0.2427±0.0008) mg GAE/mg. The total reduction capacity of polyphenols in the range of 0.2~1 mg/mL was slightly lower than that of tea polyphenols,but the DPPH free radical scavenging rate,hydroxyl radical scavenging rate and spontaneous liver lipid oxidation were significantly higher than those of tea polyphenols. The EC₅₀ of scavenging nitrogen free radicals was(9±0.01) μg/mL,the EC₅₀ of scavenging hydroxyl free radicals was(0.47±0.01) mg/mL,and the EC₅₀ of inhibiting spontaneous liver lipid oxidation was(122±2) μg/mL. Phyllanthus emblica L. polyphenols would have good antioxidant activity and good application prospects.