Ultrasound‐assisted extraction of phenolic compounds from Phyllanthus emblica L. and evaluation of antioxidant activities

Abstract

The objective of this study was to optimize ultrasound-assisted extraction of phenolic compounds from Phyllanthus emblica. Extracts obtained by UAE were evaluated for their antioxidant activities. Extraction experiments were carried out with three factors and three levels namely extraction time (varying from 15 to 60min), ethanol concentration (varying from 50 to 90%) and frequency (varying from 28 to 56kHz). The results showed that the UAE optimal conditions of extracting total phenol components were as follows: 15min of extraction time, 60°C of extraction temperature, 70% of ethanol concentration, 56kHz of ultrasonic frequency and a 1: 50 solid to solvent ratio. Under optimal conditions, the leaching-out rate of phenolic compounds was up to 55.34mgg(-1) , and the yield of crude extract of P.emblica was up to 56.82%. The results reveal that the yield of phenolic compounds of UAE (56.82%) is higher than that of conventional solvent extraction (16.78%). Furthermore, the antioxidant activities of ethanol extracts obtained by UAE were evaluated in terms of activities of DPPH (1,1'-diphenyl-2-2'-picrylhydrazyl) radical scavenging activity, total antioxidant activity, metal chelating activity, and reducing power. P.emblica extracts obtained by UAE showed high antioxidant activity (26.00, 50.11 and 115.91μgmL(-1) of IC50 values for DPPH radicals, total antioxidant ability and chelating ability of ferrous ion). The result of this study showed that UAE was a suitable method for the extraction of total phenolic compounds. Moreover, the author's main finding in this work is the fact that phenolic compounds from P.emblica show excellent antioxidant activity in multi-test systems.