Extraction of strawberry leaves with supercritical carbon dioxide and entrainers: Antioxidant capacity, total phenolic content, and inhibitory effect on uric acid production of the extract

The recovery of useful components such as antioxidants from strawberry leaves would be desirable because this byproduct is usually disposed of as agricultural waste. In this study, strawberry leaves were extracted with supercritical carbon dioxide (sc-CO2) and the effects of various entrainers were evaluated under the following conditions: temperature from 308 to 333 K, pressure from 15 to 30 MPa, and a molar ratio of entrainer to CO2 of 0.1. The use of ethanol, acetone, and water improved the extraction yield, antioxidant capacity and total phenolic content of the extract. In sc-CO2+ ethanol, the antioxidant capacity and total phenolic content exhibited maximum values for a given temperature at 20 MPa. The antioxidant capacity was almost independent of pressure and total phenolic content had a maximum at 308 K. The solvent density, solubility of organics, and vapor pressure of compounds appeared to influence the antioxidant capacity and total phenolic content. Furthermore, the strawberry leaf extract obtained using sc-CO2+ ethanol significantly and dose-dependently suppressed uric acid production in cultured hepatocytes. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.