L-lactic acid and alternative solvent to ethanol for propolis extraction

The active substances of propolis are easily soluble in ethanol. However, ethanolic extracts cannot be used in the treatment of certain conditions. The main bioactive substances of propolis are less soluble in other solvents used in the pharmaceutical industry. L-Lactic acid is a non-toxic, bio-based, weak acid which is also approved as a food additive with no ADI value. Therefore, the aim of this study is to evaluate the phenolic compounds, and antioxidant activity analyzes of propolis extracted by using lactic acid in comparisson with ethanol. Extracts were prepared in different concentrations (10, 20, 30 and 40 %) for comparison. Phenolic compounds were determined in the obtained solutions by LC-MS/MS procedure and antioxidant activity analyzes were performed by DPPH and CUPRAC methods. It was determined that the total phenolic content in the 40% propolis-lactic acid solution was significantly higher than the ethanol-propolis solution of the same concentration (p<0.05). In addition, with the CUPRAC method, there was no difference in the antioxidant capacities between ethanol and lactic acid solutions of that concentration. The results suggest that lactic acid may be used as an alternative to ethanol for propolis extraction.
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