Determination of the effect of green extraction solvents on the phenolic acids and flavonoids of propolis

Abstract

Propolis is an important bee product with many biological activities due to its containing phenolic compounds. The phenolic compounds of propolis vary depending on the plant source, season, altitude, extraction method and solvent. The present study investigated the extraction of phenolic compounds from propolis according to solvent factors. The propolis samples were extracted in four different solvents, which were water, ethanol-water (70%), dimethyl sulfoxide (DMSO), and L-lysine (8%), and were analyzed 36 phenolic compounds by HPLCDAD. Statistically significant differences in solubility of the phenolic compound at various levels were detected among the solvents (P <0.05). Only water and ethanol-water (70%) more successful than the other solvents were determined in the extraction of phenolic components of propolis. Phenolic acids generally dissolved higher in water, while flavonoids dissolved higher in ethanol were determined. Certain phenolic compounds were detected only in some of the propolis extract: syringic acid and daidzein in water, vitexin, rutin, and epigallocatechin in ethanol, and emodin in DMSO. Consequently, the chemical content is affected significantly depending on the extraction solvent of propolis. Therefore, it is essential to determine the extraction solvent and analyses of propolis before application for therapeutic purposes.