Application of microwave-assisted extraction to the fast extraction of plant phenolic compounds

The analysis of phenolic compounds in plants attracts considerable attention. Conventional (reflux) extraction as well as microwave-assisted extraction of phenolic substances from aromatic plants using different solvents has been studied. RP-HPLC with UV detection was employed for the analysis of phenolic compounds. Total phenolic compounds were determined by the Folin–Ciocalteu assay. The amount of extractable phenolic substances for this method decreased with decreasing polarity of the solvent in the order water, 60% methanol, 60% acetone, and ethyl acetate/water (60:30, v/v) by using the conventional method. When microwave-assisted extraction was performed, the previous order was changed to 60% acetone, 60% methanol, water and ethyl acetate/water. The HPLC results have shown similar solvent effect for the two extraction methods. It was also proved that microwave-assisted extraction is a more effective technique compared to the conventional method. The extraction time was reduced, less solvent was used and the amount of extracted phenolic compounds was increased.