The Influence of Microwave-Assisted Extraction on the Isolation of Sage (Salvia officinalis L.) Polyphenols

Summary In order to determine the optimal conditions for the extraction of sage polyphenols, the influence of extraction solvent (water, 30 % (by volume) aqueous ethanol and 30 % (by volume) aqueous acetone), extraction time (3, 5, 7, 9 and 11 min) and microwave power (500, 600 and 700 W) on the composition and concentration of phenolic compounds of dry wild sage (Salvia officinalis L.) during microwave-assisted extraction (MAE) was studied. Optimized MAE method was compared with conventional extraction (CE). Based on the amount of total phenols, microwave power of 500 W and extraction time of 9 min were selected as optimal extraction conditions, resulting in higher content of polyphenols when compared with CE. Ethanol and acetone solutions were equally effective extraction solvents, both producing higher extraction capacity than water. Using HPLC coupled with UV/PDA, fourteen polyphenols were identified (caffeic and rosmarinic acid derivatives, luteolin- and apigenin-glycosides) with rosmarinic acid and luteolin glycosides at the highest concentrations. The mass fractions of all individual polyphenols were higher in the MAE extracts than in the CE ones.