Selection of a suitable solvent for bioactive compounds extraction of myrtle (Myrtus communis L.) leaves using ultrasonic waves

The aim of this study was to evaluate the effect of solvent properties on bioactive extraction of myrtle leaves using ultrasound waves. Experimental design was performed using response surface methodology and optimized by Box-Behnken design. The effect of extraction variables such as temperature (30, 45, and 60 degrees C), time (5, 20, and 35 min) and solid to solvent ratio (0.2, 0.3, and 0.4 g/10 ml) was examined for estimation of total phenolic content (TPC) and total flavonoid content (TFC) of water, ethanol, methanol, and ethyl acetate as extraction solvents using ultrasonic waves. The result of water extract showed highest contents of TPC (269.36 +/- 3.83 mg gallic acid equivalent/g dry weight) and TFC (21.39 +/- 0.43 mg quercetin equivalent/g dry weight) compared with other solvents. The optimal condition was obtained at the extraction temperature of 58 degrees C, extraction time of 34 min, and solid to solvent ratio of 0.2 g/10 ml. Novelty impact statement Water as a cheap and green solvent resulted in high total phenolic and flavonoid compounds in myrtle extract. Ultrasonic waves facilitated penetration of water into leaf tissue. The solvent polarity was most important in extraction efficiency of phenolic and flavonoid compounds.