The Effect of Ultrasound-Assisted Conditions on the Extraction of Phenolic Compounds and Flavonoids from Autumn Olive Fruits (Elaeagnus umbellate)

Introduction:   Plants are rich source of phenolic compounds (phenolic acids, flavonoids and tannins) that are natural antioxidants. The purpose of the present study was to use two   ultrasonic methods including probe and bath for the extraction of phenolic compounds and   flavonoids from autumn olive and   evaluate the ability of the extracts to scavenge DPPH free radical using three extraction solvents consisting of water, 80% methanol and 70% ethanol. Materials and Methods:   Water, 80% methanol and 70% ethanol were used as extracting solvents and the effect of different extraction periods (30, 60 and 90 min) for bath method and   5, 10 and 20 min for probe method were evaluated on the extraction of phenolic compounds.   Results:   The results showed that in the probe method of ultrasonic, the highest phenolic compounds (13.8 ± 0.05 milligrams gallic acid/ g dried sample) and DPPH radical scavenging   activity (98.94%) were obtained using70% ethanol as solvent within 20 minutes of extraction   period. In the ultra sound bath, the highest extraction rate of phenolic compounds (15.82 ±   0.057mg gallic acid equivalent/ g dry sample) and flavonoids (7.09 ± 0. 110 mg of quercetin   per gram of dry sample) were obtained by the application of 70% ethanol within 90 minutes.   Conclusion:   The results indicated that the probe and bath methods of ultrasound had different effects on extraction of bioactive compounds from autumn olive. In each extraction method,   the rate of extraction of phenolic compounds and flavonoids were solvent dependent and in all   the extraction method, 70% ethanol showed the best effect as extracting solvent   .