摘要：Milk thistle seeds present high amount of phenolic compounds with antioxidant properties. The extraction of these compounds may be considered a way to increase in value both agro-food by-products. Ultrasound is widely applied in extraction due to its effects (cavitation, micro-stirring or sponge effect) over the process. The aim of this work was to investigate the application of ultrasound on the extraction of phenolic compounds included in milk thistle. For that purpose, the extraction of phenolic compounds from milk thistle seeds, previously dried, was carried out with ultrasound assisted extraction at different time intervals (30, 60, 90, 120, 150 min) and classic solvent extraction using methanol as solvent while other factors (power, temperature etc.) being constant. At the same time silymarin content was determined by HPLC and their antioxidant properties were evaluated by determining its ability to scavenge the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical by measuring induction period. There were slight increases in the amount of phenolic content and antioxidant activity with increasing extraction times. It was found that the amount of total silymarin content varied from 0.77 to 1.37 g/100 g dried nonfat milk thistle sample and the extracts showed a DPPH inhibition that change between 30-60 %.
