The effects of temperature, time and solvent concentration on ultrasonic extraction of propolis bioactive compounds

In this study, propolis bioactive compounds extracted with ultrasound assisted extraction methods. Four different parameters (ethanol concentration, temperature, time and solid solvent ratio) were selected for determination of extraction efficiency. These selected parameters were optimized to achieve highest total phenolic content, total flavonoid content, antioxidant activity and balsam yield by using four variable, and second order central composite design. Furthermore, the extraction of bioactive compounds of propolis was carried out by conventional extraction and compared to ultrasonic extraction in terms of extraction efficiency. Results showed that the ethanol concentration and solid solvent ratio among the extraction parameters was significantly effective on total phenolic content and total flavonoid content (p<0.0001). Ethanol concentration was also found significantly effective on antioxidant activity and balsam yield (p<0.0001). The optimum condition to reach efficient extraction was determined as 90% ethanol concentration, 32 minute at 51°C with 1:300 solid solvent ratio. In this optimum condition, the amount of total phenolic content was 252,74±5,77 mg GAE/g, total flavonoid content was 222,32±1,27 mg CE/g, antioxidant activity was 1,43±0,004 mmol TEAC/g and balsam yield was %71,99±6,31. In conventional extraction, which was carried out 75% ethanol concentration, 1:200 solid solvent ratio at 50°C during 1 day, the total phenolic content was 231,48±2,48 mg GAE/g, total flavonoid content was 240,13±4,39 mg CE/g, antioxidant activity was 1,50±0,04 mmol TEAC/g and balsam yield was %58,87±0,12. In both propolis extracts obtained conventional and ultrasonic extraction, ferulic acid (5,31-6,55 mg/g propolis), caffeic acid (3,34-3,73 mg/g propolis), syringic acid (2,12-2,24 mg/g propolis) and p-coumaric acid (2,63-2,95 mg/g propolis) were found major phenolic acid while quercetin (0,14-0,15 mg/g propolis) and rutin (0,0027-0,0032 mg/g propolis) were found major flavonoids. Results showed that ultrasound assisted extraction was better in terms of extraction efficiency and time when comparing conventional method.