Ultrasound-Assisted Extraction And In Vitro Biological Activity Of Anthocyanins From Red Raspberry

Known as the "golden fruit", raspberry is rich in anthocyanins, ellagic acid, flavonoids and other bioactive substances. There are abundant resources of wild raspberry in China. However, raspberry industrial products did not get a better development because of the variety, cultivation, preservation, processing, product promotion, etc. In order to provide a theoretical basis for using and developing raspberry resource, the optimization of extraction process conditions, composition identification and in vitro biological activities of anthocyanins were investigated. The main results are as follows:1. The effects of the four factors including ultrasonic power, internal time, extraction time and temperature on the yield of anthocyanins were investigated. Based on above result, the significance and interaction of each factor were analyzed in accordance with Box-Behnken. Extraction parameters of anthocyanins from red raspberry were optimized by response surface methodology, which were determined as follows:ultrasonic power of 900 W, internal time of 3 s, extraction time of 50 min and extraction temperature of 50℃. Under above conditions, the extraction yield of anthocyanins was 0.163 mg/g freshmatter.2. 100g fresh red raspberry was extracted and freeze-dried to obtain 10.09g anthocyanin extract freeze-dried powder. The chemical composition in freeze-dried powder of red raspberry anthocyanin extracts were purified and analyzed. Before and after macroporous resin purification, the contents of total anthocyanins, total sugar, total phenols, total ascorbic acid in the extracts were 1.70 and 18.27 mg/g,513.60 and 304.50 mg/g,3.14 and 15.67 mg/g,18.06 and 72.20 mg/g, respectively. The anthocyanins content was 10.78 times higher than that of before purification. The anthocyanins were identified by HPCL-MS, and three anthocyanins were identified as cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside and peonidin-3-O-glucoside.3. The antioxidation of anthocyanins from red raspberry were investigated using the methods of DPPH radical, superoxide anion radical, hydroxyl radicals and total reductive ability. Results show that raspberry anthocyanins have a strong biological activity. The antioxidant capacity was significantly (P<0.01) stronger than ascorbic acid. The half inhibitory concentration (IC50) values of raspberry anthocyanins in DPPH radical scavenging, hydroxyl radical scavenging, superoxide anion scavenging were 0.30,1.70 and 8.90μg/mL, respectively. DPPH radical scavenging capacity of raspberry anthocyanins was the best, followed by the scavenging capacity of hydroxyl radicals and superoxide anion.4. Raspberry anthocyanin extract could effectively inhibit the activity of HMG-CoA reductase, but the inhibition efficiency was lower than simvastatin. The half inhibitory concentration for a-glucosidase and lipase were 178.89 and 21.01 μg/mL, which were lower than those of the positive control acarbose (433.40 μg/mL) and orlistat (244.58 μg/mL), respectively. The inhibition capacity of raspberry anthocyanin extract on a-glucosidase and lipase activity was better than those of positive control significantly (P<0.01).