Purification,Structure Identification And Antioxidant Activity Of Anthocyanins From Purple Sweet Potato

Purple sweet potato is an annual herb convolvulaceae.Anthocyanins of it`s tuberous roots,which as natural pigments have strong antioxidant activity,has wide development prospects.This study took anthocyanins from purple sweet potato as test subject,the extraction and purification process,stability,chemical structure and antioxidant activity were analyzed.The main results were as follows:The optimal ultrasound-assisted extraction was temperature 51 ?,ultrasonic time of 24.00,liquid ratio of 53?1?mL/g?,by using 30% aqueous ethanol?containing0.5% CH₃COOH?to the extraction solvent,and the extraction rate of anthocyanins was 1.175 mg/g.AB-8 as the most suitable resin in five kinds of resins.The optimal conditions for the purification of anthocyanins using AB-8 resin were determined as follows: The solution concentration is 0.4 mg/mL,pH 2.0,40% ethanol?containing0.5% CH₃COOH?as elution solvent.The Anthocyanin recovery rate was 86.3%.The stability experiments showed that anthocyanins in dark acidic environment remains stable.Its stability impact of Cu²⁺,Fe³⁺,Mg²⁺ metal ions,oxidants and deoxidizers when environmental conditions changed.The components of the Purple sweet potato anthocyanins were analyzed by HPLC-DAD and UPLC-MS methods.Nine constituent parts of the anthocyanins were identified: With 4 kinds of Cyanidin and 5 kinds of Peonidin.7 kinds of anthocyanins were acylated by ferulic acid,caffeic acid and p-hydroxybenzoic acid.The main glycoside were sophorose and glucose.The total antioxidant activities of the anthocyanins were higher than Trolox.The result of anthocyanins and scavenging the DPPH were similar to antioxidant capacity in the low concentration range,and the result of scavenging the superoxide anion was higher than Vc with increased concentration.The effect of anthocyanins of Purple sweet potato on apoptosis induced by UVA radiation was investigated.The results showed that 125 ?g/mL anthocaynins added to the medium could decrease ROS and MMP-1 content,which were lower than that inUVA radiation group.Thus,the appropriate concentration of Purple sweet potato anthocaynins was able to reduce UV irradiation-induced oxidative damage and played an anti-UV radiation role in human skin fibroblast.