Purification And Biological Activities Of Saponins From Allium Chinense G. Don

Chinese jiaotou (Allium chinense G. Don), also known as’rakkyo’which is native to China was one of the oldest cultivated plants and was used since ancient times both as food and medicine. Its use has been widely documented since ancient times. It has been used as a spice food and as a remedy for a variety of diseases including heart problems, headache and tumors in traditional Chinese medicine for over2000years. To further develop the jiaotou, studies were carried on isolation and purification of saponins from Allium chinense G. Don, and its biological Activities were also estimated.In order to optimize the extraction technique for saponins of Allium chinense G. Don, Response surface method was used in this research. Two extracting methods were compared to find the best extract technology. By response surface optimize, ultrasonicc-assisted extraction method was selected,and the optimum extraction conditions were obtained as follows:extraction time of40min, content of ethanol of71%, extraction temperature of55℃and the ratio of sample to solvent of1:16. Under such conditions the yield of total saponin could be up to3.71%, which indicated that response surface analysis could be an effective method to optimize the extraction technology for the saponins of Allium chinense G. Don.In order to select the best purifying process for saponins from Allium chinense G. Don. Several resins were compared in this paper. And D101macro porous resin was selected as the best column. The best purification process was as follows:the extracts were adsorbed by D101macro porous resin for2.5h and eluted by water and5%ethanol. Then the resin was eluted by5volume of70%ethanol. Then70%ethanol eluant components were collected. After the purification process the purity increase to63.06%. The result of qualitative test showed that the major saponins are steroid saponins.In this study, we assessed the antioxidant efficacy of Allium chinense G. Don saponins.The total reducing power and scavenging activity of three free radical were investigated. Results showed that saponin of Allium chinense G. Don have a strong total reducing Power, but lower than the positive control. And a remarkable DPPH radical scavenging activity which was94.8%, the scavenging activities against-OH and-O2were relatively low.The a-glucosidase inhibition activity of saponins from Allium chinense G. Don was evaluated compared with acarbose in this paper. The results showed that saponin of Allium chinense G. Don has a better inhibitory activity than the positive control, and the inhibition rate was dose-dependent and affected by concentration, reaction time and pH. With an inhibitory rate of more than50%obtained after25min of reaction at37.5℃. The Lineweaver-Burk plot showed that saponins from Allium chinense G. Don inhibited a-glucosidase activity in a competitive pattern.The capability of scavenging nitrite and blocking nitrosamine synthesis in vitro were studied in this paper. Results showed that in mimic gastric juice saponins from Allium chinense G. Don has a remarkable nitrite scavenging capacity and nitrosamine synthesis blocking capacity which was almost100%. The scavenging and blocking ability were also studied in non mimic gastric juice, but the nitrite scavenging capacity and nitrosamine synthesis blocking capacity were lower, and pH has a great influence on that. The best scavenging capacity was98.3%. When in a pH of1.3, the nitrosamine synthesis blocking capacity of saponins from Allium chinense G. Don was dose-dependent, when the concentration comes to4.0mg/mL. The blocking rate reaches97.0%. And results showed that when concentration comes to2.0mg/mL, the blocking rate become steady, which indicated that2.0mg/mL will be the best concentration. The best blocking rate was reached when it comes to75min, which indicated the reaction was completed.