Extraction,Physiochemical Properties And Biological Activities Of Polysaccharides From Roots Of Arctium Lappa L.

Arctium lappa L. is a biennial herb which come from Arctium, Compositae family. The root of Arctium lappa L. and Fructus Arctii are used as traditional Chinese medicine. In this work, The roots of Arctium lappa L. was used as a material to investigate the extraction process of polysaccharides by the method of ultrasonic-assisted extraction and studied the effects of different drying methods on physiochemical properties and antioxidant activities of polysaccharides from roots of Arctium lappa L. Meanwhile,using the best drying methods to dry polysaccharides from roots of Arctium lappa L. and isolation, purification, physicochemical properties, antioxidant activity and antibacterial activity of the purified polysaccharides from roots of Arctium lappa L. The main research results are as follows:1. The ultrasonic-assisted method was used to investigate the extraction process of polysaccharides from roots of Arctium lappa L..The result showed that the factors (including ratio of water to ratio material, ultrasonic power, extraction time and extraction temperature,) had a good effect on the extraction rate of polysaccharides within a certain extent. We optimized the extraction process of ultrasonic-assisted extraction for polysaccharides:ratio of water to ratio material of 31.4 mL/g, ultrasonic power of 158.3 W, extraction time of 82.9 min, and extraction temperature of 50.2 ?. Under this set combination, the model predicted that the maximum response of ALPs is 8.26%. Given the operating convenience, the optimal parameters were determined as follows:ratio of water to ratio material of 31 mL/g; ultrasonic power of 158 W; extraction time of 83 min; and extraction temperature of 50 ?. To ensure the predicted result was biased toward the practical value, experimental rechecking was performed using this deduced optimal condition. A mean value of 8.22% was obtained by the verification experiment. "No statistically significant difference was found between experimental and predicted values, which demonstrated the validation of the model.2. The influences of different drying methods (hot air drying, vacuum drying and freeze drying) on the physiochemical properties and antioxidant activities of polysaccharides from roots of Arctium lappa L. were studied. Freezing drying Arctium Lappa polysaccharides had higher total sugar content and protein. Vacuum drying Arctium Lappa polysaccharides had higher uronic acid content. Three different drying methods have no significant difference effect on the polysaccharides from roots of Arctium lappa L. Three different drying methods polysaccharides from roots of Arctium lappa L. have a certain influence on antioxidant activities. It was clearly demonstrated that ALP-F showed the best DPPH, hydroxyl, and superoxide radical scavenging activities than ALP-H and ALP-V.3. The crude polysaccharides of ALPs were purified for three components of ALP40-1, ALP60-1 and ALP80-1. The influences on physiochemical properties was studied. The result showed that the purified polysaccharides didn't contain nucleic acid and protein. The molecular weight of ALP40-1, ALP60-1, and ALP80-1 were 218 KDa, 178 KDa, and 60 KDa. The monosaccharide composition of ALP40-1, ALP60-1, and ALP80-1 have no significant difference for each other. Mannose, glucose, fructose, and galactose were the predominant monosaccharides of ALP40-1, ALP60-1, and ALP80-1. The highest content of mannose was seen in ALP60-1 (5.72%). The highest content of fructose was shown in ALP40-1 (38.29%). The highest content of glucose and galactose was given in ALP80-1 (72.23% and 8.05%).4. The result of purified polysaccharides on antioxidant activities showed that: ALP40-1, ALP60-1, and ALP80-1 showed strong antioxidant activities in vitro. However, ALP60-1 showed the best DPPH, hydroxyl, and superoxide radical scavenging activities. The IC50 of ALP60-1 on DPPH, ·OH, and O2-· were 0.76g/mL, 1.38g/mL, and 0.79g/mL. Meanwhile, ALP80-1 showed the highest reducing power activity.5. According to the vitro tests of inhibitory bacteria activity, ALP40-1, ALP60-1 and ALP80-1 had different inhibitory effects on Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa. With the concentration of 5mg/mL-40mg/mL, the inhibition zone of Escherichia coli, Bacillus subtilis, Staphylococcus aureus were larger than that of 8mm of ALP40-1, ALP60-1 and ALP80-1. Meanwhile, with the same concentration, ALP40-1 had a greatest inhibitory effects on Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Pseudomonas aeruginosa than that ALP60-1 and ALP80-1. ALP40-1, ALP60-1 and ALP80-1 had no inhibitory effects on Pseudomonas aeruginosa.