Antioxidant Activity Of Arctium Lappa L. Seed Extracts

Burdock is dry and ripe fruit of Arctium lappa L. (compositae). Burdock was the secondary metabolites, and played a role in the health of human. And the studies proved that burdock contained some active substances, for example, polyphenols and lignins.Taking burdock-seed as the test material, the elementary extract was extracted by solvents of chloroform, ethyl acetate, acetone and ethanol with the polarity increasing and got four extracts. Firstly, the four extracts of the burdock-seed were used to estimate total phenols with Gallic acid as standard compound, and were used to determine total lignanoids with Arctiin as standard compound. Secondly, using BHT as the positive control, the antioxidant activities of four extracts were measured with the scavenging capacity of DPPH·,·OH, O₂^-·and H₂O₂; total antioxidant activity and reducing power in vitro. The main research results were as follows:1. The total polyphenols of chloroform, ethyl acetate, acetone, ethanol extract from burdock-seed (how many mg Gallic acid in 1g extract) were 29.79, 73.36, 91.67, 153.47; total lignanoids (how many mg Arctiin in 1g extract) were714.17, 855.00, 976.67, 913.33. According to the analysis of variance and multiple comparisons, the solvent to extract had a significant impact on the contents of total polyphenols and total lignanoids.2. The results of the antioxidant activity from four burdock extracts were as follows:(1) According to the IC₅₀ value, the scavenging ability of DPPH·and H₂O₂ of four burdock extracts show that: ethanol extract > acetone extract > chloroform extract > ethyl acetate extract; the scavenging ability of·OH and O₂^-·were approximately in the increase order of acetone extract > ethanol extract > chloroform extract > ethyl acetate extract.(2) The oxidation resistance capability and reducing power of four burdock extracts were acetone extract > ethanol extract > chloroform extract > ethyl acetate extract.3. IC₅₀ value of the scavenging rates of DPPH·,·OH, O₂^-·and H₂O₂ from four burdock extracts had negative relativity with total polyphenols and lignanoids content in corresponding extract, the total antioxidant activity and reducing power had positive correlation with total polyphenol and total lignanoids content in corresponding extract, so were the correlation with IC₅₀ value of the scavenging activities of DPPH·,·OH, O₂^-·and H₂O₂ for the different extract separately. For the first time, the thesis had a systemic and comprehensive research on the antioxidant activity of burdock-seed extracts, and found that there were a lot of total polyphenol and total lignanoids in burdock-seed, which had antioxidant capacity. This research would be good for the further development and utilization of burdock-seed, which supplyed a basis for whether burdock-seed extract could be served as an effective and natural antioxidant, and gived a theoretical foundation to comprehensive utilization of burdock-seed and development of natural antioxidants.