| Summary: | 碩士 === 台北醫學院 === 生藥學研究所 === 90 === Abstract
Dioscorin, the major tuber storage protein of Dioscorea spp. has been reported to behave many enzyme activities, such as carbonic anhydrase, trypsin inhibitor, dehydroascorbate reductase, and monodehydroascorbate reductase. In recent study, it was showed that dioscorin exhibited antioxidant activities, including DPPH radical and hydroxyl radical scavenging activities. In this study, both of Dioscorea alata L. cv. Tainong 1 (Tainong No.1 yam) and Dioscorea batatas Decne (imported from Japan) were used as plant material for comparisons. Dioscorins were purified by DE-52 ion exchange chromatography from crude extracts of yam tubers. By a series of in vitro tests, including DPPH radical and hydroxyl radical scavenging activity assay, reducing power test, anti-lipid peroxidation test, and anti-human low density lipoprotein (LDL) oxidation test, DNA damage protection, and inhibition of dihydrorhodamine 123 oxidation by peroxynitrite, it was showed that dioscorin exhibited antioxidant activities. Using dioscorins (purified from Tainong No.1 yam) as materials for pepsin and trypsin hydrolysis, it was showed that the pepsin hydrolysates also exhibited antioxidant activities against DPPH radical, and the 32 h hydrolysates got the hightest one. The hydrolysates were loaded onto Sephadex G-50(F) gel filtration chromatography, and each fraction was tested for DPPH radical scavenging activity assay. It was showed that the smaller molecule weight fractions still have antioxidant activities. The active fractions were collected and loaded onto Sephadex G-25(M) gel filtration chromatography, and each fraction was also tested for DPPH radical scavenging activity assay.
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