Antioxidant Activities of Dioscorin, the Storage Protein of Yam (Dioscorea batatas Decne) Tuber

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• 作者：Wen-Chi Hou ; Mei-Hsien Lee ; Hsien-Jung Chen ; Wen-Lee Liang ; Chuan-Hsiao Han ; Yen-Wenn Liu ; and Yaw-Huei Lin
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2001
• 出版时间：October 2001
• 年：2001
• 卷：49
• 期：10
• 页码：4956 - 4960
• 全文大小：64K
• 年卷期：v.49,no.10(October 2001)
• ISSN：1520-5118

文摘

Dioscorin, the storage protein of yam (Dioscorea batatas Decne) tuber (which is different fromdioscorine found in tubers of Dioscorea hirsuta), was purified to homogeneity after DE-52 ionexchange column according to the methods of Hou et al. (J. Agric. Food Chem. 1999, 47, 2168-2172). A single band of 32 kDa dioscorin was obtained on a sodium dodecyl sulfate-polyacrylamidegel electrophoresis gel with 2-mercaptoethanol treatment. This purified dioscorin was shown byspectrophotometric method to have scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH)radical in a pH-dependent manner. There is a positive correlation between scavenging effects againstDPPH (8-46%) and amounts of 32 kDa dioscorin (5.97-47.80 nmol) added in Tris-HCl buffer (pH7.9), which are comparable to those of glutathione at the same concentrations. Using electronparamagnetic resonance (EPR) spectrometry for DPPH radical detection, it was found that theintensities of the EPR signal were decreased by 28.6 and 57 nmol of 32 kDa dioscorin in Tris-HClbuffer (pH 7.9) more than in distilled water compared to controls. EPR spectrometry was also usedfor hydroxyl radical detection. It was found that 32 kDa dioscorin could capture hydroxyl radical,and the intensities of the EPR signal were significantly decreased dose-dependently by 1.79-14.32nmol of 32 kDa dioscorin (r = 0.975) compared to the control. It is suggested that 32 kDa dioscorin,the storage protein of yam tuber, may play a role as antioxidant in tubers and may be beneficial forhealth when people take it as a food additive or consume yam tubers.Keywords: Antioxidant; dioscorin; 1,1-diphenyl-2-picrylhydrazyl (DPPH); electron paramagneticresonance (EPR); hydroxyl radical; yam