Studies on antioxidant activity of flavonoids quercetin, keampferol, geneistein, and glutathione in proteins and 3T3-LA1 cells.

摘要

Oxidative stress can do extensive damage to all components of cells, and subsequently causing variety of diseases such as cancer. Studies had shown that oxidative stress can increase the level of Akt expressed within cells, while can potentially lead to development of cancer. Within most of the cells, there is a defense mechanism against oxidative stress that uses glutathione (GSH), a natural, ubiquitous tripeptide. Glutathione reductase, glutathione peroxidase, and superoxide dismutase are three enzyme that are the three major enzyme in the defense mechanism against oxidative stress. Recent studies also shown that a class of secondary metabolite, flavonoids, possesses medicinal property, including antioxidant activities. In this study, the fluorescence and absorption spectroscopy technique were used to access the effects that the flavonoids quercetin and kaempferol and the tripeptide glutathione had in protecting protein residues lysine, arginine, and cysteine in myoglobin and hemoglobin from oxidative stress. The myoglobin, hemoglobin and the 3T3-L1A cells samples were put under oxidative stress condition through the Fenton's Pathway, using 20 muM Fe2+ and 0.1 mM hydrogen peroxide (H 2O2), and was treated with or without flavonoid (quercetin or kaempferol) or glutathione at dosage level of 5, 10, 15, 20 and 25 muM respectively dissolved in dimethyl sulfoxide. We found that glutathione protects the lysine and cysteine residue from oxidation and not the arginine residue in a dosage depended manner. Both flavonoids protects cysteine residue from oxidation and not the lysine or arginine residue in a dosage dependent manner. We found that quercetin and glutathione treatment decreased the expression of phosphor Akt level in these cells under oxidative stress in a dosage dependent manner, while kaempferol did not have any significant effects on Akt level in these cells under oxidative stress condition. We found that all three flavonoids increases the activities of all these enzyme under oxidative stress.