Cysteine antioxidant properties

Other antioxidant species are synthesized by cells like uric acid, ubiquinol or thiols (cystein, homocystein, etc.). In addition, many compounds found in food display antioxidant properties retinol (vitamin A) and its precursor /(-carotene, and polyphenols (flavonoids, etc.). Figure 8.2 shows the apparent standard potential of some LMWA and ROS explaining the spontaneous oxido-reduction reactions at the origin of the antioxidant protection system. 

Garlic oil and S-allyl-cysteine sulfoxide (Alliin), a garlic compound, exhibited similar antioxidant properties. Aged garlic extract prevents ischemia and reperfusion injuries to the heart and brain. 

Antioxidative Properties. When cooked meat is refrigerated, a rancid or stale flavor usually develops within 48 hrs. This character has been termed warmed-over flavor (WOF) and is generally attributed to the oxidation of lipids. Various synthetic and natural antioxidants have been used to reduce the development of WOF. Among the natural antioxidants used are the sulfur containing amino acid cysteine, and various Maillard reaction products. Eiserich and Shibamoto (Chapter 20) found that certain volatile sulfur heterocycles derived from Maillard reaction systems can function as antioxidants. 

From aU studies of biologically active compounds, hyaluronan reveals the lowest level of antioxidative properties. This correlates with the fact that rate constant of the reaction of OH with sodium hyaluronate is approximately three times lower than values of the rate constants of glutathione, sodium ascorbate and cysteine [18], Based on the data mentioned previously, we try to evaluate the maximum antioxidative effect from the introduction of the studied compounds into derma. 

Metallothioneins (MT) are unique 7-kDa proteins containing 20 cysteine molecules bounded to seven zinc atoms, which form two clusters with bridging or terminal cysteine thiolates. A main function of MT is to serve as a source for the distribution of zinc in cells, and this function is connected with the MT redox activity, which is responsible for the regulation of binding and release of zinc. It has been shown that the release of zinc is stimulated by MT oxidation in the reaction with glutathione disulfide or other biological disulfides [334]. MT redox properties led to a suggestion that MT may possesses antioxidant activity. The mechanism of MT antioxidant activity is of a special interest in connection with the possible antioxidant effects of zinc. (Zinc can be substituted in MT by some other metals such as copper or cadmium, but Ca MT and Cu MT exhibit manly prooxidant activity.)... 

Wuweizisu B from Schisandra chinensis showed strong protective effects on lipid peroxidation damage to the surface of cultured hepatocytes of rats treated with Fe2+/cystein and also scavenger free radical properties [240], On the other hand, the oral administration of wuweizisu B increases the activities of antioxidant enzymes. 

Kyung KH, Lee YC (2001) Antimicrobial activities of sulfur compounds derived from S-alk (en) yl-L-cysteine sulfoxides in Allium and Brassica. Food Rev Int 17 183-198 Lee YS, Kang OH, Choi JG, Oh YC, Keum JH, Kim SB, Jeong GS, Kim YC, Shin DW, Kwon DY (2010) Synergistic effect of emodin in combination with ampicillin or oxacillin against methicUlin-resistant Staphylococcus aureus. Pharm Biol 48 1285-1290 Li Y, Du Y, Zou C (2009) Effects of pH on antioxidant and antimicrobial properties of tea saponins. Eur Food Res Technol 228 1023-1028... 

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