A qualitative fluorescence-based assay for tyrosyl radical scavenging activity: Ovothiol A is an efficient scavenger
✍ Scribed by Tod P. Holler; Paul B. Hopkins
- Publisher
- Elsevier Science
- Year
- 1989
- Tongue
- English
- Weight
- 476 KB
- Volume
- 180
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
A method for determining relative tyrosyl radical scavenging activity of antioxidants which requires only a standard fluorometer and commercially available materials is presented. Ultraviolet irradiation of aqueous tyrosine solutions containing superoxide dismutase and catalase produces fluorescent dityrosine residues via dimerization of photogenerated tyrosyl radicals. Added antioxidants suppress the buildup of fluorescence by scavenging the tyrosyl radicals. A correlation exists between the ability of a substance to suppress dityrosine formation and the substance's oneelectron oxidation potential. This method demonstrates that ovothiol A scavenges tyrosyl radicals much more efficiently than glutathione or cysteine, resembling instead the known biological radical scavengers uric acid and ascorbic acid and the a-tocopherol analog trolox. ~ 1989 Academic Press, Inc.
Natural substances such as ascorbic acid (1), uric acid (2), and glutathione (3) are believed to act as biological antioxidants, protecting living organisms from disease by scavenging oxidizing species and free radicals. During the investigation of the possibility that the recently discovered ovothiols (4) also serve as biological antioxidants (5,6), a simple method for determining their free radical scavenging ability was needed. Simple assays of free radical scavenging ability exist which are based upon the reaction of the putative scavenger with the stable free radicals 1,1-diphenyl-2-pichydrazyl (DPPH) 3