NMR Studies on Redox Changes of Salicylates as a Hydroxyl Radical Scavenger

• Main Authors: Yu-Shin Chen, 陳育欣
• Other Authors: Chien-Tsu Chen, Ph.D.
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/16525566087025540592

碩士 === 台北醫學院 === 醫學研究所 === 89 === It is widely accepted that reactive oxygen species (ROS) are involved in the pathogenesis of inflammatory and degenerative diseases. Natural antioxidants used for scavenging ROS have been focused on phenolic compounds. Aspirin, a phenolic compound, is commonly used as analgesic and in the treatment of rheumatic arthritis. The metabolites of aspirin, salicylates, involved in many redox reactions. Most studies demonstrated that salicylates decrease the oxidative stress via reacting with free radicals. Electron spin resonance spectroscopic is a well known technique to detect radicals directly, but it lacks the ability to determine the structural changes between reactants and products. In our experiments, NMR offers an ability to observe the real-time changes of products with some preparation. Salicylate reacted with hydroxyl radical via Fenton reaction and produced several hydroxylated derivatives. The proton spectra of salicylate reveals the diminish of proton δ6.9 (C3, 5-2H), δ7.4 (C4-H) and δ7.7 (C6-H) after Fenton reaction. Hydroxylation rate of salicylate was therefore detected by measuring the proton integral changes. Salicylate exhibited a hydroxyl radical scavenging ability in a time dependent manner. Different antioxidants or scavengers were measured for the ability to clear hydroxyl radical in the presence of salicylate. Vitamin C, tiron and DMSO highly inhibited the hydroxylation of salicylate. In contrast, mannitol and NAC have low preventing ability on the hydroxylation of salicylate. The use to NMR spectrometry to follow the hydroxylation of salicylate could be a new approachl to evaluate the redox potential of many antioxidants.