ABSTRACT
Department o f Medical Pharmacology and Toxicology; Texas A&M University Health Science Center, College Station, Texas, USA
Xenobiotic Metabolism • Phase-1 Transformations • Phase-2 Transformations Biooxidation • Superoxide • Hydrogen Peroxide • Lipid Peroxidation • Glutathione Oxidation Xenobiotic Metabolism, Biooxidation, and Ophthalmic Toxicology • Ocular Xenobiotic Metabolism • Ocular Biooxidation References
To deal with the stress of foreign substances (xenobiotics), the body has developed enzyme-mediated transformations. These transformations can be divided into two phases. Phase 1 reactions include hydroxylation, oxidation, and reduction, while phase-2 reactions include conjugation reactions, such as glucuronidation, acetyla tion, and sulfation. These biotransformation reactions generally increase the polarity of xenobiotics. Through these reactions, the xenobiotics are made less hydropho bic and more easily excretable. However, toxic compounds, such as free radicals, are sometimes generated from these reactions. The eye is especially sensitive to the toxic species produced from the metabolic reactions. This is because the eye is ex posed extensively to light each day, and a large amount of oxygen is consumed by the retina.
