Introduction 111 1.1 Hydrogen peroxide 113 1.2 Antioxidants 114 1.3 Oxidative distress and the redox equilibrium 115 2. Glutathione 115 2.1 Structure and synthesis 115 2.2 Degradation of glutathione 118 3. The many roles of glutathione as an antioxidant 118 3.1 Direct antioxidant action 119 3.2 Regeneration of vitamins E and C 120 3.3 Glutathione peroxidases 121 3.4 Glutathione S-transferases 123 3.5 Dicarbonyl stress and glyoxalases 125 4. S-glutathionylation and role of glutathione in redox regulation 130 4.1 S-glutathionylation and redox regulation 130 4.2 Protein deglutathionylation 134 5. Conclusions and future directions 136 Acknowledgments 137 References 137