Measurement of Oxidized/Reduced Glutathione Ratio - Protein Misfolding and Cellular Stress in Disease and Aging - page 257

Chapter 18
Measurement of Oxidized/Reduced Glutathione Ratio
Joshua B. Owen and D. Allan Butterfield
Abstract
Glutathione (GSH) is the most abundant antioxidant in aerobic cells, present in micromolar (mM)
concentrations in bodily fluids and in millimolar (mM) concentrations in tissue. GSH is critical for protect-
ing the brain from oxidative stress, acting as a free radical scavenger and inhibitor of lipid peroxidation.
GSH also participates in the detoxification of hydrogen peroxide by various glutathione peroxidases. The
ratio of reduced GSH to oxidized GSH (GSSG) is an indicator of cellular health, with reduced GSH
constituting up to 98% of cellular GSH under normal conditions. However, the GSH/GSSG ratio is
reduced in neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease (AD).
Measuring the GSH/GSSG ratio in pathological tissues and experimental models thereof in comparison
to the results in controls is an excellent way to assess potential therapeutics efficacy in maintaining
cellular redox potential. The availability of UV/Visible instruments equipped with 96-well plate readers
as common laboratory equipment has made measuring the GSH/GSSG ratio on multiple samples a
manageable procedure.
Key words : Glutathione, GSH, Glutathione disulfide, GSSG, GSH/GSSG ratio, Redox potential
1. Introduction
Glutathione (GSH) is a tri-peptide (g-glutamylcysteinylglycine)
that acts as an endogenous antioxidant, a xenobiotic detoxifier,
and is involved in metabolic regulation. GSH is the most abun-
dant antioxidant in aerobic cells, present in micromolar (mM)
concentrations in bodily fluids and in millimolar (mM) concen-
trations in tissue ( 1 ). The central nervous system (CNS) has GSH
concentrations ranging from 1 to 3 mM, depending on the
region. The forebrain and cortex have the highest concentration
of GSH, followed by the cerebellum, brain stem, and spinal cord
( 1 ). With high oxygen consumption and rich poly-unsaturated