A Simple Growth Test of a Saccharomyces cerevisiae Cu, Zn-Superoxide Dismutase-Deficient Mutant in Hypertonic Medium for Biological Evaluation of Antioxidants

Abstract

Osmotic stress hampers the growth of Saccharomyces cerevisiae, and this effect is mediated by oxidative stress. A simple test for the biological evaluation of antioxidants was developed on the basis of recovery of growth delay of Cu, Zn-superoxide dismutase-lacking yeast (SOD1Δ)under hyperosmosis. The SOD1Δstrain suffered from growth inhibition in a medium containing 1.7 M sorbitol. Protein oxidation in SOD1Δ cells was greatly increased by exposure to a hypertonic medium, indicating the accumulation of reactive oxygen species followed by oxidation of cellular materials. The hyperosmosis-induced growth arrest of SOD1Δ was abolished by the addition of L-ascorbic acid to the medium; the antioxidant effect depended on the concentration, ranging from 1 to 10 mM.Cysteine, N-acetyl-cysteine, and glutathione were also able to restore the growth of SOD1Δ cells. High concentrations of these thiol compounds proved less effective, probably due to adverse effects of an excess of these antioxidants. No growth restoration was seen for typical polyphenol antioxidants, including curcumin, quercetin and catechin.