Important role of antioxidant enzymes in the Saccharomyces cerevisiae survival to the toxicity of vanadium pentoxide

Abstract

Vanadium pentoxide, V2O5 (V5+) behaves as powerful oxidizing agent which participates in free radicals generation. Although some biological studies reveals that vanadium compounds have mutagenic and genotoxic effects, other authors reveal that vanadium exerts antitumoral effects by activating signaling pathways leading to apoptosis or inducing xenobiotic metabolizing enzymes which degrade active carcinogens. In other hand, several industrial processes contributes to increase the vanadium concentration in the environment, making it a pollutant. Following from the above, the main objective of this work was to evaluate the survival and enzymatic antioxidant response to V2O5, by Saccharomyces cerevisiae: UEME3, a wildtype strain; Red Fruit, a wine commercial strain and a BY4741 strain. Cells at midexponential phase were inoculated in YEPD medium with 2% (w/v) glucose and incubated during 72 h in a water bath with orbital stirring, at 28 ◦C, in the absence or in the presence of 2mMV2O5. Samples from each treatment were used to obtain growth curves and to determine mitochondrial, microsomal and cytosolic fractions, used for determination of NADH cit c reductase, (NADHred), NADPH(P450) reductase, (NADPH(P450)red), glutathione peroxidase (GPx), glucose6phosphate dehydrogenase (G6PD) and catalase T (CAT T) activities. The results show that V2O5 inhibited cell growth of any yeast strains in study, although drastically pronounced in the case of BY4741 strain. Inhibition of the respiratory chain at the NADHred activity, as well as the activation of the microsomal electrons transport, via microsomal NADPH(P450)red, by vanadium appear to be important sources of ROS and toxicity for studied strains. However higher levels of CAT T in native and wine commercial strains are vital to significantly prevent cell death by V2O5, since GPx decrease significantly.