New Phenolic Antioxidants of PYA and PYE Class Increase the Resistance S. cerevisiae Strain SP4, its SOD- and Catalase-Deficient Mutants

ABSTRACT. Was demonstrate he protection ability against reactive oxygen species afforded to S. cerevisiae (wild-type strain SP4 and its mutants deficient in major antioxidant enzymes- catalase T and A, CuZnSOD) by PYA and PYE, new groups of phenolic anti-oxidants (quaternary ammonium salts of dihydrocinnamic a id amino esters with different alkyl chains; synthesized in this laboratory). The survival of strains exposed to the lipophilic oxidation inducers tert-butyl hydroperoxide (TBHP) and I,l'-azobis(4-cyclohexane carbonitrile) (ACCN) with or without antioxidant pretreatment was determined by plating. S. cerevisiae mutant deficient in SOD was found to be hypersensitive to TBHP and ACCN while the sensitivity of the strain deficient in catalase T and A was about he same as in the wild-type strain. A I-h preincubation of cells of both the wild-type and the mutant strains with the phenolic antioxidants prior to exposure to TBHP or ACCN substantially increased the cell survival. The magnitude of protection depended on the strain and the length of the alkyl chain of the antioxidant; he best average protection against TBHP was provided by PYE and PYA compounds with 12- and 16-membered alkyl chains whereas PYE-8 and PYA-12 derivatives afforded the best average protection against ACCN. Reactive oxygen species (ROS), such as the superoxide radical O~., the hydroxyl radical HOo, H202 or organic peroxides, are generated endogenously in all aerobic cells by incomplete reduction of molecular oxygen to water in the electron transport chain (Pinkus et al. 1996). Their action on cell constitu-ents leads to oxidative stress that can cause lipid and protein peroxidation, changes in the structure of nuclei