, Volume 52, Issue 1, pp 45-51

Assaying the antioxidant and radical scavenging properties of aliphatic mono- and Di-N-oxides in superoxide dismutase-deficient yeast and in a chemiluminescence test

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Abstract

The antioxidative action of amphiphilic mono-(alkanoylamino) ethyldimethylamine-N-oxides (EDA), di-N-oxides 1,1-bis{[2-(N,N-dimethylamino)ethyl]amido}alkane-di-N-oxides (MEDA) and 1,1-bis {[3-(N,N-dimethylamino)propyl]amido}alkane-di-N-oxides (MPDA) with a 12- and 14-membered acyl chain againsttert-butylhydroperoxide (TBHP)-produced peroxyl and paraquat (PQ)-generated superoxide radicals was determined in superoxide dismutase-deficient mutants ofSaccharomyces cerevisiae, and, in parallel, in a chemical assay based on chemiluminescence changes caused in a luminol system by peroxyl radicals generated from the azo-compound 2,2′-azobis(2-amidinopropane dihydrochloride) (AAPH). At 30 µmol/L, the shorter-chain compounds did not affect strain survival while longer-chain ones, in some cases, lowered the survival ofsod2 andsod1 sod2 cells. Whether nontoxic or medium-toxic, allN-oxides protected thesod strains against the toxic effect of PQ and TBHP, the protection being stronger with the di-N-oxides. The survival was lowered only by 14-MPDA in the TBHP-exposedsod2 mutant. Membrane lipids isolated from all strains were protected against TBHP-induced peroxidation by both mono- and di-N-oxides, the protection being dependent on the alkyl chain length. Mono-N-oxides were again less active than di-N-oxides with the same alkyl chains, the antiperoxidative activity being also dependent on lipids isolated from the individual mutants. In the chemiluminescence assay, the IC50 value of theN-oxides for scavenging of radicals generated from AAPH generally decreased (i.e. the scavenging efficiency increased) with increasing chain length and was the highest in MEDA.

This work was supported by thePolish Committee for Scientific Research (grant 3 T09B 075 27), by theWrocław University (grant 2483/W/IGIM), by theMinistry of Education, Youth and Sports of the Czech Republic (Research Center 1M0570), and by theInstitutional Research Concept AV 0Z 5020 0510.