Oxidative Modification of Blood Serum Proteins in Multiple Sclerosis after Interferon Beta and Melatonin Treatment.

Multiple sclerosis (MS) is a disease involving oxidative stress (OS). This study was aimed at examination of the effect of melatonin supplementation on OS parameters, especially oxidative protein modifications of blood serum proteins, in MS patients. The study included 11 control subjects, 14 de novo diagnosed MS patients with the relapsing-remitting form of MS (RRMS), 36 patients with RRMS receiving interferon beta-1b (250 µg every other day), and 25 RRMS patients receiving interferon beta-1b plus melatonin (5 mg daily). The levels of N'-formylkynurenine, kynurenine, dityrosine, carbonyl groups, advanced glycation products (AGEs), advanced oxidation protein products (AOPP), and malondialdehyde were elevated in nontreated RRSM patients. N'-Formylkynurenine, kynurenine, AGEs, and carbonyl contents were decreased only in the group treated with interferon beta plus melatonin, while dityrosine and AOPP contents were decreased both in the group of patients treated with interferon beta and in the group treated with interferon beta-1b plus melatonin. These results demonstrate that melatonin ameliorates OS in MS patients supporting the view that combined administration of interferon beta-1b and melatonin can be more effective in reducing OS in MS patients than interferon beta-1b alone.

Yeast as a biosensor for antioxidants: simple growth tests employing a Saccharomyces cerevisiae mutant defective in superoxide dismutase.

Mutants of Saccharomyces cerevisiae devoid of Cu,Zn-superoxide dismutase are hypersensitive to a range of oxidants, hyperbaric oxygen and hyperosmotic media, show lysine and methionine auxotrophy when grown under the atmosphere of air and have a shortened replicative life span when compared to the wild-type strain. Ascorbate and other antioxidants can ameliorate these defects, which may be a basis of simple tests sensing the presence of antioxidants. In particular, tests of growth on solid medium (colony formation) in the absence of methionine and/or lysine, or in the presence of 0.8 M NaCl can be useful for detection and semiquantitative estimation of compounds of antioxidant properties. Hypoxic atmosphere was found to increase the sensitivity of detection of antioxidants. The test of abolishment of lysine auxotrophy showed a concentration dependence of the antioxidant effects of cysteine and N-acetylcysteine which, however, lost their protective action at high concentration, in contrast to glutathione which was effective also at higher concentrations.

Ascorbate abolishes auxotrophy caused by the lack of superoxide dismutase in Saccharomyces cerevisiae. Yeast can be a biosensor for antioxidants.

Yeast (Saccharomyces cerevisiae) mutants lacking cytoplasmic superoxide dismutase (CuZnSOD) show Lys and Met auxotrophy under aerobic conditions. This metabolic defect can be ameliorated by exogenous ascorbate as well as other antioxidants (glutathione, cysteine and N-acetylcysteine). Restoration of growth of CuZnSOD- yeast mutants on media devoid of Met and/or Lys may therefore be a simple and useful means to detect and quantify antioxidants. The protective effect of antioxidants is oxygen-dependent: the lower the oxygen content of the atmosphere, the lower antioxidant concentrations are required to restore prototrophy. Therefore, the sensitivity of the test can be augmented by growing the yeast under lowered partial oxygen pressure. While 6 mM, 10 mM and 30 mM ascorbate was necessary to restore the growth in the absence of Met, in the absence of Lys, and in the absence of Lys and Met, respectively, under 21% oxygen, 3 mM and 6 mM ascorbate was sufficient for growth restoration in the absence of Lys and in the absence of Lys and Met, respectively, under 3% oxygen. The protective effects of cysteine and N-acetylcysteine peaked at 0.5 mM and 6 mM, respectively, disappearing at higher concentrations of these compounds, pointing to the detection of not only protective but also toxic cellular effects of the compounds studied by the test proposed.