Formation Of Free-radical Products Research Articles

CHANGES OF THIOL-DISULFIDE BALANCE IN PARKINSON’S DISEASE

Parkinson’s disease (BP) is one of the most common neurodegenerative pathologies. It is characterized by a selective death of DA neurons in the black substance of the midbrain, resulting from the formation of an excess of free radicals and the development of oxidative stress. Attempts to use antioxidants as a means of pathogenetic therapy of BP have been unsuccessful. Modern concepts of the understanding of the role of oxidative stress in the development of Parkinson’s disease (PD), as well as other neurodegenerative diseases suggest that an important role in the mechanisms of metabolic changes leading to the death of nervous tissue is played not only by the enhancement of formation of free radical products but also by the weakening of antioxidant defense systems in brain tissue. The most important components of the thiol/disulphide buffer systems involved in maintaining the redox balance in the brain are pairs of oxidized and reduced glutathione (GSH/GSSG), as well as thiol/disulfide oxidoreductases. Controlling the intensity of formation of free radical products from cellular antioxidant redox enzymes, primarily glutathione and thioredoxin-dependent enzyme systems, is extremely important not only to prevent brain tissue damage due to oxidative stress, but also to maintain the redox balance. The review presents the data showing pronounced changes in the redox potential of the glutathione system, thiol-disulphide balance, S-glutathionylation of in brain tissue proteins in experimental PD models, and in postmortem brain tissue samples of patients with PD. The elucidation of the mechanisms of maintaining the redox balance in brain tissue under oxidative stress in PD can serve as a justification for a new direction in neuroprotection and a search for new agents for pathogenetic therapy of PD.

Formation of free radical products by the reaction of dehydro-ascorbic acid or ninhydrin with aromatic amines.

Reactions of DHA with aromatic amines in ethanol produced fairly stable esr signals with characteristic hyperfine structures that indicated the presence of the aromatic moiety in the radical molecules. Several intermediates of ninhydrin reactions, i.e., carbinolamines and SchifF bases, were isolated and these two were found to give rise to similar esr signals when subjected to reaction with ascorbic acid. This also provided basis for the elucidation of the structures of the radical species from the reaction of DHA and aromatic amines.

Formation of free-radical products by the reaction of dehydroascorbic acid with amino acids

Formation of free-radical products by the reaction of dehydroascorbic acid with amino acids

On the formation of free radical products by the reaction of dehydroascorbic acid with amines.

Production of fairly stable radical intermediates was detected in an early stage of reaction of DHA with primary amines in ethanol. These intermediates showed characteristic hyper-fine esr signals apparently different from those formed by reaction of DHA with amino acids. These were separated as blue spots on tlc plates, and their Rf values suggested presence of amine residues in their molecules. Esr examination of aqueous extracts showed their common basic compositions as of 2 units of DHA and 1 unit of amines. In the case of reaction of secondary or tertiary amines with DHA, no characteristic esr spectra could be detected other than the signal probably due to the radical product by the reduction of DHA.