Antioxidant properties of dimethyl sulfoxide and its viability as a solvent in the evaluation of neuroprotective antioxidants.
BACKGROUND
Dimethyl sulfoxide is an amphiphilic compound whose miscibility with water and its ability to dissolve lipophilic compounds make it an appreciated solvent in biomedical research. However, its reported antioxidant properties raise doubts about its use as a solvent in evaluating new antioxidants. The goal of this investigation was to evaluate its antioxidant properties and carry out a comparative study on the antioxidant properties of some known neuroprotective antioxidants in the presence and absence of dimethyl sulfoxide.


METHODS
The antioxidant properties of dimethyl sulfoxide were studied in rat brain homogenates by determining its ability to reduce both lipid peroxidation (TBARS formation) and protein oxidation (increase in protein carbonyl content and decrease in free thiol content) induced by ferrous chloride/hydrogen peroxide. Its ability to reduce the production of hydroxyl radicals by 6-hydroxydopamine autoxidation was also estimated. The same study was also performed with three known antioxidants (α-phenyl-N-tert-butylnitrone; 2-methyl-2-nitrosopropane; 5,5-dimethyl-1-pyrroline N-oxide) in the presence and absence of dimethyl sulfoxide.


RESULTS
Our results showed that dimethyl sulfoxide is able to reduce both lipid peroxidation and protein carbonyl formation induced by ferrous chloride/hydrogen peroxide in rat brain homogenates. It can also reduce the production of hydroxyl radicals during 6-hydroxydopamine autoxidation. However, it increases the oxidation of protein thiol groups caused by ferrous chloride/hydrogen peroxide in rat brain homogenate.


CONCLUSIONS
Despite the here reported antioxidant and pro-oxidant properties of dimethyl sulfoxide, the results obtained with α-phenyl-N-tert-butylnitrone, 2-methyl-2-nitrosopropane, and 5,5-dimethyl-1-pyrroline N-oxide corroborate the antioxidant properties attributed to these compounds and support the potential use of dimethyl sulfoxide as a solvent in the study of the antioxidant properties of lipophilic compounds.


CONCLUSIONS
Dimethyl sulfoxide is a very useful solvent that may be used at relatively low concentrations in the development of new antioxidants with neuroprotective properties.
Laboratory of Neurochemistry, Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Santiago de Compostela, San Francisco 1, 15782 Santiago de Compostela, Spain.
Carolina
C
Sanmartín-Suárez
Ramón
R
Soto-Otero
Inés
I
Sánchez-Sellero
Estefanía
E
Méndez-Álvarez
D000818:Animals; D000975:Antioxidants / Q000737:chemistry / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects; D001923:Brain Chemistry; D004121:Dimethyl Sulfoxide / Q000737:chemistry* / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000187:drug effects; D008297:Male; D018696:Neuroprotective Agents / Q000737:chemistry / Q000494:pharmacology*; D010084:Oxidation-Reduction / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012997:Solvents / Q000737:chemistry
D000975:Antioxidants; D018696:Neuroprotective Agents; D012997:Solvents; D006861:Hydrogen Peroxide; D004121:Dimethyl Sulfoxide