1,2-Dithiol-3-thione analogs: effects on NAD(P)H:quinone reductase and glutathione levels in murine hepatoma cells.

The 1,2-dithiol-3-thiones are a class of five-membered cyclic sulfur compounds which have chemotherapeutic and chemoprotective properties. The parent 1,2-dithiol-3-thione nucleus and a series of six substituted analogs all induced NAD(P)H: quinone reductase (EC 1.6.99.2) activity and elevated glutathione levels in Hepa 1c1c7 murine hepatoma cells in culture thereby enhancing detoxification potential. These analogs included monosubstituted derivatives with phenyl, p-methoxyphenyl or 2-pyrazinyl groups at C-4 or C-5, and disubstituted compounds bearing phenyl or 2-pyrazinyl moieties at C-5 and an additional methyl group at C-4. This system can be used as an in vitro model for the study of the specificity and mechanism of action of the 1,2-dithiol-3-thiones as already demonstrated for several other classes of chemoprotective agents. The 1,2-dithiol-3-thiones also elevated quinone reductase and glutathione levels in the Hepa 1c1c7 cell mutants (BPrc1 and TAOBPrc1) that are defective in aryl hydrocarbon receptor functions. We conclude that the 1,2-dithiol-3-thiones are largely concerned with the stimulation of metabolic inactivation of electrophiles.