Diamide: A New Radiosensitizer for Anoxic Cells

Abstract

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Thiyl free radicals and the oxidation of ferrocytochrome c Direct observation of coupled hydrogen-atom- and electron-transfer reactions

“…Thiol-containing compounds have often been proposed as protective agents against free-radical-mediated tissue injury. Indeed, there is now considerable evidence that cells deprived of GSH, as the result of a mutation or because of the presence of exogenous agents such as diamide, are more sensitive to the damaging action of ionizing radiation (Edgren et al, 1970;Harris & Power, 1973). The most common mechanism proposed for such a protective action is the repair of an initial lesion Cyt(Il).c Scheme 1.…”

The effects of ionizing radiation on mammalian cells

“…the sulfhydryl oxidizing agent diamide there is a synergistic effect on the radiation response that is greater than that obtainable by either agent alone (31,32). Harris and Power reported a lower survival at both 800 and 1200 rads for anoxic cells irradiated in the presence of diamide and nifuroxime (a nitrofuran) than was observed for either sensitizer alone (32). Similarly, Chapman et al (33) showed that diamide plus NF-269, another nitrofuran, sensitized to a greater degree than that of either agent alone, and more than oxygen.…”

“…The pretreatment effects with misonidazole (25,35) and the combination studies with the thiol oxidant diamide (31)(32)(33)(34) suggest that endogenous reducing species are important in the overall mechanism of radiation damage and repair. As mentioned previously, the reaction of the DNA radicals with hydrogen donor or reducing substrates will result in chemical repair of the radiation damage.…”

Radioprotective Agents in the Treatment of Cancer and the Role of Amifostine : Kanser Tedavi̇si̇nde Radyoprotekti̇f Bi̇leşi̇kler Ve Ami̇fosti̇ni̇n Rolü

“…Cellular radiosensitivity is affected by the presence of endogenous intracellular thiols. Oxydation of these thiols by diamide (20,21) renders the cells more sensitive. Monoethyl and diethyl esters of glutathione had the capacity to provide some protection of normal and buthionine sulfoxime pretreated cells against X-…”