DIARYL TELLURIDES AS INHIBITORS OF LIPID-PEROXIDATION IN BIOLOGICAL AND CHEMICAL-SYSTEMS

Diaryl tellurides carrying electron-donating substituents in the para positions were found to efficiently inhibit peroxidation of rat hepato cytes, rat liver microsomes and a chlorobenzene solution of phosphatid ylcholine. The most active compound in the microsomal assay, bis(4-dim ethylaminophenyl) telluride, showed an IC50-value of 30 nM. This compo und also caused a dose-dependent delay of the onset of the linear phas e of microsomal peroxidation stimulated by iron/ADP/ascorbate. The pea k oxidation potentials of the diaryl tellurides (0.50-1.14 V in MeCN) correlated linearly with the IC50-values in this assay, with a point o f inflection around 0.85 V. In the hepatocyte system, all compounds sh owed similar protective activity. It is proposed that diaryl telluride s exert an antioxidative effect by deactivating both peroxides and per oxyl radicals under the formation of telluroxides. These oxides may re generate the active divalent organotellurides upon exposure to a suita ble reducing agent.