Protection of cell proteins against free-radical attack by nootropic drugs: scavenger effect of pyritinol confirmed by electron spin resonance spectroscopy.

The potency of nootropic drugs to protect cell proteins and lipids against free radical attack was studied. In an in vitro system, generating hydroxyl radicals by a Fenton-type reaction, the soluble proteins (bovine serum albumin and cytosol protein from brain) were quickly insolubilized and precipitated. Pyritinol (and tamitinol) exhibited the best protection against insolubilization of protein while centrophenoxine (meclophenoxate) and its dimethylaminoethanol moiety were less effective, piracetam (and oxiracetam) being without effect. The lipid peroxidation induced by free radicals from cyclic redox reactions of iron-ascorbate was not influenced by pyritinol, indicating the selectivity of its scavenger action. The efficient scavenging of hydroxyl radicals by pyritinol was confirmed by electron spin resonance spectroscopy measurement of hydroxyl radicals entrapped by spin trap. Millimolar concentrations of pyritinol competitively decreased the formation of spin adducts. The results suggest that the protective effect of pyritinol against free-radical induced derangement of cell proteins may be an important part of its antirheumatic, as well as nootropic, action.