No abstract

The treatment with G. biloba extract is effective against oxidative stress - a crucial factor of cataractogenesis in rat pups, possibly by preventing depletion of antioxidant enzymes and by inhibiting lipid peroxidation.

Spectroscopic techniques were used to investigate the interaction between vanadate and human erythrocyte ghosts. Direct evidence from 51 V nuclear magnetic resonance (NMR) studies suggested that the monomeric and polymeric vanadate species may bind to the anion binding sites of band 3 protein of the erythrocyte membrane. The results of 51V NMR studies and the quenching effect of vanadate on the intrinsic fluorescence of the membrane proteins indicated that in the low concentration range of vanadate (< 0.6 mM), monomeric vanadate binds mostly to the anion sites of band 3 protein with the dissociation constant close to 0.23 mM. The experiments of sulfhydryl content titration by the method of Ellman and residue sulfhydryl-labeled fluorescence spectroscopies clearly displayed that vanadate reacts directly with sulfhydryl groups. The appearance of the anisotropic election spin resonance (ESR) signal of vanadyl suggests that a small (c.3%) amount of vanadate was reduced by sulfhydryl groups of membrane proteins. The fluidity and order of intact ghost membrane were reduced by the reaction with vanadate, as shown by the ESR studies employing the protein- and lipid-specific spin labels. It was concluded that although vanadates mainly bind to band 3 protein, a minor part of vanadate may oxidize the residue sulfhydryl groups of membrane proteins, and thus decrease the fluidity of erythrocyte membrane.

The biomembrane is postulated as the initial target when Platinum(II) complexes attack cells. In this work, a spin-labeling ESR technique has been used to study the effects of cis-DCDP, cis-DBDP, cis-DIDP, trans-DCDP, and cis-DADP on the permeability of human erythrocyte membrane. We monitored the reduction processes of the ESR signal of a nitroxide spin label, (TEMPO), which leaks out through the membrane and is reduced by the external ascorbate. Our results indicate that cisplatin and its analogues can enhance the permeability of membranes to small moieties such as TEMPO and ascorbate, and the differences between these compounds are related to features of the leaving group. In addition, changes in the order parameter of 5DS spin label in membrane indicate that hydrolysis of these Pt(II) complexes result in membrane damage.