Alterations in integrity of goldfish membrane induced by edetate disodium

5-azacytosine compounds in medicinal chemistry: current stage and future perspectives

This review summarizes the basic milestones of the research of 5-azacytosine nucleosides chronologically from their discovery and anticancer activity identification, through to subsequent unveiling of their mechanism of action based on DNA hypomethylation and tumor-suppressor gene reactivation, to the final US FDA approval of 5-azacytidine (Vidaza®) and 2´-deoxy-5-azacytidine (Dacogen®) for the treatment of myelodysplastic syndromes. 5,6-dihydro-2´-deoxy-5-azacytidine, a compound with anti-HIV activity through lethal mutagenesis, representing a unique mechanism of action among existing anti-retroviral drugs, is discussed together with quite recent discovery of its so far unexpected hypomethylation activity. Special attention is paid to 5-azacytosine acyclic nucleoside analogues and phosphonomethyl derivatives with the emphasis on the new potent anti-DNA virus agent (S)-1-[3-hydroxy-2-(phosphonomethoxy)propyl]-5-azacytosine and its prodrug forms. Considering the potential pharmaceutical applications, 5-azacytosine and 5,6-dihydro-5-azacytosine appear to be so far the most effective cytosine mimics for the design of novel antiviral and anti-tumor drug candidates.

Effect of cationic micelles on the decomposition of alpha-aminophenyl cephalosporins

The intramolecular rates of degradation of alpha-aminophenyl cephalosporins were determined with and without hexadecyltrimethylammonium bromide (CTAB). Micellar-derived spectral shifts were used to measure the bind of the ionic forms as well as to determine the effect of CTAB on the apparent dissociation constant of the antibiotics. The rate of the degradation of cephalexin (Cp), cefadroxil (Cf), and cephradine (Cph), increased with surfactant concentration reaching a plateau at high surfactant concentrations. In the plateau region, the rate constant was salt sensitive decreasing with NaBr concentrations. These effects were quantitatively analyzed within the framework of the pseudo-phase model with explicit considerations of ion exchange. All the experimental results were fitted to this model. The intramolecular degradation of Cf, Cp and Cph was catalyzed by 96-, 59-, and 29-fold, respectively. A working hypothesis to rationalize these effects was suggested. The obtained results demonstrate that the quantitative analysis can be used to assess, predict and control the effects of surfactants on the drug stability.