pyridoxal-isonicotinoyl-hydrazone and salicylaldehyde-isonicotinoyl-hydrazone

The interaction of pyridoxal isonicotinoyl hydrazone (PIH) and salicylaldehyde isonicotinoyl hydrazone (SIH), two important biologically active chelators, with iron has been investigated by spectrophotometric methods. High iron(III) affinity constants were determined for PIH, logβ

Topics: Aldehydes; Ascorbic Acid; Edetic Acid; Electrochemical Techniques; Electrodes; Ferric Compounds; Ferrous Compounds; Hydrazones; Hydrogen-Ion Concentration; Iron Chelating Agents; Isoniazid; Kinetics; Oxidation-Reduction; Pyridoxal

Topics: Aldehydes; Animals; Deferoxamine; Humans; Hydrazones; Iron Chelating Agents; Iron Overload; Isoniazid; Myocardial Reperfusion Injury; Neoplasms; Pyridines; Pyridoxal; Rats; Reactive Oxygen Species; Thiosemicarbazones

Novel aromatic hydrazones derived from pyridoxal isonicotinoyl hydrazone (PIH) are interesting compounds from the viewpoint of their pharmacodynamic activity. However, they were recently shown to suffer from relatively short biological half-lives. The purpose of the present study was to investigate the stability of novel aroylhydrazones in plasma and related biological media in order to reveal its potential involvement in the pharmacokinetics of these drugs. Three different aroylhydrazones (pyridoxal isonicotinoyl hydrazone - PIH, salicylaldehyde isonicotinoyl hydrazone - SIH and pyridoxal 2-chlorobenzoyl hydrazone - o-108) were incubated in plasma from different species, plasma ultrafiltrate, bovine serum albumin, RPMI cell medium and phosphate buffer saline (PBS) at 37 degrees C. Stability of these compounds was determined using precise, selective and validated HPLC methods. Although the aroylhydrazones were relatively stable in PBS, they underwent rapid degradation in plasma. Plasma proteins as well as low molecular weight components were involved in this matter. Furthermore, the products of hydrazone bond splitting revealed in this study were also found in the chromatograms from pharmacokinetic experiments. In the light of short biological half-lives determined in vivo, these in vitro findings strongly suggest that hydrolysis of investigated aromatic hydrazones in plasma could have a significant impact on their pharmacokinetics. Furthermore, these results also suggest that plasma stability of other novel drug candidates containing the hydrazone bond deserves to be considered.

Topics: Aldehydes; Animals; Buffers; Cattle; Chromatography, High Pressure Liquid; Culture Media; Drug Stability; Half-Life; Hemofiltration; Hydrazones; Hydrogen-Ion Concentration; Iron Chelating Agents; Isoniazid; Molecular Structure; Phosphates; Pyridoxal; Rabbits; Serum Albumin, Bovine; Temperature

The anticancer drugs doxorubicin and bleomycin are well-known for their oxidative stress-mediated side effects in heart and lung, respectively. It is frequently suggested that iron is involved in doxorubicin and bleomycin toxicity. We set out to elucidate whether iron chelation prevents the oxidative stress-mediated toxicity of doxorubicin and bleomycin and whether it affects their antiproliferative/proapoptotic effects.. Cell culture experiments were performed in A549 cells. Formation of hydroxyl radicals was measured in vitro by electron paramagnetic resonance (EPR). We investigated interactions between five iron chelators and the oxidative stress-inducing agents (doxorubicin, bleomycin and H(2)O(2)) by quantifying oxidative stress and cellular damage as TBARS formation, glutathione (GSH) consumption and lactic dehydrogenase (LDH) leakage. The antitumour/proapoptotic effects of doxorubicin and bleomycin were assessed by cell proliferation and caspase-3 activity assay.. All the tested chelators, except for monohydroxyethylrutoside (monoHER), prevented hydroxyl radical formation induced by H(2)O(2)/Fe(2+) in EPR studies. However, only salicylaldehyde isonicotinoyl hydrazone and deferoxamine protected intact A549 cells against H(2)O(2)/Fe(2+). Conversely, the chelators that decreased doxorubicin and bleomycin-induced oxidative stress and cellular damage (dexrazoxane, monoHER) were not able to protect against H(2)O(2)/Fe(2+).. We have shown that the ability to chelate iron as such is not the sole determinant of a compound protecting against doxorubicin or bleomycin-induced cytotoxicity. Our data challenge the putative role of iron and hydroxyl radicals in the oxidative stress-mediated cytotoxicity of doxorubicin and bleomycin and have implications for the development of new compounds to protects against this toxicity.

Topics: Aldehydes; Antibiotics, Antineoplastic; Apoptosis; Bleomycin; Cell Line, Tumor; Cell Proliferation; Cell Survival; Deferoxamine; Doxorubicin; Electron Spin Resonance Spectroscopy; Free Radicals; Humans; Hydrazones; Hydrogen Peroxide; Iron; Iron Chelating Agents; Iron Compounds; Isoniazid; Lipid Peroxidation; Lung Neoplasms; Oxidative Stress; Pyridoxal; Razoxane; Time Factors

A major obstacle to the therapeutic use of anthracyclines, highly effective anticancer agents, is the fact that their administration results in dose-dependent cardiomyopathy. According to the currently accepted hypothesis, anthracyclines injure the heart by generating oxygen free radicals. The ability of pyridoxal isonicotinoyl hydrazone (PIH) and salicylaldehyde isonicotinoyl hydrazone (SIH) -- new iron chelators -- to protect against peroxidation as well as their suitable biological, physical and chemical properties make the compounds promising candidates for pre-clinical and clinical studies. Activities of carbonyl reductase CR (1.1.1.184), dihydrodiol dehydrogenase DD2 (1.3.1.20), aldehyde reductase ALR1 (1.1.1.2) and P450 isoenzymes (CYP1A1, CYP1A2, CYP2B, CYP3A) involved in the metabolism of daunorubicin, doxorubicin and other drugs or xenobiotics were studied. Various concentrations of the chelators were used either alone or together with daunorubicin or doxorubicin for in vitro studies in isolated hepatocytes. A significant decrease of activity was observed for all enzymes only at PIH and SIH concentrations higher than those presumed to be used for therapy. The results show that PIH and SIH have no effect on the activities of the enzymes studied in vitro and allow us to believe that they will not interfere with the metabolism of co-administered drugs and other xenobiotics. Daunorubicin (Da) and doxorubicin (Dx) significantly reduce cytochrome P450 activity, but the addition of SIH and PIH chelators (50 microM) reverses the reduction and restores the activity to 70-90 % of the activity of relevant controls.

Topics: Aldehydes; Animals; Anthracyclines; Antibiotics, Antineoplastic; Antineoplastic Agents; Cells, Cultured; Chelating Agents; Cytochrome P-450 Enzyme System; Cytosol; Dose-Response Relationship, Drug; Enzyme Activation; Hepatocytes; Hydrazones; Isoniazid; Male; Oxidoreductases; Pyridoxal; Rabbits

Chromatographic methods have been developed for the separation of the three novel biocompatible iron chelators pyridoxal isonicotinoyl hydrazone (PIH), salicylaldehyde isonicotinoyl hydrazone (SIH), and pyridoxal 2-chlorobenzoyl hydrazone (o-108) from their synthetic precursors and iron chelates. The chromatographic analyses were achieved using analytical columns packed with 5 microm Nucleosil 120-5 C18. For the evaluation of all chelators in the presence of the synthetic precursors, EDTA was added to the mobile phase at a concentration of 2 mM. The best separation of PIH and its synthetic precursors was achieved using a mixture of phosphate buffer (0.01 M NaH2PO4, 5 mM 1-heptanesulfonic acid sodium salt; pH 3.0) and methanol (55:45, v/v). For separation of SIH and its synthetic precursors, the mobile phase was composed of 0.01 M phosphate buffer (pH 6.0) and methanol (60:40, v/v). o-108 was analyzed employing a mixture of 0.01 M phosphate buffer (pH 7.0), methanol, and acetonitrile (60:20:20, v/v/v). These mobile phases were slightly modified to separate each chelator from its iron chelate. Furthermore, a RP-TLC method has also been developed for fast separation of all compounds. The chromatographic methods described herein could be applied in the evaluation of purity and stability of these drug candidates.

Topics: Aldehydes; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Hydrazones; Iron Chelating Agents; Isoniazid; Pyridoxal