New, Substituted Derivatives of Dicarboximides and their Cytotoxic Properties.

A large group of aminoalkyl and aminoalkanol derivatives of selected dicarboximides were synthesized and characterized by 1HNMR, 13CNMR and ESI MS spectra analysis. The thirty nine new compounds were tested for their cytotoxic properties in human chronic (K562), acute leukemia (HL-60), and cervical cancer cells (HeLa) as well as in normal endothelial cells (HUVEC). The most promising compounds are 4-[2-(dimethylamino)ethyl]-, (diethylamino) ethyl]-, 4-[2-(piperidin-1-yl)ethyl]-, 4-[3-(dimethylamino)propyl]- and 4-[2-hydroxy-3-(propan- 2-ylamino)propyl]- derivatives of 1,7-diethyl-8,9-diphenyl-4-azatricyclo[5.2.1.0(2,6)]dec-8-ene-3,5,10-trione exhibiting high and selective cytotoxicity towards K562 and HL-60 cells (IC50 in the range of 1-10 µM) while being non-toxic towards HUVEC and HeLa cells (IC50> 100 µM). Moreover, the preliminary studies have showed that 4-[2-(piperidin-1-yl)ethyl]- 1,7-diethyl-8,9-diphenyl-4-azatricyclo [5.2.1.0(2,6)]dec-8-ene-3,5,10-trione induces programmed cell death (apoptosis) in leukemia cells.

Synthesis and in vitro cytotoxicity of cross-conjugated prostaglandin A and J series and their hydroxy derivatives.

The synthesis of two cross-conjugated prostaglandin analogues of known neurotrophic activity and their new hydroxy derivatives was accomplished starting from the diastereoisomeric (+)-camphor protected 3-[(dimethoxyphosphoryl)methyl]-4,5-dihydroxycyclopent-2-enones. The cytotoxicity of these compounds was determined against HeLa, K562, HL-60 human cancer cell lines and normal human cells (HUVEC). We found that NEPP11 and its C7-hydroxy derivative demonstrated high anticancer activity against the HeLa and HL-60 human cancer cell lines at concentrations ranging from 1 to 2 µM. Moreover, the C7-hydroxy derivative of NEPP11 displayed high cytotoxic selectivity between cancer cell lines and normal human cells. On the other hand, the J-type prostaglandin analogue of NEPP11 and its C13-hydroxy derivatives were much less toxic or nontoxic against the cancer and normal cells at concentrations up to 1 mM.

Chelating ability and biological activity of hesperetin Schiff base.

Hydrazone hesperetin Schiff base (HHSB) - N-[(±)-[5,7-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)chroman-4-ylidene]amino]benzamide has been synthesized and its crystal structure was determined. This compound was used for the formation of Cu(II) complexes in solid state and in solution which were characterized using different spectroscopic methods. The analyses of potentiometric titration curves revealed that monomeric and dimeric complexes of Cu(II) are formed above pH7. The ESI-MS (electrospray ionization-mass spectrometry) spectra confirmed their formation. The EPR and UV-visible spectra evidenced the involvement of oxygen and nitrogen atoms in Cu(II) coordination. Hydrazone hesperetin Schiff base can show keto-enol tautomerism and coordinate Cu(II) in the keto (O(-), N, Oket) and in the enolate form (O(-), N, O(-)enol). The semi-empirical molecular orbital method PM6 and DFT (density functional theory) calculations have revealed that the more stable form of the dimeric complex is that one in which the ligand is present in the enol form. The CuHHSB complex has shown high efficiency in the cleavage of plasmid DNA in aqueous solution, indicating its potential as chemical nuclease. Studies on DNA interactions, antimicrobial and cytotoxic activities have been undertaken to gain more information on the biological significance of HHSB and copper(II)-HHSB chelate species.

Synthesis and cytotoxic properties of halogen and aryl-/heteroarylpiperazinyl derivatives of benzofurans.

A series of seven derivatives of 1,1'-(5,6-dimethoxy-3-methyl-1-benzofuran-2,7-diyl)diethanone was synthesized and characterized by (1)HNMR and ESI MS spectra and elemental analyses. The obtained new compounds and three halogen derivatives of benzofuran, reported in our earlier work, were tested for their cytotoxic properties in human chronic (K562) and acute (HL60) leukemia cells, human cervical cancer (HeLa), and normal endothelial cells (HUVEC). Four compounds (2, 3, 4, 5), which contain halogens in their structure showed significant anticancer activity. The most promising was 1,1'-[3- (bromomethyl)-5,6-dimethoxy-1-benzofuran-2,7-diyl]diethanone (2), which was highly and selectively toxic for K562 cells (IC50 of 5µM) and HL60 cells (IC50 of 0.1µM), which showed no cytotoxicity toward HeLa and HUVEC cells. Moreover, the observed remarkable cytotoxicity of this compound toward K562 cells resulted from cells apoptosis.

N-Acyl-phosphoramidates as potential novel form of gemcitabine prodrugs.

Gemcitabine (dFdC) is a cytidine analog remarkably active against a wide range of solid tumors. Inside a cell, gemcitabine is phosphorylated by deoxycytidine kinase to yield gemcitabine monophosphate, further converted to gemcitabine di- and triphosphate. The most frequent form of acquired resistance to gemcitabine in vitro is the deoxycytidine kinase deficiency. Thus, proper prodrugs carrying the 5'-pdFdC moiety may help to overcome this problem. A series of new derivatives of gemcitabine possessing N-acyl(thio)phosphoramidate moieties were prepared and their cytotoxic properties were determined. N-Acyl-phosphoramidate derivatives of gemcitabine have similar cytotoxicity as gemcitabine itself, and have been found accessible to the cellular enzymes. The nicotinic carboxamide derivative of gemcitabine 5'-O-phosphorothioate occurred to be the best inhibitor of bacterial DNA polymerase I and human DNA polymerase α.

Synthesis and biological activity of novel series of 1,3-benzoxazol-2(3H)-one derivatives.

In the search for novel biological agents, a series of new derivatives N-substituted 1,3-benzoxazol-2(3H)-one, 5-chloro-1,3-benzoxazol-2(3H)-one, 6-bromo-1,3-benzoxazol-2(3H)-one were prepared. All of the compounds were characterized by 1H NMR, 13C NMR and ESI MS spectra. Moreover, for compound 1 an Xray structure was determined. All derivatives were tested for antimicrobial activity against a selection of Gram-positive, Gram-negative bacteria and yeasts. The selected compounds (2-8, 10) were tested for their cytotoxic properties in K562, HeLa and normal cells.

Design, synthesis and cytotoxicity of a new series of isoxazolidine based nucleoside analogues.

5-Arylisoxazolidin-3-yl-3-diethoxyphosphonates have been synthesized from N-methyl-C-diethoxyphosphorylnitrone and vinyl aryls in good yields and their transformation into the respective phosphonic acids has been accomplished via dealkylation procedure using trimethylsilyl bromide. Phosphonates having 1- and 2-naphthyl substituents at C5 in the isoxazolidine ring as well as the respective phosphonic acids have been found cytotoxic to HeLa and K562 cells with IC(50) in the 0.1-0.3 mM range. Preliminary studies on mechanism of action imply that intercalation to DNA is not responsible for their cytotoxic properties.

Design, synthesis and cytotoxicity of a new series of isoxazolidines derived from substituted chalcones.

A new series of isomeric isoxazolidin-3-yl-3-phosphonates were synthesised from N-methyl-C-diethoxyphosphorylnitrone and substituted chalcones. The respective isoxazolidin-3-yl-3-phosphonic acids were obtained from phosphonates via dealkylation procedure using trimethylsilyl bromide. Selected phosphonates and their respective phosphonic acids were screened for their cytotoxic activity to HeLa and K562 cells with IC(50) in the 0.1-0.3mM range.

(1→3)-ß-D-Glucan inhibits a dual mechanism of peroxynitrite stroke.

AIM: The antioxidative and antinitrative activities of (1→3)-ß-D-glucan (1-4µg/ml) from the yeast cell walls of Saccharomyces cerevisiae in human plasma treated with strong oxidants - peroxynitrite (ONOO(-)) (0.1mM) and hydrogen peroxide (H(2)O(2)) (2mM) were studied in vitro. The main purpose of this study was to assess if (1→3)-ß-D-glucan, a well known strong immunostimulatory agent, possesses a protective function against dual mechanism of ONOO(-) stroke associated with nitrative and oxidative damages to human plasma biomolecules. SCOPE: The protein changes were determined in vitro by estimating the level of oxidative stress markers - carbonyl groups, and nitrative products - 3-nitrotyrosine residues. The plasma lipid peroxidation was also investigated. The obtained results show that (1→3)-ß-D-glucan inhibits in vitro ONOO(-)-induced oxidation and nitration of plasma proteins, even by 50% and 30%, respectively. The antioxidative activity of (1→3)-ß-D-glucan was confirmed by its inhibitory effect on plasma lipids peroxidation induced by ONOO(-) or by H(2)O(2). CONCLUSIONS: The obtained results demonstrate that (1→3)-ß-D-glucan from S. cerevisiae protects plasma components against toxic effects of ONOO(-) and H(2)O(2) due to its antioxidative and antinitrative activities. Therefore (1→3)-ß-D-glucan supplementation during inflammatory may be beneficial not only regard for its ability to stimulate the immune system but also by antioxidative properties.

beta-glucan from Saccharomyces cerevisiae as a blood platelet antioxidant.

Blood platelets in addition to their haemostatic role can function as inflammatory cells. The aim of our study was to assess if beta-D-glucan, the natural, very strong biological response modifier, may protect platelet proteins and lipids against oxidative/nitrative damages. The antioxidative activity of the beta-D-glucan, a known immunomodulator derived from the yeast cell walls of species such as Saccharomyces cerevisiae, on blood platelets treated with oxidants-peroxynitrite and hydroperoxide-was studied in vitro. The levels of different specific markers of oxidative stress, thiobarbituric acid reactive substances (TBARS), carbonyl groups and 3-nitrotyrosine (3-NT) were measured. Our studies showed that beta-glucan possesses significant defence properties against peroxynitrite or hydroperoxide induced lipid peroxidation. The level of TBARS was decreased by 80% at the highest dose of beta-glucan. In the presence of beta-glucan the distinct reduction of platelet protein oxidation was observed; the level of carbonyl groups was decreased by 50%. The results indicate that beta-glucan may also be effective in the protection against the nitrative action of peroxynitrite on platelet proteins, as in the presence of beta-glucan the level of 3-nitrotyrosine, measured by a competition-ELISA method, was diminished. The obtained in vitro results demonstrate that antiplatelet activity of beta-glucan from Saccharomyces cerevisiae is dependent on its antioxidative properties, and therefore beta-glucan supplementation may be beneficial in the prevention of excessive blood platelet activation-related diseases, such as cardiovascular or inflammatory diseases.

Response of blood platelets to beta-glucan from Saccharomyces cerevisiae.

The effects of the beta-D-glucan, a polysaccharide derived from the yeast cell walls of species such as Saccharomyces cerevisiae, on blood platelets activation induced by physiological agonists (thrombin, ADP, collagen) in vitro were studied. The aim of our study was to assess in vitro if beta-glucan, a naturally strong biological response modifier, may modify platelet activation, i.e. platelet aggregation and degranulation (release of proteins and adenine nucleotides) induced by thrombin, ADP and collagen. Cytochrome c reduction method was used to test the ability of beta-glucan to change superoxide anion generation in platelets. Moreover, we determined also its effect on enzymatic arachidonic acid cascade. The obtained results indicate that beta-glucan has the inhibitory effects on platelet aggregation and secretion. beta-glucan distinctly reduced the arachidonic acid pathway and superoxide anion radical generation in platelets stimulated by biological agonists. The results of the present study suggest that beta-glucan from Saccharomyces cerevisiae has antiplatelet and antioxidative activities, and therefore may be beneficial in the prevention of the excessive blood platelet activation-related diseases, such as cardiovascular or inflammatory diseases.