Cytotoxic Mannich bases of 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones.

A series of 12 new Mannich bases with chalcone core structure were synthesized as potential antineoplastic agents, via N-aminomethylation of two parent 6-(3-aryl-2-propenoyl)-2(3H)-benzoxazolones. The newly synthesized compounds as well as the chalcone prototypes were evaluated for cytotoxicity in the human pre-B-cell leukemia cell line BV-173 using the MTT-dye reduction assay. The tested compounds exhibited concentration-dependent cytotoxic effects at low micromolar concentrations. Ten of the Mannich bases characterized by significant activity in BV-173 were further evaluated against the chronic myeloid leukemia cell line K-562 and were found to suppress the growth of these cells at relatively higher concentrations as compared to the former tumor model. Selected Mannich bases induced programmed cell death in BV-173 at a concentration of 2.5muM as evidenced by the encountered DNA-laddering. Taken together our data suggest that the presented heterocyclic chalcone derived Mannich bases necessitate detailed pharmacological evaluation in order to define further the structure activity relationships, in a larger spectrum of tumor models and to elucidate the mechanisms implicated in the observed cytotoxic effects.

Erufosine: a membrane targeting antineoplastic agent with signal transduction modulating effects.

The ether lipid analog erufosine (erucylphospho-N,N,N,-trimethylpropylammonium, ErPC3) has high activity against leukemic cells without affecting the normal hematopoiesis. It belongs to the group of alkylphosphocholines (APC) that are inhibitors of protein kinase C and phospholipase C. However, the mechanism of action of erufosine remains rather unclear. We focused on combination effects with the tyrosine kinase inhibitor imatinib mesylate (gleevec, former STI-571 or CGP-57148) against two chronic myeloid leukemia (CML)-derived cell lines (K-562 and BV-173). The influence of erufosine on proteins involved in the phosphatidylinositol-3-phosphate pathway and on expression of the retinoblastoma protein Rb was studied, the latter being a key component for cell cycle entry and progression in mammalian cells. The consecutive treatment of K-562 and BV-173 cells with erufosine (2.5, 5, 15, 30 microM) and imatinib mesylate (0.05, 0.1 microM) led to synergism as measured by the MTT-dye reduction assay and this is reason to hypothesize that such combinations could be beneficial for relapsed patients with drug-resistant disease. Whole cell lysates from K-562 and BV-173 were investigated for the expression of Rb, PKB/Akt, pAkt, and p27 by Western blot. Erufosine caused decreases of pAkt and CML fusion protein p210 (BCR-ABL) protein expression, but induced the Rb protein expression in K-562 cells. A parallel increase in p27 level was observed after 24 and 48 h treatment. These alterations in signal transduction could be an explanation for the drug interaction found. Furthermore, Rb is a substrate of caspases and is cleaved during apoptosis as already evidenced for BV-173 cells. Our experimental findings suggest that erufosine acts through induction of changes in protein signaling and especially through Rb induction. This unique mode of action makes it an attractive partner for combination therapies, for example, in combination with imatinib mesylate for treatment of CML.

Synthesis, Structural Characterization, and Cytotoxic Activity of Novel Paramagnetic Platinum Hematoporphyrin IX Complexes: Potent Antitumor Agents.

Three novel stable Pt(III) complexes with distorted octahedral structure and (dz2)1 ground state have been obtained in the course of Pt(II)-hematoporphyrin IX ((7,12-bis(1-hydroxyethyl)-3,8,13,17-tetramethyl-21H-23H-porphyn-2,18-dipropionic acid), Hp) interaction in alkaline aqueous medium and aerobic conditions. A redox interaction also takes place together with the complexation process leading to the formation of Pt(III) species and organic radicals. The processes in the reaction system and the structure of the complexes formed cis-[Pt(III)(NH3)2(Hp-3H)(H2O)2]H2O1, [Pt(III)(Hp-3H)(H2O)2]H2O2, and [Pt((O,O)Hp-2H)Cl(H2O)3] 3, were studied by UV-Vis, IR, EPR and XPS spectra, thermal (TGS, DSC), potentiometric and magnetic methods. The newly synthesized complexes show promising cytotoxic activity comparable with that of cis-platin in in vitro tests against a panel of human leukemia cell lines. The observed cytotoxicity of the complex 2 against SKW-3 cells (KE-37 derivative) is due to induction of cell death through apoptosis.

Comparative assessment of the cytotoxic effects of carboxylato-bridged dinuclear platinum (II) complexes against human tumor cell lines.

The cytotoxic effects of a series of carboxylato-bridged dinuclear platinum (II) complexes with acetate (BAP), propionate (BPP) and valerate (BVP) ligands were evaluated in a panel of human tumor cell lines. BAP proved to be the most potent antineoplastic agent, whose cytotoxic effect reached and even outclassed that of the referent drug cisplatin. This compound also exerted substantial efficacy against a broader spectrum of tumor models including the multidrug-resistant HL-60/Dox cell line. In the latter case, BAP showed lower resistance index than cisplatin. BAP was furthermore found to induce apoptosis in different cell lines as evidenced by DNA-laddering and Cell-death ELISA. Our experimental data give us reason to conclude that the dinuclear Pt(II) complex with acetate ligands is perspective for further detailed pharmacological and toxicological evaluation as an antineoplastic drug candidate.

Preparation, physicochemical characterization and pharmacological study of novel ruthenium(III) complexes with imidazole and benzimidazole derivatives.

Complex compounds of ruthenium(III) with 1,2-dimethylimidazole (CAS 1739-84-0), 2-phenylimidazole (CAS 670-96-2) and 2-aminobenzimidazole (CAS 934-32-7) were prepared and were characterised by physicochemical methods. Coordination sites were determined. The complexes were tested for cytotoxic activity using MTT (3-(4,5-dimethyithiazol-2-yl)-2,5-diphenyltetrazolium bromide) dye-reduction assay and the values LD50 were evaluated.

New lanthanide complexes of 4-methyl-7-hydroxycoumarin and their pharmacological activity.

Complexes of cerium(III), lanthanum(III) and neodymium(III) with 4-methyl-7-hydroxycoumarin (Mendiaxon, Hymecromone) were synthesized by the mixing of equimolar amounts of the respective metal nitrates and 4-methyl-7-hydroxycoumarin sodium salt in water. The complexes were characterized and identified by elemental analysis, conductivities, IR, (1)H and (13)C NMR spectroscopies and mass spectral data. DTA and TGA have been applied to study the compositions of the compounds. The newly synthesized compounds were assayed for acute intraperitoneal and per oral toxicity, influence on blood clotting time and the most active complex was investigated for spasmolytic activity. The complexes of cerium(III) and neodymium(III) showed marginal cytotoxic activity against transformed leukemic cell lines (P3HR1 and THP-1) as compared to the inorganic salts.

Synthesis, physicochemical characterization, and cytotoxic screening of new zirconium complexes with coumarin derivatives.

Zirconium complexes of mendiaxon, warfarin, coumachlor, and niffcoumar have been synthesized by reaction of the ligands with zirconium chloride in stoichiometric ratio 1:2. The formation of the complexes has been proved on the basis of elemental analysis, IR-spectroscopy, 1H-NMR spectroscopy, and thermal studies. Differential thermal analyses and thermogravimetric analyses have been applied to study the compositions of the new complexes. It is concluded that the lactone- and the keto-carbonyl groups of warfarin, coumachlor, and niffcoumar are bonded to the metal ion as bidentate ligands, but mendiaxon is bonded as monodentate ligand. Cytotoxic screening by MTT-assay was carried out. Among these compounds the zirconium complex of mendiaxon showed highest cytotoxic activity against human promyelocytic leukemic HL-60 cells. The inorganic salt was found to be active against this cell line.

Cytotoxic activity of cerium complexes with coumarin derivatives. Molecular modeling of the ligands.

Cerium complexes of Umbellipherone, Mendiaxon, Warfarin, Coumachlor, and Niffcoumar have been synthesized by reaction of the ligands with cerium nitrate in a stoichiometric ratio of 1:2. The formation of the complexes has been proved on the basis of elemental analysis, conductivities, IR spectroscopy, and 1H-NMR spectroscopy. The molecules of the ligands were optimized by means of the semiempirical quantum mechanical method PM3 to the energetically most stable conformers. All the ligands were characterized by molecular and submolecular electronic indices and the putative donor centers are proposed. It is concluded that the lactone- and the keto-carbonyl groups of Warfarin, Coumachlor, and Niffcoumar are bonded to the metal ion as bidentate ligands. The other two coumarins are bonded as monodentate ligands. Conductivity measurements show the non-electrolytic nature of the complexes. Cytotoxic screening by MTT assay was carried out. The cerium complexes were found to be more active than the inorganic salts.

[The use of ketamine in an experimental model of generalized cerebral ischemia]. / Prilozhenie na ketamin pri eksperimentalen model na generalizirana mozuchna iskhemiia.

Thus far, a sufficiently effective cerebroprotective substances has not been discovered. Glutamate overproduction plays a key role in ischemic brain lesion. Ketamine is assigned to the group of commonly used clinical anesthetics, being also familiar as NMDA antagonist. Sodium fluoride-induced cerebral ischemia in mice is used as a model of circulatory ischemic lesion. As shown by the experimental data, simultaneous administration of NaF + ketamine has no effect whatsoever on the survivorship of animals, as compared to that in the control group treated with NaF alone. Beforehand treatment of mice with 150 mg/kg ketamine brings about considerable prolongation of the survival term (15 per cent of the animals survive for more than 2 hours). The inference is reached that ketamine is endowed with cerebroprotective activity largely attributable to glutamate antagonism at the level of ischemia involved neurons.

Synthesis and tumor inhibiting activity of lanthanum (III) complexes with some 1-aminocycloalkancarboxylic acids.

Complexes of La(III) with 1-aminocyclopentane-, -hexane, -heptane and -4-ethylcyclohexanecarboxylic acids were obtained. The compounds were characterized by elemental analyses, IR spectroscopy and conductivity measurements. The following general formula was derived: LaL3Cl3 x 5 H2O, where L is the corresponding 1-aminocycloalkanecarboxylic acid. The pharmacological studies showed that all complexes manifested higher cytostatic and cytotoxic effects in comparison with lanthanum chloride. Much higher cytotoxic (anti-P388/D1) and cytostatic (anti-L-1210 and anti-melanoma-B16) activity was found for the lanthanum complex with 1-aminocyclopentanecarboxylic acid.

Antitumor, nephrotoxic and clastogenic effect of cis-DDP with DDTC or NAC.

Diethyldithiocarbamate (DDTC) and N-acetylcysteine (NAC) are nucleophile sulfur-containing compounds which can protect the platinum-induced nephrotoxicity. Combinations of cis-diamminedichloroplatinum(II) (cis-DDP) and DDTC or NAC were tested on the leukemia L1210 and melanoma B 16 tumor models. Nephrotoxicity of cis-DDP alone and in combination with DDTC or NAC was evaluated. On both of the investigated tumor models clastogenic effects in bone marrow cells were detected. DNA synthetic and mitotic activity of L1210 cells in vivo were evaluated by 3H-thymidine incorporation and cytogenetic analysis. Amelioration of the platinum induced nephrotoxicity and preservation of the antitumor activity of cis-DDP through combined application with DDTC or NAC were obtained at the L1210 model. Maximal inhibition of the DNA synthesis in L1210 cells was detected with the cis-DDP treatment. The sulfurcontaining nucleophiles DDTC or NAC could modulate the inhibitory effect of cis-DDP on the incorporation of 3H-thymidine into the nuclei of L1210 cells. Enhanced mitotic activity was detected during cytotoxic therapy with cis-DDP. Cis-DDP alone and in combination with DDTC or NAC caused a significant growth inhibition on the s.c. tumor of the melanoma B16 bearing mice. Two times better therapeutic results at this model were obtained with cis-DDP alone (T/C = 234.09%, T/C = 136.36% for cis-DDP+DDTC and T/C = 151.14% for cis-DDP+NAC). The usefulness of DDTC or NAC as adjuvants in the platinum based chemotherapy of human cancers have been discussed. Clastogenic effect and antitumor activity are probably connected and it is supposed that the reduction of the genotoxicity could lead to a decreased antitumor activity of the platinum complex.

Studies on the photodynamic effect of haematoporphyrin derivative.

A case-control photodynamic therapy (PDT) was studied on adenocarcinoma (AC755) in BDF1 mice. Haematoporphyrin derivative (HPD; Porphyrin Products, U.S.A.) and a Bulgarian HPD were used as photosensitizers at doses of 10 mg kg-1. An argon dye laser system with lambda em=630 nm (400 mW cm-2) was used for PDT with a total light dose of 400 J cm-2. The therapeutic effect was assessed by the changes in tumour dimensions, the size of photonecrosis and the mean survival time of the animals. Histologic and ultrastructural studies were carried out. No significant difference was recorded between the antitumour effects of the two photosensitizers. Best results were obtained in small tumours (less than 10 mm) with incision of covering skin. Results are discussed in an attempt to advocate an optimal regimen for PDT in experimental tumours.

[An evaluation of the toxic and antitumor action of farmorubicin administered to H-strain mice with Ehrlich ascitic cancer]. / Otsenka toksicheskogo i protivoopukholevogo deistviia farmorubitsina pri vvedenii mysham linii H s astsitnym rakom Erlikha.

The toxic and antitumour action of farmorubicin was investigated in experiments on mice. Data on the high antitumor activity were obtained after single application of the drug and at 5-day treatment of mice bearing the Ehrlich ascites tumour. It has been established that farmorubicin used in the tolerant dose was comparatively nontoxic--nonmyelotoxic. At higher doses the toxic damages manifested in different periods and depended on the employed doses. A decrease in the heart weight has permitted revealing the formorubicin-induced cardiotoxicity which was confirmed (after 5 injections of the preparation in a dose of LD 50) by electron microscopy.

[A modification of the toxic effects of platinum complexes with antocyans]. / Modifitsirane na toksichnite efekti na platinovi kompleksi s antotsiani.

The toxic and antitumor properties of biocysplantinum (cis-diaminodichlo-platinum) as well as a new platinum complex with acetic acid after their single and combined usage with antocyanes were studied on healthy mice and mice with transplanted ascitic tumour of Ehrlich. There was a reduction in total toxicity of biocysplatinum after simultaneous administration with antocyanes (300 mg/kg per os). Protective effect of antocyanes was observed on leukocytopoiesis. Preservation of antitumor activity of platinum complexes was found in the tumour of Ehrlich. The obtained data indicate possibilities for usage of antocyanes as chemioprotectors during therapy with drugs, containing platinum.

Synthesis and antitumor activity of alkyltriazenopyrazoles.

The chemical synthesis of certain mono- and bis-dialkyltriazenopyrazoles is described. In antitumor studies it was found that none of the compounds produced increase in life span (ILS) of L 1210 bearing mice or inhibition of adenocarcinoma 755 growth above the criteria established. The introduction of a second triazenogroup increases the toxicity of the compounds tested.

Antitumor effect of N alpha-benzyloxycarbonyl-N,N-bis-(2-halogenethyl)-hydrazide derivatives of amino acids.

The antitumor effect of some N alpha-benzyloxycarbonyl-N,N-bis-(2-halogenethyl)hydrazide derivatives of lysine, glycine, cystine, phenylalanine and p-chlorophenylalanine, was studied. Six of eight newly synthesized compounds show considerable antitumor effect on solid Walker carcinosarcoma 256 (about 95% tumor growth inhibition). Three of these compounds under study increased the lifespan of mice with leukemia L1210. The investigation of the effect of N alpha-benzyloxycarbonyl,D,L-phenylalanine-N,N-bis(2-chloroethyl)hydrazine on various mouse tumors showed remarkable growth inhibition of the Ehrlich ascites carcinoma, sarcoma 37, colon adenocarcinoma akatol and lesser antitumor effect also on solid adenocarcinoma 755, Lewis lung carcinoma and melanoma B16. All investigated compounds exhibited depression of leukocyte count--their toxicity being, however, lower than that of sarcolysine in parallel experiments.

Growth characteristics and therapeutic response of transplantable colon tumors in animals.

The growth characteristics and the effect of clinically available chemotherapeutic agents on two transplantable colon tumor lines were studied. These are subcutaneously transplanted undifferentiated carcinoma AKATOL, originating from tumors "spontaneously" appearing after foetal colon implantation, and moderately differntiated carcinoma No. 173 obtained likewise with additional treatment by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Some basic kinetic parameters of tumor growth are determined. The tumors show a relatively slow growth, the median survival time of animals being approximately 50 and 38 days, respectively. The investigation of the sensitivity of tumor lines shows that they are sensitive to many standard antitumor drugs. In the case of AKATOL a high responsiveness to antibiotics and to a smaller degree to other groups agents was observed excluding sarcolysine, CCNU, alexan (cytosine arabinoside) and vinblastine. In the case of colon tumor No. 173 strong antitumor effect for CCNU, 5-fluorouracil, cyclophosphamide, methotrexate and vinblastine was observed. The possibilities to use these tumor systems for screening and evaluation of antitumor agents are discussed.

[Antitumor activity of cytostatics on a newly transplanted tumor in mice, myosarcoma ISM]. / Izuchvane protivotumornata aktivnost na tsitostatitsi vurkhu nov transplantiruem tumor u mishki miosarkom ISM.

The author examined the action of 14 known antitumor preparations on mice BAIB/c with newly transplanted tumour occurred after induction with tetrachlormethane. The tumour myosarcoma ISM showed high sensitivity to cyclophosphamide, administration of which caused complete inhibition of tumour growth and regression of tumours. A comparative high antitumour effect was found after usage of sarcolysine, brunemycine and mitomycine C (over 70% of inhibition). There was a moderately manifested inhibition of the tumour growth (around 50%) after administration of cytostatics degranol, purinetol, 5-fluorouracyl and ftorafur. The substances alexan, rubomycine and 1-(2-chlorethy)-3-cyclohexyl-1-nitrosourea were without effect on myosarcom ISM. The obtained data showed that then tumour well differentiated substances in accordance with their action. It is a prorer model for thorough investigation of antitumour substances.

Growth characteristics of the RL-67 lung tumor -- a new model for experimental therapy of metastatic processes.

Implantation of the RL-67 tumor in to the limb muscle of C57Bl strain mice resulted in the tumor growth at the site of implantation and the metastatic process became manifest predominantly in the lungs of all animals. A direct correlation was established between the primary tumor and its metastases. The number of metastases on the 20th day after the transplantation amounted to about 60. The mean survival time of the tumor-bearing mice was approximately 24 days. Seven different substances were administered intraperitoneally to tumor-bearing animals and their effect on the tumor and its metastases was established. It was found out that heparin and carboxymethyldextran led approximately to a 50% decrease in the number of lung metastases in comparison with the controls. A certain "prophylactic" effect on metastases was achieved with Bleomycin. The data of the biological and histological studies suggested that the RL-67 lung tumor may be used as a suitable model for investigation of the factors influencing the tumor metastases.