Anthraquinone-induced cell injury: acute toxicity of carminomycin, epirubicin, idarubicin and mitoxantrone in isolated cardiomyocytes

Acute toxic effects of the antineoplastic anthraquinones carminomycin, epirubicin, idarubicin and mitoxantrone were studied in primary cultures of cardiomyocytes, which were isolated from adult rats. Both time- and concentration-dependent changes of cell structure and viability (trypan blue exclusion) following incubation of myocytes with subclinical, clinical and toxic concentrations of the anthraquinones were examined by light microscopy. The area under the decay curve of viable and rod-shaped myocytes was used to express cytotoxicity of the drugs. Mitoxantrone was found to reduce cell viability and number of rod-shaped cells to the greatest extent, followed by carminomycin, idarubicin and epirubicin. A significantly lower accumulation in cardiomyocytes was obtained with epirubicin and idarubicin compared with carminomycin. An inhibitory effect on oxygen consumption by the cells occurred already at 0.1 microM with epirubicin, whereas inhibition caused by other anthraquinones was less pronounced. Our data indicate a weak association of net accumulation and the toxicity parameter IC50 for carminomycin and idarubicin. In contrast to these results, a more significant correlation of cytotoxicity and anthraquinone lipophilicity was found, which suggests that the lipophilic character of a particular anthraquinone may be an important factor in drug-induced acute cardiotoxicity.

[The cytotoxicity of mevalonate, lovastatin and carminomycin with respect to MOLT-4 human malignant T-lymphoblasts in vitro]

It was shown in vitro that high concentrations of lovastatin, a competitive inhibitor of hydroxymethyl glutaryl coenzyme A (HMG-CoA) reductase inhibited human malignant cells MOLT-4. The activity of lovastatin in doses of 50-250 microM was dose-dependent. Addition of mevalonate in a concentration of 3 mM to the growth medium completely prevented the cytotoxic effect of 100 microM of lovastatin. At the same time, exogenous mevalonate did not decrease the cytotoxicity of the anthracycline antibiotic carminomycin. Moreover, in a high concentration (7 mM) mevalonate slowly but significantly inhibited the growth of the malignant target cells and the effect was added to the cytotoxic effect of carminomycin low concentrations (0.08 to 0.175 microgram/ml). The results and the literature data suggested that combination of mevalonate, HMG-CoA reductase inhibitors and anthracyclines could be useful in tumor chemotherapy. The suggestion needs further investigation.

Induction of MDR1 gene expression by anthracycline analogues in a human drug resistant leukaemia cell line

The effects of 4-demethoxydaunorubicin (idarubicin, IDA) and MX2, a new morpholino-anthracycline, on up-regulation of the MDR1 gene in the low-level multidrug resistant (MDR) cell line CEM/A7R were compared at similar concentrations (IC10, IC50 and IC90) over a short time exposure (4 and 24 h). The chemosensitivity of each drug was determined by a 3-day cell growth inhibition assay. Compared with epirubicin (EPI), IDA and MX2 were 17- and eightfold more effective in the CEM/A7R line respectively. No cross-resistance to 5-FU was seen in the CEM/A7R line. Verapamil (5 microM) and PSC 833 (1 microM), which dramatically reversed resistance to EPI in the CEM/A7R line, had no sensitizing effect on the resistance of this line to MX2, but slightly decreased resistance to IDA. The sensitivity to 5-FU was unchanged by these modulators. The induction of MDR1 mRNA expression by IDA, MX2 and 5-FU was analysed by Northern blotting and semiquantitatively assessed by scanning Northern blots on a phosphorimager. The relative level of MDR1 expression was expressed as a ratio of MDR1 mRNA to the internal RNA control glyceraldehyde-3-phosphate dehydrogenase (GAPDH). IDA, MX2 and 5-FU differentially up-regulated MDR1 mRNA in the CEM/A7R line in a dose-dependent manner. Both IDA and MX2 induced MDR1 expression within 4 h. 5-FU up-regulated MDR1 expression only when drug exposure was prolonged to 24 h. Based on MRK 16 binding, flow cytometric analysis of P-glycoprotein (Pgp) expression paralleled the increase in MDR1 mRNA levels. For the three anthracyclines, the increase in MDR1 expression was stable in cells grown in the absence of drug for more than 3 weeks after drug treatment. The induction of MDR1 expression by 5-FU was transient, associated with a rapid decrease in the increased Pgp levels which returned to baseline 72 h after the removal of 5-FU. This study demonstrates that MDR1 expression can be induced by analogues of anthracyclines not pumped by Pgp, and that this induction appears to be stable despite a 3-week drug-free period.

Differential single- versus double-strand DNA breakage produced by doxorubicin and its morpholinyl analogues

The morpholinyl analogues of doxorubicin (DOX) have previously been reported to be non-cross-resistant in multidrug resistant (MDR) cells due to a lower affinity for P-glycoprotein relative to the parent compound. In order to further investigate the mechanisms of action of these morpholinyl anthracyclines, we examined their ability to cause DNA single- and double-strand breaks (SSB, DSB) and their interactions with topoisomerases. Alkaline elution curves were determined after 2-h drug treatment at 0.5, 2 and 5 microM, while neutral elution was conducted at 5, 10 and 25 microM in a human ovarian cell line, ES-2. A pulse-field gel electrophoresis assay was used to confirm the neutral elution data under the same conditions. Further, K-SDS precipitation and topoisomerase drug inhibition assays were used to determine the effects of DOX and the morpholinyl analogues on topoisomerase (Topo) I and II. Under deproteinated elution conditions (pH 12.1), DOX, morpholinyl DOX (MRA), methoxy-morpholinyl DOX (MMDX) and morpholinyl oxaunomycin (MX2) were equipotent at causing SSB in the human ovarian carcinoma cell line, ES-2. However, neutral elution (pH 9.6) under deproteinated conditions revealed marked differences in the degree of DNA DSB. After 2-h drug exposures at 10 microM, DSBs were 3300 rad equivalents for MX2, 1500 for DOX and 400 for both MRA and MMDX in the ES-2 cell line. Pulse-field data substantiated these differences in DSBs, with breaks easily detected after MX2 and DOX treatment, but not with MRA and MMDX. DOX and MX2 thus cause DNA strand breaks selectively through interaction with Topo II, but not Topo I. In contrast, MRA and MMDX cause DNA breaks through interactions with both topoisomerases with a predominant inhibition of Topo I.

[Genotoxic and mutagenic activity of antineoplastic anthracyclines and their aglycones: study in two test-systems]

Mutagenic (Ames tests) and genotoxic (SOS chromotest) activities of highly-efficient natural anthracycline monosaccharides possessing antitumor activity-daunorubicin (also known as daunomycin or rubomycin), doxorubicin (adriamycin), and carminomycin-were studied. At the same time, the hypothesis was tested that intercalation of the antibiotic moiety into the helix of cell DNA, which was mediated by the saccharide amino group, played a crucial role in genotoxicity of these anthracyclines. The hydrolysis products of these antibiotics (the corresponding aglycones) and aclacynomycin A (an anthracycline trisaccharide), as well as aclavinone (its derivative aglycone), were studied. All these compounds lacked the saccharide amino group necessary for intercalation. It was found that all anthracycline monosaccharides studied had a strong mutagenic effect on strain TA98 and a moderate effect on strain TA100 of Salmonella typhimurium. Aclacynomycin A was found to have no mutagenic effect on any strain. Lack of the glycoside amino group did not necessarily result in loss of mutagenic activity in the derivative aglycones of anthracycline monosaccharides: they exhibited moderate mutagenic activity in strain TA98 and low but significant activity in strain TA100. The S9 microsomal fraction did not alter the mutagenic activity of either anthracycline monosaccharides or their aglycones; however, it dramatically increased the mutagenic activity of aclavinone: correspondence between positive responses in Ames tests and the SOS chromotest was found. Apparently, the mutagenic activity of the substances studied in bacterial cells was mediated by inducing the SOS-repair process. If the compound contained the amino glycoside moiety, functional and structural precursors of the SOS response were formed via intercalation of the reagents into the DNA duplex; if the substance did not contain this moiety, the precursors were formed via ionic interaction.

[The structural bases of the cardiotoxic action of the anti-tumor antibiotic carminomycin]

The authors substantiate morphological and structural-functional basis of the cardiotoxic effect of the antitumor anthracycline antibiotic carminomycin after its single intraperitoneal administration in maximum tolerable doses. Results indicate that the cause of development of cardiac failure after administration of carminomycin to experimental animals in the development of an alternative and plastic cardiac failure prevalence of type I.

[The morphological aspects of the protective action of enterosorbent K(2)9 during the use of the antitumor anthracycline antibiotic carminomycin]

The authors substantiate morphologically the protector effect of K(2)9 enterosorbent during its parallel use with the antitumour anthracyclin antibiotic carminomycin. The agent was administered intraperitoneally in animals at the maximum tolerable dose. Use of the K(2)9 enterosorbent reduces the cardiotoxic effect of carminomycin.

[Experience with using carminomycin in oncological clinical practice]

Carminomycin is an original antitumor antibiotic from the anthracycline group isolated at the Institute of New Antibiotics (USSR) in 1973. Pharmacological investigation of carminomycin revealed its satisfactory absorption from the gastrointestinal tract which proved to be a distinguishing property of the antibiotic as compared to other anthracyclines such as adriamycin and rubomycin. The clinical trials of carminomycin showed that it was mainly active against soft tissue sarcoma and breast cancer, lymphosarcoma, neuroblastoma, Wilms' tumor and Ewing's sarcoma in children, as well as acute leukemia. Various regimens for the antibiotic administration were applied: short-term, single and long-term. Suppression of hemopoiesis was considered as a limiting toxic effect. By the data available carminomycin had lower cardiotoxicity as compared with rubomycin and adriamycin. Development of oral carminomycin is believed promising.

Comparative cardiotoxicity of doxorubicin and a morpholino anthracycline derivative (KRN8602)

The toxicities of doxorubicin (DXR) and 3'-deamino-3'-morpholino-13-deoxy-10-hydroxycarcminomycin (KRN8602) were compared in perfused rat heart preparations. In addition, their toxicities in isolated myocytes as well as their abilities to cause oxidation of intracellular reduced glutathione (GSH) were evaluated. Finally, their capacities to initiate oxygen consumption and lipid peroxidation in isolated microsomes were determined. DXR caused a dramatic decrease in left ventricular pressure in the perfused hearts and a leak of lactic acid dehydrogenase (LDH) from isolated myocytes. These effects were not observed with KRN8602 at comparable concentrations although KRN8602 caused oxidation of GSH to oxidized glutathione (GSSG) in the myocytes. Both anthracyclines caused an increase in oxygen consumption and lipid peroxidation in isolated microsomes although these effects were more pronounced with KRN8602. The results of these experiments demonstrate that, despite the high capacity to redox cycle and to generate oxygen-derived oxidants, KRN8602 exhibited no measurable cardiotoxicity. The findings are consistent with a view that, if the formation of such oxidants is central to the cardiotoxicity of DXR, these substances must be formed in cellular compartments, e.g. plasma membranes, where the morpholino derivative (KRN8602) does not accumulate.

[Thiol-dependent protective systems in alimentary prevention of the toxic effect of carminomycin]

The state of the thiol-dependent systems i.e. concentration of the SH-groups, activity of glutathione reductase and glutathione-S-transferase, carminomycin antitumor and toxic effects was studied under conditions of tumor growth and carminomycin therapy with the use of prophylactic rations (PR) aimed at stimulating the cell thiol-dependent and antioxidant systems for decreasing the drug toxic action. It was shown that addition of sulfur-containing amino acids, selenium and vitamin E to the ration of healthy and tumor-bearing rats (Walker carcinosarcoma 256) induced a decrease in the level of the SH-groups in the liver just likely promoting efficient extrahepatic usage of glutathione. After administration of carminomycin a long with the PR use, the liver showed the thiol-preserving capacity evidenced by a decrease or complete elimination of the above effect of the ration. The use of PR resulted in a marked increase in the glutathione-S-transferase activity in cytosol and to a lesser extent in the liver microsomes. A regulating effect of the PR on the activity of glutathione reductase was observed: its inhibition in the healthy animals and stimulation after carminomycin administration in the heart of the healthy animals and the liver of the tumor-bearing animals.

[Study of toxicity and antineoplastic activity of 14-substituted derivatives of rubomycin and carminomycin]

Toxicity and antitumor activity of five derivatives of rubomycin and carminomycin were studied in animals. The derivatives were prepared by modification of the methyl C-14 group. These were the following: 14-chlorrubomycin, 14-chlorcarminomycin, 14-salicyloyloxyrubomycin, 14-salicyloyloxycarminomycin and 14-quinaldinoyloxyrubomycin. The chemotherapeutic study revealed that, in their activity, all the compounds were inferior to the starting antibiotics. Unlike the other derivatives, 14-chlorcarminomycin induced a significant inhibition of leukemia P-388 development (the average lifespan of the mice amounted to 165 per cent as compared to the control). However, in the magnitude of its effect, the derivative was inferior to carminomycin.

[Late effects of the hematotoxic action of antineoplastic antibiotics of the anthracycline group]

The morphological and functional states of hemopoiesis at late periods (up to 6 months) after using daunorubicin, carminomycin and doxorubicin, antitumor antibiotics of the anthracycline group in doses of 1/10 LD50 for 10 days were studied on 764 noninbred rats and 240 BALB/c mice. On various compensatory-functional models of hemopoiesis strain there was shown persisting inhibition of hematopoietic tissue functional activity and limited reserve reactions of granulocyto- and erythropoiesis 3 and to a lesser extent 6 months after the cytostatic action.

[Comparative evaluation of the cytogenetic action of anthracycline-group antitumor antibiotics (daunomycin, doxorubicin and carminomycin)]

The cytogenetic effect of antitumor antibiotics of the anthracycline group was studied with the use of the routine analysis of chromosomes in the metaphase plates of the bone marrow cells and the micronuclear test (the procedure of counting erythrocytes with micronuclei in peripheral blood). It was shown that by the level of the mutagenic effect the antibiotics might be arranged as follows with respect to the decrease in their activity: carminomycin----doxorubicin----daunomycin. The micronuclear test provided estimation of the cytogenetic damage of the bone marrow. In this connection the procedure may be recommended for rapid evaluation of the mutagenic effect of various anthracyclines and probably other cytostatics characterized by mutagenic activity.

[Comparative evaluation of the myelotoxic action of rubomycin, adriamycin and carminomycin by their delayed effects in an experiment]

The experiments were performed on intact noninbred rats and BALB/c mice with the use of different models of the hemopoiesis compensatory-functional tension and the morphofunctional methods. It was shown that at the period of complete recovery of the morphological composition of the peripheral blood 30 days after discontinuation of the 10-day course of daily administration of rubomycin, adriamycin and carminomycin in equivalent doses (1/10 of the LD50) pronounced inhibition of hemopoiesis was preserved in the animals. This could not be detected with the routine methods used for investigation of the cell homeostasis and was evident from limited compensatory reactions of granulocytopoiesis and erythropoiesis under conditions of additional action on hemopoiesis.

[Mechanisms of hemopoiesis inhibition and recovery after the administration of carminomycin and rubomycin in an experiment]

The experiments on 766 albino non-inbred rats and 270 mice BALB/c showed that when there were no basic differences in the mechanism of the anthracycline myeloinhibitory effect associated with a decrease in the number of the exogenic trunk hemopoietic cells, inhibition of the bone marrow proliferative activity and a decreased rate of the hemopoietic elements differentiation, carminomycin induced a more pronounced and persisting impairment of the hematopoietic tissue proliferation, as compared to rubomycin on their administration in doses equivalent by the total toxicity.

[Liver mono-oxygenases and the pharmacodynamics of carminomycin and rubomycin]

The effect of carminomycin on the activity of liver monohydroxygenases was estimated. It mas noted that in doses of 2, 3 and 4 mg/kg the antibiotic had no effect on the sleep duration in mice treated with hexenal. This meant that it did not change the activity of the enzymatic system. Induction and inhibition of liver monohydroxygenases did not influence the toxic effect of carminomycin used in doses of 5 and 10 mg/kg. It was also shown that the toxicity of both rubomycin and adriamycin decreased on induction and increased on inhibition of liver monohydroxygenases. Like adriamycin rubomycin lowered the activity of this enzymatic system. Administration of rubomycin in a dose of 5 mg/kg prolonged the duration of the hexenal sleep almost 1.5-2 times as compared to the control. The possible participation of liver monohydroxygenases in metabolic transformations of the antracycline antibiotics is discussed.

Mechanism of acute anthracycline cardiotoxicity in isolated rat hearts: carminomycin versus daunomycin

Cardiotoxicity limits the use of anthracyclines which are potent anticancer agents. In the isolated rat heart, we investigated the mechanism of acute anthracycline cardiotoxicity and compared a new anthracycline, carminomycin, with daunomycin which is in established use. Daunomycin 1.75 X 10(-5) M produced a fall in cardiac output (36 +/- 2 versus 58 +/- 1 ml/min; p less than 0.01), left ventricular power production (9 +/- 0.7 versus 16 +/- 0.3 mJ/sec/g; p less than 0.01), and efficiency of heart work (3.3 +/- 0.2 versus 6.3 +/- 0.2 mJ/sec/ml O2; p less than 0.01; mean +/- S.E. 40 min after daunomycin). Carminomycin (1.75 X 10(-5) M) produced a greater fall in cardiac output than equimolar daunomycin (26 +/- 2 versus 36 +/- 2 ml/min; p less than 0.01). Daunomycin did not reduce coronary flow rate, heart rate, or oxygen consumption. From the preceding data, we inferred that, since afterload and preload were constant in this model, heart failure was due to a depressed inotropic state. Procedures that increased cytosolic calcium relieved heart failure namely, pretreatment with digoxin (62.4 micrograms), isoproterenol (10(-6) M), and increased perfusate Ca2+ (5 mM versus 2.5 mM) all prevented carminomycin-induced fall in cardiac output (41 +/- 1, 47 +/- 5, and 52 +/- 1, respectively, versus 26 +/- 2 ml/min; p less than 0.01). Acute anthracycline contractile failure was also associated with a fall in high-energy phosphate compounds which could also have contributed to the decreased inotropic state. We conclude that carminomycin is more cardiotoxic than daunomycin in equimolar concentrations and that a lowered cytosolic calcium and decreased energy stores might cause the contractile failure. The cytosolic calcium and high-energy phosphate compounds were lowered by separate mechanisms.

[Study of the toxicity of carminomycin 13-cyclohexylidenhydrazone]

The systemic effect and toxicity of carminomycin 13-cyclohexylidenhydrazone (CCH) were studied on noninbred albino mice in comparison to carminomycin. The preparation was administered intravenously and orally. It was shown that CCH was 1.3 or 2.5 times less toxic than carminomycin on its intravenous or oral administration, respectively. The cumulative properties of CCH and carminomycin on their intravenous administration were practically equal. On oral administration of CCH the level of its cumulation in mice was higher than that of carminomycin. By its nature the effect of the preparations on hemopoiesis of the mice was the same. CCH had a low cardiotoxic effect.

[Synthesis and study of the antitumor properties of 13-hydrazone-substituted carminomycin]

13-Tret-butoxycarbonyl hydrazone (BOC hydrazone) of carminomycin was prepared by interaction of carminomycin with tret-butoxycarbonyl hydrazine. Interaction of carminomycin with N-amino-N'-methyl piperazine resulted in 13-(4-methyl piperazinyl) imine (MP imine) of carminomycin. BOC hydrazone and MP imine of carminomycin had a significant antiblastomic activity against lymphosarcoma LIO-1. Still, they had no advantages over carminomycin.

[Acute toxicity of the N-acyl derivatives of carminomycin and rubomycin]

Synthesis of 2 new N-acyl derivatives of carminomycin and rubomycin (N-L-leucylcarminomycin and N-sarcolysylrubomycin) is described. Acute toxicity of the new and 4 known N-acyl derivatives: N-acetylcarminomycin, N,L-alanylcarminomycin, N-D-phenylalanylcarminomycin and N-D-phenylalanylrubomycin was studied on albino mice. It was shown that the N-acyl derivatives of carminomycin and rubomycin had lower acute toxicity than the initial drugs. When added to blood serum in vitro N-D-phenylalanylcarminomycin and N-D-phenylalanylrubomycin induced precipitation. The carminomycin derivatives containing the residues of L-leucine and L-alanine were less toxic than the initial antibiotic, still they had a markedly pronounced retarded toxicity.

[Synthesis, toxicity and antitumor action of carminomycin azine (carminazine)]

Carminomycin azine designated as carminazine was prepared by condensation of carminomycin with hydrazine hydrate. It was shown in the experiments on mice that the toxicity of carminazine was 2 and 7 times lower than that of carminomycin on its intravenous and oral administration respectively. The effect of both drugs on hemopoiesis of the mice was similar. As regards the selectivity of the antitumor effect on lymphosarcoma, strain L10-1, carminazine was inferior to carminomycin.

[Comparison of the antitumor, immunodepressive and toxic properties of carminomycin-albumin complexes differing in carminomycin content]

Bovine serum albumin (BSA) and carminomycin, an anthracycline antibiotic, were subjected to conjugation with glutaraldehyde and their complexes with various contents of the antibiotic were prepared. The molar ratios of carminomycin and BSA were 8:1, 4:1, and 2:1. The antitumor effect of the preparations was studied on the models of mouse transplantable lymphosarcoma LIO equal 1 and ascitic forms of mouse lymphadenosis NK/Ly in vivo and in vitro. Their immunodepressant effect was evaluated from the decrease in the hemagglutinin titers in the mice immunized with sheep red blood cells. It was shown that when the toxicity of the complexes was the same, their antitumor and immunodepressant activities were different. The therapeutic activity of carminomycin in the four- and eight-substituted complexes was much higher than that of carminomycin alone. It is suggested that the differences in the activity of the complexes were connected with differences in their pharmacokinetics. It was found that the chemotherapeutic properties of the complexes may have changed by variation of the number of the cytostatic residues in the albumin molecule. The findings indicate that the whole complex molecule interacts with the malignant cell and not carminomycin preliminarily detached from it.

Toxic effects of violamycin Bi, carminomycin and daunorubicin on the myocardium of rabbits

Cardiac toxicity of the new anthracycline antitumour antibiotics violamycin BI (V) and carminomycin (C) was studied in comparison with daunorubicin (D). Rabbits were intravenously given total doses of 0.1-1.5 mg/kg V or C, and 0.64-18 mg/kg D, respectively, twice weekly for one month. When examined two to six days, two and four weeks, respectively, after the last drug administration the gross findings consisted of hydropericard, hydrothorax and ascites in some animals. Histologically, loss of striation and focal necrosis of cardiac muscle cells and subsequently chronic inflammatory reactions and/or proliferation of mesenchyma cells were mostly found. These alterations were somewhat more pronounced in rabbits treated with V than in animals received D or C. At equitoxic doses of the antibiotics tested the ultrastructural lesion in the myocardial cells were altogether less marked after treatment with D than with C or V.

The toxicological evaluation of carminomycin - an antineoplastic anthracycline antibiotic

Carminomycin, an anthracycline antibiotic discovered in the Soviet Union, possesses antitumor activity and is chemically related to adriamycin and daunorubicin. The toxic effects of carminomycin observed in single-dose toxicologic studies in mice iv (4.5-13.5 mg2) and po (18.9-52.2 mg/m2), rats iv (6.0-21.0 mg/m2), dogs iv (1.0-16.0 mg/m2) and po (16.0-80.0 mg/m2), Rhesus monkeys po (24.0-144.0 mg/m2); and in multiple-dose studies in dogs iv (18 doses 0..6-5.0 mg/m2, 2X/week) and rats sc (9 doses 3.0-12.0 mg/m2, 3X/week), were dose-related and primarily manifested as suppression of hematopoiesis. Other toxicities observed included nephrotoxicity, gastrointestinal toxicity, decreased spermatogenesis, decrease in size and activity of the prostate and seminal vesicles, and ovarian alterations. In general, these toxicities were reversible in surviving animals during recovery periods. Cardiotoxicity, similar to that seen with adriamycin sc (13 doses 12.0 mg/m2, 1X/week) was not observed with carminomycin sc (13 doses 6.0 mg/m2, 1X/week).

Embryotoxicity and teratogenicity of the anthracycline antibiotic carminomycin in mice

Carminomycin, a new antitumor anthracycline antibiotic, has embryolethal, embryotoxic and teratogenic effects during early postimplantation stages of development in mice. These effects depend on the dose and route of administration and the gestational age of the exposed embryos.

Comparative toxicity of carminomycin, rubomycin and adriamycin in mice and experience with carminomycin in spontaneous tumors of dogs

LD50 of carminomycin, rubomycin and adriamycin were determined after their single administration of 3-, 5-, 10- and 15-fold administration once a day to 540 hybrid male mice F1 (C57Bl x CBA). Comparison of the cumulative indices for these antibiotics showed that after 3 injections they were similar. After 5 injections the cumulative properties were more pronounced for adriamycin. After 10 or 15 injections the cumulative properties were less pronounced for carminomycin. The increased sensitivity to carminomycin was determined in dogs with spontaneous tumors (in 3 with osteosarcoma and 4 with hemablastoses) comparing with healthy animals. The therapeutic effect was not evaluated because of severe toxicity. Bone marrow and gastrointestinal toxicity prevailed. The therapeutic dose for sick dogs should not exceed 0.1--0.125 mg/kg i.v., once within 3--5 days during 3 weeks.

[Protein-nitrogen metabolism in the liver of rats intraperitoneally administered carminomycin]

It was found in the experiments with rats that in response to carminomycin administration in a single LD50 and the therapeutic doses during the treatment course the intracellular fond of the amino acids in the liver tissue increased, the autolytic processes activated, the activity of the transamination enzymes, histidine and ammonia lyases increased. The level of the residual nitrogen increased mainly at the expense of increased ammonia production and urea levels. These changes were more pronounced when the antibiotic was administered in LD50. Independent of the administration multiplicity and the antibiotic dosage they were of reversible nature and mainly disappeared by the end of the observation.

[Antitumor properties and toxicity of a carminomycin and protein complex]

The properties of carminomycin complexes with protein, a bovine serum albumin prepared with two different methods using glutaraldehyde or carbodiimine were studied. The complex prepared with the use of carbodiimine was biologically inactive. The complex prepared with the use of glutaraldehyde had a molecular mass of about 15 000 000 dalton, was more toxic than carminomycin and possessed proportionally higher antitumor activity and a wider antitumor spectrum. The studies on the use of the method of carminomycin complex formation with antitumor immunoglobulins are promising.

[Antiviral action of carminomycin and some of its derivatives]

Carminomycin was shown to inhibit the development of both the DNA-containing variolovaccine virus and the RNA-containing grippe virus in chick embryos. Comparison of the effects of rubomycin, carminomycin, 14-oxy-carminomycin and carminomycin complex with bovine serum albumin in experiments with chick embryos showed that the inhibitory effect of carminomycin and its derivatives on the development of the grippe virus was much higher than that of rubomycin. The carminomycin derivatives proved to be much more active in this respect than the initial antibiotic. Carminomycin and its derivatives had a therapeutic effect on mice with experimental grippe pneumonia also on their oral use.

[Comparative pathomorphological study of the experimental action of carminomycin and rubomycin on the heart]

Comparative histological investigation of the toxic effect of carminomycin and rubomycin on the myocardium was carried out on mice BDF. It was found that the level of the morphological changes in the heart muscle depended on the antibiotic dose. The cardiotoxic effect of carminomycin was less pronounced than that of rubomycin.

[Effect of the multiple peroral administration of carminomycin on the body of animals]

Toxicity of carminomycin used orally for many times was mainly evident from suppression of blood formation, the level of the suppression being dependent on the antibiotic dose. Carminomycin had a low suppressing effect on the white blood in rats. At low doses even moderate leucocytosis was observed. The indices of the functional state of the liver, kidneys, sugar blood levels, content of glycogen and fat in the liver, relative mass of the rat organs after repeated oral administrations of karminomycin to the animals remained mainly unchanged. A change in wave T on the ECG of the dogs treated with high doses of the antibiotic was registered. Histological examination of the organs and tissues of the animals killed after repeated oral administrations of carminomycin revealed pathological changes only in the spleen and thin intestine. Such changes were not more pronounced than those after repeated intravenous administration of the equivalent doses of the antibiotic (by the effect on the blood formation). This allowed the author to recommend the oral administration route for carminomycin trials in clinics.

[Production and antitumor properties of carminazone]

Karminazon (13-benzoylhydrazon) was prepared by condensation of karminomycin with benzoylhydrazine. In its intravenous use in the treatment of mice with lymphosarcoma L10-1 karminazon was less toxic and had lower antitumor activity than karminomycin. Karminazon had a lower selective antitumor activity with respect to lymphosarcoma than karminomycin.

[Morphological changes in the digestive organs on the administration of the antineoplastic antibiotics, rubomycin and carminomycin]

The effect of antitumour antibiotics, such as rubomycin and karminomycin on the digestive tract as one of the most vulnerable systems during chemotherapy was studied. Investigation of the tongue, oesophagus, stomach, small and large intestine of mice with the current morphological and some histochemical methods showed that the most pronounced changes in the above organs occurred during the first 10 days after the drug administration. The damages were of the same type, i.e. dystrophic changes in the tegmental and granular epithelium with edema and infiltration of the mucosa and tunica submucosa. The drugs induced a decrease in the levels of the nucleic acids, protein and hydrolytic enzymes and impairement of the distribution pattern of these substances in the cells. Karminomycin had a more pronounced effect and its damaging effect was more stable as compared to rubomycin.

[Acute toxicity of carminomycin administered perorally to laboratory animals]

Rather high species sensitivity to carminomycin was found in the experiment with albino mice, rats, guinea pigs, rabbits and dogs. The highest difference in the antibiotic toxicity for various species of the laboratory animals was shown on oral administration of the drug which was due to the differences in the antibiotic absorption from the gastro-intestinal tract. On single oral administration to the dogs in toxic or lethal doses the antibiotic suppressed the blood formation up to aplasia of the bone marrow. The equitoxic doses of carminomycin on its single oral and intravenous administration differed approximately by 3 times. Carminomycin had no effect on the smooth muscles of the isolated rabbit ear vessels and cat intestine in situ. The antibiotic had an irritating effect on the rabbit eye mucosa. Carminomycin had no skin-irritating effect.

[Comparative study of the cardiotoxicity of the anthracycline antibiotics, rubomycin, carminomycin and dihydrocarminomycin, in experiments on white mice]

The experiments on albino mice treated with rubomycin, carminomycin or dihydrocarminomycin on its 5-fold intravenous administration in doses equal to similar portions of LD50 of the respective antibiotic on its use in a single dose showed that all the 3 antibiotics induced changes in the myocardium close by their character. The heart affections were evident from swelling of separate muscle fibers, degeneration of the myofibrils, homogenization, vacuolization and resorption of the sarcoplasma, pathological changes in the nuclei, atrophy of some muscle fibers. Rubomycin had the highest cardiotoxic effect. Then followed dihydrocarminomycin and carminomycin. All the antibiotics studied in the experiments with mice had mainly an inhibitory effect on the lymphoid hemopoiesis. The effect of carminomycin was the highest. The animal death during the injections and immediately after administrations of the antibiotics must be due to their suppressing effect on hemopoiesis. The deaths at more remoted periods must be due to the cardiotoxic effect of the antibiotics.

[Obtaining 14-oxycarminomycin and a study of its antitumor activity]

The authors obtained 14-oxykarminomycin by alkaline hydrolysis of 14-bromokarminomycin. On two-fold intravenous administration to mice with lymphosarcoma, strain L10-1, 14-oxycarminomycin showed the same toxicity as karminomycin. The preparation had the same selective antitumor activity as karminomycin.

[Comparative study of the cardiotoxicity of the anthracycline antibiotics, carminomycin and adriamycin, in white mice]

The cardiotoxic effect of karminomycin and adriamycin administered intravenously for 5 times in equitoxic doses constituting equal portions of LD50 of the respective antibiotic on its single intravenous administration was studied on albino mice. Histological examination of the heart showed that almost identical damages of the myocardium occured after administration of karminomycin and adriamycin in doses of 0.45 of LD50 (1.5 mg/kg) and 0.3 of LD50 (6.3 mg/kg) respectively. The character of the damages due to the antibiotics was close, the most significant changes were observed when the animals were sacrificed 1 month after the last administration of the drug. The histological method is of value in estimation of the cardiotoxic effect of the drugs, using mice as the model suitable for the investigation. Adriamycin had more pronounced cumulative properties as compared to karminomycin: suppression of the weight gain in the mice and their death rate were higher with the use of adriamycin.

[Toxicity and cumulative properties of carminomycin, rubomycin and adriamycin at different times of use]

LD50 of karminomycin, rubomycin and adriamycin were determined after their single administration or 3-, 5-, 10- and 15-fold administration once a day to 540 hybrid male mice F1(C57B1 X CBA). Comparison of the cumulative indices for these antibiotics showed that after injections they were close. After 5 injections the cumulative properties were more pronounced for adriamycin. After 10 or 15 injections the cumulative properties were less pronounced for karminomycin.

[Preliminary results of a cooperative clinical study of the new antitumor antibiotic, carminomycin]

The clinical trials of karminomycin, a new Soviet antitumor antibiotic in treatment of different malignant tumors showed that the drug had a pronounced antitumor activity against the soft tissue sarcomas of various histogenesis, lympho- and reticulosarcoma, acute leukemia and some other neoplasms.

[Dependence of the toxicity of the antineoplastic antibiotics rubomycin and carminomycin, on the age and sex of white mice and rats]

Karminomycin was more toxic with respect to 2-6 week mice than to adult animals when administered both intravenously or orally. 5-6 week rats were more stable than adult animals to the effect of karminomycin administered intravenously or orally. Significant species sensitivity to karminomycin was noted. When administered intravenously karminomycin administered intravenously was 2 times more toxic as compared to the oral use in the experiments with adult mice and 23 times more toxic in the experiments with adult rats. LD10 and LD50 of rubomycin administerean in adult animals. LD50 of karminomycin and rubomycin administered intravenously to adult female mice was somewhat lower than that for adult male mice.

[Toxicity and pharmacological properties of carminomycin complex components]

Acute toxicity of the components of the carminomycin complex after intravenous administration to albino mice increased as follows. I less than II less than III. Component II induced a decrease in all the indices of the bone marrow and peripheral blood of the animals. It was most pronounced in dogs. The dogs died after administration of component II in the lethal doses as a result of the bone marrow aplasia. The indices of the functional state of the liver and kidneys in the animals after administration of components I and II changed slightly. Component III administered repeatedly to rabbits even in low doses induced significant impairments in the function of the liver and kidneys. Component II differed from component I by more pronounced cardiotoxicity. On the basis of the experimental data and the results published earlier component I is recommended for clinical trials as the least toxic one.