SYSTEM FOR DETECTING INDUCERS OF LYSOGENIC ESCHERICHIA COLI W1709 (LAMBDA) AND ITS APPLICABILITY AS A SCREEN FOR ANTINEOPLASTIC ANTIBIOTICS

Platinum complexes with anticancer potential and their evaluation by a colorimetric lambda prophage induction assay

A simple biochemical phage induction assay (BIA) showed significant activity with 90% of the antitumor platinum compounds tested and lack of activity for all Pd(II) compounds and Pt(II) cationic complexes, compounds that are expected to be inactive. Structure-activity relationships for a large number of chemicals can be studied simultaneously by this simple, rapid, inexpensive and quantitative biochemical assay. Fifty-three platinum complexes were tested, including a number of ethylenediamines synthesized for this work. The magnitude of inducing activity varied over a 25-fold range; differences among analogs reflected structural differences in a chemically consistent manner. Seven platinum complexes showed greater activity than that of cis-diamminedichloroplatinum(II) (cisplatin, cis-DDP), while other compounds appeared to be substantially less toxic. The assay was predictive for most compounds with very high or very low activity in vivo against L1210. For compounds with intermediate levels of activity, no correlation between inducing and antitumor activity was observed.

Antitumor activity of platinum complexes

Contemporary ideas about the mechanism of antitumor activity of platinum complexes are reviewed and discussed. The induction of SOS functions in bacteria is emphasized and an analogous mechanism in animal cells is suggested. The fate of the leaving ligand in the body is not known. Therefore the complex which reaches the target DNA may be very different from the applied compound. Even the amino ligand may be detached in the body, probably as part of the detoxication by binding to proteins. In the case of fast or medium-speed reactive complexes most of the platinum is inactivated by binding to proteins, whereas slow-reacting drugs are mostly excreted unchanged in the urine. Thus, the quantity of the complex which reaches the target is also difficult to assess. Due to peculiar pharmacokinetics, the results obtained with poorly soluble compounds administered in the solid form cannot be compared with those obtained in true solutions. There are many reasons for believing that the study of a coordination anticancer drug may contribute to our understanding of cancer growth and its reversal.

Use of covalently closed circular deoxyribonucleic acid for prescreening for antitumor compounds

The interactions of PM-2 deoxyribonucleic acid (DNA) with 20 known antineoplastic agents were studied using agarose gel electrophoresis and fluorescence assay systems. Actinomycin D and adriamycin (and all other anthracyclines studied) induced superhelical conformational changes in PM-2 DNA. Bleomycin A2, tallysomycin, neocarzinostatin, macromomycin, and hedamycin degraded PM-2 DNA under various conditions. The potential utility of PM-2 DNA as an antitumor antibiotic prescreening tool was further studied by examining the effects of 200 broths on PM-2 DNA employing both fluorescence and agarose gel electrophorectic assays. The assays were shown to be sensitive and rapid and to provide information not provided by other prescreens with which the PM-2 DNA assays were compared.

Prophage induction of Escherichia coli (lambda) by N-nitrosamines

Carcinogenic N-nitrosamines were tested for their ability to induce lambda in a lysogenic strain of Escherichia coli K-12 (58-161 F+ Dimethylnitrosamine, di-n-propylnitrosamine, methyl-n-propylnitrosamine, and N-nitrosopiperidine were shown to be inducers of prophage.

Prophage induction in lysogenic Escherichia coli with N-nitroso compounds and derivatives

Prophage induction in lysogenic Escherichia coli W1709 (iota) was determined for 29 N-nitroso compounds, 13 of their denitrosated derivatives, and 7 hydroxylamino and hydrazino analogues of nitrosamines. Minimal inducing concentrations of 0.1 to 2.0 mug/ml were demonstrated for eight nitrosamidines, and concentrations of 0.5 to 25.0 mug/ml were shown for six nitrosamides. Weak inducing activities were found with N,N-diethylhydroxylamine oxalate and N-methyl-N-phenylhydrazine sulfate, derivatives of inactive N-nitrosodiethylamine and N-nitrosomethylphenylamine, respectively. Inactive compounds including N-methyl-N-nitroso-p-toluenesulfonamide, 11 nitrosamines, 3 N, N'-dialkyl substituted-N-nitrosoureas, 13 denitrosated derivatives, and 5 hydroxylamino and hydrazino analogues of nitrosamines are listed. Since 7 of the 14 prophage-inducing nitrosamidines and nitrosamides reported thus far have carcinostatic activity in rodent tumor systems, it is concluded that the induction test may provide a useful screen for the detection of potential antitumor compounds. The induction test may also be useful for the detection of responsive N-nitroso compounds which may be potential toxicological hazards in the environment since, of the six active nitrosamides, five have already been reported to produce mutagenic and carcinogenic effects, four produce chromosomedamaging effects, and two produce teratogenic effects. Use of the prophage induction system for detection of biologically active intermediates formed by N-nitroso compounds under physiological conditions is considered.

Prophage induction in lysogenic Escherichia coli with simple hydroxylamine and hydrazine compounds

The prophage-inducing capability of hydroxylamine sulfate and 36 of its derivatives, and of hydrazine dihydrochloride and dihydrazine sulfate and 43 of their derivatives, was determined in Escherichia coli W1709 (lambda). Maximal nontoxic concentrations up to 1 mg/ml were tested. Hydroxylamine sulfate was active at 2.5 mug/ml and the following 17 derivatives were active at concentrations ranging up to 500 mug/ml: alpha-naphthylhydroxylamine, N-hydroxy-2-aminofluorene, oxamyl hydroxamic acid, O-carbamoyl hydroxylamine (isohydroxyurea), N-hydroxyurethane, N-methylhydroxylamine HCl, salicylhydroxamic acid, oxalohydroxamic acid, methoxyamine HCl, ethoxyamine HCl, N, N-diethylhydroxylamine oxalate, formaldoxime, formamidoxime, acetohydroxamic acid, acetaldoxime, acetone oxime, and hydroxyguanidine sulfate. Hydrazine dihydrochloride and dihydrazine sulfate were effective inducers at 5.0 and 2.5 mug/ml, respectively, and the following nine derivatives of them were active at concentrations ranging up to 500 mug/ml: phthalic acid hydrazide, phenylhydrazine HCl, p-nitrophenylhydrazine, p-chlorophenylhydrazine HCl, formylhydrazine, carbohydrazide, semicarbazide HCl, 1-methyl-1-phenyl-hydrazine sulfate, and acetic acid hydrazide. Nineteen hydroxylamine and 34 hydrazine derivatives were ineffective as inducers. Application of the prophage-induction system as a tool for detection of responsive hydroxylamino and hydrazino compounds which may be potential toxicological hazards in the environment is discussed.