Comparison of DNA lesions produced by tumor-inhibitory 1,2-bis(sulfonyl)hydrazines and chloroethylnitrosoureas

1,2-Bis(sulfonyl)hydrazine derivatives, designed to generate several of the electrophilic species classically believed to be responsible for the alkylating (chloroethylating) and/or carbamoylating activities of the chloroethylnitrosoureas (CNUs), were compared with respect to the cross-linking and nicking of T7 DNA to that caused by 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), 1-(2-chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU), and 1-(2-chloroethyl)-3-(4-trans-methylcyclohexyl)-1-nitrosourea (MeCCNU). In the case of BCNU, a large proportion of T7 DNA strand nicking was found to be due to the generation of 2-chloroethylamine, produced from the hydrolysis of 2-chloroethylisocyanate, in turn formed during the decomposition of the parental nitrosourea. 1,2-Bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine (compound 1) gave a greater yield of DNA cross-links than the CNUs. Compound 1, as well as its derivatives that were incapable of generating 2-chloroethylisocyanate, did not produce detectable levels of strand nicking, indicating that N7-alkylation of guanine did not occur to a significant extent with these agents. Since compound 1 and its derivatives are believed to generate chloronium and chloroethyldiazonium ions, it would appear that these species could not be significantly involved in the N7-alkylation of guanine caused by the CNUs. The relatively low level of N7-alkylation of guanine residues and the relatively high yield of cross-links generated by some of the 1,2-bis(sulfonyl)-1-(2-chloroethyl)hydrazine derivatives implies that they are more exclusive O6-guanine chloroethylating agents than the CNUs. O6-Guanine chloroethylation is believed to be the therapeutically relevant event produced by the CNUs; therefore, compound 1 derivatives represent promising new cancer chemotherapeutic agents, since they appear to generate lower quantities of therapeutically unimportant, yet carcinogenic lesions, and more of the therapeutically relevant O6-guanine chloroethylation than the CNUs.

Hypoxia-selective nitrobenzyloxycarbonyl derivatives of 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazines

Some 4- and 2-(nitrobenzyloxycarbonyl)-1, 2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazines (4, 6, and 7) were synthesized and evaluated for their ability to exert preferential toxicity to hypoxic EMT6 mammary carcinoma cells using a colony-forming assay. Of these, the 4,5-dimethoxy-2-nitro analogue 6 (50 microM, 1-h exposure) caused greater than 3 logs of kill of hypoxic cells, with relatively minor toxicity to corresponding aerobic cells. The ability of 4-nitro (4) and 4,5-dimethoxy-2-nitro (6) analogues to reach and kill hypoxic cells of solid tumors was also demonstrated using intradermally implanted EMT6 solid tumors in mice. In addition, a possible source of toxicity to normal tissue, i. e., the activation of the 4-nitrobenzyl derivative 4 by glutathione S-transferase-catalyzed thiolysis, was essentially eliminated by replacing one of the benzylic methylene protons by a methyl group. The 4-nitro (4) and 4,5-dimethoxy-2-nitro (6) analogues also appear to be reduced more easily under acidic conditions (pH 6.0) than under neutral conditions, as measured by differential pulse polarography. Since the pH in hypoxic regions is often lower than that in adjacent aerobic regions, this property should aid in the cytotoxic action of these agents against hypoxic cells of solid tumors.

Induction of the differentiation of HL-60 promyelocytic leukemia cells by curcumin in combination with low levels of vitamin D3

Previous studies have shown that an antisense phosphorothioate oligonucleotide to the Rel A subunit of NF- kappa B, as well as vitamin E and related antioxidants, significantly enhanced the differentiation of HL-60 leukemia cells when combined with low levels of 1 alpha, 25-dihydroxyvitamin D3 (vitamin D3) an effect accompanied by a marked inhibition of the transcription factor, NF-kappa B. Curcumin, a potent inhibitor of tumor promotion and of tumor cell growth, has also been shown to have antioxidant properties and to inhibit NF-kappa b. to ascertain whether curcumin would also enhance the differentiation of HL-60 leukemia cells produced by vitamin D3, presumably by interfering with NF- kappa B activity, the effects of curcumin on the differentiation of HL-60 cells produced by low levels of vitamin D3 were measured. Curcumin used alone did not produce a significant degree of differentiation of HL-60 cells; however, this agent markedly enhanced the expression of differentiation markers induced by low levels of vitamin D3. Curcumin also increased the differentiation of HL-60 cells when combined with vitamin D analogues (1,25-dihydroxy-16-ene-23-yne vitamin D3 and 1,25-dihydroxy-16-ene vitamin D3) that share the receptor binding properties of vitamin D3, whereas as vitamin D analogue (1,25-dihydroxy-16,23-diene vitamin D3) that caused significant calcium mobilization, but was less effective than vitamin d3 in binding the receptor, did not cause the differentiation of HL-60 cells in the presence or absence of curcumin. Several dietary compounds structurally related to curcumin (i.e., caffeic acid, chlorogenic acid, and ferulic acid) did not increase the differentiation of HL-60 cells produced by vitamin D3. However, the more lipophilic ethyl of ferulic and caffeic acid were capable of inducing the differentiation of HL-60 cells, as well as enhancing the maturation produced by vitamin D3. Curcumin caused a marked reduction in NF-kappa B activity in nuclear extracts of HL-60 cells exposed to this agent in the presence or absence of vitamin D3, supporting the possibility that NF-kappa B may be a factor in the regulation of the state of differentiation of leukemia cells.

Spectrophotometric assay for processes involving changes in hydrogen ion concentration in aqueous solution

A strategy for the design of simple colorimetric assays to follow any process that involves the net generation or consumption of hydrogen ions in aqueous solutions over the pH range of 3-10 is described. This procedure relies upon the measurement of the change in absorption when a weakly or moderately buffered solution of a pH indicator is subjected to a small change in pH. Buffers and indicators are chosen with closely matching pKa values. The versatility of this type of assay technique is illustrated using three examples.

Antitumor 2-(aminocarbonyl)-1,2-bis(methylsulfonyl)-1-(2-chloroethyl)- hydrazines

Several 2-(aminocarbonyl)-1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydr azi nes were synthesized and primarily evaluated for antitumor activity against the murine L1210 leukemia. All of the compounds tested were capable of producing "cures" of mice bearing this tumor. One of the most active agents of this class, 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)- 2(-)[[2-chloroethyl)-amino]carbonyl]hydrazine, was further evaluated against a spectrum of transplanted murine and human solid tumors. Pronounced activity was found against all of the tumors including the murine B16F10 melanoma, M109 lung carcinoma, M5076 reticulum cell sarcoma, and the human LX-1 lung carcinoma. The activities observed compared favorably with those of the established antitumor drugs, cyclophosphamide, mitomycin C, and the nitrosoureas, evaluated concomitantly.

Studies on the mechanism of decomposition and structural factors affecting the aqueous stability of 1,2-bis(sulfonyl)-1-alkylhydrazines

1,2-Bis(sulfonyl)-1-alkylhydrazines are highly active experimental antineoplastic agents which decompose with first-order kinetics in neutral aqueous solutions. These agents generate approximately 2 mol of the corresponding sulfinate, 1 mol of nitrogen, and 1 mol of the appropriate alcohol, produced as a consequence of the alkylation of water. Increasing the leaving-group ability of the sulfonyl moiety on N-1 shortens the half-life, while the converse happens with N-2 substitutions. Linear Hammett relationships are found for both types of substitutions. The predictable kinetics of decomposition makes these agents potential candidates for use in regional chemotherapy, where compounds with tunable short half-lives may offer some advantage. Prodrugs of extremely short-lived derivatives of this class may also have utility as targeted alkylating agents.

Synthesis and evaluation of 1-acyl-1,2-bis(methylsulfonyl)-2-(2- chloroethyl)hydrazines as antineoplastic agents

A series of 1-acyl-1,2-bis(methylsulfonyl)-2-(2-chloroethyl)hydrazines, conceived as more potent analogs of 1-(2-chloroethyl)-1,2,2-tris(methylsulfonyl)hydrazine, were synthesized and evaluated for antineoplastic activity against the L1210 leukemia in mice. Of these, 1-acetyl-1,2-bis-(methylsulfonyl)-2-(2-chloroethyl)hydrazine produced "cures" of mice bearing the L1210 leukemia at dosage levels that were considerably less than those at which the tris(sulfonyl) analog produced its antineoplastic effects. This compound was also found to have pronounced activity against the P388 leukemia and against several solid tumors, including the B16F10 melanoma, the M5076 reticulum cell sarcoma, and the M109 lung carcinoma. Furthermore, the acyl derivatives were in general considerably more resistant to hydrolysis in aqueous media and more prone to protease- and thiol-mediated activation than the tris(sulfonyl) analog. The former property is important to formulation, while the latter properties may result in some degree of drug targeting and enhancement of the therapeutic indices of these agents.

Anticonvulsant properties of some Mannich bases of conjugated arylidene ketones

Thirty 1-aryl-5-dimethylamino-1-penten-3-one hydrohalides and related compounds were prepared as candidate anticonvulsants and evaluated in maximal electroshock seizure (MES), subcutaneous pentylenetetrazole threshold, and neurotoxicity screens. Following administration by the intraperitoneal route, many of the compounds were active in the MES screen, whereas only 10% of the Mannich bases afforded protection in the subcutaneous pentylenetetrazole test. Quantitation of half of the compounds prepared revealed that many had activity comparable with that of clinically useful drugs in the MES screen. The anticonvulsant properties of eight of the compounds following oral administration were reduced considerably or abolished compared with those following intraperitoneal administration. Various synthetic strategies for future development of potential anticonvulsants are outlined.

The effects of the methylating agent 1,2-bis(methylsulfonyl)-1-methylhydrazine on morphology, DNA content and mitochondrial function of Trypanosoma brucei subspecies

Repeated exposure of trypanosomes in vitro or in vivo to low concentrations of the methylating agent 1,2-bis(methylsulfonyl)-1-methylhydrazine induces a series of moderately synchronous morphological and biochemical changes. Cell division halts and the long-slender bloodstream forms transform to short-stumpy forms via larger intermediate-stage cells which contain approximately double the normal G2 content of DNA. In common with naturally occurring short-stumpy trypanosomes, drug-induced short-stumpy forms do not infect rodents and when transferred to Cunningham's medium, transform to and replicate as procyclics. Furthermore, these short-stumpy forms exhibit alpha-ketoglutarate supported motility and oxygen consumption, acquire the ability to reduce nitroblue tetrazolium (NADH diaphorase positivity) and appear to be in the G1 or G0 stage of the cell cycle based upon DNA content.

Synthesis and evaluation of 1,2,2-tris(sulfonyl)hydrazines as antineoplastic and trypanocidal agents

Several 1,2,2-tris(sulfonyl)hydrazines, conceived as prodrugs of 1,2-bis(sulfonyl)hydrazines, were synthesized and evaluated for antineoplastic and trypanocidal activities in mice. 1-Methyl-1,2,2-tris(methylsulfonyl)hydrazine emerged as an extremely efficacious antitrypanosomal agent, whereas 1-(2-chloroethyl)-1,2,2-tris(methylsulfonyl)hydrazine was inactive. In contrast, 1-(2-chloroethyl)-1,2,2-tris(methylsulfonyl)hydrazine displayed potent antineoplastic activity, producing several 60-day "cures" of mice bearing leukemia L1210, leukemia P388, or Sarcoma 180. Furthermore, the fact that the tris(sulfonyl) derivatives will not generate isocyanates, which contribute to the host toxicity of nitrosoureas like 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), makes them agents of significant promise in trypanosomal and cancer chemotherapy.

Methylating agents as trypanocides

Methylating agents, such as streptozotocin, procarbazine, N-methyl-N-nitrosourea, dimethyl sulfate, 1,2-dimethylhydrazine, and a series of 1,2-bis(sulfonyl)-1-methylhydrazines synthesized in this laboratory, were evaluated and shown to be therapeutically active against murine models of African trypanosomiasis. At high dose levels, methylating agents halted trypanosome proliferation and transformed cells into bizarre forms containing multiple nuclei and kinetoplasts. These cells disappeared from the bloodstream of mice bearing these organisms in 48-72 h. When administered at repetitive low doses, methylating agents induced the entire population of trypanosomes to differentiate into biochemically distinct short-stumpy forms in a synchronous manner. These results suggest that methylating agents may be used as biochemical tools in the study of trypanosome differentiation.

Cytotoxic and DNA-damaging effects of 1,2-bis(sulfonyl)hydrazines on human cells of the Mer+ and Mer- phenotype

A series of 1,2-bis(sulfonyl)hydrazines with the capacity to function as alkylating agents have been evaluated for their toxicity towards Mer- HT29 and Mer- BE cells, and for their ability to produce DNA damage expressed as single-strand breaks and DNA interstrand cross-links. Compounds of this class with methylating potential showed a marked difference in their capacity to inhibit the growth of Mer- and Mer+ cells, being considerably more toxic to BE Mer- cells. Dose-dependent DNA single-strand breaks were induced by these agents, with the quantity of breaks produced in Mer- and Mer+ cells being essentially the same. Maintenance of these lesions did not appear to explain the differential in toxicity to BE and HT29 cells. A chloroethylating compound of this class was also more toxic to Mer- BE cells than to Mer+ HT29 cells, but the differential toxicity was considerably less than that of the methylating agents of the series. The chloroethylating agent did not produce measurable single-strand breaks of the DNA of treated cells, but caused more DNA interstrand cross-links in Mer- cells than in Mer+ cells. Thus, DNA interstrand cross-links may be at least in part responsible for the cell kill produced by this agent. The findings suggest that methylating and chloroethylating derivatives of the 1,2-bis(sulfonyl)hydrazine family have different biochemical determinants of their cytodestructive actions.

Novel 1-haloalkyl-2-nitroimidazole bioreductive alkylating agents

Solid tumors contain hypoxic cells which are relatively resistant to radiation treatment and to most forms of chemotherapy. These cells can be preferentially targeted using chemotherapeutic agents that are specifically activated by cellular reductase enzymes in the absence of oxygen. A new class of bioreductive alkylating agents based on the 2-nitroimidazole nucleus has been developed which contains a haloalkyl substituent on the N-1 position of the imidazole ring. Compounds of this series were readily reduced by mammalian NADPH-cytochrome c reductase, and reduction led to the production of an electrophilic center. This reactive component was hypothesized to be responsible for the preferential cytotoxicity of the agents of this class to hypoxic tumor cells through alkylation of cellular components.

1,2-Bis(sulfonyl)hydrazines. 3. Effects of structural modification on antineoplastic activity

A series of 1,2-bis(sulfonyl)hydrazines was synthesized and evaluated for antineoplastic activity against the L1210 leukemia and the B16 melanoma. The most active agent to emerge from this study, 1,2-bis(methylsulfonyl)-1-methylhydrazine, produced a maximum % T/C for mice bearing the L1210 leukemia or the B16 melanoma of 340% and 278%, respectively. Two N-chloroethyl analogues, conceived as bifunctional alkylating agents, were also synthesized and evaluated for antineoplastic activity against the L1210 leukemia and the B16 melanoma. Although such a modification resulted in retention of antineoplastic activity against both tumor cell lines, it did not result in enhanced antineoplastic activity.

Synthesis and evaluation of 1-(arylsulfonyl)-2-[(methoxycarbonyl)sulfenyl]-1-methylhydrazines++ + as antineoplastic agents

1-(Arylsulfonyl)-2-[(methoxycarbonyl)sulfenyl]-1-methylhydrazines, with the potential to function as biological methylating agents, were synthesized and evaluated as antineoplastic agents against the L1210 leukemia and the B16 melanoma in mice. All of the compounds of this class had significant activity against the B16 melanoma, with the most active compound, 2-[(methoxycarbonyl)sulfenyl]-1-methyl-1-[(4- methylphenyl)sulfonyl]hydrazine, producing percent T/C values for B16 melanoma tumor bearing mice of between 182 and 232 at dosage levels of from 12.5 to 50 mg/kg daily for 6 consecutive days. In contrast to the related class of agents, the N,N'-bis(sulfonyl)hydrazines reported earlier by this laboratory,1 the 1-(arylsulfonyl)-2-[(methoxycarbonyl)sulfenyl]-1-methylhydrazines were found to be inactive against the L1210 leukemia in vivo.

Synthesis and evaluation of 2-substituted 1-methyl-1-(4-tolylsulfonyl)hydrazines as antineoplastic agents

Several N-2 substituted 1-methyl-1-(4-tolylsulfonyl)hydrazines were synthesized and evaluated for antineoplastic activity against the L1210 leukemia and the B16 melanoma. The most active compound to emerge from this study, 2-(methylsulfonyl)-1-methyl-1-(4-tolylsulfonyl)hydrazine, produced maximum percent T/C values with L1210 leukemia and B16 melanoma tumor bearing mice of 207 and 209, respectively. While the attachment of an aryl-, aralkyl-, or alkylsulfonyl moiety to N-2 resulted in retention of activity against both tumor systems, the corresponding benzoyl, 4-nitrobenzoyl, and (2-nitrophenyl)sulfenyl analogues only displayed activity against the L1210 leukemia.

1,2-bis(arylsulfonyl)hydrazines. 2. The influence of arylsulfonyl and aralkylsulfonyl substituents on antitumor and alkylating activity

Several 1,2-bis(arylsulfonyl)-1-methylhydrazines were synthesized and evaluated for antineoplastic activity against the L1210 leukemia. The most active compound to emerge from this study, 2-[(4-chlorophenyl)sulfonyl]-1-methyl-1-(4-tolylsulfonyl)hydrazine , increased the survival time of tumor-bearing mice by 88%. The alkylating activity of the synthesized analogues and several compounds reported earlier was determined by measuring the absorbance at 540 nm of the alkylated product of 4-(4-nitrobenzyl)pyridine. The results obtained support the concept that the ability to alkylate is a necessary but not a sufficient condition for the expression of antitumor activity by agents of this class.

Synthesis and evaluation of N,N'-bis(arylsulfonyl)hydrazines as antineoplastic agents

Several N,N'-bis(arylsulfonyl)hydrazines, with the potential to function as biological methylating agents, were synthesized and evaluated for antineoplastic activity against the L1210 leukemia and other transplanted rodent tumors. In general, the N-methyl-N,N'-bis(arylsulfonyl)hydrazines that possess the capacity to generate an alkylating species under physiological conditions showed significant antineoplastic activity, while N,N'-bis(phenylsulfonyl)-hydrazine and N-methyl-N,N'-dibenzoylhydrazine were inactive.

Relationship between structure and antineoplastic activity of (arylsulfonyl)hydrazones of 4-pyridinecarboxaldehyde

The effects of various structural modifications on the antineoplastic activity of (arylsulfonyl)hydrazones of 4-pyridinecarboxaldehyde were examined in mice bearing either Sarcoma 180 or P388 leukemia. The introduction of different functional groups into the phenyl ring of the benzenesulfonyl moiety did not alter tumor inhibitory activity appreciably, and the pyridine ring could be replaced by 4-nitrobenzene without loss of antineoplastic activity. However, the aldehyde proton and the hydrazone proton alpha to the sulfonyl group were essential, and their substitution resulted in inactive anticancer agents.

Decomposition of 1-aryl-3-dimethylamino-1-propanone methobromides under weakly acidic conditions

Under basic conditions, some 1-aryl-3-dimethylamino-1-propanone methodbromides (2) were shown to decompose too readily to measure by the electronic absorption spectroscopy technique available. However, at pH = 5.9 and 20 degrees centigrade, the rate of deamination to the corresponding 1-aryl-2-propen-1-ones was able to be followed using Guggenheim's method and a Hammett plot showed that the rate of deamination correlated with the arly substituent constants (o). The rho value for this process was +1.00. In contrast the corresponding 1-arly-3-dimethylamino-1-propanone hybrobromides (1) did not decompose under simulated physiological conditions (pH = 7.4, 37 degrees centigrade). Neither 1 or 2 were active against P388 lymphocytic leukemia in mice but the methobromides displayed greater murine toxicity.