Activity of bis-carbamoyloxymethyl derivatives of pyrroles and pyrrolizines against human tumor xenografts in nude mice.

The activities of the pyrrolizines, Compounds I and II, and the pyrroles, Compounds IV and V, are reported in nude mouse-grown HT-29 human adenocarcinoma of the colon, DO 1 human oat carcinoma of the lung, and CL 1 human duct cell carcinoma of the breast (coded as CX-1, LX-1, and MX-1, respectively, by the National Cancer Institute). Compounds II and IV were active against all three experimental tumors; both compounds produced significant tumor regression in the human breast tumor xenograft and Compound IV caused tumor regression in the human lung tumor xenograft.

In vivo and in vitro evaluation of the alkylating agent carmethizole.

Carmethizole, a novel bis-carbamate alkylating agent, was evaluated in vitro for potential mechanisms of interaction with DNA and in vivo for spectrum and degree of antitumor activity. In vitro, the concentration of carmethizole required to produce a 50% reduction in clonogenic cell survival was identical in O6-alkylguanine DNA alkyltransferase-positive and -negative human cell lines. The CHO cell line UV4, hypersensitive to mono- and bifunctional alkylating agents, was 37-fold more sensitive to carmethizole than normal cells. The UV5 cell line, which is not hypersensitive to cross-linkers, was 13-fold more sensitive to carmethizole than normal cells. Alkaline elution studies in L1210 cells exposed to carmethizole showed the presence of DNA-protein and DNA-DNA cross-links but not DNA strand breaks. These data suggested that the interaction of carmethizole with DNA produces monoadducts, DNA-protein, and DNA-DNA interstrand cross-links at several sites. In vivo, carmethizole was not cross-resistant with 1,3-bis(2-chloroethyl)-1-nitrosourea or Cytoxan as determined by testing against P388 leukemias resistant to the latter 2 agents. Carmethizole activity was similar to that of melphalan across the murine solid tumor panel, which consisted of B16 melanoma; colon adenocarcinomas 11a, 26, and 36; and the KHT sarcoma. Carmethizole, Cytoxan, and melphalan were all active and had comparable activity against the HCT-8 and MX-1 human tumor xenografts. The in vivo spectrum of activity and efficacy of carmethizole was similar to that of melphalan.

Synthesis and evaluation of furan, thiophene, and azole bis[(carbamoyloxy)methyl] derivatives as potential antineoplastic agents.

A series of bis(hydroxymethyl)-substituted heterocycles were synthesized and converted to the corresponding bis(methylcarbamate) derivatives. The heterocyclic systems studied were based on 2-phenyl-3-methylfuran (2-4), 1-phenylpyrazole (5-7), 1-phenyl-5-methylpyrazole (9-11), 1-phenyl-5-methylthiophene (13), 1-phenyl-1,2,3-triazole (14), 3-phenylisoxazole (15), 3-phenylisothiazole (16), 2-phenylthiazole (17), and 2-phenyloxazole (18). None of the bis(carbamates) prepared was active against murine P388 lymphocytic leukemia. Pyrrole bis(carbamates) 20 and 21, which exhibited antileukemic activity, also showed reactivity toward 4-(p-nitrobenzyl)pyridine while the inactive bis(carbamates) were unreactive in the 4-(p-nitrobenzyl)pyridine assay.

Synthesis of 8-methoxy-15,16-dinor-6,8,10-trichothecatriene 12,13 alpha-epoxide and 12,13 beta-epoxide as potential antineoplastic agents.

8-Methoxy-15,16-dinor-6,8,10-trichothecatriene 12,13 alpha-epoxide (5) and 12,13 beta-epoxide (3) were prepared; the stereochemistry of the epoxides was assigned on the basis of 13C NMR. The epoxide 5 was active against 9KB in vitro and P388 in vivo, while the isomeric epoxide 3 was inactive in both test systems.

Synthesis and antileukemic activity of 5-substituted 2,3-dihydro-6,7-bis(hydroxymethyl)-1H-pyrrolizine diesters.

Treatment of N-acylproline derivatives, 2, with acetic anhydride--dimethyl acetylenedicarboxylate (DMAD) gave 5-substituted derivatives of dimethyl 2,3-dihydro-1H-pyrrolizine-6,7-dicarboxylate (5). The reaction proceeds via a 1,3-dipolar addition of DMAD with the mesoionic oxazalone intermediate 3, generated in situ, with concomitant elimination of carbon dioxide. Reduction of 5 gave the diols 6 which upon subsequent acylation gave 1. The bis(N-methylcarbamate) 1d and the diacetate li show a modest level of in vivo antileukemia activity in the L1210 assay. A majority of the diesters, 1, showed significant antileukemic activity in the in vivo P-388 assay. The bis(carbamate) 1d afforded "cures" at dose levels as low as 12.5 mg/kg; 1 q showed potent activity at doses as low as 0.78 mg/kg. Several other compounds showed potent activity against P-388 over a greater than fourfold dose range with no acute toxicity. Half-lives for several diacetate derivatives of 1 were determined for aqueous Me2SO solutions. The preparation of 7 and 8 shows that 1 may react by O-alkyl ester cleavage.

Synthesis and structure-activity relationship studies of cytotoxic epoxide derivatives of 7-oxabicyclo[2.2.1]heptane.

Dimethyl exo-5,6-oxido-7-oxabicyclo[2.2.1]hept-2-ene-2,3-dicarboxylate (1) and the 1-methyl homologue 2 were shown to exhibit significant cytotoxicity in the 9KB tissue culture assay. Several analogues of 1 were prepared and it was found that removal of the epoxide, or the oxygen bridge, or the 2,3 double bond from 1 resulted in loss of significant cytotoxic activity. One compound which lacked the epoxide moiety, dimethyl 1-methyl-7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate (5), also exhibited marginal cytotoxic activity.

Antileukemic activity of derivatives of 1-phenyl-2,5-dimethyl-3,4-bis(hydroxymethyl)pyrrole bis(N-methylcarbamate).

Treatment of N-aryl-N-acetylalanine derivatives, 3, with acetic anhydride-dimethyl acetylenedicarboxylate gave the dimethyl N-aryl-2,5-dimethylpyrrole-3,4-dicarboxylates, 4. Reduction of 4 and acylation of 5 gave 2a-j and 6. All of the title compounds 2a-j and 6 showed significant reproducible activity in the P388 in vivo antileukemic assay.

Antileukemic activity of derivatives of 1,2-dimethyl-3,4-bis(hydroxymethyl)-5-phenylpyrrole bis(N-methylcarbamate).

A series of phenyl-substituted derivatives of 1,2-dimethyl-3,4-bis(hydroxymethyl)-5-phenylpyrrole bis(N-methylcarbamate) (1) were synthesized and tested for antileukemic activity against P388 lymphocytic leukemia in the mouse. All of the compounds tested, 1a--r, showed significant activity in this assay. Selected derivatives of 1 were tested against several bacteria and were found to have little or no antibacterial activity in the systems examined.

Synthesis and antineoplastic activity of bis[[[(alkylamino)carbonyl]oxy]methyl]-substituted 3-pyrrolines as prodrugs of tumor inhibitory pyrrole bis(carbamates).

A series of bis[(carbamoyloxy)methyl]pyrrolines 2-4 were synthesized from either the appropriate alpha-silylated iminium salt, or an aziridine, or a 2H-azirine in a sequence involving 1,3-dipolar cycloaddition reactions. The antineoplastic activities of the pyrrolines were compared to the corresponding pyrroles. The C-2 gem-dimethyl-substituted pyrroline, 4, which cannot be converted to the pyrrole in vivo, was inactive. The activity of the 2-phenyl-substituted pyrrolines 3 was markedly dependent on the nature of the phenyl substituent, although the corresponding phenylpyrroles all showed comparable activity. The differences in the activities of the pyrrolines 3 may be due to the rate of metabolic conversion of the pyrroline to the pyrrole. Electron-withdrawing substituents on the phenyl ring appear to retard this process.

Comparison of the chemical reactivities and antineoplastic activities of alpha,beta-, alpha,beta'-, beta,beta'-, and alpha,alpha'-bis[[[(2-propylamino)carbonyl]oxy]methyl]-substituted pyrroles.

The bis[N-(2-propyl)carbamate] derivatives of 2,3-bis(hydroxymethyl)-4,5-diphenyl-1-methylpyrrole (4a), 3,4-bis-(hydroxymethyl)-2,5-diphenyl-1-methylpyrrole (4b), 2,4-bis(hydroxymethyl)-3,5-diphenyl-1-methylpyrrole (4c), and 2,5-bis(hydroxymethyl)-3,4-diphenyl-1-methylpyrrole (4d) were synthesized and the reactivities of the four compounds were compared using the model nucleophile 4-(p-nitrobenzyl)pyridine (NBP). No significant correlation was seen between NBP reactivity and either toxicity or antineoplastic activity in this series. Three compounds 4a, 4b, and 4c gave significant reproducible activity against P388 lymphocytic leukemia; the alpha,alpha'-bis(carbamate) 4d was inactive. The alpha,beta- and alpha,beta'-bis(carbamates) 4a and 4c were evaluated against a panel of mouse tumor homografts and human tumor xenografts implanted under the kidney capsule of mice.

Synthesis, chemical reactivity, and antileukemic activity of 5-substituted 6,7-bis(hydroxymethyl)pyrrolo[1,2-c]thiazole biscarbamates and the corresponding sulfoxides and sulfones.

A series of bis(N-methylcarbamate) and bis[N-(2-propyl)carbamate] derivatives of 5-substituted 6,7-bis(hydroxy-methyl)pyrrolo[1,2-c]thiazoles was prepared. The compounds were tested for activity in vivo against P388 lymphocytic leukemia, and the chemical reactivities of the compounds were compared by using the model nucleophile 4-(4-nitrobenzyl)pyridine (NBP). The 5-(3,4-dichlorophenyl)-substituted biscarbamates 6b, 8b, and 12b were inactive and unreactive toward NBP. The 5-methyl-substituted biscarbamates 6a, 7a, 8a, 9a, 12a, and 13a were all active against murine P388 lymphocytic leukemia. The chemical reactivities of the active compounds depended on the oxidation state of the sulfur. The reactivity toward NBP followed the order S greater than SO much greater than SO2. The sulfones 12a and 13a are the most active compounds in this series, and their lack of reactivity toward NBP led to the suggestion that 12a and 13a are activated in vivo.

3-Pyrroline N-oxide bis(carbamate) tumor inhibitors as analogues of indicine N-oxide.

The 2,3-bis[[(N-methylcarbamoyl)oxy]methyl]-3-pyrroline 1-oxide 5 was synthesized and tested in the murine P388 lymphocytic leukemia model. The compound showed significant reproducible activity and was more potent than indicine N-oxide. 1-Methyl-2-phenyl-3,4-bis[[(N-2- propylcarbamoyl)oxy]methyl]-3-pyrroline N-oxide (6) was less active than 5, and the 5,5-dimethyl analogue of 6, the pyrroline N-oxide 7, was inactive. The N-oxide 7 cannot be converted to a pyrrole in vivo because of the gem-dimethyl substitution at C-5.

Design, synthesis, and study of 9-substituted ellipticine and 2-methylellipticinium analogues as potential CNS-selective antitumor agents.

N,N-Dimethylformamide (DMF) dineopentyl acetal-mediated O-alkylations of 9-hydroxyellipticine gave 9-ethoxy-, 9-(1-methylethoxy)-, and 9-(1,1-dimethylethox)ellipticine (3a, 4a, and 5a, respectively). Methylation of the O-alkylellipticines gave the corresponding N-methylpyridinium iodides (3b, 4b, and 5b). The iodides were converted to the acetates (3c, 4c, and 5c) by ion-exchange resin. Attempts to prepare 9-(2,2,2-trifluoroethoxy)ellipticine (6a) using the DMF acetal gave 10-(2,2,2-trifluoroethoxy)-9-hydroxyellipticine (8a). 9-(2,2,2-Trifluoroethoxy)- and 9-phenoxyellipticine (6a and 7a, respectively) were prepared by total synthesis. The ellipticines and N-methylellipticinium derivatives were evaluated for in vitro antitumor activity against a panel of human tumors. 2-Methyl-9-(1,1-dimethylethoxy)ellipticinium acetate (5c) was inactive, but all of the other compounds exhibited significant antitumor activity. The ellipticines showed no significant subpanel specificity; however, the N-methylellipticinium compounds tested did exhibit specificity for the CNS tumor subpanel.

Design, synthesis, antineoplastic activity, and chemical properties of bis(carbamate) derivatives of 4,5-bis(hydroxymethyl)imidazole.

A series of bis(carbamate) derivatives of 1,2-substituted 4,5-bis(hydroxymethyl)imidazoles were prepared and evaluated against murine P388 lymphocytic leukemia. Electron-withdrawing substituents at either N-1 or C-2 gave rise to inactive compounds. However, electron-donating substituents gave active compounds and the 2-(methylthio)-1-methyl derivative 2i (carmethizole), as the bis(N-methylcarbamate), was found to be very active. The derivative 2i, referred to by the name carmethizole, was also shown to be active against the MX-1 mammary xenograft, the human amelanotic melanoma cell line (LOX) xenograft, the M5076 sarcoma, and L1210 lymphocytic leukemia. The solution stability, water solubility, pKa, and log P of carmethizole are also reported.

Synthesis, chemistry, and antineoplastic activity of alpha-halopyridinium salts: potential pyridone prodrugs of acylated vinylogous carbinolamine tumor inhibitors.

A series of 4- and 5-[2,3-dihydro-6,7-bis[[(N-alkylcarbamoyl)oxy]methyl]-1H-pyrrol izin-5- yl]-2-halopyridinium iodides were synthesized. The rates of hydrolysis of the alpha-halopyridinium salts to the corresponding pyridones, and the reactivities of the carbamate moieties were studied as a function of pH, buffer composition, and ionic strength. The 4- and 5-pyrrolizinyl-2-halopyridinium iodides and the corresponding pyridones were evaluated against P388 lymphocytic leukemia in vivo. The alpha-fluoropyridinium compounds were active but the alpha-chloro compounds were not. This activity was correlated with the rates of hydrolysis of the alpha-halopyridinium compounds to the active pyridone. Compounds that were active in the P388 screen were evaluated in L1210 leukemia, M5076 carcinoma, and MX-1 mammary xenograft assays in mice.

Allylic esters as potential antitumor agents. Derivatives and analogues of 2,3-bis(hydroxymethyl)-7-oxabicyclo[2.2.1]hept-2-ene.

Derivatives and analogues of 2,3-bis(hydroxymethyl)-7-oxabicyclo[2.2.1]hept-2-ene were synthesized. Of the compounds prepared, dimethyl 2,3-bis(acetoxymethyl)-7-oxabicyclo[2.2.1]hepta-2,5-diene-5,6-dicarboxylate (5) was the most potent in a leukemia L1210 tissue culture assay (93% inhibition at 10(-6) M). None of the compounds showed significant reproducible in vivo antileukemic activity.

Synthesis, chemical reactivity, and antitumor evaluation of congeners of carmethizole hydrochloride, an experimental "acylated vinylogous carbinolamine" tumor inhibitor.

A series of analogues of 4,5-bis(((N-methylcarbamoyl)oxy)methyl)-1-methyl-2-(methylthio)-im idazole (1, carmethizole) were synthesized. The chemical reactivities of the analogues (as electrophiles) were evaluated and related to the antitumor activity (in vivo and in vitro). Changes in the alkylthio moiety had a significant effect upon the chemical reactivity. Electron-withdrawing groups on the sulfur decreased chemical reactivity and, in parallel, decreased antitumor activity. Carmethizole sulfoxide (11a) was unreactive as an electrophile and exhibited no antitumor activity either in vivo or in vitro; this led to the conclusion that carmethizole sulfoxide was not acting as a "carrier form" of carmethizole. The disulfides 17 and 18 were unreactive as electrophiles but did exhibit antitumor activity. The activity of 17 and 18 was attributed to the thiol 10 that would be generated upon cleavage of the disulfide bond.

Synthesis, evaluation of chemical reactivity, and murine antineoplastic activity of 2-hydroxy-5-(3,4-dichlorophenyl)-6,7-bis(hydroxymethyl)-2,3-dihydro-1H- pyrrolizine bis(2-propylcarbamate) and 2-acyloxy derivatives as potential water-soluble prodrugs.

2-Hydroxy-5-(3,4-dichlorophenyl)-6,7-bis(hydroxymethyl)-2,3-dihydro-1H- pyrrolizine bis(2-propylcarbamate) (11) was prepared in a multistep synthesis. The 2-hydroxy group was used to prepare ester prodrugs 14 and 15, and the antineoplastic activities of 11, 14, and 15a were compared to 1 (the 2-deoxy analogue of 11) in murine P388 lymphocytic leukemia and B16 melanocarcinoma. The alcohol 11 showed comparable activity to 1, while 14 was less active and 15a showed very low activity. The hydrolytic rates of 1, 11, 14, 15a, and 15b were compared, and it was found that the two carbamate moieties were much more susceptible toward hydrolysis than the C-2 esters. The salts 15a and 15b exhibited good water solubility, 3.0 X 10(-2) and 3.88 X 10(-2) M, respectively.

Synthesis and antileukemic activity of bis[[(carbamoyl)oxy]methyl]- substituted pyrrolo[2,1-a]isoquinolines, pyrrolo[1,2-a]quinolines, pyrrolo[2,1-a]isobenzazepines, and pyrrolo[1,2-a]benzazepines.

A series of bis[[(carbamoyl)oxy]methyl]-substituted pyrrole-fused tricyclic heterocycles were synthesized by using 1,3-dipolar cycloaddition reactions with a trifluoromethanesulfonate salt of an appropriate Resissert compound or with a mesoionic oxazolone intermediate. All of the bis(carbamates) were active in vivo against P388 lymphocytic leukemia with 5,6-dihydro-8-methoxy-1,2- bis(hydroxymethyl)pyrrolo[2,1-a]isoquinoline bis[N-(2-propyl)carbamate] (3c) showing the highest level of activity.

Synthesis and antileukemic activity of 1-methyl-2,5-diphenyl-3,4-bis(hydroxymethyl)-, 1,2,3-triphenyl-4,5-bis(hydroxymethyl)-, and 1-methyl-2,3-diphenyl-4,5-bis(hydroxymethyl)pyrrole bis(N-methylcarbamate).

The syntheses for the bis(N-methylcarbamates) 3, 4a, 4b, and 5 are described. All four compounds were active in the in vivo P388 lymphocytic leukemia assay, with 3 being the most active.