Antimalarial activity of 2-(substituted amino)-4,6-bis(trichloromethyl)-1,3,5-triazines and N-(chlorophenyl)-N'-[4-(substituted amino)-6-(trichloromethyl)-1,3,5-triazin-2-yl]guanidines.

A series of 2-[[(dialkylamino)alkyl]amino]-4,6-bis(trichloromethyl)-1,3,5-triazines (III) and N-(4-chlorophenyl)-N'-[4-[[(dialkylamino)alkyl]amino]-6- (trichloromethyl)-1,3,5-triazin-2-yl]guanidines (IV) were prepared from 2,4,6-tris(trichloromethyl)-1,3,5-triazine and 2-chloro-4,6-bis(trichloromethyl)-1,3,5-triazine. Compounds of type III showed modest antimalarial activity while XIa with the camoquin side chain was more potent. Analogues of type IV broadly exhibited modest antimalarial activity.

Anthrapyrazole anticancer agents. Synthesis and structure-activity relationships against murine leukemias.

Chromophore modification of the anthracenediones related to mitoxantrone in an attempt to provide agents with diminished or no cardiotoxicity has resulted in a novel class of DNA binders, the anthrapyrazoles. Their synthesis was carried out by a two-stage condensation sequence starting from requisite 1,4- or 1,5-dichloro-9,10-anthracenedione precursors. Reaction with a monoalkylhydrazine gave a chloroanthrapyrazole intermediate whose subsequent condensation with primary or secondary alkylamines provided the target "two-armed" anthrapyrazoles. A-ring 7,10-dihydroxy anthrapyrazoles were derived from amine condensation with intermediate 5-chloro-7,10-dihydroxyanthrapyrazoles or, alternatively, from intermediate 5-chloro-7,10-bis(benzyloxy)anthrapyrazoles followed by hydrogenolysis of the benzyl protecting groups to provide the target compounds. Potent in vitro activity was demonstrated against murine L1210 leukemia in vitro (IC50 = 10(-7)-10(-8) M) as well as against P388 leukemia in vivo over a wide range of structural variants. In general, activity against the P388 line was maximized by basic side chains at N-2 and C-5, two to three carbon spacers between proximal and distal nitrogens of the side chain, and A-ring hydroxylation. Besides having curative activity against the P388 line, the more active compounds were curative against murine B-16 melanoma in vivo. On the basis of their exceptional in vivo anticancer activity, A-ring dihydroxy compounds 71 and 74 reported in this study have been selected for development toward clinical trials.

Pyrazole derivatives. 5. Synthesis and antineoplastic activity of 3-(2-chloroethyl)-3,4-dihydro-4-oxopyrazolo[5,1-d]-1,2,3, 5-tetrazine-8-carboxamide and related compounds.

Two pyrazolotetrazine derivatives were synthesized as the analogous prodrugs of the light-sensitive antineoplastic agents dacarbazine and BIC. Both the pyrazole derivatives are stable under ordinary light illumination. Biological evaluation of these pyrazoles revealed that the compound containing a 2-chloroethyl function (6a) demonstrated good antineoplastic activity in experimental animals, but the one containing a methyl function (6b) was inactive. The inactivity of compound 6b may suggest that compound 6a and related imidazotetrazines may simply act as biological alkylating agents per se rather than as prodrugs. The information could also imply that the postulated dealkylation mechanism for the triazene derivatives should be reexamined.

In vitro activity of the novel antitumor antibiotic fostriecin (CI-920) in a human tumor cloning assay.

A human tumor cloning assay was utilized to evaluate the antineoplastic activity of the novel antitumor antibiotic fostriecin (CI-920). Initial screening with 10.0 mcg/ml continuous exposure against a variety of histologic tumor types resulted in 14/51 (27%) in vitro responses (defined as greater than 50% decrease in TCFUs). Further investigation of the compound was performed in 1-hr preincubation experiments. The in vitro response rate at a concentration of 1.0 mcg/ml (which was considered to correspond to a clinically achievable concentration) was 15/43 (35%). Response rates for specific tumor types included: 5/15 in ovarian cancer, 5/12 in breast, and 4/11 in human lung cancer. The impression of significant antitumor activity of the compound at this dose was further substantiated by comparing its in vitro activity with a variety of simultaneously tested standard anticancer agents. In addition, these data indicated the possibility of non-cross resistance of CI-920 to several established cytostatics. CI-920 is a compound with good in vitro activity which should be further developed for clinical trials.

Synthesis, antimalarial activity, and quantitative structure-activity relationships of tebuquine and a series of related 5-[(7-chloro-4-quinolinyl)amino]-3-[(alkylamino)methyl] [1,1'-biphenyl]-2-ols and N omega-oxides.

A series of 5-[(7-chloro-4-quinolinyl)amino]-3-[(alkylamino)methyl] [1,1'-biphenyl]-2-ols and N omega-oxides was prepared from the substituted 1-phenyl-2-propanones proceeding through the 5-nitro[1,1'-biphenyl]-2-ols, the corresponding amino, and acetamido derivatives to the N-[5-[(alkylamino)methyl]-6-hydroxy[1,1'-biphenyl]-3-yl]acetamides and final condensation with 4,7-dichloroquinoline or the N-oxide. In a quantitative structure-activity relationship study first run on 28 and later expanded to 40 substituted phenyl analogues and their N omega-oxides, increasing antimalarial potency vs. Plasmodium berghei in mice was found to be correlated with decreasing size (sigma MR) and electron donation (sigma sigma) of the phenyl ring substituents. A significant correlation with N omega-oxidation could not be demonstrated. Initial high activity against P. berghei infections in mice led to expanded studies that demonstrated in addition excellent activity against resistant strains of parasite, activity in primate models, and pharmacokinetic properties apparently allowing protection against infection for extended periods of time even after oral administration. Such properties encourage the clinical trial of a member of this class in man.

Folate antagonists. 21. Synthesis and antimalarial properties of 2,4-diamino-6-(benzylamino)pyrido[3,2-d]pyrimidines.

The synthesis and antimalarial activity of a series of 2,4,6-triaminopyrido[3,2-d]pyrimidines (4) is described. Several 6-substituted benzylmethylamino analogues were more active against trophozoite induced Plasmodium berghei in mice than the corresponding quinazoline analogues. These agents, however, are cross-resistant to other antifolate compounds and are thus of limited potential as human agents.

Folate antagonists. 22. Antimalarial and antibacterial effects of 2,4-diamino-6-quinazolinesulfonamides.

The synthesis and antimalarial activity of a series of 2,4-diamino-6-quinazolinesulfonamides (III) is described. Chlorosulfonation of 2,4-quinazolinediamine affords the 6-sulfonyl chloride, which upon treatment with the appropriate amine produces the desired products. Alternatively the sulfonyl chloride could be introduced by diazotization of the corresponding amine followed by treatment with SO2 in the presence of CuCl2. Although substantial antimalarial activity was demonstrated for several members of this class, studies were discontinued in light of the potency of related series.

Biochemical pharmacology of the lipophilic antifolate, trimetrexate.

Trimetrexate is a novel lipophilic folate antagonist that causes growth inhibition, inhibition of nucleic acid biosynthesis, and cytotoxicity at nanomolar concentrations in tissue cultures. The potency of trimetrexate cytotoxicity against most cell lines is greater than that of methotrexate. Trimetrexate has antitumor activity in vivo in several murine leukemia and solid tumor systems, including tumors in which methotrexate is inactive. Antitumor activity was seen following oral, intravenous, or intraperitoneal administration. Trimetrexate causes a pronounced and early depression in incorporation of deoxyuridine into DNA. In tumor cell lines resistant to methotrexate because of a drug transport defect, trimetrexate retains activity. In many such cases the methotrexate-resistant tumors show collateral sensitivity to trimetrexate. In methotrexate-resistant cells with impaired drug transport, trimetrexate sensitivity was even more pronounced when cells were grown in folate-free medium supplemented with physiological levels of tetrahydrofolate cofactor. In the human tumor stem cell colony assay, trimetrexate, at concentrations achievable in vivo, gave activity against many human tumors, including samples that were unresponsive to methotrexate. Trimetrexate crosses the blood-brain barrier, and at very high doses may cause neurotoxicity. At conventional doses the primary toxic effects in mice are gastrointestinal. This toxicity is reversible at therapeutic doses. Unlike earlier lipophilic antifolates, trimetrexate has rapid plasma clearance (t1/2 in mice of 45 minutes). Trimetrexate is a tight-binding competitive inhibitor of dihydrofolate reductase. The Ki,slope for inhibition of the human enzyme was 4 X 10(-11) M. A dose-dependent decrease in cellular purine ribonucleotide pools is given by trimetrexate. Pyrimidine ribonucleotide pools tend to increase in treated cells. Trimetrexate caused a marked depression of cellular pools of dTTP and dGTP, and a lesser depression in dATP. Cytotoxicity of trimetrexate in vitro was prevented by leucovorin. Leucovorin also protected mice from trimetrexate toxicity. Thymidine protected cells from lethal effects of low concentrations of trimetrexate, but not from high concentrations. The combination of thymidine and hypoxanthine completely protected cells from low and high concentrations of trimetrexate. A new, stable and highly water-soluble formulation of trimetrexate has been developed. Because of the interesting biochemical and pharmacological properties of trimetrexate, and its experimental antitumor activity, clinical trials are planned.

Folate antagonists. 20. Synthesis and antitumor and antimalarial properties of trimetrexate and related 6-[(phenylamino)methyl]-2,4-quinazolinediamines.

A series of 6-[(arylamino)methyl]-2,4-quinazolinediamines have been prepared by catalytic hydrogenation of the requisite 2,4-diamino-6-quinazolinecarbonitriles in the presence of the appropriate benzenamine. Formylation, acetylation, and nitrosation provided N omega derivatives of these compounds. A variety of the compounds exhibited potent antimalarial, antibacterial, and antitumor activity. In particular, 5-methyl-6-[[(3,4,5-trimethoxyphenyl)-amino]methyl]-2, 4-quinazolinediamine (trimetrexate, 15) has shown a broad spectrum of antitumor effects and is undergoing preclinical toxicology evaluation prior to trial in man.

Folate antagonists. 19. Synthesis and antimalarial effects of 6-(arylthio)-2,4-pteridinediamines.

A series of 6-(arylthio)-2,4-pteridinediamines (IIIa) was prepared by allowing 6-chloro-2,4-pteridinediamine to react with the requisite benzenethiols in dimethyl sulfone at 190-200 degrees C. Attempts at oxidation to the corresponding sulfoxide (IIIb) or sulfone (IIIc) were unsuccessful. The compounds exhibited a spectrum of antibacterial activity similar to, but below the potency of, the related quinazolinediamines and pteridinediamines. Unlike these related types, however, they were devoid of antimalarial activity when tested against a normal drug-sensitive strain of Plasmodium berghei in mice by the parenteral route.

Synthesis and antimalarial effects of N2-aryl-N4-[(dialkylamino)alkyl]- and N4-aryl-N2-[(dialkylamino)alkyl]-2,4-quinazolinediamines.

A series of N2(and N4)-aryl-N4(and N2)-[(dialkylamino)alkyl]-2,4-quinazolinediamines has been synthesized for antimalarial evaluation. Condensation of the appropriate 2,4-dichloroquinazoline (IV) with the requisite N,N-dialkylalkylenediamine afforded a series of 2-chloro-N-[(dialkylamino)alkyl]-4-quinazolinamines (V) which were condensed with the appropriate arylamine to provide the corresponding N2-aryl-N4-[(dialkylamino)alkyl]-2,4-quinazolinediamines (VI). Hydrolysis of 2,4-dichloroquinazoline to 2-chloro-4-quinazolinol was followed by condensation with the appropriate N,N-dialkylalkylenediamine to give an array of 2-[[(dialkylamino)alkyl]amino]-4-quinazolinols (IXa). Chlorination with phosphorus oxychloride and condensation with a requisite arylamine provided the N2-[(dialkylamino)alkyl]-N4-phenyl-2,4-quinazolinediamines (X). Antimalarial activity was general among the N2-aryl-N4-[(dialkylamino)alkyl]-2,4-quinazolinediamines (VI), while the reverse isomers were of lower activity. Phototoxic liability precluded clinical evaluation of a member of the series.

Folate antagonists. 18. Synthesis and antimalarial effects of N6-(arylmethyl)-N6-methyl-2,4,6-pteridinetriamines and related N6,N6-disubstituted 2,4,6-pteridinetriamines.

N6-(Arylmethyl)-N6-methyl-2,4,6-pteridinetriamines (1-15) and related N6-substituted 2,4,6-pteridinetriamines (16-20) were obtained by the condensation of 6-chloro-2,4-pteridinediamine with N-methylarylmethanamine and other selected secondary amines. The requisite N-methylarylmethanamines (21-32) were prepared by the hydrogenation over Pt/C of the corresponding arylcarboxaldehyde in the presence of methanamine. Several of the N6-(arylmethyl)-N6-methyl-2,4,6-pteridinetriamines exhibited exceptional suppressive antimalarial activity against a drug-sensitive line of Plasmodium berghei in mice. N6-Methyl-N6-(1-naphthalenylmethyl)-2,4,6-pteridinetriamine (9), the most active of these compounds, was also shown to be curative at 3.16 mg/kg in a single oral dose against P. cynomolgi in the rhesus monkey. This compound was also shown to be effective against a chloroquine-resistant line of P. berghei in the mouse but showed cross-resistance to a pyrimethamine-resistant strain. Most of the 2,4,6-pteridinetriamines showed strong antibacterial action against Streptococcus faecalis and Staphylococcus aureus.

Folate antagonists. 15. 2,3-Diamino-6-(2-naphthylsulfonyl)quinazoline and related 2,4-diamino-6-[(phenyl and naphthyl)sulfinyl and sulfonyl]quinazolines, a potent new class of antimetabolites with phenomenal antimalarial activity.

Oxidation of an array of 2,4-diamino-6-(arylthio)quinazolines provided the corresponding arylsulfinyl and arylsulfonyl analogues. A variety of these nonclassical analogues of methotrexate exhibited suppressive antimalarial activity superior to that of the parent thioquinazolines against drug-sensitive lines of Plasmodium berghei in mice and P. gallinaceum in chicks, and several displayed potent prophylactic activity against P. gallinaceum. The sulfinyl- and sulfonylquinazolines also retained antimalarial effects against chloroquine-, cycloguanil-, and DDS-resistant lines of P. berghei in mice and against chloroquine- and pyrimethamine-resistant strains of P. falciparum in owl monkeys. Coadministration of one of the most active of these compounds, 2,4-diamino-6-(2-naphthylsulfonyl)-quinazoline (35), with sulfadiazine to monkeys infected with P. falciparum of P. vivax led to greatly enhanced activity and prevented the development of quinazoline resistance.

Folate antagonists. 13. 2,4-Diamino-6-](alpha,alpha,alpha-trifluoro-m-tolyl)thio]quinazoline and related 2,4-diamino-6-[(phenyl- and naphthyl)thio]quinazolines, a unique class of antimetabolites with extraordinary antimalarial and antibacterial effects.

An array of nonclassical thioquinazoline analogues (VIII) of methotrexate was prepared by cyclization of the requisite 2-amino-5-(arylthio)benzonitrile with chloroformamidine hydrochloride (28--79%). The aminonitrile precursors were obtained by SnCl2-HCl reduction (28--99%) of the corresponding 2-nitro-5-(arylthio)benzonitriles, which were synthesized by the condensation of the appropriate 5-chloro-2-nitrobenzonitriles with various arylthiols (36--83%). Many of the thioquinazolines (VIII) showed suppressive antimalarial activity comparable with or superior to chloroquine, cycloguanil, and pyrimethamine against drug-sensitive lines of Plasmodium berghei in mice and Plasmodium gallinaceum in chicks, and several displayed potent prophylactic activity with P. gallinaceum. Moreover, the thioquinazolines retained potent antimalarial effects against chloroquine-, cycloguanil-, pyrimethamine- and DDS-resistant lines of P. berghei in mice and against chloroquine- and pyrimethamine-resistant strains of Plasmodium falciparum in owl monkeys. The most active compound, namely, 2,4-diamino-6-[alpha,alpha,alpha-trifluoro-m-tolyl)thio]quinazoline, was designated for preclinical toxicological studies. Numerous substances exhibited in vitro activity against a broad spectrum of pathogenic bacteria at concentrations of less than 0.25 microgram/mL. The thioquinazolines also prove to be potent folate antagonists, causing 50% inhibition of Streptococcus faecalis R (ATCC 8043) at drug concentrations ranging from 0.2 to 2.0 ng/mL. Structure--activity relationships are discussed.

Folate antagonists. 12. Antimalarial and antibacterial effects of 2,4-diamino-6-[(aralkyl and alicyclid)thio-, sulfinyl-, and sulfonyl]quinazolines.

A series of 2,4-diamino-6-[(aralkyl and alicyclic)thio-, sulfinyl-, and sulfonyl]quinazolines was prepared via condensation of 5-chloro-2-nitrobenzonitrile or 5,6-dichloro-2-nitrobenzonitrile with the appropriate aralkyl or alicyclic thiopseudourea, reduction of the resulting 2-nitro-5-[(aralkyl or alicyclic)thio]benzonitrile with stannous chloride to the amine, and cyclization with chloroformamidine hydrochloride. Oxidation was effected with hydrogen peroxide or the bromine complex of 1,4-diazabicyclo[2.2.2]octane. These analogues when examined for suppressive activity against drug-sensitive lines of Plasmodium berghei in mice were not as active as 2,4-diamino-6-[3,4-dichlorobenzyl)amino]quinazoline (Ia).

Folate antagonists. 10. Synthesis and antimalarial effects of 6-[[(aryl and aralkyl)amino]methyl]-2,4-pteridinediamines and -pteridinediamine 8-oxides.

Various 6-[[(aryl and aralkyl)amino]methyl]-2,4-pteridinediamines and their 8-oxides have been synthesized for antimalarial evaluation. Condensation of 3-amino-6-(bromomethyl)-2-pyrazinecarbonitrile 4-oxide (V) with the appropriately substituted amine afforded a series of 3-amino-6-[[(aryl and aralkyl)amino]methyl]-2-pyrazinecarbonitrile 4-oxides VI. Deoxygenation gave the corresponding pyrazines VII. Cyclization of VI and VII with guanidine then produced the desired 6-(aminomethyl)-2,4-pteridinediamine N-oxides VIII and teridinediamines IX, respectively. Formylation of 6-[[(3,4-dichlorophenyl)amino]methyl]-2,4-pteridinediamine gave N-[(2,4-diamino-6-pteridinyl)-methyl]-N-(3,4-dichlorophenyl)formamide. The N-oxides VIII did not exhibit significant activity against Plasmodium berghei infections in mice. Activity among the 2,4-pteridinediamines IX was generally poor with the exception of the 3,4,5-trimethoxyphenyl and 1-naphthalenyl analogues which showed strong suppressive activity at doses ranging from 80 to 640 mg/kg. Furthermore, several of the 2,4-pteridinediamines exhibited potent prophylactic activity against Plasmodium gallinaceum infections in the chick and also showed strong antibacterial action against Streptococcus faecalis and Staphylococcus aureus.

Folate antagonists. 11. Synthesis and antimalarial effects of 6-[(aryloxy- and arylthio-)methyl]-2,4-pteridinediamines and -pteridinediamine 8-oxides.

Condensation of 3-amino-6-(bromomethyl)-2-pyrazinecarbonitrile 4-oxide with 4-chlorophenol gave 3-amino-6-[(4-chlorophenoxy)methyl]-2-pyrazinecarbonitrile 4-oxide (1), which was deoxygenated to obtain the de-N-oxide 4. Cyclization of 4 and 1 produced 6-[(4-chlorophenoxy)methyl]-2,4-pteridinediamine and the 8-oxide, respectively. 6-[(Arylthio)methyl]-2,4-pteridinediamines and their 8-oxides were produced analogously. Controlled oxidation of the former gave the anticipated sulfoxide 12 and sulfone 13. None of these compounds showed significant activity when tested against lethal Plasmodium berghei infections in mice or a select list of bacteria in vitro.

Antischistosomal effects of 5-(2,4,5-trichlorophenyl)hydantoin and related compounds.

5-(2,4,5-Trichlorophenyl)hydantoin and several analogues effected an 80-90% reduction of live schistosomes in infected mice at doses ranging from 265 to 329 mg/kg per day when administered orally in the diet for 14 days. The sodium salt of 5-(2,4,5-trichlorophenyl)hydantoin, when given by gavage to rhesus monkeys infected with Schistosoma mansoni at 200 mg/kg/day for 5 or 10 days, removed all but a few live worms with no evidence of intolerance.