Quinolone antibacterials: preparation and activity of bridged bicyclic analogues of the C7-piperazine.

A series of quinolone and naphthyridine antibacterial agents possessing as the C7-heterocycle bicyclic 2,5-diazabicyclo[n.2.m]alkanes, where n = 2, 3 and m = 1, 2, and a series including 4-aminopiperidine and 3-amino-8-azabicyclo[3.2.1]octanes have been prepared and evaluated in vitro and in vivo for antibacterial activity against a variety of Gram-negative and Gram-positive organisms. These compounds were also tested against the target enzyme bacterial DNA gyrase. All the examples investigated are nearly equipotent with the parent 7-piperazinyl analogues. Only endo-7-(3-amino-8-azabicyclo[3.2.1]oct-8-yl)-1-cyclopropyl-6,8-difluoro- 1,4- dihydro-4-oxo-3-quinolinecarboxylic acid displays activity that surpasses that of the piperazine parent.

Benzothiopyranoindazoles, a new class of chromophore modified anthracenedione anticancer agents. Synthesis and activity against murine leukemias.

The synthesis of the benzothiopyranoindazoles, a new class of chromophore modified anthracenediones related to mitoxantrone, is described. In this structural class the quinone moiety, which is believed to be responsible for the cardiotoxicity of the anthracyclines, has been designed out. The synthesis of the benzothiopyranoindazoles was carried out by a multistep sequence from requisite 1-chloro-4-nitro-9H-thioxanthen-9-one precursors. Reaction with a monoalkylhydrazine gave a 5-nitrobenzothiopyranoindazole adduct, which was catalytically reduced to a corresponding C-5 anilino intermediate. Alkylation of 7 with a requisite X(CH2)nNR1R2 (X = Cl, Br; R1, R2 = H, alkyl, acyl; n = 2,3) provided target "two-armed" benzothiopyranoindazoles or A-ring methoxy and/or side chain acyl intermediates, which could be converted to 3 by appropriate deprotection methodologies. Alternatively, certain target compounds 3 were synthesized by reaction of 7 with appropriately functionalized glycine precursors under Schotten-Bauman or BOP chloride condensation conditions to provide C-5 acylamino intermediates, followed by Red-Al reduction and deprotection steps. Described also is the synthesis of selected benzothiopyranoindazole congeners with proximal acylamino side chains at C-5 and B-ring sulfone functionality at S-6. Potent activity was demonstrated against murine L1210 leukemia in vitro (IC50 = 10(-7)-10(-9) 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 (a) a basic side chain at N-2 and a dibasic side chain at C-5 with primary or secondary distal amine substitution, (b) certain patterns of A-ring hydroxylation with 8-OH and 9-OH most favorable, and (c) sulfide oxidation state at S-6. 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 broad-spectrum in vivo anticancer activity, selected compounds in this series have been chosen for development toward clinical trials.

1-Substituted 7-[3-[(ethylamino)methyl]-1-pyrrolidinyl]-6,8- difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acids. New quantitative structure-activity relationships at N1 for the quinolone antibacterials.

A series of 18 1-substituted 7-[3-[(ethylamino)methyl]-1- pyrrolidinyl]-6,8-difluoro-1,4-dihydro-4-oxo-3-quinoline- carboxylic acids (N1 analogues of CI-934) were synthesized and evaluated for antibacterial activity and DNA-gyrase inhibition. Correlations between the inhibition of DNA gyrase and antibacterial potency were established. A quantitative structure-activity relationship (QSAR) was derived by using the antibacterial potency for each of 11 strains of bacteria and the Gram-negative mean. The equations indicated that antibacterial potency was strongly dependent on STERIMOL length and width and the level of unsaturation of the N1 substituent. Some strains also showed a dependence on the presence of heteroatoms (O, N, S) in the N1 group. No significant correlations between gyrase inhibition and combinations of these parameters were found. These QSAR results are discussed in conjunction with the conformational analyses from molecular modeling studies. The substituent that most enhanced the activity of the quinolone in all regards was the cyclopropyl group. This analogue, 1-cyclopropyl-7-[3-[(ethylamino)-methyl]-1-pyrrolidinyl]-6, 8-difluoro-1,4-dihydro-4-oxo-3-quinolinecarboxylic acid (PD 117558), demonstrated outstanding broad spectrum activity both in vitro and in vivo when compared to relevant standards.

Synthesis and structure-activity relationships of pyrazolo[4,3-d]pyrimidin-7-ones as adenosine receptor antagonists.

A series of 21 1,3-dialkylpyrazolo[4,3-d]pyrimidin-7-ones substituted in the 5-position with various phenyl substituents has been synthesized and found to have affinity for the adenosine A1 receptor. The potency pattern due to substituents of the phenyl ring was found to parallel that found in a previously reported 1,3-dialkyl-8-phenylxanthine series. A quantitative structure-activity relationship was developed between these two series that correctly predicted the potencies of six additional 5-substituted pyrazolo[4,3-d]pyrimidines that were synthesized during the course of the analysis. With use of the correlation as a guide, one additional 5-phenylpyrazolo[4,3-d]pyrimidine containing a 4-[[(dimethylamino)ethyl]amino]sulfonyl substituent to improve aqueous solubility was prepared. On the basis of the high correlation between adenosine binding affinities of analogously substituted xanthines and pyrazolo-[4,3-d]pyrimidines and the close superposition of the heterocyclic rings and substituents that is apparent from molecular models of these two series, it is hypothesized they fit the receptor in an analogous fashion.

Basically substituted ellipticine analogues as potential antitumor agents.

Installation of a basic side chain on the ring nitrogen of ellipticine did, as expected, improve the DNA binding properties of these molecules as measured by an ethidium displacement assay. In vivo antitumor activity was not, however, improved.

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.

Synthesis of xanthines as adenosine antagonists, a practical quantitative structure-activity relationship application.

A set of 56 8-phenylxanthines, previously tested for adenosine antagonism (adenosine A1 receptor affinity), was analyzed by quantitative structure-activity relationship (QSAR) techniques. The resulting QSAR revealed that (1) the most potent receptor binders had already been made in this series and thus suggested the termination of synthesis of compounds with additional phenyl substituents to increase potency and (2) potency was much more strongly affected by changes in ortho than para phenyl substitution. On the basis of this study, an additional 20 compounds were synthesized that contained primarily para substituents designed to increase aqueous solubility. High potency was maintained among the resulting sulfonamide derivatives (as predicted by the QSAR), and aqueous solubility was dramatically increased. Furthermore, in vitro antagonism of an adenosine receptor mediated physiological effect was demonstrated.

Long-acting, repository antimalarial agents. Duration of protection in mice and monkeys following administration of pyrimethamine pamoate.

The duration of protection from blood-stage malarial challenge following single injections of pyrimethamine pamoate was assessed in mice and monkeys. This duration was dose-related and ranged from several weeks in mice to over 4 months in the monkeys. Comparisons with the previously reported repository drugs, cycloguanil pamoate and acedapsone (diacetyldiaminodiphenyl sulfone), in mice demonstrated that pyrimethamine pamoate provides an equal or greater duration of protection. Studies with mixtures containing acedapsone gave good protection against a pyrimethamine-resistant strain of Plasmodium berghei.

N2-1H-benzimidazol-2-yl-N4-phenyl-2,4-pyrimidinediamines and N2-1H-benzimidazol-2-yl-5,6,7,8-tetrahydro-N4-phenyl-2,4-quinazolinediamines as potential antifilarial agents.

A series of N2-1H-benzimidazol-2-yl-N4-phenyl-2,4-pyrimidinediamines and N2-1H-benzimidazol-2-yl-5,6,7,8-tetrahydro-N4-phenyl-2,4-quinazolinediamines (XI) was synthesized for antifilarial evaluation. Condensation of the requisite beta-keto ester (VI) with N-cyanoguanidine afforded 2-pyrimidinylcyanamides (VIIa,b) and (5,6,7,8-tetrahydro-4-hydroxy-2-quinazolinyl)cyanamide (VIIc). Reaction of VII with a substituted o-phenylenediamine gave 2-(1H-benzimidazol-2-ylamino)-4-pyrimidinols and 2-[(5,6-dichloro-1H-benzimidazol-2-yl)amino]-5,6,7, 8-tetrahydro-4-quinazolinol (IX). Chlorination with phosphoryl chloride, followed by condensation with the appropriate substituted benzenamine, gave the desired N2-1H-benzimidazol-2-yl-N4-phenyl-2,4-pyrimidinediamines and N2-1H-benzimidazol-2-yl-5,6,7,8-tetrahydro-N4-phenyl-2,4-quinazolinediamines (XI). None of these compounds possessed antifilarial activity against Litomosoides carinii or Brugia pahangi infections in jirds.

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. 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.