Selective protection and functionalization of morphine: synthesis and opioid receptor binding properties of 3-amino-3-desoxymorphine derivatives.

As part of an effort to identify novel opioid receptor interactive agents, we recently prepared a series of 8-(substituted)amino analogues of cyclazocine. We found the chiral 8-phenylamino (NHC(6)H(5)) cyclazocine derivative to have subnanomolar affinity for kappa opioid receptors and a 2-fold lower affinity for mu, opioid receptors. To determine if the benefits of (substituted)amino groups could be extended to the morphine core structure, we have made five novel 3-amino-3-desoxymorphine derivatives of general structure 5 where RR'N = H(2)N, CH(3)NH, (CH(3))(2)N, C(6)H(5)NH, and C(6)H(5)CH(2)NH. Relative to morphine, these derivatives had 38-273-fold, 11-41-fold, and 10-141-fold lower affinity for mu, delta, and kappa opioid receptors, respectively. Target compounds were made via Pd-catalyzed amination of a morphine 3-trifluoromethylsulfonate substrate where the 6-OH group was protected with a tert-butyldiphenylsilyl group. To make 6-tert-butyldiphenylsilyloxymorphine selectively, a new high-yield method was developed whereby morphine was bis-silylated using normal conditions followed by selective removal of the 3-tert-butyldiphenylsilyl group with catalytic tetrabutylammonium fluoride.

Synthesis and pharmacology of 8-amino-3-(cyclopropylmethyl)-1,2,3,4,5,6-hexahydro-cis-6,11-dimethyl-2,6-methano-3-benzazocine and related compounds.

The little compound 1a has been prepared and was found to be a strong, orally active agonist with narcotic--antagonist properties. 1a was prepared by two independent routes: (1) nitration of volazocine and subsequent reduction and (b) a sequence involving dissolving metal reduction of cyclazocine methyl ether, followed by oximination and Semmler--Wolff rearrangement. Several analogues were prepared and tested.

The in vitro dental plaque inhibitory properties of a series of N-[1-alkyl-4(1H)-pyridinylidene]alkylamines.

A series of novel N-[1-alkyl-4(1H)-pyridinylidene]alkylamine hydrohalides has been prepared and evaluated as inhibitors of dental plaque formation, in vitro. Several members of the series exhibited potency ca. 9-fold greater than that of chlorhexidine vs Streptococcus sobrinus 6715-13. The di-n-octyl analogue, 11 (pirtenidine), was found to be highly efficacious against several other oral plaque-forming microorganisms and is presently undergoing preclinical evaluation.

Synthesis and bacterial DNA gyrase inhibitory properties of a spirocyclopropylquinolone derivative.

A novel conformationally restricted 1-cyclopropylquinolone (1) that incorporates structural features of both ofloxacin and ciprofloxacin has been prepared. Compound 1 was found to be a DNA gyrase inhibitor having potency similar to ofloxacin but less than ciprofloxacin. The cellular inhibitory and in vivo antibacterial potencies of 1 were found to be less than those of the two reference agents.

Synthesis and antidepressant properties of novel 2-substituted 4,5-dihydro-1H-imidazole derivatives.

A unique combination of alpha 2-adrenoreceptor antagonist and serotonin-selective reuptake inhibitory activities has been identified in a series of 2-substituted 4,5-dihydro-1H-imidazole derivatives. This combination of blocking activities has provided one of these derivatives, napamezole hydrochloride (2), with potential as an antidepressant. A discussion of the syntheses of these compounds includes a convenient method for the conversion of nitriles to imidazolines with ethylenediamine and trimethylaluminum.

Novel amino-substituted 3-quinolinecarboxylic acid antibacterial agents: synthesis and structure-activity relationships.

A series of novel 3-quinolinecarboxylic acid derivatives have been prepared and their antibacterial activity evaluated. These derivatives are characterized by fluorine attached to the 6-position and substituted amino groups appended to the 1- and 7-positions. Structure-activity relationship studies indicate that antibacterial potency is greatest when the 1-substituent is methylamino and the 7-substituent is either 4-methyl-1-piperazinyl, 16, or 1-piperazinyl, 21. Derivatives 16 and 21, the 1-methylamino analogues of pefloxacin and norfloxacin, respectively, show comparable in vitro and in vivo antibacterial potency to these two known agents. The activity (vs. Escherichia coli Vogel) of 16 (amifloxacin) is the following: in vitro MIC (microgram/mL) = 0.25; in vivo (mice) PD50 (mg/kg) = 1.0 (po), 0.6 (sc).

Mammalian topoisomerase II inhibitory activity of 1-cyclopropyl-6,8- difluoro-1,4-dihydro-7-(2,6-dimethyl-4-pyridinyl)-4-oxo-3-quinolinecarb oxylic acid and related derivatives.

1-Cyclopropyl-6,8-difluoro-1,4-dihydro-7-(2,6-dimethyl-4-pyridinyl)-4-ox o-3-quinolinecarboxylic acid (1), a previously reported potent inhibitor of bacterial DNA gyrase, was found to be interactive with mammalian topoisomerase II (topo II). In a DNA-cleavage assay using topo II isolated from HeLa cells, 1 exhibited an EC50 value of 7.6 microM (VP-16; EC50 = 0.81 microM). A series of analogues modified at the 1-, 2-, 3-, 5-, and 7-positions of 1 were subsequently made and assessed for topo II inhibition. Compound 1 was considerably more potent than derivatives where the 1-substituent was alkyl, aryl, or H, or when N-c-C3H5 was replaced with S. The descarboxyl (i.e., 3-H) analogue had potency comparable to that of 1; when both these compounds were substituted at the 2-position with methyl or phenyl, an interesting relationship between activity and the conformation of the carboxyl group emerged. Upon replacement of the 5-H of 1 with NH2 or F, sustained potency was seen. No enhancement of activity was evident upon replacing the 7-substituent of 1 with other pyridinyl groups, 4-methyl-1-piperazinyl, or pyrrolidinyl groups; however, the 7-(4-hydroxyphenyl) analogue (CP-115,953) was 6-fold more potent than 1. The topo II inhibitory properties of 1 translated to modest in vitro cytotoxicity and in vivo activity versus P388.

3-Quinolinecarboxamides. A series of novel orally-active antiherpetic agents.

A series of novel 3-quinolinecarboxamides that are structurally similar to the quinolone class of antibacterial agents possess excellent antiherpetic properties. By modifying the quinoline ring at the 1-, 2-, 3-, and 7-positions, analogues were identified that have up to 5-fold increased HSV-2 plaque-reduction potency relative to acyclovir. In a single-dose mouse model of infection, one of the most potent derivatives in vitro, 1-(4-fluorophenyl)-1,4-dihydro-4-oxo-7-(4-pyridinyl)-3-quinolinecarbo xamide (97), displayed comparable oral antiherpetic efficacy to acyclovir at 1/16 the dose; in a multiple-dose regimen, however, 97 was 2-fold less potent. In mice dosed orally with 97, sustained plasma drug levels were evident that may account for the high efficacy observed. The molecular mechanism of action of these agents is not known; however, based on in vitro studies with acyclovir resistant mutants, it is likely that the mechanism differs from that of acyclovir. In vitro plaque-reduction potency was not generally predictive of oral efficacy in mice. An X-ray crystal structure of 97 corroborated the assignment of structure and provided useful insights as to the effect of conformation on plaque-reduction potency.

Synthesis and antibacterial activity of some novel 1-substituted 1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylic acids. Potent antistaphylococcal agents.

The palladium-catalyzed coupling of 3- and 4-(trialkylstannyl)pyridines with 7-bromo or 7-chloro 1-substituted 1,4-dihydro-4-oxo-3-quinolinecarboxylates has provided access to the corresponding 1-substituted 1,4-dihydro-4-oxo-7-pyridinyl-3-quinolinecarboxylic acids. The antibacterial activity of these derivatives was studied with the finding that the optimal 1- and 7-position substituents for Gram positive activity are cyclopropyl and 4-(2,6-dimethylpyridinyl), respectively. We find that for the fluorine-substituted derivatives studied, the position of the fluorine on the quinolone nucleus or the number of fluorine atoms does not seem to be important for good Gram positive activity. For 1-cyclopropyl 7-(2,6-dimethyl-4-pyridinyl) derivatives, the 6-fluoro 4a, 8-fluoro 10d, 6,8-difluoro 10b, and 5,6,8-trifluoro 8, all provided equal antibacterial activity against Staphylococcus aureus ATCC 29213. There is also a correlation between the substitution on the 7-(4-pyridinyl) group and the Gram positive activity, particularly for S. aureus, clearly indicating that the 2,6-dimethylpyridinyl group is optimal. The MIC50 value for the most potent agents in this study against S. aureus ATCC 29213 is 0.008 microgram/mL. By comparison, ciprofloxacin and aminopyrrolidine 28 gave values of 0.25 and 0.015 microgram/mL, respectively, against this organism.

Cyclic variations of 3-quinolinecarboxamides and effects on antiherpetic activity.

Supported by the antiherpetic properties of 3-quinolinecarboxamides and the importance of the planar intramolecular H-bonded beta-keto amide pharmacophore, a series of novel conformationally rigid analogues that contain a heterocyclic bridge between the 3- and 4-positions of the quinoline ring have been evaluated. Two isoxazolo-fused derivatives 17 and 23 displayed good in vitro antiherpetic potency that was similar to that of 1, the 3-quinolinecarboxamide that served as the comparison structure for this study. The pyrazolo, pyrrolo, and pyrimido derivatives showed considerably less or no activity. In vitro activity did not translate to in vivo efficacy. For 17, the lack of in vivo activity is likely a consequence of insufficient plasma drug levels (both Cmax and duration) in mice relative to the MIC versus HSV-2.

Synthesis and antitumor activity of 4-aminomethylthioxanthenone and 5-aminomethylbenzothiopyranoindazole derivatives.

Two new series of antitumor agents, 4-aminomethylthioxanthenones (6-50) and 5-aminomethylbenzothiopyranoindazoles (51-61), are described and compared. Nearly all members of both series display excellent in vivo activity versus murine pancreatic adenocarcinoma 03 (Panc03) although there is little to distinguish the two series from each other. In both series there is no discernible relationship between structure and in vivo efficacy. Selected analogues were evaluated in vitro; all were observed to have moderate to strong DNA binding via intercalation. However, varying degrees of in vitro P388 cytotoxicity and topoisomerase II inhibition were seen. In general, those molecules which exhibited strong topoisomerase II inhibition were significantly more cytotoxic than those which did not. In both series, those derivatives (48-50, 60, and 61) having a phenolic hydroxy substitution exhibited the most potent P388 cytotoxicity and topoisomerase II inhibition.

Mechanism of action and antitumor activity of (S)-10-(2,6-dimethyl-4-pyridinyl)-9-fluoro-3-methyl-7-oxo-2,3-dihydro-7 H- pyridol[1,2,3-de]-[1,4]benzothiazine-6-carboxylic acid (WIN 58161).

(S)-10-(2,6-Dimethyl-4-pyridinyl)-9-fluoro-3-methyl-7-oxo-2,3-dihydro-7H - pyrido[1,2,3-de][1,4]benzothiazine-6-carboxylic acid (WIN 58161) is an enantiomerically pure quinolone with outstanding bacterial topoisomerase II (DNA gyrase, EC 5.99.1.3) inhibitory and antibacterial activity. Unlike most quinolones, WIN 58161 also exhibits significant inhibitory activity against mammalian topoisomerase II (EC 5.99.1.3). DNA gyrase and topoisomerase II inhibitory activities are enantioselective. Consequently, WIN 58161 and its enantiomer (WIN 58161-2) provide useful tools to probe the contribution of topoisomerase II inhibition to the mechanism of cytotoxicity of quinolones and the potential utility of quinolone-topoisomerase II inhibitors as antitumor agents. WIN 58161 inhibited both highly purified Escherichia coli DNA gyrase and HeLa cell topoisomerase II by the promotion of enzyme-DNA covalent complexes. WIN 58161 did not bind stably to DNA via intercalation and did not enhance the formation of topoisomerase I (EC 5.99.1.2)-DNA covalent complexes. At drug concentrations that are cytotoxic to P388 murine leukemia cells, WIN 58161 promoted intracellular DNA single-strand breaks (SSBs) that exhibited the hallmarks of being mediated by topoisomerase. DNA fragments were complexed with protein, and SSBs were readily resealed at 37 degrees following drug removal. WIN 58161-2 was neither cytotoxic nor did it promote intracellular SSBs in P388. These observations suggest that the mechanism of cytotoxicity of WIN 58161 is predominantly, if not exclusively, a result of topoisomerase II inhibition. When studied in tumor-bearing mice, WIN 58161 exhibited a significant antitumor effect against each of five tumors tested, whereas neither toxicity nor antitumor activity was observed with WIN 58161-2. We conclude from these studies that WIN 58161 represents the prototype of a novel chemical class of topoisomerase II inhibitor with potential clinical utility in treating cancer.

Partial opioids. Medications for the treatment of pain and drug abuse.

Pentazocine and cyclazocine are two benzomorphans that were synthesized by the late Sydney Archer in 1962. These benzomorphans were synthesized as part of an effort to develop analgesics with little or no abuse potential. Pentazocine is used as an analgesic, often in individuals who have sever pain or in those who have drug-abuse problems. Cyclazocine is a low-liability analgesic and potential therapeutic for the treatment of drug abuse. The risk of drug dependence is lower with the benzomorphans, which usually act as partial agonists at the mu opioid receptor and as kappa agonists. In an attempt to synthesize analogs of cyclazocine with increased bioavailability and varying kappa agonist and partial mu agonist properties, a series of 8-amino derivatives of cyclazocine were synthesized. These compounds were characterized in radioligand binding assays for their affinity and selectivity for the mu, delta, and kappa opioid receptors. Mouse antinociceptive tests were used to characterize the agonist and antagonist properties of each compound at the mu, delta and kappa receptors.

In vitro and in vivo antibacterial activities of the fluoroquinolone WIN 49375 (amifloxacin).

WIN 49375 (amifloxacin) is a synthetic antibacterial agent of the quinolone class. It is similar in chemical structure to pefloxacin but differs by containing a methylamino, rather than an ethyl, substituent at the 1-N position. The activity of WIN 49375 in vitro was comparable to those of norfloxacin and pefloxacin against Enterobacteriaceae and generally greater than those of tobramycin and cefotaxime. WIN 49375 was more active in vitro than carbenicillin and mezlocillin against Pseudomonas aeruginosa isolates and showed moderate activity against Staphylococcus aureus, with MICs of less than or equal to 2 micrograms/ml. The in vitro activity of WIN 49375 was not markedly affected by the presence of human serum, the size of the bacterial inoculum, or changes in pH between 6 and 8. Against systemic, gram-negative bacterial infections in mice, WIN 49375 was generally less active than cefotaxime but more active than gentamicin. WIN 49548, the major piperazinyl-N-desmethyl metabolite of WIN 49375, was aa effective as the parent drug against experimental infections in mice when given parenterally. When administered orally, however, this metabolite was less potent than WIN 49375. WIN 49375 was highly active by the oral route, with 50% effective doses within two- to threefold of those obtained with parenteral medication.

8-Carboxamidocyclazocine analogues: redefining the structure-activity relationships of 2,6-methano-3-benzazocines.

Unexpectedly high affinity for opioid receptors has been observed for a novel series of cyclazocine analogues where the prototypic 8-OH was replaced by a carboxamido group. For mu and kappa opioid receptors, the primary carboxamido derivative of cyclazocine ((+/-)-15) displayed high affinity (Ki=0.41 and 0.53 nM, respectively) nearly comparable to cyclazocine. A high enantiopreference ((2R,6R,11R)-) for binding was also observed. Compound (+/-)-15 also displayed potent antinociception activity in mice when administered icv.

3-Carboxamido analogues of morphine and naltrexone. synthesis and opioid receptor binding properties.

In response to the unexpectedly high affinity for opioid receptors observed in a novel series of cyclazocine analogues where the prototypic 8-OH was replaced by a carboxamido group, we have prepared the corresponding 3-CONH(2) analogues of morphine and naltrexone. High affinity (K(i)=34 and 1.7nM) for mu opioid receptors was seen, however, the new targets were 39- and 11-fold less potent than morphine and naltrexone, respectively.

8-Aminocyclazocine analogues: synthesis and structure-activity relationships.

Opioid binding affinities were assessed for a series of cyclazocine analogues where the prototypic 8-OH substituent of cyclazocine was replaced by amino and substituted-amino groups. For mu and kappa opioid receptors, secondary amine derivatives having the (2R,6R,11R)-configuration had the highest affinity. Most targets were efficiently synthesized from the triflate of cyclazocine or its enantiomers using Pd-catalyzed amination procedures.

DNA sequence preferences at sites cleaved by human DNA topoisomerase II in response to novel quinolone derivatives.

We have examined the DNA cleavage site specificity of human type II DNA topoisomerase in the presence of each of five novel quinolone derivatives. Each quinolone derivative inhibited the human enzyme, inducing double-strand breaks with a four-base stagger. Break sites generated in response to each derivative had a predominance of C in the 3'-terminal position. Consensus sequences derived for cleavage sites induced by each derivative were strikingly similar, not only at the 3'-terminal position, but also at additional positions on either side of the broken phosphodiester bond. Analysis of these consensus sequences yielded information about possible interactions of specific substituents on the quinolone derivatives with DNA and/or topoisomerase. Comparison of the quinolone-based consensus sequences with those derived for cleavage sites generated by the human type II topoisomerase in the presence of either m-AMSA or VM-26, or in the absence of drug, provided compelling evidence that DNA cleavage sites include two domains: one which interacts with drug and a second, larger domain which interacts with topoisomerase.

Antiviral properties of 3-quinolinecarboxamides: a series of novel non-nucleoside antiherpetic agents.

Novel antiherpetic 3-quinolinecarboxamides were discovered as part of a drug discovery program at Sterling Winthrop Inc. A major goal of this research was to identify novel non-nucleoside agents possessing activity against acyclovir resistant herpes simplex virus. From screening compound libraries in an HSV-2 plaque reduction assay, 1-ethyl-1,4-dihydro-4-oxo-7-(4-pyridinyl)-3-quinolinecarboxamide (1) emerged as an attractive lead structure. By modifying the quinoline ring at the 1-, 2-, 3-, 4-, and 7-positions, analogues were identified that have up to 5-fold increased in vitro potency relative to acyclovir. In a single dose mouse model of infection the 1-(4-FC6H4) analogue 17, one of the most potent derivatives in vitro, displayed comparable oral antiherpetic efficacy to acyclovir at 1/16 the dose; in a multiple dose regimen, however, it was 2-fold less potent. Mechanism of action studies indicate that these new compounds interact with a different, as yet undefined, molecular target than acyclovir.