Naphthyridines. 3. Preparation of pyrimido[1,2-a]-and imidazo-[1,2-a]-[1,8]naphthyridines from 2-amino-1,8-naphthyridines.
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A series of novel chiral 7-(1-, 3-, 4-, and 6-methyl-[(1R,4R)-2,5- diazabicyclo[2.2.1]heptan-2-yl]-substituted naphthyridines has been prepared with the aim of obtaining good in vitro and in vivo antibacterial agents with a decrease of the pseudoallergic type reaction when compared to that observed with 7[(1R,4R)-2,5-diazabicyclo[2.2.1]heptan-2-yl]-1-(1,1-dimethylethyl )1,4- dihydro-6-fluoro-4-oxo-1,8-naphthyridine-3-carboxylic acid (1a) (BMY 40062). The derivatives 7-[(1R,4R,6S)-6-methyl-2,5-diazabicyclo[2.2.1]heptan-2-yl]- 1-(1,1-dimethylethyl)-6-fluro-1,4-dihydro-4-oxo-1,8-naphthyridine- 3-carboxylic acid (41) and 7-[(1R,4R,6S)-6-methyl-2,5-diazabicyclo[2.2.1]heptan-2- yl]-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-1,8-naphthyridine-3-carboxy lic acid (49) showed potent in vitro and in vivo antibacterial activity against Gram-positive and Gram-negative bacteria. The derivative 49 displayed a less marked decrease in blood pressure (MAP), compared to that of 1a, after intravenous infusion in dogs and was selected as a potential candidate for preclinical trials.
Most N,N-disubstituted 5-amino-N,N-diethyl-9-isopropyl [1,2,4]triazolo[4,3-a] [1,8]naphthyridine-6-carboxamides 9 (compounds 9a, c-i) and the N-monosubstituted one 8c were obtained by treating with excess amine the corresponding 5-chloroderivative 7a, which was in turn prepared by cyclocondensation of the 2,4-dichloro-N,N-diethyl-1,8-naphthyridine-3-carboxamide (4a) with isobutyrohydrazide. Compounds 8a,b and 9b,j-m were obtained according with the methods shown in Scheme 1. The above now synthesized compounds, along with the previously described 8d and 8e, were tested for their anti-inflammatory, analgesic and antipyretic properties, and most compounds also for their effect on spontaneous mice locomotor activity and their acute gastrolesivity in rats. Several compounds showed potent anti-inflammatory and/or analgesic activities, and all the compounds tested proved to be completely lacking in acute gastrolesivity. In many cases compounds 8 and 9 produced hypothermic effect, usually at high doses. On the whole, the N-monosubstituted 5-aminoderivatives 8 appeared to be more potent anti-inflammatory agents than the corresponding N,N-disubstituted 9, whereas these latter compounds exhibited higher analgesic activity.
The push-pull conjugated molecules 2,7-bis-(1H-pyrrol-2-yl)ethynyl-1,8-naphthyridine (BPN) and 2,7-bis(1H-indol-2-yl)ethynyl-1,8-naphthyridine (BIN) adopting daad relays of proton donors (d) and acceptors (a) form multiple hydrogen-bonding complexes with various monosaccharides that possess complementary adda sequences. Although the free BPN emits blue light at lambda(max) = 475 nm in CH(2)Cl(2), its complexation with octyl beta-d-glucopyranoside gives green fluorescence at lambda(max) = 535 nm. The excellent photophysical properties make BPN a highly sensitive probe for monitoring glucopyranoside to a detection limit of approximately 100 pM. On the other hand, the CD-silent BIN molecule binds with monosaccharides to form the CD-active multiple hydrogen-bonding complexes, which exhibit the remarkable chirality dependent helicities consistent with the prediction by the ab initio approaches. On the basis of the similar daad cleft and hence the binding property, the fluorescence and CD absorption methods in BPN and BIN, respectively, are complementary, which, in combination with computational molecular modeling, not only give a detailed insight into the structures of the receptor-saccharide complexes in solution, but also differentiate octyl beta-d-glucopyranoside from its enantiomer and other monosaccharides.
We investigated the pharmacology of a new class of phosphodiesterase 4 (PDE4) inhibitor, 6,8-disubstituted 1,7-naphthyridines, by using 4-(8-benzo[1,2,5]oxadiazol-5-yl-[1,7]naphthyridin-6-yl)-benzoic acid (NVP-ABE171) as a representative compound and compared its potency with the most advanced PDE4 inhibitor, undergoing clinical trials, Ariflo [cis-4-cyano-4-(3-cyclopentyloxy-4-methoxyphenyl-r-1-cyclohexanecarboxylic acid)]. NVP-ABE171 inhibited the activity of phosphodiesterase 4A, 4B, 4C, and 4D with respective IC(50) values of 602, 34, 1230, and 1.5 nM. Ariflo was about 40 times less potent. In human cells, NVP-ABE171 inhibited the eosinophil and neutrophil oxidative burst, the release of cytokines by T cells, and the tumor necrosis factor-alpha release from monocytes, in the nanomolar range. Ariflo presented a similar inhibition profile but was 7 to 50 times less potent. In BALB/c mice challenged with lipopolysaccharide, NVP-ABE171 inhibited the airway neutrophil influx and activation with an ED(50) in the range of 3 mg/kg. Ariflo was inactive up to a dose of 10 mg/kg. In ovalbumin sensitized Brown Norway rats, NVP-ABE171 inhibited the lipopolysaccharide-induced airway neutrophil influx and activation (ED(50) of 0.2 mg/kg) and the ovalbumin-induced airway eosinophil influx and activation (ED(50) of 0.1 mg/kg). Ariflo was about 100 times less potent in both models. In the ovalbumin model, NVP-ABE171 had a duration of action of more than 24 h. NVP-ABE171 is a novel PDE4 inhibitor that shows activity both in vitro on human inflammatory cells and in vivo in animal models of lung inflammation. This compound class may have potential for the treatment of airway inflammatory conditions such as asthma and chronic obstructive pulmonary diseases.
The reactivity of some 6H-indolo[2,3-b] [1,8]naphthyridines (II) and 11H-indolo[3,2-c] [1,8]naphthyridines (III) in displacing specific [3H] diazepam binding from bovine brain membranes was examined. All the indolonaphthyridines tested are active and show a higher activity than indole and tryptophan. The inhibition is due to direct interaction with the benzodiazepine binding sites. Some structure-activity relationships are discussed.
The cytological effects of two water soluble compounds, viz. 2-(3-pyridyl)-1,8-naphthyridine and 2-methyl-3-acetyl-1,8-naphthyridine, on the chromosomes of the male germ cells of grasshopper Poekilocerus pictus were studied. Of these two compounds, the former was more potent in inducing structural changes in the chromosomes.
The preparation of the novel N,N-dialkyl-2,4-dichloro-1,8-naphthyridine-3-carboxamides 1c, e and N,N-dialkyl-2-(alkylamino or cycloalkylamino)-4-chloro-1,8-naphthyridine-3- carboxamides 2b, d-g, j-p is described. These compounds and the previously obtained analogs 1a, b, d, f and 2a, c, h, i have been tested for their anti-inflammatory and antiaggressive activities, as well as for their gross behavioral effects and acute toxicity. Nine of the twenty-two tested compounds exhibited a statistically significant anti-inflammatory activity in the carrageenin-induced edema assay in the rat (1e, f and 2h, o were the most active compounds). On the other hand, an interesting antiaggressive activity was displayed by ten compounds in the isolation-induced aggressiveness test in mice (compounds 2d, i, k showed the highest activity). Structure-activity relationships are briefly discussed.
Fifteen N,N-dialkyl-5-chloro[1,2,4]triazolo[4,3-a][1,8]naphthyridine-6-carboxami des (7a-o) were synthesized through the cyclocondensation of the corresponding N,N-dialkyl-2,4-dichloro-1,8-naphthyridine-3-carboxamides with proper hydrazides, in order to evaluate their anti-inflammatory, antiaggressive, and analgesic properties. Four of the compounds tested showed a statistically significant and dose-dependent anti-inflammatory activity.
The title compounds (8) were synthesized through the cyclocondensation of the corresponding N-substituted 4-amino-2-chloro-1,8-naphthyridine-3-carboxamides (4) with the proper hydrazides, in order to evaluate their anti-inflammatory and anti-aggressive properties. Several compounds 8 exhibited high anti-inflammatory activity (carrageenin-induced paw edema assay in the rat) along with appreciable anti-aggressive properties (isolation-induced aggressiveness test in mice). With respect to anti-inflammatory activity, the most active compounds (8n and 8c) produced a 61% edema inhibition at the 25 mg/kg dose, and 50 or 35% inhibition, respectively, at the 12.5 mg/kg dose. The structure-activity relationships are discussed.
New fluorescent molecular sensors for 9-alkylguanines were constructed by conjugation of 2-acetamido-1,8-naphthyridine with N-Boc-pyrrole, N-Boc-pyreno[2,1-b]pyrrole, or acetanilide moieties via an ethynyl bridge. In combination with the triple hydrogen-bonding motif of 2-acetamidonaphthyridine toward alkylguanine, an additional binding site was provided by the substituent properly located on the pyrrole or aniline ring to enhance the affinity of these receptor molecules. Besides the ESI-MS analyses, the binding events were readily monitored by the absorption and fluorescence changes in the visible region.
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