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PubMed2001

SB-334867-A: the first selective orexin-1 receptor antagonist.

The pharmacology of various peptide and non-peptide ligands was studied in Chinese hamster ovary (CHO) cells stably expressing human orexin-1 (OX(1)) or orexin-2 (OX(2)) receptors by measuring intracellular calcium ([Ca(2+)](i)) using Fluo-3AM. Orexin-A and orexin-B increased [Ca(2+)](i) in CHO-OX(1) (pEC(50)=8.38+/-0.04 and 7.26+/-0.05 respectively, n=12) and CHO-OX(2) (pEC(50)=8.20+/-0.03 and 8.26+/-0.04 respectively, n=8) cells. However, neuropeptide Y and secretin (10 pM - 10 microM) displayed neither agonist nor antagonist properties in either cell-line. SB-334867-A (1-(2-Methyylbenzoxanzol-6-yl)-3-[1,5]naphthyridin-4-yl-urea hydrochloride) inhibited the orexin-A (10 nM) and orexin-B (100 nM)-induced calcium responses (pK(B)=7.27+/-0.04 and 7.23+/-0.03 respectively, n=8), but had no effect on the UTP (3 microM)-induced calcium response in CHO-OX(1) cells. SB-334867-A (10 microM) also inhibited OX(2) mediated calcium responses (32.7+/-1.9% versus orexin-A). SB-334867-A was devoid of agonist properties in either cell-line. In conclusion, SB-334867-A is a non-peptide OX(1) selective receptor antagonist.

Animals↗
PubMed2003

Resolution of the oedema associated with allergic pulmonary inflammation in rats assessed noninvasively by magnetic resonance imaging.

1. Magnetic resonance imaging (MRI) was used to study noninvasively the effects of compounds to resolve inflammation induced by ovalbumin (OVA) challenge in the lungs of actively sensitised rats. 2. Marked oedematous signals were detected between 24 and 96 h following OVA in vehicle-treated animals. When administered 24 h after OVA, budesonide, a glucocorticosteroid, or 4-(8-benzo[1,2,5]oxadiazol-5-yl-[1,7]naphthyridin-6-yl)-benzoic acid (NVP-ABE171), a selective phosphodiesterase 4 inhibitor, increased the rate of resolution of established oedematous signals detected by MRI. The effect was evident 3 h after drug administration and the signals were nearly fully resolved at 96 h postchallenge. 3. The drug-induced rapid resolution of MRI signals was not accompanied by changes in parameters of inflammation in the bronchoalveolar lavage fluid, but was associated with perivascular oedema detected histologically. 4. In conclusion, the effects of anti-inflammatory drugs on a component of allergic inflammation can be monitored by following with MRI the rate of resolution of the associated oedematous signals.

Animals↗
PubMed2001

General pharmacological properties of YJA20379-8, a new H+/K(+)-ATPase inhibitor with anti-ulcer activities.

The general pharmacological properties of YJA20379-8 (3-butyryl-4-[(R)-1-methylbenzylamino]-8-ethoxy-1,7-naphthyridine, CAS 187654-40-6), a new H+/K(+)-ATPase inhibitor with anti-ulcer activities, were investigated in mice, rats and guinea pigs. YJA20379-8 at oral doses of 25, 50 and 100 mg/kg did not affect the locomotor activity, hexobarbital hypnosis and motor coordination in mice. The drug did not have analgesic action and anticonvulsant action at the doses of 100 mg/kg p.o. The respiration and blood pressure were not affected at 10 mg/kg i.v. in rats. YJA20379-8 at 2 x 10(-4) g/ml did neither produce any contraction nor relaxation of isolated organs, such as guinea pig ileum, rat fundus, rat uterus and guinea pig vas deferens, and the drug antagonized the contractile responses to several spasmogens, such as acetylcholine, histamine, serotonin, L-phenylephrine, oxytocin and BaCl2. The drug up to 100 mg/kg p.o. did not affect pupil size and the intestinal propulsion of mice. And it did not show an anticarrageenan action at 100 mg/kg. In this general pharmacology study, hypothermic effect in mice, retardation in gastric emptying in rats, decreases in urine excretion in rats at oral doses of 50 and 100 mg/kg of YJA20379-8 and the spasmolytic activity could be found. However, no other effects were exhibited at a high oral dose of 100 mg/kg in animals in this study.

Animals↗
PubMed2002

Differences in the absorption, metabolism and biliary excretion of a diastereomeric pair of alphavbeta3-antagonists in rat: limited role of P-glycoprotein.

1. The study investigated mechanisms underlying the pharmacokinetic differences of two zwitterionic diastereomers ((3S)-3-[(3R or 3S)-2-oxo-3-[3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propyl]pyrrolidin-1-yl]-3-quinolin-3-ylpropanoic acid) with different lipophilicities using a combination of in vivo and in vitro approaches. 2. In rat, both isomers possessed comparable plasma clearances (CL). However, the more lipophilic diastereomer I exhibited a higher metabolic clearance (>2-fold higher than II), whereas the hydrophilic zwitterion II exhibited a higher biliary clearance (approximately 5-fold higher than I). Following oral administration, the bioavailability (F) of I (17%) was much higher than that of II (1%). 3. Consistent with these in vivo observations and the expectation based on their lipophilicity differences, the metabolism in rat liver microsomes was faster and the permeability in Caco-2 and LLC-PK1 cells and in situ rat intestinal loop was better for I than for II. 4. Only the absorption of the more lipophilic diastereomer I was subjected to an efflux system in the Caco-2 and in situ rat intestinal loop models. I was a good substrate for P-glycoprotein (P-gp) in both the human MDR1 and mouse mdr1a transfected cell lines, and in the wild-type mdr1a (-/-) mouse when compared with the P-gp-deficient mdr1a (-/-) mouse. Concomitant administration of I with verapamil in rat caused significant increases in oral AUC, F and Cmax of I without affecting its CL, further supporting the effect of P-gp in limiting the intestinal absorption of I in vivo in this animal model. 5. Since the findings that the lipophilic diastereomer I, but not II, was a good P-gp substrate were not in line with the observations that I was excreted to bile much slower than II and that I was absorbed better than II, the results suggested that P-gp played a minor role to the observed differences in the biliary excretion and intestinal absorption of the diastereomers I and II in rat.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2003

Stereoselective hepatic disposition of a diastereomeric pair of alphavbeta3 antagonists in rat.

1. The study investigated mechanisms underlying the stereoselective hepatic disposition observed in rats of a zwitterionic diastereomeric pair ((3S)-3-[(3R or 3S)-2-oxo-3-[3-(5,6,7,8-tetrahydro-1,8-naphthyridin-2-yl)propyl]pyrrolidin-1-yl]-3-quinolin-3-ylpropanoic acid) with different lipophilicities. 2. In a recirculating isolated rat liver system, the more hydrophilic diastereomer II possessed biliary clearance, CLb, and bile-to-liver concentration ratio higher (about 10-30-fold) than the lipophilic zwitterion I, whereas both I and II exhibited comparably high concentration ratios between liver and perfusate. Although MK-571, a known multidrug resistance protein (MRP) inhibitor, significantly inhibited the CLb of both compounds, it did not inhibit their canalicular transport, as evident by unchanged concentration ratios between bile and liver of either I or II. 3. Following an intravenous infusion of I or II to Sprague-Dawley rats, the biliary clearance calculated either based on plasma (CL(b,p)) or liver concentration (CL(b,l)), of II was much higher than that of I (about 5-50-fold). In rats lacking multidrug resistance protein 2 (Mrp2) (Eisai hyperbilirubinemic rat, EHBR), the biliary excretion rate and CL(b,p) of II were also higher than the corresponding values for I. However, both CL(b,p) or CL(b,l) of either I or II were not reduced in EHBR, as compared with control SD rats. 4. In the in vitro rat canalicular membrane vesicle study, I and II exhibited no differences in their inhibitory effect on the Mrp2 mediated ATP-dependent [3H]DNP-SG initial uptake (no inhibition at 10 microM and only about 40% inhibition at 100 microM). 5. Collectively, these results suggested that (1) the difference in the hepatic disposition between the two isomers was due primarily to the difference in their transport mechanism across the canalicular membrane and (2) Mrp2 did not play a major role in the observed differences in the biliary excretion of the diastereomers I and II in rats.

Animals↗
PubMed2004

Disposition of a novel and potent alpha(v)beta3 antagonist in animals, and extrapolation to man.

1. The disposition of 3-[2-oxo-3-[3-(5,6,7,8-tetrahydro-[1,8]naphthyridin-2-yl) propyl]-imidazolidin-1-yl]-3(S)-(6-methoxy-pyridin-3-yl)propionic acid (compound A), a potent and selective alpha(v)beta(3) antagonist, was characterized in several animal species in support of its selection for preclinical safety studies and potential clinical development. 2. Compound A exhibited marked species differences in pharmacokinetics; the plasma clearances and bioavailabilities ranged from 33-47 ml min(-1) kg(-1) in rats and mice to 4-9 ml min(-1) kg(-1) in dogs and monkeys, and about 20% in rats to 70-80% in dogs and monkeys, respectively. Both the intravenous (i.v.) and oral kinetics of compound A were linear over the dose range studied in dogs (0.1-5 mg kg(-1) i.v. and 0.25-20 mg kg(-1) orally [p.o.]) and rats (1-30 mg kg(-1) i.v. and 4-160 mg kg(-1) p.o.). 3. Compound A was eliminated substantially by urinary excretion; the urinary recovery of the unchanged drug was 67% in rhesus, 48% in dogs and about 30% in rats. In these animal species, biotransformation was modest. 4. Following i.v. administration of [(14)C]-compound A to rats, the radioactivity rapidly distributed to all tissues investigated, with high levels of the radioactivity detected in liver, kidney and intestine soon after the drug administration. The radioactivity declined rapidly, with less than 1% of the i.v. dose remaining at 30-h post-dose. 5. Compound A was moderately bound to plasma proteins, with unbound fractions of 26, 20, 14 and 5% for rats, dogs, monkeys and humans, respectively. It was bound primarily to human alpha(1)-acid glycoprotein (about 85% binding at 0.1% concentration), as compared with human albumin (< 50% binding at 4% concentration). 6. Using simple allometry, compound A was predicted to exhibit relatively low clearance (1-3 ml min(-1) kg(-1)) and low volume of distribution (0.1-0.3 l kg(-1)) in humans. Based on the predicted values, compound A was projected to exhibit a favourable oral pharmacokinetic profile in humans, with good bioavailability (50-80%). These predicted values provided a basis for compound selection for further development.

Administration, Oral↗
PubMed1999

Physicochemical characterization of YJA20379-8, a new proton pump inhibitor.

The physicochemical properties of the potent reversible proton pump inhibitor YJA20379-8, 3-butyryl-4-[(R)-1-methylbenzylamino]-8-ethoxy-1,7-naphthyridine, were studied. YJA20379-8 is essentially nonhygroscopic pale yellowish crystalline powder. It is practically insoluble in water, and its lipid solubility is high. The pH solubility profile exhibits an L-shaped curve, indicating YJA20379-8 is a basic substance having a soluble ionized form in acidic conditions. This is consistent with the result of an experiment to determine pKa. The solid-state stability study shows that YJA20379-8 is stable at various temperatures and humidities, but is decomposed by light.

Anti-Ulcer Agents↗
PubMed1986

Effects of ethylenediaminetetraacetic acid and gentamicin on the antibacterial activity of pyridone carboxylic acid derivatives against gram-negative bacilli.

Ofloxacin (9-fluoro-3-methyl-10-(4-methyl-1-piperazynyl)-7-oxo-2,3-dihydro-7 H-pyrido-(1,2,3-de)1,4-benzoxazine-6-carboxylic acid) and enoxacin (1-ethyl-6-fluoro-1,4-dehydro-4-oxo-7-(1-piperazinyl)-1, 8-naphthyridine-3-carboxylic acid) are newly developed pyridone carboxylic acid derivatives with broad and potent antibacterial activities against Gram-negative and Gram-positive bacteria. Antibacterial activities of six pyridone carboxylic acid derivatives, including these two new antibiotics, were examined against Gram-negative bacilli in the presence and absence of ethylenediaminetetraacetic acid (EDTA) or gentamicin. The minimal inhibitory concentrations (MICs) of nalidixic acid, cinoxacin and piromidic acid were reduced by the addition of EDTA or gentamicin. However, the MICs of pipemidic acid, ofloxacin and enoxacin were unaffected. These findings indicated the high permeability of pipemidic acid, ofloxacin and enoxacin through the outer membrane. The effects of EDTA and gentamicin against Serratia marcescens were different from those against other Gram-negative bacilli.

Anti-Bacterial Agents↗
PubMed1988

In-vitro and in-vivo activities of T-3262, a new pyridone carboxylic acid.

T-3262[p-toluenesulfonic acid salt of dl-7-(3-amino-1-pyrrolidinyl)-1-(2,4-difluorophenyl)-6-fluoro-1, 4-dihydro-4-oxo-1, 8-naphthyridine-3-carboxylic acid monohydrate] is a new pyridone carboxylic acid with a broad spectrum of antibacterial activity against Gram-positive and Gram-negative bacteria. The activity of T-3262 against most Enterobacteriaceae was comparable with that of ciprofloxacin except Proteus spp. and Providencia rettgeri and exceeded that of ofloxacin and norfloxacin. The activity of T-3262 against Pseudomonas aeruginosa was comparable with that of ciprofloxacin, and T-3262 was more active than the other new quinolones against Acinetobacter calcoaceticus, Branhamella catarrhalis and Haemophilus influenzae, and also against staphylococci, streptococci, and Bacteroides fragilis. The protective effects of a single oral dose of T-3262 on systemic infection in mice were greater than norfloxacin. T-3262 was as effective as ofloxacin and ciprofloxacin against systemic infections in an animal model with Escherichia coli and Klebsiella pneumoniae, and more active against Ps. aeruginosa infections. T-3262 showed excellent activity against staphylococcal and streptococcal infections.

4-Quinolones↗
PubMed1993

Comparative in-vitro activities of the new quinolone, Bay y 3118, and ciprofloxacin, sparfloxacin, tosufloxacin, CI-960 and CI-990.

The in-vitro activity of the new quinolone, Bay y 3118, was compared with that of ciprofloxacin, tosufloxacin, sparfloxacin, CI-960 and CI-990 against 1640 isolates belonging to 117 bacterial species. Against members of the Enterobacteriaceae, Bay y 3118 was as active as CI-960 and CI-990, up to four-fold more active than ciprofloxacin and tosufloxacin and up to 16-fold more active than sparfloxacin. The majority of Enterobacteriaceae which were resistant to ciprofloxacin (MICs > or = 2 mg/L) were sensitive to Bay y 3118. With the exception of ciprofloxacin which was less active, the activities of Bay y 3118 and the other comparator compounds were similar against Acinetobacter baumannii, Acinetobacter genospecies 3 and Acinetobacter strain 84. Bay y 3118 inhibited Pseudomonas aeruginosa isolates at concentrations comparable with those of ciprofloxacin. However, non-aeruginosa Pseudomonas spp. were four times more susceptible to Bay y 3118 than to ciprofloxacin. All of the agents tested were equally active against Haemophilus, Moraxella, Neisseria and Bordetella spp. Against staphylococci, Bay y 3118 was the most active compound, followed jointly by CI-990, sparfloxacin, CI-960 and tosufloxacin, and then ciprofloxacin. Bay y 3118 remained highly active against Staphylococcus aureus strains resistant to ciprofloxacin; the MIC90 (0.5 mg/L) was 16-fold less than that of CI-990 and sparfloxacin, 32-fold less than that of CI-960 and 128-fold less than that of tosufloxacin and ciprofloxacin. Against haemolytic and non-haemolytic streptococci and Enterococcus faecalis, Bay y 3118 was two- to 16-fold more active than the other compounds. It had only moderate activity against Listeria spp., but this was superior to that of all the other compounds tested. Bay y 3118 was also the most active agent overall against anaerobic bacteria, although CI-960 and CI-990 had slightly better activity against Gardnerella vaginalis. It inhibited Mycobacterium spp. other than Mycobacterium tuberculosis (Mycobacterium kansasii, Mycobacterium scrofulaceum, Mycobacterium gordonae, Mycobacterium xenopi, Mycobacterium flavescens, Mycobacterium avium and Mycobacterium fortuitum) at concentrations < or = 0.06-4 mg/L and was between two- and 128-fold more active than the other compounds against these isolates; the two strains each of Mycobacterium terrae and Mycobacterium nonchromogenicum were resistant to Bay y 3118. In this study, Bay y 3118 was shown to be the most active and most broad-spectrum of the new quinolone and naphthyridine derivatives.

Anti-Infective Agents↗
PubMed2006

BENA435, a new cell-permeant photoactivated green fluorescent DNA probe.

N'-(2,8-Dimethoxy-12-methyl-dibenzo [c,h] [1,5] naphthyridin-6-yl)-N,N-dimethyl-propane-1,3-diamine (BENA435) is a new cell-membrane permeant DNA dye with absorption/emission maxima in complex with DNA at 435 and 484 nm. This new reagent is unrelated to known DNA dyes, and shows a distinct preference to bind double-stranded DNA over RNA. Hydrodynamic studies suggest that BENA435 intercalates between the opposite DNA strands. BENA435 fluoresces much stronger when bound to dA/dT rather than dG/dC homopolymers. We evaluated 14 related dibenzonaphthyridine derivatives and found BENA435 to be superior in its in vivo DNA-binding properties. Molecular modelling was used to develop a model of BENA435 intercalation between base pairs of a DNA helix. BENA435 fluorescence in the nuclei of cells increases upon illumination, suggesting photoactivation. BENA435 represents thus the first known cell-permeant photoactivated DNA-binding dye.

Animals↗
PubMed2003

2,6-Diaminonaphthyridine derivatives bind to a single nucleotide bulge in DNA.

2,6-Diamino-1,8-naphthyridine derivative (daNpt), which possesses hydrogen bonding groups in an alignment of donor-acceptor-acceptor-donor binds to a single nucleotide bulge in the duplex. The melting temperatures (Tm) of all duplexes containing a bulge were increased, especially for the cytosine (C) and thymine (T) bulges, in the presence of daNpt, whereas only a small increase of Tm was observed for the fully matched duplexes. It was suggested by pH dependency of Tm and UV spectra, that a protonation of daNpt should play an important role for the recognition of C and T bulges.

Base Sequence↗
PubMed2005

Hydrogen bond-mediated binding of ligands to a nucleobase at a gap site in a DNA duplex and its use for fluorescence detection of single-nucleotide polymorphisms.

Here we report on the strong and selective binding of a hydrogen bond-forming ligand, 2-amino-7-methyl-1,8-naphthyridine (AMND), to a nucleobase at a gap site in DNA duplexes. In solutions buffered to pH 7.0 (at 20 degrees C, I = 0.11 M), AMND is found to selectively recognize cytosine (C) base over other nucleotides, and the 1:1 association constant reaches 3.2x10(5) M(-1) when binding to C. The ligand-nucleotide interaction results in significant fluorescence quenching of AMND, which is highly selective to C. These sensing functions of AMND at the gap site are utilized for the development of ligand-based fluorescence assay for SNPs (single-nucleotide polymorphisms) typing.

Cytosine↗
PubMed2005

Assignment of hydrogen-bond structure in a ligand-nucleobase complex inside duplex DNA: combined use of quantum chemical calculations and 15N NMR experiments.

We present a combined experimental and theoretical approach, whereby a comparison of calculated and experimental 15N NMR chemical shifts allows the elucidation of hydrogen-bond structure in a ligand-nucleobase complex inside duplex DNA. In this work, we focus on the highly selective interaction of 2-amino-7-methyl-1,8-naphthyridine (AMND) to cytosine (C) base opposite the abasic site in DNA duplexes, despite the hydrogen-bond array of neutral AMND being fully complementary to guanine (G). Examination of the salt dependence of the binding constants reveals that the effective number of charges on the ligand is +1.0, indicating protonated AMND does bind to C. This is clearly supported by 15N NMR measurements, where the drastic changes in chemical shift are observed for the aromatic nitrogens on the ligand when binding to C. Furthermore, from the complexation-induced changes in chemical shift at 15N1 (83.1 ppm upfield), 15N8 (14.1 ppm upfield), and 15NH2 (18.3 ppm downfield) on AMND, the ligand is found to bind to C via three point hydrogen-bonds. The chemical shifts of the AMND-C complex, calculated by gauge-independent atomic orbital-DFT method, are in fair agreement with the experimental values. These results clearly explain the selective binding of AMND to C over G in abasic site-containing duplex DNA.

Cytosine↗
PubMed2006

Inhibition of DNA replication by a d(CAG) repeat binding ligand.

Trinucleotide repeat expansions in genomic DNA are the molecular basis of a number of genetic diseases. The (CAG)n, (CTG)n, and (CGG)n repeats share the common sequence CXG, and inherently produce a hairpin structure involving X-X mismatch base pairs flanked by two G-C base pairs. The chance of a strand slippage leading to the repeat expansion is considered to increase with increasing stability of the hairpin form. Here we show our synthetic ligand naphthyridine-azaquinolone (NA) stabilized a hairpin form of the (CAG)n repeat and inhibited the polymerase-mediated DNA synthesis.

Adenine↗
PubMed1979

Fine structure of contrasting choroid plexus lesions caused by tertiary amines or cyclophosphamide.

Hydropic alterations of the fine structure of the choroid plexus epithelium following administration of three different tertiary amines to rats were compared with alterations produced by cyclophosphamide and with normal choroid plexus. Single doses of 2,7-bis(2-diethylamino)-ethoxy)-4-methyl-1,8-naphthyridine HCl or 2,6-di-(omega-dimethyl aminoethoxy)-pyridine produced dramatic accumulations of membrane-limited vacuoles. Multiple doses of 2,7-bis-(diethylaminoethoxy)fluoren-9-one HCl (tilorone) produced accumulations of dense cytoplasmic bodies in choroid epithelial cells in addition to the hydropic vacuoles. Differential responses to these agents suggested functional specialization or temporal variation in function among adjacent choroidal cells. Despite the occurrence of pronounced plasma exudation in the plexitis following cyclophosphamide treatment, there was no hydropic vacuolization.

Animals↗
PubMed1988

Structure of suriclone, a benzodiazepine receptor agonist.

6-(7-Chloro-1,8-naphthyridin-2-yl)-2,3,6,7-tetrahydro-4-methyl-7- oxo-5H-1,4-dithiino[2,3-c]-pyrrol-5-yl-1-piperazinecarboxylic++ + acid, C20H20C1N5-O3S2, Mr = 477.9, triclinic, P1, a = 8.7066 (3), b = 9.7665 (8), c = 14.2515 (16) A, alpha = 80.986 (9), beta = 75.168 (6), gamma = 65.884 (5) degrees, V = 1067.4 (2) A3, Z = 2, F(000) = 496, room temperature, Dm = 1.482, D chi = 1.487 g cm-3, lambda(Cu K alpha) = 1.54178 A, Ni filter, mu = 36.3 cm-1, R = 0.053, omega R = 0.070 for the 3538 reflections included in the refinement. Comparisons of the structures of the two enantiomers of suriclone and the active conformer of the 1,4-benzodiazepine anxiolytics allow the identification of the active form of suriclone as the R isomer.

Anti-Anxiety Agents↗