Synthesis and antimicrobial activity of 5-hydroxymethyl- 8-methyl-2-(N-arylimino)-pyrano[2,3-c]pyridine-3-(N-aryl)-carboxamides

Several novel 2-imino-5-hydroxymethyl-8-methyl-2H-pyrano[2,3-c]pyridine-3-(N-aryl) carboxamides were prepared by reaction of pyridoxal hydrochloride with various N-arylcyanoacetamides. Reaction of these compounds with aromatic amines furnished a wide series of 2-(N-R-phenyl) imino-5-hydroxymethyl-8-methyl-2H-pyrano[2,3-c]pyridine-3-carboxamides. Antibacterial and antifungal activities of the synthesized compounds were studied. Most of the obtained compounds demonstrated significant activity against bacterial or fungal strains (MIC in the range of 12.5–25 μg/mL), displaying comparable or even better efficacy than the standard drugs.     

Synthesis and antibacterial activity of N-[2-[5-(methylthio)thiophen-2-yl]-2-oxoethyl] and N-[2-[5-(methylthio)thiophen-2-yl]-2-(oxyimino)ethyl]piperazinylquinolone derivatives

A number of N-substituted piperazinylquinolone derivatives were synthesized and evaluated for antibacterial activity against Gram-positive and Gram-negative bacteria. Preliminary results indicated that most compounds tested in this study demonstrated comparable or better activity against Staphylococcus aureus and Staphylococcus epidermidis than their parent piperazinylquinolones as reference drugs. Among these derivatives, ciprofloxacin derivative 5a, containing N-[2-[5-(methylthio)thiophen-2-yl]-2-oxoethyl] residue, showed significant improvement of potency against staphylococci, maintaining Gram-negative coverage.     

Optically active antifungal azoles: synthesis and antifungal activity of (2R,3S)-2-(2,4-difluorophenyl)-3-(5-[2-[4-aryl-piperazin-1-yl]-ethyl]-tetrazol-2-yl/1-yl)-1-[1,2,4]-triazol-1-yl-butan-2-ol

A series of (2R,3S)-2-(2,4-difluorophenyl)-3-(5-[2-[4-aryl-piperazin-1-yl]-ethyl]-tetrazol-2-yl)-1-[1,2,4]-triazol-1-yl-butan-2-ol (11a-n) and (2R,3S)-2-(2,4-difluorophenyl)-3-(5-[2-[4-aryl-piperazin-1-yl]-ethyl]-tetrazole-1-yl)-1-[1,2,4]-triazol-1-yl-butan-2-ol (12a-n) has been synthesized. The antifungal activity of compounds was evaluated by in vitro agar diffusion and broth dilution assay. Compounds 11d and its positional isomer 12d having 3-trifluoromethyl substitution on the phenyl ring of piperazine demonstrated significant antifungal activity against variety of fungal cultures (Candida spp. C. neoformans and Aspergillus spp.). The compound 12d showed MIC value of 0.12 microg/mL for C. albicans, C. albicans V-01-191A-261 (resistant strain); 0.25 microg/mL for C. tropicalis, C. parapsilosis ATCC 22019 and C. krusei and MIC value of 0.5 microg/mL for C. glabrata, C. krusei ATCC 6258, which is comparable to itraconazole and better than fluconazole. Further, compound 11d showed significant activity (MIC; 0.25-0.5 microg/mL) against Candida spp. and strong anticryptococcal activity (MIC; 0.25 microg/mL) against C. neoformans.     

Correlation of antibacterial activity of some N-[5-(2-furanyl)-2-methyl-4-oxo-4H-thieno[2,3-d]pyrimidin-3-yl]-carboxamide and 3-substituted-5-(2-furanyl)-2-methyl-3H-thieno[2,3-d]pyrimidin-4-ones with topological indices using Hansch analysis

The antimicrobial activity of the N-[5-(2-furanyl)-2-methyl-4-oxo-4H-theino[2,3-d]pyrimidin-3-y1]-carboxamides and 3-substituted-5-(2-furanyl)-2-methyl-3H-thieno[2,3-d]pyrimidin-4-ones was correlated with different topological indices using Hansch analysis. Good correlations were obtained through a simple regression equation with third order molecular connectivity index (3chi). The developed QSAR models were crossvalidated by leave-one-out technique.     

Iron-chlorophyllin-mediated conversion of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2(NHOH)) into its nitroso derivative

Early work from our laboratory has shown that the mutagenicity of heterocyclic amines in Salmonella can be inhibited by hemin and chlorophyllins. We have speculated that the inhibition is a result of complex formation between heterocyclic amines and the pigments, and the speculation has been given a line of experimental evidence. We have now found that ferric-chlorophyllin (Fe-chlorophyllin) can modify the mutagenicity of 3-hydroxyamino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2(NHOH)), a metabolically activated form of 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2). The mutagenicity of Trp-P-2(NHOH)) in Salmonella typhimurium TA 98 (without S9) was strongly inhibited by an addition of an equimolar Fe-chlorophyllin in the pre-incubation mixture. Fe-chlorophyllin also inhibited the mutagenicity of 2-hydroxyamino-6-methyldipyrido[1,2-a:3′,2′-d] imidazole (Glu-P-1(NHOH)). A rapid change in the UV spectrum of a mixture of Trp-P-2(NHOH) and Fe-chlorophyllin was observed. Analysis by high performance liquid chromatography showed that Trp-P-2(NHOH) was converted into 3-nitroso-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2(NO)), the mutagenic potency of which is a quarter of that of Trp-P-2(NHOH). Furthermore, the mutagenicity of Trp-P-2(NO), in turn, was inhibited by Fe-chlorophyllin. We conclude that the suppression of the mutagenicity of Trp-P-2(NHOH) is ascribable to the oxidative function of Fe-chlorophyllin, coupled with its ability to form complex formation with the planar surface of the heterocyclic amine molecules.     

Synthesis and antibacterial activity of 1-[1,2,4-triazol-3-yl] and 1-[1,3,4-thiadiazol-2-yl]-3-methylthio-6,7-dihydrobenzo[c]thiophen-4(5H)ones

A series of 1-[1,2,4-triazol-3-yl] and 1-[1,3,4-thiadiazol-2-yl]-3-methylthio-6,7-dihydrobenzo[c]thiophen-4(5H)ones were synthesized and tested to demonstrate in vitro antimicrobial activity. Some of these compounds exhibited a good activity against Staphylococcus aureus, S. epidermidis and Bacillus subtilis.     

Synthesis and antibacterial activity of N-[2-(5-bromothiophen-2-yl)-2-oxoethyl] and N-[(2-5-bromothiophen-2-yl)-2-oximinoethyl] derivatives of piperazinyl quinolones

A series of N-[2-(5-bromothiophen-2-yl)-2-oxoethyl] and N-[2-(5-bromothiophen-2-yl)-2-oximinoethyl]derivatives of piperazinyl quinolones were synthesized and evaluated for antimicrobial activity against Gram-positive and Gram-negative microorganisms. Some of these derivatives exhibit comparable or better activity against Gram-positive bacteria, Staphylococcus aureus, Staphylococcus epidermidis and Bacillus subtilis, than ciprofloxacin, norfloxacin and enoxacine as reference drugs.     

Design and synthesis of 3-(4,5,6,7-tetrahydro-3H-imidazo[4,5-c]pyridin-2-yl)-1H-quinolin-2-ones as VEGFR-2 kinase inhibitors

A series of 3-(4,5,6,7-tetrahydro-3H-imidazo[4,5-c]pyridin-2-yl)-1H-quinolin-2-ones have been identified as a new class of VEGFR-2 kinase inhibitors. A variety of (4,5,6,7-tetrahydro-imidazo[5,4-c]pyridin-2-yl)-acetic acid ethyl esters were synthesized, and their VEGFR-2 inhibitory activity was evaluated. Described herein are the preparation of the series and the effects of the compounds on VEGFR-2 kinase activity.     

2-(Dimethylaminomethyl)-tetrahydroisoxazolopyridobenzazepine derivatives. Synthesis of a new 5-HT(2C) antagonist with potential anxiolytic properties

Following the program started at Johnson & Johnson Pharmaceutical Research & Development searching for 5-HT_2A/2C antagonists, we now report on the synthesis of 2-(dimethylaminomethyl)-2,3,3a,8-tetrahydroisoxazolo[3,2-a]pyrido[3,4-c]-[2]benzazepine and 2-(dimethylaminomethyl)-2,3,3a,8-tetrahydroisoxazolo[3,2-a]pyrido[3,2-c]-[2]benzazepine. A new method for the synthesis of pyridobenzazepines is described as well. The affinities for several receptors as well as the mCPP antagonistic activity of the compounds synthesised are described.     

1-[4-(1H-Benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea derivatives as small molecule heparanase inhibitors

A novel class of 1-[4-(1H-benzoimidazol-2-yl)-phenyl]-3-[4-(1H-benzoimidazol-2-yl)-phenyl]-ureas are described as potent inhibitors of heparanase. Among them are 1,3-bis-[4-(1H-benzoimidazol-2-yl)-phenyl]-urea (7a) and 1,3-bis-[4-(5,6-dimethyl-1H-benzoimidazol-2-yl)-phenyl]-urea (7d), which displayed good heparanase inhibitory activity (IC(50) 0.075-0.27 microM). Compound 7a showed good efficacy in a B16 metastasis model.     

Synthesis and KCNQ2 opener activity of N-(1-benzo[1,3]dioxol-5-yl-ethyl, N-[1-(2,3-dihydro-benzofuran-5-yl)-ethyl, and N-[1-(2,3-dihydro-1H-indol-5-yl)-ethyl acrylamides

Bioisosteric replacement studies led to the identification of N-(1-benzo[1,3]dioxol-5-yl-ethyl)-3-(2-chloro-phenyl)-acrylamide ((S)-3) as a highly potent KCNQ2 opener, and 3-(2,6-difluoro-phenyl)-N-[1-(2,3-dihydro-benzofuran-5-yl)-ethyl]-acrylamide ((S)-4), and N-[1-(2,3-dihydro-1H-indol-5-yl)-ethyl]-3-(2-fluoro-phenyl)-acrylamide ((S)-5) as highly efficacious KCNQ2 openers. In contrast, their respective R enantiomers showed significantly less or no appreciable KCNQ2 opener activity even at the highest concentration tested (10 microM). Because of its high potency and moderate efficacy as well as its convenient synthesis, (+/-)-3 was selected as a reference compound for analyzing efficacies of KCNQ openers in electrophysiology studies. Compounds (S)-4 and (S)-5 demonstrated significant activity in reducing neuronal hyperexcitability in rat hippocampal slices. The synthesis and the KCNQ2 opener activity of these acrylamides are described.     

3-[2-Amino-2-imidazolin-4(5)-yl]alanine (enduracididine) and 2-[2-amino-2-imidazolin-4(5)-yl] acetic acid in seeds of Lonchocarpus sericeus

3-[2-Amino-2-imidazolin-4(5)-yl]alanine (enduracididine) and 2-[2-amino-2-imidazolin-4(5)-yl] acetic acid have been isolated from seeds of Lonchocarpus sericeus. The concentration of each compound was ca 0.5 % of the fresh seed weight.     

Differentiation of [H]phencyclidine and ( + )-[H]SKF-10,047 binding sites in rat cerebral cortex

The potency of a series of opioid and non-opioid psychotomimetic drugs to inhibit the specific binding of [³H]PCP and ( + )-[³H]SKF-10,047 to rat cerebral cortical membranes was examined. ( + )-PCMP, the 3-methylpiperidino analog of PCP, was a potent inhibitor of the specific binding of both ligands. All of the other 12 compounds examined, however, displayed a 3-277-fold selectivity for either [³H]PCP or (+)-[³H]SKF-10,047 binding. These results suggest that although these opioid and non-opioid psychotomimetics bind to both sites, most have significantly different affinities. The binding sites for [³H]PCP appear to be distinct from the ‘sigma’ binding sites labeled with (+)-[³H]SKF-10,047.

SKF-10,047 Sigma receptor Phencyclidine Phencyclidine receptor Psychotomimetic activity     

Farnesyl pyrophosphate synthase enantiospecificity with a chiral risedronate analog, [6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl(hydroxy)methylene]bis(phosphonic acid) (NE-10501): Synthetic, structural, and modeling studies

The complex formed from crystallization of human farnesyl pyrophosphate synthase (hFPPS) from a solution of racemic [6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl(hydroxy)methylene]bis(phosphonic acid) (NE-10501, 8), a chiral analog of the anti-osteoporotic drug risedronate, contained the R enantiomer in the enzyme active site. This enantiospecificity was assessed by computer modeling of inhibitor–active site interactions using Autodock 3, which was also evaluated for predictive ability in calculations of the known configurations of risedronate, zoledronate, and minodronate complexed in the active site of hFPPS. In comparison with these structures, the 8 complex exhibited certain differences, including the presence of only one Mg²⁺, which could contribute to its 100-fold higher IC₅₀. An improved synthesis of 8 is described, which decreases the number of steps from 12 to 8 and increases the overall yield by 17-fold.     

Synthesis and positive inotropic activity of N-(4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolin-7-yl)-2-(piperazin-1-yl)acetamide derivatives

A series of N-(4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolin-7-yl)-2-(piperazin-1-yl)acetamide derivatives were synthesized and their positive inotropic activity was evaluated by measuring left atrium stroke volume on isolated rabbit heart preparations. Several compounds showed favorable activity compared with the standard drug, milrinone, among which N-(1-benzyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolin-7-yl)-2-(4-benzylpiperazin-1-yl)acetamide 6j was found to be the most potent with the 13.2% increased stroke volume (milrinone 4.7%) at concentration of 3x10(-5) M in our in vitro study. The chronotropic effects of those compounds having inotropic effects were also evaluated in this work.     

Spin-crossover iron(II) complexes [Fe(Medpq)(py)2(NCS)2] and [Fe(Medpq)(py)2(NCSe)2]: syntheses, characterization and magnetic properties

Two new spin-crossover complexes, [Fe(Medpq)(py)₂(NCS)₂] · py · 0.5H₂O (1) and [Fe(Medpq)(py)₂(NCSe)₂] · py (2) (Medpq = 2-methyldipyrido[3,2-f:2′,3′-h]-quinoxaline, py = pyridine), have been synthesized. The crystal structures were determined at both room temperature (298 K) and low temperature (110 K). Complexes 1 and 2 crystallize in the orthorhombic space group Pbca and monoclinic space group P2₁/n, respectively. In both complexes, the distorted [FeN₆] octahedron is formed by six nitrogen atoms from Medpq, the trans pyridine molecules and the cis NCX⁻ groups. The thermal spin transition is accompanied by the shortening of the mean Fe–N distances by 0.194 Å for 2. The mononuclear [Fe(Medpq)(py)₂(NCS)₂] and [Fe(Medpq)(py)₂(NCSe)₂] neutral species interact each other via π-stacking, resulting in a one-dimensional extended structure for both 1 and 2. There exist C–HX (X = S, Se) hydrogen bonds for both complexes. Variable-temperature magnetic susceptibility measurements and Mössbauer spectroscopy reveal the occurrence of a gradual spin transition. The transitions are centered at T_1/2 = 120 K for 1 and T_1/2 = 180 K for 2, respectively.     

Synthesis of 3-(1H-benzimidazol-2-yl)-5-isoquinolin-4-ylpyrazolo[1,2-b]pyridine, a potent cyclin dependent kinase 1 (CDK1) inhibitor

The novel compound 3-(1H-benzimidazol-2-yl)-5-isoquinolin-4-ylpyrazolo[1,2-b]pyridine was discovered to be a potent CDK1 inhibitor. Described here is the chemistry for its synthesis, including Pd(II) catalyzed Stille coupling reaction and sulfur(0) induced benzimidazole formation. Its effects on VEGFR-2 kinase activity and tumour cell proliferation are also described.     

Enantioselective microbial reduction of 6-oxo-8-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane-7,9-dione: Cloning and expression of reductases

The enantioselective microbial reduction of 6-oxo-8-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane-7,9-dione (1) to either of the corresponding (S)- and (R)-6-hydroxy-8-[4-[4-(2-pyrimidinyl)-1-piperazinyl]butyl]-8-azaspiro[4.5]decane-7,9-diones (2 and 3, respectively) is described. The NADP⁺-dependent (R)-reductase (RHBR) which catalyzes the reduction of 6-ketobuspirone (1) to (R)-6-hydroxybuspirone (3) was purified to homogeneity from cell extracts of Hansenula polymorpha SC 13845. The subunit molecular weight of the enzyme is 35,000 kDa based on sodium dodecyl sulfate gel electrophoresis and the molecular weight of the enzyme is 37,000 kDa as estimated by gel filtration chromatography. (R)-reductase from H. polymorpha was cloned and expressed in Escherichia coli. To regenerate the cofactor NADPH required for reduction we have cloned and expressed the glucose-6-phosphate dehydrogenase gene from Saccharomyces cerevisiae in E. coli. The NAD⁺-dependent (S)-reductase (SHBR) which catalyzes the reduction of 6-ketobuspirone (1) to (S)-6-hydroxybuspirone (2) was purified to homogeneity from cell extracts of Pseudomonas putida SC 16269. The subunit molecular weight of the enzyme is 25,000 kDa based on sodium dodecyl sulfate gel electrophoresis. The (S)-reductase from P. putida was cloned and expressed in E. coli. To regenerate the cofactor NADH required for reduction we have cloned and expressed the formate dehydrogenase gene from Pichia pastoris in E. coli. Recombinant E. coli expressing (S)-reductase and (R)-reductase catalyzed the reduction of 1 to (S)-6-hyroxybuspirone (2) and (R)-6-hyroxybuspirone (3), respectively, in >98% yield and >99.9% e.e.