Solution conformation of asparagine-linked oligosaccharides: alpha(1-2)-, alpha(1-3)-, beta(1-2)-, and beta(1-4)-linked units

The solution conformation is presented for representatives of each of the major classes of asparaginyl oligosaccharides. In this report the conformation of alpha(1-3)-, alpha(1-2)-, beta(1-2)-, and beta(1-4)-linked units is described. The conformational properties of these glycopeptides were determined by high-resolution 1H nuclear magnetic resonance in conjunction with potential energy calculations. The NMR parameters that were used in this analysis were chemical shifts and nuclear Overhauser enhancements. Potential energy calculations were used to evaluate the preferred conformers available for the different linkages in glycopeptides and to draw conclusions about the behavior in solution of these molecules. It was found that the linkage conformation of the Man alpha 1-3 residues was not affected by substitution either at the 2-position by alpha Man or beta GlcNAc or at the 4-position by beta GlcNAc or by the presence of a bisecting GlcNAc on the adjacent beta Man residue.     

Dual DAT/sigma1 receptor ligands based on 3-(4-(3-(bis(4-fluorophenyl)amino)propyl)piperazin-1-yl)-1-phenylpropan-1-ol

Ester analogs of (+/-)3-(4-(3-(bis(4-fluorophenyl)amino)propyl)piperazin-1-yl)-1-phenylpropan-1-ol were synthesized and evaluated for binding at DAT, SERT, NET, and sigma1 receptors, and compared to GBR 12909 and several known sigma1 receptor ligands. Most of these compounds demonstrated high affinity (K(i)=4.3-51 nM) and selectivity for the DAT among the monoamine transporters. S- and R-1-(4-(3-(bis(4-fluorophenyl)amino)propyl)piperazin-1-yl)-3-phenylpropan-2-ol were also prepared wherein modest enantioselectivity was demonstrated at the DAT. However, no enantioselectivity at sigma1 receptors was observed and most of the ester analogs of the more active S-enantiomer showed comparable binding affinities at both DAT and sigma1 receptors with a maximal 16-fold DAT/sigma1 selectivity.     

Biomonitoring of environmental tobacco smoke (ETS)-related exposure to 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)

The exposure of non-smokers to the tobacco-specific N-nitrosamine 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a rodent lung carcinogen, was determined in the air of various indoor environments as well as by biomonitoring of non-smokers exposed to environmental tobacco smoke (ETS) under real-life conditions using the urinary NNK metabolites 4-(N-methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) and [4-(N-methylnitrosamino)-1-(3-pyridyl)but-1-yl]-beta-O-D-glucosiduronic acid (NNAL-Gluc). NNK was not detectable (<0.5 ng m^-3) in 11 rooms in which smoking did not occur. The mean NNK concentration in 19 rooms in which smoking took place was 17.5 (2.4-50.0) ng m^-3. The NNK levels significantly correlated with the nicotine levels (r=0.856; p< 0.0001). Of the 29 non-smokers investigated, 12 exhibited no detectable NNAL and NNAL-Gluc excretion (<3 pmol day) in their urine. The mean urinary excretion of NNAL and NNAL-Gluc of the 17 remaining non-smokers was 20.3 (<3-63.2) and 22.9 (<3-90.0) pmol day^-1, respectively. Total NNAL excretion (NNAL+NNAL-Gluc) in all non-smokers investigated significantly correlated with the amount of nicotine on personal samplers worn during the week prior to urine collection (r=0.88; <0.0001) and with the urinary cotinine levels (r=0.40; p=0.038). No correlation was found between NNAL excretion and the reported extent of ETS exposure. Average total NNAL excretion in the non-smokers with detectable NNAL levels was 74 times less than in 20 smokers who were also investigated. The cotinine/total NNAL ratios in urine of smokers (9900) and non-smokers (9300) were similar. This appears to be at variance with the ratios of the corresponding precursors (nicotine/NNK) in mainstream smoke (16400) and ETS (1000). Possible reasons for this discrepancy are discussed. The possible role of NNK as a lung carcinogen in non-smokers is unclear, especially since NNK exposure in non-smokers is several orders of magnitude lower than the ordinary exposure to exogenous and endogenous N-nitrosamines and the role of NNK as a human lung carcinogen is not fully understood.     

1-(4-Phenylpiperazin-1-yl)-2-(1H-pyrazol-1-yl)ethanones as novel CCR1 antagonists

A novel series of CCR1 antagonists based on the 1-(4-phenylpiperazin-1-yl)-2-(1H-pyrazol-1-yl)ethanone scaffold was identified by screening a compound library utilizing CCR1-expressing human THP-1 cells. SAR studies led to the discovery of the highly potent and selective CCR1 antagonist 14 (CCR1 binding IC₅₀ = 4 nM using [¹²⁵I]-CCL3 as the chemokine ligand). Compound 14 displayed promising pharmacokinetic and toxicological profiles in preclinical species.     

Synthesis and Fungicidal Activity of 5-Aryl-1-(aryloxyacetyl)-3-(tert-butyl or phenyl)-4-(1H-1,2,4-triazol-1-yl)-4,5-Dihydropyrazole

A series of novel 5-aryl-1-(aryloxyacetyl)-3-(tert-butyl or phenyl)-4-(1H-1,2,4-triazol-1-yl)-4,5-dihydropyrazole 3a-3n were synthesized by the annulation of 2-aryloxyacetohydrazides with 3-aryl-1-t-butyl(or phenyl)-2-(1H-1,2,4-triazol-1-yl)prop-2-en-1-ones(1)in the presence of a catalytic amount of acetic acid.Compounds 2 were obtained by the Knoevenagel reactions of 1-t-butyl(or phenyl)-2-(1H-1,2,4-triazol-1-yl)ethanone(2)with aromatic aldehydes in the presence of piperidine.Their structures were confirmed by IR,1H-NMR,ESIMS,and elemental analyses.The preliminary bioassay indicated that some compounds displayed moderate to excellent fungicidal activity.For example,compounds 31,3m,and 3n possessed100%inhibition against Cercospora arachidicola Hori at the concentration of 50 mg/L.     

Synthesis and histamine H3 receptor activity of 4-(n-alkyl)-1H-imidazoles and 4-(omega-phenylalkyl)-1H-imidazoles

The influence of lipophilic moieties attached to a 4-1H-imidazole ring on the histamine H₃ receptor activity was systematically investigated. Series of 4-(n-alkyl)-1H-imidazoles and 4-(ω-phenylalkyl)-1H-imidazoles were prepared, with an alkyl chain varying from 2–9 methylene groups and from 1–9 methylene groups, respectively. The compounds were tested for their activity on the H₃ receptor under in vitro conditions. For the 4-(n-alkyl)-1H-imidazoles the activity is proportional to chain length, ranging from a pA₂ value of 6.3±0.2 for 4-(n-propyl)-1H-imidazole to a pA₂ value of 7.2±0.1 for 4-(n-decyl)-1H-imidazole. For the series 4-(ω-phenylalkyl)-4H-imidazoles an optimum in H₃ activity was found for the pentylene spacer: 4-(ω-phenylpentyl)-1H-imidazole has a pA₂ value of 7.8±0.1.     

Synthesis of (1R,2S)-1-(3'-chloro-4' -methoxyphenyl)-1,2-propanediol (trametol) and (1R,2S)-1-(3',5'-dichloro-4'-methoxyphenyl)-1,2-propanediol,chlorinated fungal metabolites in the natural environment

(1R,2S)-1-(3'-Chloro-4'-methoxyphenyl)-1,2propanediol (Trametol, 3), a metabolite of the fungus Trametes sp. IVP-F640 and Bjerkandera sp. BOS55, was synthesized by employing Sharpless asymmetric dihydroxylation as the key step. Similarly, the (1R,2S)-isomer of 1-(3',5'-dichloro-4'-methoxyphenyl)-1,2-propanediol (4), another metabolite of Bjerkandera sp. BOS55, was synthesized by asymmetric dihydroxylation.     

Synthesis and biological activities of octyl 2,3-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2-O-sulfo-alpha-L-fucopyranosyl-(1-->4)-2,3-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2-O-sulfo-alpha-L-fucopyranosyl-(1-->4)-2,3-di-O-sulfo-beta-L-fucopyranoside

Octyl 2,3-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2-O-sulfo-alpha-L-fucopyranosyl-(1-->4)-2,3-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2-O-sulfo-alpha-L-fucopyranosyl-(1-->4)-2,3-di-O-sulfo-beta-L-fucopyranoside, a fucosyl pentasaccharide with a regular structure resembling the repeating unit of a natural sulfated fucan, was chemically synthesized using a convergent '2+3' strategy. Regioselective 3-O-silylation of beta-thiofucopyranoside and AgOTf-catalyzed glycosylation of the protected glycosyl trichloroacetimidate facilitated a one-pot trisaccharide synthesis. The synthesized target compound showed good antitumor activity in vivo, and promising anticoagulant activity in vitro.     

Discovery of 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) as a potent,selective and orally efficacious cannabinoid-1 receptor antagonist

Structure–activity relationship studies in a series of diarylpyrazolyl thiadiazoles identified cannabinoid-1 receptor antagonists with excellent potency and selectivity. Based on its exceptional in vivo efficacy in animal models and its favorable pharmacokinetic and toxicological profiles, 2-(4-((1H-1,2,4-triazol-1-yl)methyl)-5-(4-bromophenyl)-1-(2-chlorophenyl)-1H-pyrazol-3-yl)-5-tert-butyl-1,3,4-thiadiazole (GCC2680) was selected as a preclinical candidate for the treatment of obesity.     

Regioselective sulfonylation at O-2 of cyclomaltoheptaose with 1-(p-tolylsulfonyl)-(1H)-1,2,4-triazole

2(I)-O-p-Tolylsulfonylcyclomaltoheptaose was obtained in 42% yield by reaction of 1-(p-tolylsulfonyl)-(1H)-1,2,4-triazole on NaH-deprotonated cyclomaltoheptaose in DMF and further converted into the corresponding mono-2(I),3(I)-manno-epoxide.     

New osmoregulated beta(1-3),beta(1-6) glucosyltransferase(s) in Azospirillum brasilense.

A linear beta(1-3),beta(1-6) glucan was detected in the periplasm of Azospirillum brasilense cells growing in a medium of low osmotic strength. This glucan was produced in vitro by purified bacterial inner membranes with UDP-glucose as the sugar donor in the presence of Mg2+. Growth in a high-osmotic-strength medium strongly reduced the amount of this glucan accumulated in the periplasmic space, and the inhibition was associated with a reduction in the enzymatic activity of the beta(1-3),beta(1-6) glucosyltransferase(s).     

1-(2-Aminoethyl)-3-(arylsulfonyl)-1H-indoles as novel 5-HT6 receptor ligands

Novel 1-(2-aminoethyl)-3-(arylsulfonyl)-1H-indoles were prepared. Binding assays indicated they are 5-HT(6) receptor ligands, among which N,N-dimethyl-N-(2-[3-(1-naphthylsulfonyl)-1H-indol-1-yl]ethyl)amine 8t and N-methyl-N-(2-[3-(1-naphthylsulfonyl)-1H-indol-1-yl]ethyl)amine 8u showed high affinity for 5-HT(6) receptors with K(i)=3.7 and 5.7 nM, respectively.     

Synthesis of 9-[1-(1-Hydroxyethyl)-3-(Phosphonomethoxy)Propyl] Adenine and Prodrug as Possible Antiviral Agents

The appropriately protected C-1′-hydroxyethyl-3-hydroxypropyl-N⁹-adenine nucleoside was prepared from 1-pivaloyloxy-5-tert-butyldiphenylsilyloxy-3-pentanol and adenine through the Mitsunobu reaction. One of the terminal hydroxyls was converted to the phosphonomethoxy derivative and the prodrug.     

Antioxidant activity and low toxicity of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one

The aim of the present study was to evaluate the potential pharmacological and toxicological properties of (E)-1-(1-(methylthio)-1-(selenopheny) hept-1-en-2-yl) pyrrolidin-2-one (compound 1), an organoselenium compound. In vitro experiments showed that compound 1 presented a reduction in the lipid peroxidation induced by Fe2? in thiobarbituric acid-reactive species (TBARS) production, and in the generation of reactive species caused by Fe2?/malonate in DCFH-DA oxidation. The high dose (500 mg/kg) induced an increase on ALT but not on AST activity. Hepatic, but not cerebral, δ-ALA-D activity from mice treated with 500 mg/kg presented a significant inhibition. Brain catalase activity was significantly inhibited by 100 mg/kg whereas hepatic catalase activity showed a significant increase at all doses. Hepatic lipid peroxidation was diminished only at lowest dose (100 mg/kg) whereas for brain tissue, all doses induced a significant reduction in TBARS levels. Brain and liver ascorbic acid contents were increased only at highest dose of compound 1. Urea and creatinine levels were not significantly altered by treatments. This is a promising compound with antioxidant activity and low toxicity, suggesting the potential beneficial activity of compound 1 against oxidative damage in many parameters studied in rats and mice.     

Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by inducible and constitutive cytochrome P450 enzymes in rats.

The tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induces tumor formation in the liver, lung, nasal cavity, and pancreas of rats. Metabolic activation is required for the tumorigenicity of this compound. The involvement of cytochrome P450 enzymes in NNK bioactivation was investigated in rats by studies with chemical inducers and antibodies against P450s. Liver microsomal enzymes catalyzed the formation of 4-oxo-1-(3-pyridyl)-1-butanone (keto aldehyde), 4-hydroxy-1-(3-pyridyl)-1-butanone (keto alcohol), 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone (NNK-N-oxide), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) from NNK. When the activity was expressed on a per nanomole P450 basis, treatments of rats with 3-methylcholanthrene (MC), phenobarbital (PB), pregnenolone 16-alpha-carbonitrile (PCN), Aroclor 1254 (AR), safrole (SA), and isosafrole (ISA) increased the keto aldehyde formation in liver microsomes 2.0-, 2.4-, 3.8-, 2.5-, 2.1-, and 1.8-fold, respectively; PB, AR, SA, and ISA increased the keto alcohol formation 1.7-, 1.3-, 2.0-, and 1.3-fold, respectively. The extents of induction were more pronounced when expressed on a per milligram protein basis, due to the higher microsomal P450 contents in the induced microsomes. The formation of NNK-N-oxide was markedly increased by PB and PCN and slightly increased by AR, SA, and ISA. However, the formation of NNAL, the major metabolite due to carbonyl reduction, was not increased by the treatments but was decreased by AR, ISA, and acetone (AC). The kinetic parameters of NNK metabolism by control, MC-, PB-, and PCN-induced liver microsomes were obtained. A panel of monoclonal (anti-1A1, -2B1, -2C11, and -2E1) and polyclonal (anti-1A2, -2A1, and -3A) antibodies were used to assess the involvement of constitutive hepatic P450 enzymes in NNK metabolism. Keto aldehyde formation was inhibited by anti-1A2 and anti-3A (about 15%) but not by others; the formation of keto alcohol was inhibited by anti-1A2, anti-2A1, and anti-3A (by 13-26%). In incubations with lung microsomes, the formation of keto aldehyde, keto alcohol, NNK-N-oxide, and NNAL were observed. With nasal mucosa microsomes, however, only keto aldehyde and keto alcohol formation were appreciable. SA and AC significantly decreased NNK metabolism in lung and nasal mucosa microsomes.(ABSTRACT TRUNCATED AT 400 WORDS)     

Salicylate poly(vinyl chloride) membrane electrode based on (2-[(E)-2-(4-nitrophenyl) hydrazono]-1-phenyl-2-(2-quinolyl)-1-ethanone) Cu(II)

A new salicylate-selective electrode based on the complex of (2-[(E)-2-(4-nitrophenyl)hydrazono]-1-phenyl-2-(2-quinolyl)-1-ethanone) Cu(II) as the membrane carrier was developed. The electrode exhibited a good Nernstian slope of -59.6+/-1.0 mV/decade and a linear range of 1.0 x 10(-6) to 1.0M for salicylate. The limit of detection was 5.0 x 10(-7) M. The electrode had a fast response time of 10 s and can be used for more than 3 months. The selective coefficients were determined by the fixed interference method and could be used in the pH range of 4.0 to 10.5. The electrode was employed as an indicator electrode for direct determination of salicylate in pharmaceutical and biological samples.     

Transport of the beta -O-glucuronide conjugate of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) by the multidrug resistance protein 1 (MRP1). Requirement for glutathione or a non-sulfur-containing analog

Nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and its metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) play a crucial role in the induction of lung cancer, and NNAL-O-glucuronide formation and elimination are important steps in detoxification of these compounds. In the present study, we investigated the ATP-binding cassette (ABC) protein, MRP1 (ABCC1), as a candidate transporter responsible for NNAL-O-glucuronide export. MRP1 mediates the active transport of numerous GSH-, sulfate-, and glucuronide-conjugated organic anions and can transport certain xenobiotics by a mechanism that may involve co-transport with GSH. Using membrane vesicles prepared from transfected cells, we found that MRP1 transports [3H]NNAL-O-glucuronide but is dependent on the presence of GSH (Km 39 microm, Vmax 48 pmol x mg(-1) x min(-1)). We also found that the sulfur atom in GSH was dispensable because transport was supported by the GSH analog, gamma-glutamyl-alpha-aminobutyryl-glycine. Despite stimulation of NNAL-O-glucuronide transport by GSH, there was no detectable reciprocal stimulation of [3H]GSH transport. Moreover, whereas the MRP1 substrates leukotriene C4 (LTC4) and 17beta-estradiol 17beta-(d-glucuronide) (E(2)17betaG) inhibited GSH-dependent uptake of [3H]NNAL-O-glucuronide, only [3H]LTC4 transport was inhibited by NNAL-O-glucuronide (+GSH) and the kinetics of inhibition were complex. A mutant form of MRP1, which transports LTC4 but not E(2)17betaG, also did not transport NNAL-O-glucuronide suggesting a commonality in the binding elements for these two glucuronidated substrates, despite their lack of reciprocal transport inhibition. Finally, the related MRP2 transported NNAL-O-glucuronide with higher efficiency than MRP1 and unexpectedly, GSH inhibited rather than stimulated uptake. These studies provide further insight into the complex interactions of the MRP-related proteins with GSH and their conjugated organic anion substrates, and extend the range of xenotoxins transported by MRP1 and MRP2 to include metabolites of known carcinogens involved in the etiology of lung and other cancers.     

2(S)-(Cycloalk-1-enecarbonyl)-1-(4-phenyl-butanoyl)pyrrolidines and 2(S)-(aroyl)-1-(4-phenylbutanoyl)pyrrolidines as prolyl oligopeptidase inhibitors

In order to replace the P2-P1 amide group, different 1-cycloalkenyls and 2-aryls were studied in the place of the P1 pyrrolidine group of a 4-phenylbutanoyl-L-Pro-pyrrolidine structure, which is a well-known prolyl oligopeptidase inhibitor SUAM-1221. The 1-cyclopentenyl and the 2-thienyl groups gave novel compounds, which were equipotent with the corresponding pyrrolidine-analog SUAM-1221. It was shown that the P2-P1 amide group of POP inhibitors can be replaced by an alpha,beta-unsaturated carbonyl group or the aryl conjugated carbonyl group.     

Synthesis and biological activities of octyl 2,3,4-tri-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2,4-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2,4-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2,4-di-O-sulfo-beta-L-fucopyranoside

An efficient method for the regioselective 3-O-silylation of beta-thiofucopyranoside was disclosed. Based on this discovery, we described a high-yielding strategy for the synthesis of the natural core structure of L-fucan and its fully sulfated derivative. The bioassay suggested that octyl 2,3,4-tri-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2,4-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2,4-di-O-sulfo-alpha-L-fucopyranosyl-(1-->3)-2,4-di-O-sulfo-beta-L-fucopyranoside presented better antitumor activities than that of the free tetramer based on Sarcoma 180 cells and Lewis lung carcinoma model studies.     

Modulation of reduction of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone by vitamin C-palmitate

An in vitro study of effects of vitamin C-palmitate on the metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in rat microsomes was performed. A sensitive assay method has been developed for the detection of metabolites of NNK in microsomes. Only the reduced metabolite of NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-butanol (NNAL), was detected and measured in a time-course study. Vitamin C-palmitate enhanced the reduction of NNK in a concentration-dependent manner. The results indicate a significant increase in V_max and K_m in the presence of vitamin C. However, the rate of formation of NNAL at low substrate concentration varied. The ratio of V_max to K_m decreases. The results suggest that the kinetics are accounted for best by an uncompetitive activator binding model at low concentration of vitamin C. The uncompetitive binding model becomes sketchy at higher concentration of vitamin C. These observations infer that vitamin C loosely binds to the substrate-enzyme complex. Furthermore, the nature of the binding would facilitate the modulation of NNK biotransformation leading to the formation of NNAL. The results also show that vitamin C-palmitate is a potent activator of NNK reduction in rat liver microsomes. Thus, vitamin C-palmitate would mediate the metabolism of NNK through reduction. The resulting NNAL-glucuronide is more readily eliminated in urine.