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1.
The N-methylacetohydroxamic acid group has been introduced into cyclohexaamylose by the following sequence of reactions: (1) carboxymethylation of cyclohexaamylose by iodoacetic acid, (2) methylation of carboxymethylcyclohexaamylose with diazomethane, and (3) reaction of the carboxymethylcyclohexaamylose methyl ester with N-methylhydroxylamine to form the N-methylacetohydroxamic acid-substituted cyclohexaamylose. By employing purification procedures involving ionexchange chromatography, the synthesis yielded a mono-substituted cyclohexaamylose-N-methylacetohydroxamic acid with selective modification of the C-2, C-3 hydroxyl group side of the cyclohexaamylose ring.p-Nitrophenyl acetate and 2-hydroxy-5-nitro-α-toluenesulfonic acid sultone react 20- and 70-fold faster with cyclohexaamylose-N-methylacetohydroxamic acid than with N-methylmethoxyacetohydroxamic acid. Cyclohexaamylose-N-methylacetohydroxamic acid also displays a marked kinetic stereospecificity for p-nitroover m-nitrophenyl acetate (whereas cyclohexaamylose itself exhibits the reverse stereospecificity). These reactions were shown to be competitively inhibited by cyclohexanol. This evidence indicates that cyclohexaamylose-N-methylacetohydroxamic acid binds the substrate in a reversible complexation step prior to nucleophilic attack and thus is an enzyme model. 相似文献
2.
Farida Begum Noor Barak Almandil Muhammad Arif Lodhi Khalid Mohammed Khan Abdul Hameed Shahnaz Perveen 《Bioorganic & medicinal chemistry》2019,27(6):1009-1022
This study deals with the synthesis of benzophenone sulfonamides hybrids (1–31) and screening against urease enzyme in vitro. Studies showed that several synthetic compounds were found to have good urease enzyme inhibitory activity. Compounds 1 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-nitrobenzenesulfonohydrazide), 2 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-3′′-nitrobenzenesulfonohydrazide), 3 (N′-((4′-hydroxyphenyl)(phenyl)methylene)-4′′-methoxybenzenesulfonohydrazide), 4 (3′′,5′′-dichloro-2′′-hydroxy-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 6 (2′′,4′′-dichloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 8 (5-(dimethylamino)-N′-((4-hydroxyphenyl)(phenyl)methylene)naphthalene-1-sulfono hydrazide), 10 (2′′-chloro-N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide), 12 (N′-((4′-hydroxyphenyl)(phenyl)methylene)benzenesulfonohydrazide) have found to be potently active having an IC50 value in the range of 3.90–17.99?µM. These compounds showed superior activity than standard acetohydroxamic acid (IC50?=?29.20?±?1.01?µM). Moreover, in silico studies on most active compounds were also performed to understand the binding interaction of most active compounds with active sites of urease enzyme. Structures of all the synthetic compounds were elucidated by 1H NMR, 13C NMR, EI-MS and FAB-MS spectroscopic techniques. 相似文献
3.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1988,15(1):69-81
New multidentate ligands with structures similar to N,N′-bis[2-hydroxybenzyl]ethylenediamme-N,N′-diacetic acid (HBED) and N,N′-bis(pyridoxyl)ethylenediamine-N,N′-diacetic acid (PLED) were synthesized. The in vitro lipophilicity, electrophoretic behavior, and the in vivo biodistribution were studied for the 111In- and 67,68Ga-complexes of N,N′-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine-N,N′-diacetic acid (Me4HBED); N,N′-bis(5-t-butyl-2-hydroxy-3-methylbenzyl)ethylenediamine-N,N′-diacetic acid (t-butyl HBED); N,N′-bis[2-hydroxy-5-sulfobenzyl)ethylenediamine-N,N′-diacetic acid (SHBED); N,N′-bis(2-hydroxy-3,5-dimethylbenzyl)ethylenediamine-N-(2-hydroxyethyl)-N′-acetic acid (HBMA); and N,N′-bis(5-deoxypyridoxyl)ethylenediamine-N,N′-diacetic acid (DPLED). The biodistribution of the radiometal complexes were carried out in rats and an imaging study was performed in a non-human primate. The rapid clearance of the lipophilic complexes from blood and through the hepatobiliary system was easily demonstrated; as well, the hydrophilic complexes were cleared rapidly through the urinary tract. Positron emission tomographic images were generated from a study in a primate after administration of 68Ga-t-butyl HBED. These images well demonstrate the efficient liver accumulation and rapid hepatobiliary clearance (< 1 h) and well differentiate images of the liver and gall bladder. 相似文献
4.
We developed a simple protocol for high-yielding synthesis of conjugates of a deuterated dihydro-N,N,N′,N′-tetramethylrhodamine (F*) with oligodeoxyribonucleotides and a 2′-OMe RNA (a representative nuclease-resistant, chemically modified oligonucleotide) using easily accessible starting materials including NaBD4 and conjugates of oligonucleotides with N,N,N′,N′-tetramethylrhodamine (F). These compounds were found to be stable in air and insensitive to light at 525, 635 and 650 nm, whereas slow activation occurs upon their exposure to 470 nm light. However, at the conditions of the templated reaction, in the presence of a target nucleic acid and a photocatalyst based on the eosin structure, the F* is oxidized forming fluorescent F. This reaction is >30-fold faster than the background reaction in the absence of the template. Moreover, the presence of a single mismatch in the target nucleic acid slows down the templated reaction by eightfold. These activatable dyes can potentially find applications as nucleic acid-specific probes for super-resolution imaging in live cells. 相似文献
5.
The chromatographic conditions for separation of N,N′-bislysyl(?-N)adipamidine and N-lysyl(?-N)adipamidinic acid, which were the products of acid hydrolysis of proteins treated with adipimidate esters, from other amino acids on an amino acid analyzer were established including their ninhydrin color values. Kinetics of decomposition of these lysine derivatives under the conditions of total acid hydrolysis of protein are also reported. 相似文献
6.
The fatty acid compositions of the ether lipid 1(3),2-diacylglyceryl-(3)-O-4′-(N,N,N-trimethyl)homoserine (DGTS) from Ochromonas danica a 相似文献
7.
Polyacrylamide and porous-glass supports containing the dihydroxyborylphenyl group can be prepared by a method similar to that used in the synthesis of N-[N′-(m-dihydroxyborylphenyl)succinamyl]aminoethylcellulose. The reaction of aminoethylpolyacrylamide or amino-substituted glass with N-(m-dihydroxyborylphenyl)succinamic acid in the presence of N-cyclohexyl-N′-β-(4-methyl-morpholinium) ethylcarbodiimide yields products which, together with the cellulose derivative, are all capable of binding tRNA dissolved in buffers at pH 8.7. The demonstration that bound tRNA can be released with sorbitol solutions or with low pH buffers, together with studies on the binding of tRNA species that contain chemically modified 3′-terminals, indicate that the predominant binding mechanism consists of cyclic complex formation between the immobilized dihydroxyboryl groups and the 3′-terminal cis-diol groups of the tRNA molecules. Aminoacylated tRNA does not bind under the conditions necessary to bind tRNA and this permits the isolation of specific tRNA isoacceptors. The purification of tRNAPhe and the partial purification of tRNAGlu and tRNATrp are described. 相似文献
8.
《International journal of radiation applications and instrumentation. Part B, Nuclear medicine and biology》1991,18(3):323-330
Three new multidentate ligands designed to have high affinity for Ga3+, In3+ and Fe3+ have been synthesized, N-(2-hydroxybenzyl)-N′-pyridoxylethylenediamine-N,N′-diacetic acid (HBPLED), N-(2-hydroxy-3,5-dimethylbenzyl)-N′-(3-hydroxy-1,2,5-trimethyl-4-pyridylmethyl)ethylenediamine-N,N′-diacetic acid (Me4HBPLED) and N,N′-bis(3-hydroxy-1,2,5-trimethyl-4-pyridylmethyl) ethylenediamine-N,N′-diacetic acid (DMPLED). These ligands give metal-ligand (M–L) complexes with (M = Ga3+, In3+, Fe3+) overall charges of −1, 0 and + 1, respectively. The 67Ga, 68Ga and 111In complexes of each of the three ligands and the 59Fe complex of Me4HBPLED were prepared, characterized and their biodistributions determined in rats after intravenous injection. Despite the differences in overall charge, the biological behavior of all three 111In complexes were similar, in that the radioactivity cleared rapidly via the kidney. The biodistributions of the 68Ga and 67Ga complexes were comparable to that of the 111In complex counterpart. Also, the 59Fe-Me4HBPLED biodistribution was not significantly different from those of the 68Gaand 111In-Me4HBPLED. The renal clearance rate seems insensitive to the overall M-L charge; suggesting that the hydrophilic periphery of the ligand rather than the overall molecular charge determines the biological fate (with respect to renal clearance). 相似文献
9.
Jane F. Crowley Irwin J. Goldstein Jan Arnarp Jörgen Lönngren 《Archives of biochemistry and biophysics》1984,231(2):524-533
The carbohydrate-binding properties of the Datura stramonium seed lectin were studied by equilibrium dialysis, quantitative precipitation of natural and synthetic glycoproteins, and hapten inhibition of precipitation. The dimeric lectin (Mr = 86,000) possesses two carbohydrate-binding sites for N,N′,N′',N?-tetraacetylchitotetritol/mol protein, with an apparent Ka = 8.7 × 103M?1 at 4 °C. Whereas fetuin and orosomucoid reacted poorly with the Datura lectin, the asialo derivatives of these glycoproteins gave strong precipitation with the lectin. Carcinoembryonic antigen, type 14 pneumococcal capsular polysaccharide, and bovine serum albumin, highly substituted with N,N′- diacetylchitobiose units, also precipitated the lectin. Of the homologous series of chitin oligosaccharides tested, N,N′,N?-triacetylchitotriose was over 6-fold more potent than the disaccharide (N′,N′-diacetylchitobiose) which, in turn, was 90 times more reactive than N-acetyl-d-glucosamine.N-Acetyllactosamine [β-d-Gal-(1 → 4)-d-GlcNAc] was also a potent inhibitor of Datura lectin being equivalent to N,N′-diacetylchitobiose. The requirement for an N-acetyl-d-glucosaminyl unit linked at the C-4 position was established. The biantennary pentasaccharide (penta-2,6) was a 500-fold more potent inhibitor than N-acetyllactosamine, suggesting that it might interact with both saccharide-binding sites of the Datura lectin simultaneously. 相似文献
10.
Glycyrrhizic acid (GA) conjugates with methyl and ethyl esters of D-amino acids (D-Trp, D-Phe, D-Tyr, D-Val, D-Leu) have been synthesized by the activated esters method using mixtures of N-hydroxybenzotriazole or N-hydroxysuccinimide with N,N′-dicyclohexylcarbodiimide. GA conjugate with D-Trp ethyl ester exhibited antiviral activity against influenza viruses A/H3N2, A/H1N1/pdm09, A/H5N1, B (SI > 10–29), and HRSV (SI > 25). GA conjugate with D-Trp methyl ester inhibited influenza virus A/H1N1/pdm09 (SI > 30). 相似文献
11.
R D Reynolds 《Archives of biochemistry and biophysics》1982,219(1):140-148
Homogenization of rat liver in Hepes (N-2-hydroxyethylpiperazine-N′-2-ethane-sulfonic acid), MOPS (2-[N-morpholino]ethanesulfonic acid), Na phosphate, Pipes (piperazine-N,N′-bis[2-ethanesulfonic acid]), TEA (triethanolamine), TES (N-tris[hydroxymethyl]-methyl-2-aminoethanesulfonic acid), Tricine (N-tris-[hydroxymethyl]methylglycine), or Tris (tris[hydroxymethyl]aminomethane), and subsequent assay for supernatant total and holo tyrosine aminotransferase activity using these buffers yields apparent enzyme concentrations which vary depending upon the buffer composition, the ionic strength, and the fold-dilution of the supernatant. A precipitous decrease in the apparent holoenzyme concentration results from a slight dilution of the supernatant with most of the buffers. Some of the dilution effects may be due to dissociation of pyridoxal phosphate from the apoenzyme or to competition between the buffer and pyridoxal phosphate for association with the enzyme. The percentage of the apparent total enzyme which exists as holoenzyme varies from 3% for supernatant prepared in Na phosphate buffer up to 94% for that prepared in Hepes. Inactivation of total enzyme activity occurs to a similar extent resulting from incubation of liver homogenates prepared with Na phosphate, Hepes, or Pipes. The residual apparent holoenzyme activity observed when assayed in the presence of Na phosphate may be due to reaction of an enzyme other than tyrosine aminotransferase. The data provide a basis for explaining the large variation in reported percentage holoenzyme and should also serve as a warning for other holoenzyme assays which use pyridoxal phosphate as a cofactor. 相似文献
12.
A series of N-nicotinyl- and N-isonicotinyl-N′-(substituted) ureas were synthesized by a condensation of the appropriate amide with various alkyl or aryl isocyanates, and examined as potential antimetabolites of nicotinamide. No significant microbial toxicity was observed; however, several derivatives in the nicotinyl series proved to be toxic to fish, especially N-nicotinyl-N′-hexylurea which possessed a TL50 of 27 μg/ml. The toxicity was reversed by supplements of nicotinamide but not tryptophan, and may be due to the formation of an inactive NAD complex through the mediation of NADase. Evidence for this possibility is presented by the formation in vitro of an N-nicotinyl[7-14C]N′-ethylurea-NAD analog which was characterized through spectral, chemical, and chromatographic studies. 相似文献
13.
N-2′-Acetoxybenzoyl (aspirin) derivatives (degree of substitution 0·35–1·00) of chitosan, N-desulphated heparin and 2-amino-2-deoxy-d-glucose were prepared by methods that gave yields in the range 65–86%. The salicylate of chitosan was isolated with a 98% yeild. Aspirin or salicylic acid was released much more slowly from N-(2′-acetoxybenzoyl)-chitosan than from the salicylate of chitosan, and much faster at 37°C in 0·1 m NaOH solution than in 2% aqueous acetic acid solution. Salicylic acid was isolated from the dialysate (0·1 m NaOH solution) of N-(2′-acetoxybenzoyl)-chitosan. 相似文献
14.
Nicotine-1-N-oxide, trans and cis isomers of nicotine-1′-N-oxide and of nicotine-1,1′-di-N-oxide have been prepared and characterised by NMR, MS and reduction to nicotine. The trans and cis isomers of nicotine-1′-N-oxide have been identified in leaves, stems and roots of Nicotiana tabacum, N. affinis and N. sylvestris. 相似文献
15.
Jesse Pulido Maria de Cabrera Adam J. Sobczak Alejandro Amor-Coarasa Anthony J. McGoron Stanislaw F. Wnuk 《Bioorganic & medicinal chemistry》2018,26(21):5624-5630
The conjugation of 4-N-(3-aminopropanyl)-2′-deoxy-2′,2′-difluorocytidine with 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (SCN-Bn-NOTA) ligand in 0.1?M Na2CO3 buffer (pH 11) at ambient temperature provided 4-N-alkylgemcitabine-NOTA chelator. Incubation of latter with excess of gallium(III) chloride (GaCl3) (0.6?N AcONa/H2O, pH?=?9.3) over 15?min gave gallium 4-N-alkylgemcitabine-NOTA complex which was characterized by HRMS. Analogous [68Ga]-complexation of 4-N-alkylgemcitabine-NOTA conjugate proceeded with high labeling efficiency (94%–96%) with the radioligand almost exclusively found in the aqueous layer (~95%). The high polarity of the gallium 4-N-alkylgemctiabine-NOTA complex resulted in rapid renal clearance of the 68Ga-labelled radioligand in BALB/c mice. 相似文献
16.
N-(3′,4′-Dihydroxy-trans-cinnamoyl)-3-(3,4-dihydroxyphenyl)-L-alanine [(?)-clovamide], the major phenolic metabolite (0.1%) in the bark of Dalbergia melanoxylon, is associated with minor proportions of its cis-isomer, and similar pairs of geometrical isomers of their deoxy analogues N-(4′-hydroxycinnamoyl)-3-(3,4-dihydroxyphenyl)-L-alanine and N-(4′-hydroxycinnamoyl)-3-(4-hydroxyphenyl)-L-alanine. (?)-Trans-clovamide is synthesized by direct condensation of the acid chloride of caffeic acid with L-DOPA. Diagnostic CD spectra of these compounds and 13C spectra of (?)-trans- and (?)-cis-clovamides are recorded. 相似文献
17.
Cheng-Jun He Cheng Peng Xiao-Fang Xie Li Guo Qin-Mei Zhou Xiao-Hong Li Ou Dai Zhao Geng Yi-Ping Guo 《Phytochemistry letters》2013,6(2):299-301
Two new dianthramide glucosides, N-(2′-β-d-glucopyranosyl-5′-hydroxysalicyl)-4-hydroxy-3-methoxyanthranilic acid methyl ester (1) and N-(2′-β-d-glucopyranosyl-5′-hydroxysalicyl)-4-hydroxyanthranilic acid methyl ester (2), together with five known glycosides, were isolated from the lateral roots of Aconitum carmichaelii. Their structures were elucidated by spectroscopic analyses. In the in vitro assays, compounds 1 and 2 showed activity against pentobarbital sodium-induced cardiomyocytes damage by recovering beating rhythm and increasing the cell viability. 相似文献
18.
M J Pitout J J Van der Watt P G Kempff J Dijkstra J C Schabort 《Chemico-biological interactions》1973,6(4):227-235
The influence of a prolonged low level of administration to rats and mice of the potent hepatocarcinogen, B1 (aflatoxin B1) on liver nuclear acid DNAase was investigated. For comparison, the effects of 3′-methyl-N,N-dimethylaminoazobenzene (3′-MeDAB) (a potent hepatocarcinogen) and 2-methyl-N,N-dimethylaminoazobenzene (2-MeDAB) (a weak hepatocarcinogen) were also studied. Rats were dosed weekly with B1 equivalent to frsol|1/5 of the LD50 and mice were fed a diet containing 2 mg/kg feed. Both MeDAB carcinogens were fed to rats at the rate of 0.64 g/kg feed. Groups from each treatment were killed at 3 weekly intervals until the appearance of neoplasia and the levels of acid DNAase in hepatic nuclei were assayed. Histological alterations were studied throughout the period of treatment.Both B1 and 3′-MeDAB rapidly induced transient increases in the specific activity of acid DNAase in rats. After several months, markedly elevated levels were found, which suddenly declined to normal levels immediately prior to malignant transformation. Histologically, early toxic damage to the liver, seemed to be associated with moderate increases, but the appearance of regenerative nodules was accompanied by marked and sustained increases.In contrast, the weak carcinogen, 2-MeDAB induced only slight changes in the acid DNAase activity of rats. B1 induced no changes in the mouse, which is resistant to its carcinogenic effects. 相似文献
19.
Hilmer Sørensen 《Phytochemistry》1976,15(10):1527-1529
2(S),2′(S)-N6-(2′-Glutaryl)lysine (l-saccharopine) and 2(S)-2-aminoadipic acid have been isolated from Reseda odorata. When traditional isolation procedures are used l-pyrosaccharopine (5(S),5′(S)-N-(5′-amino-5′-carboxy-pentyl)-2-pyrrolidone-5-carboxylic acid) is formed from l-saccharopine by lactamisation. The degree of lactamisation during various isolation steps has been studied, The amino acids were identified by IR and PMR spectroscopy and the configurations established by enzymic and polarimetric analyses. The contents of saccharopine and 2-amino-adipic acid have been determined relative to the total nitrogen content at various stages in the growth cycle of R. odorata. 相似文献
20.
《Phytochemistry》1986,26(1):324-325
Adouetine-y′ and a new cyclopeptide alkaloid, melofoline, have been isolated from melochia corchorifolia. The latter was characterized mainly from its mass spectrum and hydrolysis products. Melofoline has N,N-dimethyl-β-hydroxyleucine as the terminal amino acid and 2-aminobutyric acid as the ring amino acid, neither of which has been found in the positions before. 相似文献