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Results 501 - 550 of 920
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Manna F - - 1999
Hyaluronic acid (HA) derivatives have been developed to try to enhance rheological properties of this molecule to make it suitable for various medical applications. The main dermatological application of HA derivatives is the augmentation of soft tissues, via injection into the dermis. HA derivatives are indicated for the correction of ...
Tremblay M R - - 1999
The C17-THP derivative of 7alpha-(11-azidoundecanyl)-estradiol (4) was synthesized and coupled to an aminomethyl resin via a photolabile o-nitrobenzyl linker. Reduction of the azide by the Staudinger reaction to its corresponding amine followed by acylation using four activated NFmoc protected amino acids gave a first level of diversity. Subsequent deprotection of ...
Uttamsingh V - - 1999
Mercapturates (S-substituted N-acetyl-L-cysteines) are terminal metabolites formed by the glutathione-dependent metabolism of electrophilic xenobiotics, including haloalkenes. Acylases catalyze the hydrolysis of N-acyl-L-amino acids, including many xenobiotic-derived mercapturates, to give fatty acids and amino acids as products. Although several acylases have been identified, the acylases that catalyze the deacetylation of the ...
del Castillo M D - - 1999
The formation of furoylmethyl derivatives of amino acids as indicators of the early stages of Maillard reaction in dehydrated orange juices and model systems was studied. In stored dehydrated orange juices, the presence of furoylmethyl derivatives of arginine, asparagine, proline, alanine, glutamic acid, and GABA was detected. Their formation increased ...
Mamer O A - - 1999
Trimethylsilylation of methylmalonic and ethylmalonic acids in the presence of headspace atmospheric oxygen is shown to produce the trimethylsilyl derivatives of pyruvic and 2-oxobutyric acids, along with 2-hydroxy-2-methylmalonic and 2-hydroxy-2-ethylmalonic acids, respectively. This may lead to overestimation of these keto acids, if they were not oximated in the original sample, ...
Suzuki S - - 1999
Two groups, producers of (+)- and (-)-mitorubrin derivatives, coexist in the series Lutei of the genus Talaromyces. The optical rotations of mitorubrins from T. emodensis, T. hachijoensis, and T. wortmannii var. sublevisporus, which produced mitorubrinol acetate (5), were all positive, whereas those from T. austrocalifornicus and T. convolutus, which produced ...
Chen Xiaoyuan - - 1999
A procedure is reported for synthesizing a novel, water-soluble bifunctional chelating agent derived from calix[4]arene. This chelate features tetracarboxylic acid groups at the lower rim as an actinium-225 ionophore, and an isothiocyanate functional group at the upper rim for labeling of the N-terminus of monoclonal antibodies through thiourea linkage.
Rezanka T - - 1999
The composition of novel brominated aliphatic compounds from lichens collected during summer from stones around the lake Issyk-Kul (Central Asia) is described. The compounds, predominantly fatty acid derivatives with unique groups (bromine, cyclopropane, oxirane) and conjugated double and triple bonds, were identified by means of 1H and 13C-NMR, MS, IR ...
Andrisano V - - 1999
The transfer of potassium salts of dinitrophenyl amino acids from water to chloroform by the lipophilic guanosine derivative 1 takes place enantioselectively. Depending on the K(+):1 ratio, G-quartets of 1 self-assemble into octamers (O) or polymers.
O'Sullivan D B - - 1999
A range of substrate-derived chloromethane inhibitors have been synthesized which have one to four amino acid residues. These have been used to inhibit both subtilisin and chymotrypsin. Using 13C NMR, we have shown that all except one of these inhibitors forms a tetrahedral adduct with chymotrypsin, subtilisin, and trypsin. From ...
Buszello K - - 1999
Parenteral O/W emulsions containing lanthanide fatty acid derivatives were prepared. With regard to enhancing the incorporation efficiency of the neutron activatable excipients, the addition of the non-ionic co-emulsifier Solutol HS 15 proved to be most suitable. Comparing the different chain lengths of the fatty acids, the long chain fatty acid ...
Jeong H J - - 1999
Betulinic acid has been coupled with a series of amino acids at C-28 carboxylic acid position and the toxicity of the derivatives has been evaluated against cultured human melanoma (MEL-2) and human epidermoid carcinoma of the mouth (KB) cell lines. A number of amino acid conjugates of betulinic acid showed ...
Redden P R - - 1999
A series of acyloxymethyl drug derivatives of the NH-acidic drugs, phenytoin and theophylline and of the carboxylic acid drugs, thioctic acid and indomethacin, were prepared in order to determine the effect of varying the nature of the drug on the in vitro rate of hydrolysis catalyzed by porcine liver esterase ...
Catalán J. - - 1999
The currently known intrinsic basicity (DeltaG degrees ) range spans about 154 kcal/mol, from the basicity of the oxygen molecule (94.7 kcal/mol) to that of 7-isopropyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (248.4 kcal/mol). In this paper, we show that the basicities of two commercially available derivatives of ammonia, viz. F(3)N and Li(3)N, differ by 182 ...
Lo L C - - 1999
A facile preparation of triacetylated derivative of 2-phenylthioglycoside of N-acetylneuraminic acid (4) was achieved by treatment with lipase PS in vinyl acetate. The major product 4 has a free hydroxyl group at C-7. Results of time-course HPLC analysis indicate that the reactivity of the hydroxyl groups under this condition is ...
Clerici F. - - 1999
A convenient synthesis of 4-sulfanylmethylene-5(4H)-oxazolones 3 was realized starting from 4-(chloromethylene)oxazolone 1 and mercaptans 2. Oxazolones 3 were used as starting materials for the preparation of unknown 2-sulfanyl-1-aminocyclopropanecarboxylic acid derivatives 5 and7. Oxazolones 3 were cyclopropanated at the exocyclic double bond with diazomethane, giving a mixture of the two (Z)- ...
Lee Y - - 1998
Heparin is clinically administered mainly by intravenous injection because of its highly hydrophilic property. A slightly hydrophobic heparin derivative which can be dissolved in organic solvent can be widely used in polymeric devices for clinical applications. In this study, hydrophobic heparin derivatives were prepared by coupling heparin with deoxycholic acid, ...
Roomi M W - - 1998
In recent years L-ascorbic acid (AA) and its isomers have raised considerable interest as anticancer agents, although the mechanism has remained largely unknown. AA isomers are nearly identical in their physical and chemical properties but differ widely in their biological properties. AA, a lactone sugar, has a number of reactive ...
Giordani A - - 1998
Kynurenine 3-hydroxylase (KYN 3-OHase) is a key enzyme in the kynurenine pathway of tryptophan degradation and its inhibition may be an effective mechanism for counteracting neuronal excitotoxic damage. We present here a new class of inhibitors derived from a structure-activity relationship (SAR) study of the benzoylalanine side-chain of 1. 2-hydroxy-4-(3,4-dichlorophenyl)-4-oxobutanoic ...
Prasad J V - - 1998
Nucleocapsid protein (NCp7), which contains highly conserved retroviral zinc fingers, is essential in the early as well as the late phase of human immunodeficiency virus (HIV) life cycle and constitutes a novel target for AIDS therapy. HIV-1 NCp7 is a basic 55 amino acid protein containing two C(X)2C(X)4H(X)4C motif zinc ...
Carrizo R - - 1998
Growth-inhibitory activities of selected natural benzofurans (4-9), trans-cinnamic acid derivatives (10-13), chromene compounds (14 and 16), and some semisynthetic derivatives were determined in last instar larvae of Tenebrio molitor via topical administration in Me2CO. The most inhibitory of the tested compounds were 3-gamma, gamma-dimethylallyl-p-coumaric acid (10) and the benzofuran derivative ...
Bernkop-Schnürch A - - 1998
In order to generate novel preservatives exhibiting a broad antimicrobial spectrum against Gram-positive as well as Gram-negative bacteria, lysozyme was modified by the covalent attachment of caffeic acid and cinnamic acid, respectively. Linkage of these organic acids to lysozyme was achieved by the constitution of amide bindings between the carboxyl ...
Pietta P - - 1998
The distribution pattern of caffeic acid derivatives in Echinacea species is complex, and problems with the identity of each drug have been recognized. Micellar electrokinetic chromatography (MEKC) has been applied to define the fingerprints of Echinacea angustifolia, Echinacea pallida, and Echinacea purpurea, and their mixtures. The results obtained evidence that ...
Albert R - - 1998
A library of thioamide derivatives of leflunomide 1a and of its bioactive metabolite 1b has been synthesised on solid phase. Thus, para-substituted phenylacetic acids were coupled to TentaGel and were subsequently reacted with aromatic isothiocyanates. Treatment of the resulting enaminothioamides with hydroxylamine led to their simultaneous cyclisation and cleavage from ...
Kim D S - - 1998
Betulinic acid has been modified at C-3, C-20, and C-28 positions and the toxicity of the derivatives has been evaluated against cultured human melanoma (MEL-2) and human epidermoid carcinoma of the mouth (KB) cell lines. This preliminary investigation demonstrates that simple modifications of the parent structure of betulinic acid can ...
Yang S W - - 1998
Bioassay-guided fractionation of Eschweilera coriacea collected in the lowland wet forest of Suriname yielded the new but only weakly active ellagic acid derivative eschweilenol A (1) and the two new but inactive ellagic acid derivatives eschweilenol B (2) and eschweilenol C (3). The four known compounds, sucrose, ellagic acid, 3-O-galloylepigallocatechin, ...
Paradis R - - 1998
Paclitaxel shows interesting clinical activity against several tumors. However, its poor solubility is an important limitation: Cremophor EL used for intravenous administration is responsible for hypersensitivity reactions. In order to improve solubility while preserving the activity, we have synthesized new paclitaxel amino acid derivatives substituted with a glutaryl group at ...
Rahman A A - - 1998
2-Alkylthiouracils 1a-f have been prepared. Nucleoside coupling of 2 with sodium salt of 1a-f gave the corresponding dioxolane derivatives 3a-f which were treated with 80% acetic acid at reflux temperature to give (S)-1-(2',3'-dihydroxypropyl)-2-alkylthiouracil derivatives 4a-f. Treatment of 4d with 1 mol tosyl chloride gives the corresponding monotosylate 5. On the ...
Laugel C - - 1998
Triterpenic derivatives stimulate the total collagen synthesis of skin fibroblasts. Their incorporation within an o/ w/o multiple emulsion should protect them against oxidation, particularly for unsaturated derivatives and should lead to a modulated release after topical application. The influence of the incorporation of madecassic acid, asiaticoside and asiatic acid on ...
el-Bary A A - - 1998
The aim of this study was to investigate the relationship between the chemical structure and release properties of certain drug products. Propionic acid derivatives were used as a model. These include ibuprofen (I), ketoprofen (K), tiaprofenic acid (T), flurbiprofen (F), and naproxen (N). They are all aryl derivatives of propionic ...
Kaiya T - - 1998
Oxidation of seven 1-methylbenzimidazole (MBI) derivatives (with pKa's ranging from 1.6 to 6.0) was carried out with m-chloroperoxybenzoic acid and structures of the products formed were identified. (Condensed benzene moiety-hydroxylated)-2-(m-chlorobenzyloxy)-MBIs and 2-oxo-MBIs were obtained from MBIs with pKa's of more than 5.6 and about 3.3, respectively.
Takayama H - - 1998
Five (20S)-10-hydroxycamptothecin derivatives carrying the long-chain fatty acid esters were prepared for the development of a new class of prodrug-type agents. In vitro experiments using three kinds of purified carboxylesterase isozymes from the liver microsomes of rat, pig, and human demonstrated that these derivatives were efficiently metabolized by enzymes compared ...
StaƄczak A - - 1998
A series of new 2,4-dioxo-1,2,3,4-tetrahydropyrimido[5,4-c]cinnolines and their 3-substituted derivatives were prepared. These compounds were obtained by cyclocondensation of the appropriate substituted 4-amino-3-cinnolinecarboxylic acid with urea or 4-amino-3-cinnolinecarboxamides with N,N'-carbonyldiimidazole (DCl), oxalyl chloride or diethyl carbonate. Most of these compounds showed a high sedative action in low doses.
Thai D L - - 1998
We report the first asymmetric synthesis of the individual enantiomers of methylphenidate (1). From d-pipecolic acid, the (2R,2'R) and (2S,2'R) enantiomers of 1 were obtained in > 99% optical purity while the (2S,2'S) and (2R,2'S) enantiomers of 1 were derived from l-pipecolic acid in 96% optical purity. The versatility of ...
Monsigny M - - 1998
Lectins are present on the surface of many cells. Many lectins actively recycle from membrane to endosomes and efficiently take up glycoconjugates in a sugar-dependent manner. On this basis, glycoconjugates, specially those obtained by chemical means, are good candidates as carriers of drugs, oligonucleotides or genes. In this paper, we ...
Sinks G D - - 1998
The relative toxicity (log IGC50(-1)) of 49 selected aliphatic amines and aminoalkanols was evaluated in the static Tetrahymena pyriformis population growth impairment assay. Excess toxicity, indicated by potency greater than predicted for non-polar narcotic alkanols, was associated with both classes of test chemicals. Moreover, the aminoalkanols were found to be ...
Terato H - - 1998
Reactivities of 5-formyl-2'-deoxyuridine (fdU) and its 5'-monophosphate (fdUMP) to amino acids, amines and thiol compounds in neutral aqueous solution have been studied to elucidate the postmodification of the 5-formyluracil (fU) moiety in cells. fdU and fdUMP specifically reacted with cysteine and its analogs to form thiazolidine derivatives. The reaction involved ...
Rokach J - - 1997
We have proposed a nomenclature system for the isoprostanes, a new class of natural products formed in vivo by the free-radical peroxidation of polyunsaturated fatty acids. Our proposed nomenclature is based on the assignment of four isoprostanes, 1, 9, 17, and 25, as representatives of the four classes of isoprostanes ...
Kasheverov I E - - 1997
Photoactivatable substance P (SP) derivatives containing the p-benzoylbenzoic moiety at the N-terminal alpha-amino group of Arg 1 or at the epsilon-amino group of Lys 3 were prepared. Both derivatives also had a p-hydroxyphenylpropionyl group for radioiodination. To obtain the analogue with the photolabel at Arg 1, SP was first reacted ...
Saintomé Carole - - 1997
UV irradiation of aqueous solutions containing either 4-thiothymin-1-ylacetic acid (1b) and adenosine (2a), 4-thiothymidine (1a) and adenin-9-ylacetic acid (2b), or 1b and 2b led to 4,5-diamino-6-formamidopyrimidine (N-6-Fapy-Ade) derivatives as observed after irradiation of a mixture of 1a and 2a (J. Am. Chem. Soc. 1996, 118, 8142-8143). These new observations demonstrate ...
Dugan L L - - 1997
Two regioisomers with C3 or D3 symmetry of water-soluble carboxylic acid C60 derivatives, containing three malonic acid groups per molecule, were synthesized and found to be equipotent free radical scavengers in solution as assessed by EPR analysis. Both compounds also inhibited the excitotoxic death of cultured cortical neurons induced by ...
Okamoto M - - 1997
The sensitivities of oligosaccharide derivatives in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) were compared using two matrixes, 2,5-dihydroxybenzoic acid (DHBA) and alpha-cyano-4-hydroxycinnamic acid (CHCA). For this purpose, maltopentaose was tagged with 2-aminopyridine (PA), 4-aminobenzoic acid ethyl ester (ABEE), and trimethyl-(p-aminophenyl)ammonium chloride (TMAPA). DHBA was more advantageous for enhancement than ...
Black R M - - 1997
1. Analytical methods were developed for the detection of N-terminal valine and histidine adducts in haemoglobin alkylated with sulphur mustard. 2. N-(2-hydroxyethylthioethyl)-N-terminal valine was selectively cleaved from globin with the Edman reagent pentafluorophenyl isothiocyanate. The resulting thiohydantoin derivative was analysed by high resolution gc-ms using negative ion chemical ionization. An ...
Adamczyk M - - 1997
Novel derivatives of barbiturates functionalized with free carboxylic acids were designed and synthesized. Coupling of 5-cyclopentyl-5-carboxycrotylbarbituric acid via its active ester to an aminofluorescein derivative produced a fluorescent tracer. Conjugation of the 5-cyclopentenyl-5-carboxyethylbarbituric acid via its mixed anhydride to thyroglobulin allowed for subsequent development of a polyclonal antibody which was ...
Kamata K - - 1997
We examined the possible existence of a novel endothelium-derived relaxing factor in the endothelium of the perfused rat kidney. Acetylcholine-induced vasodilatation was abolished by treatment with NG-nitro-L-arginine (L-NNA) and methylene blue in isotonic high K+ (60 mM) medium, whereas cyclopiazonic acid (CPA)-induced vasodilatation of the perfused kidney was slightly increased ...
Scott P M - - 1997
Heptafluorobutyrate (HFB) derivatives have not previously been used for GC of Alternaria mycotoxins. Capillary (0.5 micron film) GC-mass spectrometry (MS) showed that full and partial derivatives of alternariol (AOH), alternariol monomethyl ether (AME) and altenuene (ALT); a structurally uncharacterized derivative of altertoxin I (ALTX-I); and a tris-HFB derivative of tenuazonic ...
Greger H - - 1996
Besides the known imide ritigalin (9), six new phenethyl/styrylamine-derived amides isolated from lipophilic leaf extracts of Glycosmis cf. mauritiana, Glycosmis cf. cyanocarpa, and Glycosmis crassifolia displayed pronounced antifungal and/or insecticidal activity against Cladosporium herbarum and Spodoptera littoralis, respectively, the methylthiocarbonic acid derivatives niranin (1), dehydroniranin A (2), and dehydroniranin B ...
el-Bendary E R - - 1996
A number of quinazoline derivatives containing basic amine substituents at position 4, as well as new derivatives of triazolo[4,3-alpha]quinoxalines carrying basic amine or carboxylic acid moieties have been synthesized. A tetracyclic imidazotriazoloquinoxaline compound is also reported. Two of the new products (2b and 7b) exhibited good antiinflammatory activity in rats, ...
Li P - - 1996
A series of N-trifluoroacetyl/pentafluoropropionyl-O-trifluoroethyl/ pentafluoropropyl/heptafluorobutyl ester derivatives of 5-methoxyindole-3-acetic acid (5MIAA) were synthesized. Under electron-capture negative ionization conditions, the N-trifluoroacetyl derivatives were found to yield relatively abundant, analyte-specific M-. molecular ions and [M-HF]-., [M-HF-CF2CO]-. and [M-CF3CO]- fragment ions, while the N-pentafluoropropionyl derivatives yielded predominantly the reagent-specific pentafluoroacylium C2F5CO- ion. 5-[2H3]Methoxyindole-3-acetic ...
Yuda T - - 1996
New lipid derivatives of polyethyleneglycol (PEG) have been synthesized and tested for the ability to allow liposomes to evade uptake by the reticuloendothelial system (RES) and to prolong the circulation time of liposomes in mice. Liposomes were prepared from distearoylphosphatidylcholine (DSPC) and cholesterol (CH) (1:1, m/m) containing 6 mol% of ...
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