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Results 551 - 600 of 921
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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 ...
Takesada H - - 1996
Molecular structures of 10 metabolites, which were isolated from urine (M1-M8) or bile (M9 and M10) after administration of AY4166 (N-(trans-4-isopropylcyclohexanecarbonyl)-D-phenylalanine), a novel amino acid derivative with hypoglycemic activity, have been elucidated by mass spectrometry and nuclear magnetic resonance. Four of these (M1, M2, M3 and M8) were determined to ...
Kuo M S - - 1996
This report describes the results of a biosynthesis study of marcfortine A (MA). We report here that MA is derived from methionine, tryptophan, lysine and two isoprene units, the latter two being derived from acetic acid. From the 13C enrichment pattern of the pipecolic acid moeity we further conclude that ...
Ioneda T - - 1996
Thermospray mass spectral (TSP-MS) analyses were carried out on methyl corynomycolates, their 3-O-acetyl and 3-O-benzoyl derivatives, and on corynomycolic acids and their 3-O-acetyl derivatives, using an ion generating solvent system consisting of water/isopropanol (99:1, v/v) containing 0.1 M ammonium acetate. Methyl corynomycolates generated three groups of peaks corresponding to adducts ...
Dubreucq G - - 1996
The exopolysaccharide produced by the bacterium Alteromonas sp. strain 1644 originating from deep sea hydrothermal vents was shown to contain a novel glucuronic acid derivatives: 3-O-[(R)-1-carboxyethyl]-D-glucuronic acid. The structure of this compound was established on the basis of mass spectrometric data, methylation analysis, preparation of derivatives, and chemical synthesis of ...
Guo R - - 1996
In previous work certain hydroxylated and peroxylated derivatives of uroporphyrin (URO) have been isolated from the urine of patients suffering from porphyria. We have now investigated the mechanism of production of these oxygenated derivatives of URO, using both enzymic and chemical model systems and also the effect of exposure to ...
Carla Aragoni M - - 1996
The ionization constants in aqueous solutions of meso- and dl-dimercaptosuccinic acid and of monomethyl and dimethyl meso-succinates were carefully determined by potentiometric and spectrophotometric methods as a result of the increasing interest in these molecules as heavy metal chelators. In order to explain the influence of various substituents on ionization ...
Jolley C - - 1996
The monohydrazide derivative of diethylenetriaminepentaacetic acid, (HOOCCH2)2NCH2CH2N(CH2CO-OH)CH2CH2N(CH2COOH++ +)(CH2CO.NHNH2), is a bifunctional chelator designed for attaching the radiometal 111In selectively to the carbohydrate side chains of pre-oxidised monoclonal antibodies. A simple synthesis of this chelator (from diethylenetriaminepentaacetic acid cyclic anhydride and hydrazine), and its purification and chemical characterisation, are described. Rabbit ...
Eghbaldar A - - 1996
An artificial neural network (ANN) has been trained to recognize the presence or absence of specific structural features (SF) in trimethylsilyl derivatives of organic acids from their mass spectra. The input vector is constructed without knowledge of the molecular ion, which is generally not observed in the spectra of these ...
Miadoková E - - 1996
Potential gentoxicity of five new local anesthetics, derivatives of phenylcarbamic acid differing in the length of the alkyl chain of the alkoxy substituent, was studied on five test systems. There was a direct relationship with increased toxic effect in bacteria and yeast as a function of the elongation of the ...
Zhang M - - 1996
Novel seven N-fatty acyl derivatives (degree of substitution 0.78-0.96) of a microbial galactosaminan were prepared in 59-79% yields by its reaction with fatty acid anhydrides in aqueous acetic acid-methanol. N-Acetyl and N-propionyl derivatives were soluble in water, aqueous 2% sodium hydroxide, and aqueous 2% acetic acid, but N-higher fatty acyl ...
Prinz H - - 1996
The synthesis of 2-substituted anthracenonyl acetic acid (2-AA) derivatives is described. The key step is the Marschalk reaction of 1-hydroxy-8-methoxy-anthracenedione with glycolic acid. After protection of the resulting 2-anthracenonyl acetic acid derivative, the 2-monoalkylated derivatives are selectively obtained by direct alkylation. The methodology proves quite general and allows for the ...
Wilczek A - - 1996
The proportions in which two eumelanin monomers, namely 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and 5,6-dihydroxyindole (DHI), compose the eumelanin polymer are believed to determine properties of the pigment including its color. These proportions are, however, not well elucidated for naturally occurring eumelanins, largely because of methodological difficulties. In this study we estimate ...
Tsuda M - - 1996
3-Amino-2-hydroxyvaleric acid was prepared, and separated into its diastereomers. The relative stereochemistry was determined by 1H NMR in their oxazolidone derivatives. The threo-isomer was resolved by (S)-1-(1-naphthyl) ethylamine in the N-(p-methoxybenzyloxycarbonyl) derivative. The absolute configuration of (--)-threo-3-(p-methoxybenzyloxycarbonyl)amino-2-hydroxyvaleric acid was confirmed to be 2R, 3S. The absolute configuration of 3-amino-2- oxovaleric ...
Shindo K - - 1996
Biosynthetic studies using 13C- and 2H-labeled compounds revealed that the carbon skeletons of cochleamycins A and B were derived from eight acetic acid units and one propionic acid unit with the introduction of an acetoxy group at C-10, which was replaced by an isobutyryl residue derived from valine in cochleamycins ...
Marshall James A. - - 1996
The aminoheptose destomic acid (3.5) and the aminooctose lincosamine (6.8) were synthesized in protected form by parallel sequences starting from the oxazolidine derivatives 2.4 and 5.1 of N-CBz serinal and N-BOC threoninal. The parallel sequences feature BF(3)-promoted addition of the (R)-gamma-OTBS allylic stannane 2.8 to the homologated enals 2.7 and ...
McMorris T C - - 1996
Acylfulvene, derived from the sesquiterpene illudin S by treatment with acid (reverse Prins reaction), is far less reactive to thiols than illudin S. However, it is reduced readily to an aromatic product, in the same way as illudin S. This may explain its greatly improved therapeutic index compared to that ...
Goldberg G S - - 1996
Glycyrrhetinic acid exhibits many pharmacological activities, including the ability to block gap junctional communication. However, the mechanism of glycyrrhetinic action is not clear. Others have shown that glycyrrhetinic acid apparently binds to a single proteinatious binding site in the plasma membrane. We present evidence that while exposure to glycyrrhetinic acid ...
Midura-Nowaczek K - - 1996
Amino acids containing sulphur, dipeptide derivatives of methionine and S-substituted derivatives of cysteine are potent antifibrinolytic agents. The structural moiety of the substances responsible for the effect on the clot formation is not known. Present study was undertaken in order to evaluate the effect of some analogues of dipeptides containing ...
Brzosko W J - - 1996
Simultaneous cytotoxicity of Ukrain and protoporphyrin amino-acid derivatives was tested on four malignant cell lines and the cytotoxic effect after laser irradiation was compared with cytotoxicity of Ukrain and protoporphyrin amino-acid derivatives applied on similar cell lines separately. It was found that Ukrain and protoporphyrin amino-acid derivatives act synergistically as ...
El-Desokey S I - - 1996
Cyanoethylation of a selected group from indole derivatives 1a-i using acrylonitrile in pyridine and potassium hydroxide afforded the corresponding indole-1-propionitrile 2a-h derivatives which readily hydrolysed in basic medium to the corresponding indole-1-propionic acid derivatives 4a-c. A several attempts to cyclize the above products-to the corresponding dihydropyrroloquinolin-4-one derivatives. The indole-1-propionamide derivatives ...
Westermark P - - 1995
Amyloid deposits in the aortic intima are very common in association with atherosclerosis and aging. In the present study, a major fibril protein purified from amyloid present in human atherosclerotic plaques was shown to be a 69-amino acid N-terminal fragment of apolipoprotein AI. Although senile form of localized apolipoprotein AI-derived ...
Imamoto Y - - 1995
We report reconstitution of photoactive yellow protein (PYP) from apoPYP and p-coumaric acid derivatives. The addition of p-coumaric acid to the apoPYP sample did not result in the recovery of PYP. In contrast, yellow products were obtained by the addition of p-coumaryl thiophenyl ester or p-coumaric anhydride to the apoPYP ...
Pandey R K - - 1995
A first report on the biological evaluation of a series of isomerically pure benzoporphyrin derivatives (cis- and trans-isomers) as methyl esters is described. In preliminary in vivo studies, the n-hexyl ether analogues of both cis- and trans-isomers of benzoporphyrin derivatives were found to be more active than the industrially prepared ...
Aszalos A - - 1995
The substrate specificity of the P-glycoprotein (P-170), a multidrug transporter, was studied using N-acylated daunorubicin derivatives and four MDR1 cDNA transfected cell lines. Results showed that N-acetyl-daunorubicin is a substrate, but the longer fatty acid derivatives, N-octanoyl and N-dodecanoyl daunorubicins, are not. This conclusion was reached by flow cytometric drug ...
Singh S - - 1995
Influenza virus sialidase is a surface enzyme that is essential for infection of the virus. The catalytic site is highly conserved among all known influenza variants, suggesting that this protein is a suitable target for drug intervention. The most potent known inhibitors are analogs of 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en), particularly the ...
Schadewaldt P - - 1995
We report on an enzymatic-chemical method for the specific preparation of L-amino acid-derived quinoxalinols suitable for the sensitive estimation of 13C- or 2H-label enrichment by gas chromatography-mass spectrometry: Amino acid fractions are isolated from physiological fluids by ion-exchange chromatography. The compound of interest is converted to the corresponding 2-oxo acid ...
Ogawa T - - 1995
Twenty-four kinds of the acylated, amidated or esterified derivatives of N-acetylglucosaminyl (GlcNAc)-beta(1-->4)-N-acetylmuramyl (MurNAc)-L-alanyl (Ala)-D-isoglutaminyl (isoGln)-(L)-meso-2,6-diaminopimeric acid (A2pm)-(D)-amide (GMP3-A) which were prepared by chemical modifications of an enzymatic hydrolysate of Lactobacillus plantarum cell-wall peptidoglycans were examined for oral adjuvant activity by gastric intubation with bovine serum albumin (BSA) in liposomes into ...
Priewer H - - 1995
Acidic and basic triamterene derivatives were evaluated with respect to their acute toxicity. After single intravenous application in mice, derivatives with a basic side-chain were much more toxic than compounds with an acidic side-chain. There is a significant correlation between the potassium retaining properties (measured as ED50) and the acute ...
Blechert S - - 1995
Plant defense against microbial pathogens and herbivores relies heavily on the induction of defense proteins and low molecular weight antibiotics. The signals between perception of the aggression, gene activation, and the subsequent biosynthesis of secondary compounds are assumed to be pentacylic oxylipin derivatives. The rapid, but transient, synthesis of cis-jasmonic ...
Lurie E - - 1995
The methods for partition coefficient (Kp) determination were developed for different concentrations of N-(2-hydroxybenzyl)-omega-amino carbonic acids, a new class of amphipathic fatty acid derivatives (An), their deutero (AnD) and bromine (AnBr) derivatives. To do this the following methods were used: 2H-NMR, equilibrium dialysis, centrifugation and fluorescence spectroscopy. Kp dependence on ...
Matthews J C - - 1995
While isolating siroheme from enzymes or whole cells of Desulfovibrio species, it was discovered that the main product after metal removal and esterification was not the octamethyl ester derivative of sirohydrochlorin, but a monoamide, heptamethyl ester derivative. The structure of this derivative was established by mass spectrometry and NMR. Nuclear ...
Fehrentz J A - - 1995
N-Urethane-protected N-carboxyanhydrides (UNCAs) are very reactive amino acid derivatives. They have been successfully used in peptide synthesis, in both solution and solid phase. We have demonstrated that UNCAs are interesting starting materials for the synthesis of various amino acid derivatives. Chemoselective reduction of UNCAs with sodium borohydride led the corresponding ...
Adamczeski M - - 1995
The cyanobacteria-containing Caribbean sponge, Calyx cf. podatypa, was collected from three sites in the Bahamas. In each of the three collections, a polar solvent partition fraction contained six known compounds including five diketopiperazines [1-4,6] and phenylacetic acid, along with a new diketopiperazine, cyclo-(4-methyl-R-proline-S-norvaline) [5]. Interestingly, all six diketopiperazines are proline-derived ...
Ohsako M - - 1995
The transport of aspirin (ASP) and its derivatives (m- or p-acetoxybenzoic acid (m- or p-AcOHBA), o-propionyloxybenzoic acid (PrOHBA), o-butyryloxybenzoic acid (BuOHBA), o-acetoxyhippuric acid (AcOHPA), and o-acetoxy-N-benzoyl-beta-alanine (AcONBA)) through human erythrocyte membrane was investigated. ASP derivatives were transported into the erythrocytes where they were hydrolyzed and then released, although the derivatives ...
Zheleva A - - 1995
The synthesis of three spin labeled derivatives of N-[N'-(chloroethyl)-N'-nitrosocarbamoyl] amino acids is reported. The new nitrosoureas are obtained by condensation of the corresponding N-[N'-(2-chloroethyl)-N'-nitrosocarbamoyl] amino acid with 2,2,6,6-tetramethyl-1-oxyl-4-aminopiperidine using dicyclohexylcarbodiimide. Their chemical structures are confirmed by elemental analysis, IR, MS, and EPR spectroscopy. All newly synthesized compounds showed high antitumour ...
Sparapano L - - 1995
Cyclopaldic acid (CA), its six derivatives, and iso-cyclopaldic acid (IsoCA) were assayed for toxicity to cuttings of three species of cypress, as well as to mung bean, oat, and tomato explants. Toxicity to host and non-host plants of CA derivatives having one or both of the aldehyde groups transformed was ...
O'Malley P J - - 1994
The use of the quantum mechanically derived electrostatic potential is introduced to visualize the variation in acidity across a series of cluster molecules corresponding to models of terminal and bridged hydroxyl groups in zeolites. The electrostatic potential is color coded onto the electron density surfaces of the molecules involved, and ...
Atta F M - - 1994
3-(2'-Chloroethyl)-2-methyl-3,4-dihydroquinazolin-4-one (I) was reacted with sodio (sodium thioglycolate) in dry dioxane and yielded compound II. By using thionyl chloride, this compound was converted to the corresponding acid chloride (III). The prepared acyl chloride (III) was allowed to interact with different alpha-amino acids such as Gly, L-Ala, L-B-Phe, DL-Asp, L-Glu, L-Thr ...
Strydom D J - - 1994
An extensive retrospective comparison was conducted of the long-term repeatability and consistency of amino acid analyses using phenylisothiocyanate and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) precolumn derivatization. Amino acid standards were analyzed more than 130 times on more than 60 independent occasions by each of these two precolumn derivatization methodologies, during routine amino ...
Odake S - - 1994
Helicobacter pylori (HP) produces strong urease [EC 3.5.1.5], which is considered to play a role in the pathogenesis of gastritis and peptic ulcers. Inhibitions against this enzyme have been studied with hydroxamic acid (HXA) derivatives of aliphatic or aromatic carboxylic acids, amino acids and dipeptides. A number of HXAs potently ...
King R S - - 1994
At estrus, an oviduct-specific, estrus-associated glycoprotein (EAP) of molecular weight 85-95,000, is secreted by the oviductal epithelium and found in cannula-derived bovine oviductal fluid (ODF). The objectives of these studies were to determine if bovine sperm were capacitated by EAP in vitro, whether this effect differed for EAP derived from ...
Niederprüm H J - - 1994
The inhibition of testosterone 5oc-reductase (EC 1.3.99.5) (5αR) in vitro by lipophilic extracts from Sabal serrulata fruits effective on Benign Prostatic hyperplasia (BPH) treatment is due entirely to free fatty acid content. In order to find out structure-inhibition activity relationships of the action of free fatty acids on the enzyme, ...
Pochopin N L - - 1994
Amino acid amides of dapsone (DDS), a primary aromatic amine, have been synthesized as water-soluble, chemically stable prodrugs that target peptidase enzymes for cleavage to the parent drug in vivo. The pharmacokinetics of DDS, monoacetyldapsone (MADDS; a known metabolite), and various L- and D-amino acid derivatives of DDS were investigated ...
Spies H S - - 1994
Leishmania donovani, the causative agent of visceral leishmaniases, is an intracellular pathogen which proliferates within the host macrophages. Analysis of the thiol composition of L. donovani by means of the thiol-specific reagent, 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin, indicated that this organism produces substantial amounts of ovothiol A. This observation was further substantiated by HPLC ...
Kwong S C - - 1994
The amino acid fermentation by Corynebacterium glutamicum was monitored with an new technique that uses the first derivative of the NAD(P)H fluorescene signal. The rate of change of NAD(P)H pools is indicative of intracellular redox balance variations that correspond to metabolic changes. The profile of this signal showed several characteristics ...
Ohwada J - - 1994
A new antifungal substance, azoxybacilin (an unusual amino acid with an azoxy moiety) and its derivatives have been synthesized from Boc-L-Asp-OtBu utilizing the Moss procedure for the preparation of the azoxy moiety. The ester derivative, Ro 09-1824, showed more potent antifungal activity and a broader antifungal spectrum than azoxybacilin did.
Neustadt B R - - 1994
A broad series of N-(3-mercaptoacyl) amino acid derivatives was evaluated for their ability to inhibit atriopeptidase (neutral endopeptidase, EC 3.4.24.11) in vitro and in vivo. Structural parameters studied were (i) the substituent on the 2-position of the 3-mercaptopropionyl moiety, (ii) the amino acid component, (iii) the S-terminal derivative, and (iv) ...
Sassen K - - 1994
Following the massive 1883 Krakatoa volcanic eruption, a new atmospheric optical phenomeon was identified by Rev. S. E. Bishop. This inconspicuous one-ringed corona, or aureole, was immediately linked to the global spread of volcanic debris injected into the stratosphere, but little refinement in the mechanisms responsible for Bishop's ring has ...
Sosnovsky G - - 1994
The [N'-(2-chloroethyl)-N'-nitrosoamino]carbonyl [(2-chloroethyl)nitrosocarbamoyl, CNC] moiety containing compounds CNC-glycinamide 2d, CNC-amino acid derivatives 7a-d, and carbohydrate-CNC-amino acid conjugates 13, 18, 22, 23, 27, and 28 were synthesized and evaluated in vivo for their anticancer activities against the murine lymphocytic leukemia P388 using the National Cancer Institute (NCI) protocol. The most active ...
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