Search results for "Phosphor"
showing 10 items of 1952 documents
Drugs modulating the biological effects of peroxynitrite and related nitrogen species
2006
The term “reactive nitrogen species” includes nitrogen monoxide, commonly called nitric oxide, and some other remarkable chemical entities (peroxynitrite, nitrosoperoxycarbonate, etc.) formed mostly from nitrogen monoxide itself in biological environments. Regardless of the specific mechanisms implicated in their effects, however, it is clear that an integrated pharmacological approach to peroxynitrite and related species is only just beginning to take shape. The array of affected chemical and pathological processes is extremely broad. One of the most conspicuous mechanisms observed thus far has been the scavenging of the peroxynitrite anion by molecules endowed with antioxidant activity. T…
The transport activity of the human cationic amino acid transporter hCAT-1 is downregulated by activation of protein kinase C
2001
1 The human cationic amino acid transporter hCAT-1 contains several consensus sequences for phosphorylation by protein kinase C (PKC). This study investigates the eAect of PKC activation on hCAT-1-mediated transport. 2 When expressed in Xenopus laevis oocytes, hCAT-1-mediated L-arginine transport was reduced to 44+3% after a 30 min treatment of the oocytes with 100 nM phorbol-12-myristate-13-acetate (PMA). 4a-phorbol-12,13-didecanoate (4a-PDD, 100 nM) had no eAect. 3 In EA.hy926 endothelial cells, maximal inhibition of hCAT-1-mediated L-arginine transport (to 3‐11% of control) was observed after treatment of the cells with 100 nM PMA for 4 h. A 20‐30 h exposure of the cells to 100 nM PMA le…
New oxidative derivatives of atractyligenin and their cytotoxic activity
2006
ent-Kauranes are naturally occurring diterpenoids isolated from several families, such as Asteraceae and Lamiaceae. These compounds have attracted interest because of their structures and their biological activities as anti-tumorals, anti-HIV and anti-bacterials [1]. Extensive chemical work [2] was carried out on the structure of atractyligenin, the nor-diterpene aglycone of the glucoside atractyloside, occurring, together with its diterpene homologous carboxy-atractyloside, in the root of Atractylis gummifera L. (Compositae). The interest for these compounds was stimulated by the high toxicity [3] of both glucosides, responsible of many deadly poisoning in past time. Due to the 15-hydroxyl…
Determination of Aldicarb, Aldicarb Sulfoxide, and Aldicarb Sulfone in Oranges by Simple Gas–Liquid Chromatography with Nitrogen–Phosphorus Detection
1994
Abstract A reversed-phase liquid chromatographic method, using an acetonitrile–water gradient mobile phase, and a gas-liquid chromatographic method with nitrogen–phosphorus and flame photometric detection were compared for simultaneous and separate determinations of trace quantities of aldicarb and its metabolites aldicarb sulfone and aldicarb sulfoxide. One hundred gram samples of fortified oranges were extracted with water–acetone, water-acetonitrile, or water–methanol, and the extracts were partitioned with methylene chloride. Partitioning with other organic solvents such as chloroform, ethyl acetate, or methyl isobutyl ketone was also investigated. When performed under optimal condition…
Phosphoproteinphosphatase activity in sea urchin embryos
1964
Si e studiata l'attivita fosfoproteinfosfatasica in omogenati totali di uova ed embrioni diParacentrotus lividus e diArbacia lixula. La reazione ha un optimum a pH acido, e stimolata da K+ e Na+ ed e inibita da Ca++ e Mg++. L'attivita enzimatica aumenta tra la fecondazione e lo stadio a 64 blastomeri; in seguito rimane costante fino a blastula con mesenchima; quindi generalmente decresce.
Stereoselective synthesis of 1-aminoalkanephosphonic acids with two chiral centers and their activity towards leucine aminopeptidase
2003
The stereoselective synthesis of 1-amino-2-alkylalkanephosphonic acids, namely, compounds bearing two chiral centers, was achieved by the condensation of hypophosphorous acid salts of (R)(+) or (S)(-)-N-alpha-methylbenzylamine with the appropriate aldehydes in isopropanol. Simultaneous deprotection and oxidation by the action of bromine water provided equimolar mixtures of the RS:RR and SR:SS diastereomers of desired acids. They appeared to act as moderate inhibitors of kidney leucine aminopeptidase with potency dependent on the absolute configuration of both centers of chirality.
Phosphoribomutase- und 5-Phosphoriboisomerase-Aktivität in isolierten Zellkernen
1958
The existence of phosphoribomutase and 5-phosphoriboisomerase has been demonstrated in isolated cellular nuclei from rat liver and swine kidney. Phosphoribomutase has been shown to require Mg-ions for optimal activity.
�ber die Wirkung von Metyrapon auf den mikrosomalen Arzneimittelabbau
1967
The inhibitor of adrenal steroid-11-β-hydroxylation, Metyrapone (SU 4885), also decreases the rate of drug hydroxylation reactions, both in vitro and in vivo. The follwing oxidative microsomal reactions were studied: O-demethylation of p-nitroanisole, N-demethylation of amidopyrine, and ring hydroxylation of acetanilide. In all three cases Metyrapone inhibits the formation of the reaction products. The inhibitor concentrations required for reduction of the initial reaction rates to one half are 7.5 · 10−4 M, 5 · 10−4m and 20 · 10−4 M, respectively. Steroid C-11-β-hydroxylation is reduced to one half by 2.5 · 10−4 M Metyrapone.
A phosphonamidate containing aromatic N-terminal amino group as inhibitor of leucine aminopeptidase-design, synthesis and stability.
2006
Fully deprotected phosphonamidate dipeptides, predicted as effective inhibitors of cytosolic leucine aminopeptidase, showed unexpected instability in water solution at pH below 12. Their hydrolysis rate was strictly correlated with basicity of the N-terminal amino group. To improve this feature a phosphonamidate analogue containing less basic, aromatic 2-aminophenylphosphonate residue in P1 position of the inhibitor was designed. The target compound was synthesised starting from diethyl 2-nitrophosphonate in several step procedure. The decrease in basicity of the terminal amino moiety of the modified analogue in fact resulted in satisfactory improvement of hydrolytic stability of the P–N bo…
Mitochondrial function and energy metabolism in neuronal HT22 cells resistant to oxidative stress
2014
Background and Purpose The hippocampal cell line HT22 is an excellent model for studying the consequences of endogenous oxidative stress. Extracellular glutamate depletes cellular glutathione by blocking the glutamate/cystine antiporter system xc−. Glutathione depletion induces a well-defined programme of cell death characterized by an increase in reactive oxygen species and mitochondrial dysfunction. Experimental Approach We compared the mitochondrial shape, the abundance of mitochondrial complexes and the mitochondrial respiration of HT22 cells, selected based on their resistance to glutamate, with those of the glutamate-sensitive parental cell line. Key Results Glutamate-resistant mitoch…