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At least 91 records · Page 5Linked to original sources
PubMed1987

The characterization of the dopaminergic profile of EMD 23,448, and indolyl-3-butylamine: selective actions on presynaptic and supersensitive postsynaptic DA receptor populations.

The effects of the dopamine (DA) agonist EMD 23,448 on central normosensitive and supersensitive DA receptors were investigated. EMD 23,448 only slightly inhibits rat striatal DOPA synthesis in vivo and does not inhibit the enhanced striatal DOPA synthesis elicited by acute administration of haloperidol. Also unlike other DA agonists it does not increase striatal acetylcholine levels. However, it inhibits striatal DOPA synthesis in rats with DA receptors rendered supersensitive by chronic treatment with haloperidol. EMD 23,448 also effectively inhibits the enhanced striatal DOPA synthesis elicited by administration of GBL. Furthermore, EMD 23,448 selectively reduces, in a dose-dependant way, DA utilization in nerve terminals of the central caudate and in dotted terminals of the ventral striatum but DA utilization in the substantia nigra is unaffected. The most marked reduction of DA utilization was induced in the anteromedial frontal cortex. These results indicate that EMD 23,448 selectively stimulates presynaptic DA receptors and supersensitive postsynaptic DA receptors. Behavioral experiments in animals with normosensitive and supersensitive DA receptors also indicate that EMD 23,448 effectively stimulates presynaptic and supersensitive postsynaptic DA receptors. Receptor binding studies have shown that EMD 23,448 has a high affinity for the D2 DA receptors, but it ineffectively promotes the coupling of the DA receptors with the guanine nucleotide regulatory protein. However, at supersensitive striatal DA receptors the coupling is shown to be enhanced by EMD 23,448. The selectivity of EMD 23,448 for presynaptic DA receptors might, at least in part, be related to the presence of DA receptor reserves which are sensitive to EMD 23,448. With regard to the selectivity of EMD 23,448 for supersensitive postsynaptic DA receptors an increase in the efficiency of the coupling mechanism upon activation by EMD 23,448 is probably involved.

Acetylcholine↗
PubMed2005

Development of a new EPR spin trap, DOD-8C (N-[4-dodecyloxy-2-(7'-carboxyhept-1'-yloxy)benzylidene]-N-tert-butylamine N-oxide), for the trapping of lipid radicals at a predetermined depth within biological membranes.

We report on the development of the first member of a new family of EPR spin-trapping agents designed to trap radicals at a predetermined depth within biological membranes. By analogy to the use of nitroxide spin labels to 'report' on the environment at specific depths within biological membranes, we set out to prepare similar reporter molecules, but with a nitrone in place of the nitroxide function. The prototype compounds were tested in a model system consisting of large unilamellar vesicles exposed to a copper-dependent radical generating system. This entailed the reduction of tert-butylhydroperoxide to the tert-butoxyl radical ((t)BuO(.-)) by a membrane-permeable Cu(I) complex, which was generated in situ by reduction of the Cu(II) complex by ascorbate. To assist in the identification of the radicals detected, preliminary studies were performed in methanolic solution, where the major radical trapped was shown to be (.-)CH(2)OH, resulting from H-atom abstraction from the alcohol by (t)BuO(.-). This conclusion was shown to be in agreement with predictions based on chemical kinetics, which were then used to support the proposal that the primary species trapped in the lipid vesicles were radicals derived from membrane fatty acids. This molecule represents the first of a new generation of spin traps which, through modification, can be used to position the radical-trapping nitrone moiety at chosen depths within biological membranes.

Animals↗
PubMed2003

Competing sulfonylation and phosphonylation following rearrangement of an O-sulfonyl-N-phosphinoylhydroxylamine with tert-butylamine: demonstration of a phosphonamidic-sulfonic anhydride intermediate and 18O-labelling evidence on how it may be formed.

Reaction of R(Ph)P(O)N HOSO2Bn (R = PhMeCH) with Bu(t)NH2 in CH2Cl2 gives a mixture of RP(O)(NHPh)-NHBu(t) and Bu(t)NHSO2Bn, the proportion of the sulfonamide increasing steadily (14.6% to 32.9%) as the concentration of amine is reduced (8.0 to 0.2 mol dm(-3)). Apparently the phenyl and sulfonate groups in the substrate become transposed, giving a phosphonamidic-sulfonic anhydride RP(O)(NHPh)OSO2Bn which then reacts at the phosphorus or sulfur atom to give the final products; an authentic sample of the anhydride gives similar mixtures of products. Substrate labelled with 18O in the sulfonyl position (57 mol% one 18O atom) gives sulfonamide containing most but not all of the label (43.7 mol% one 18O atom with 2.0 mol dm(-3) amine). This implies partial equilibration of the three sulfonate oxygen atoms during rearrangement, or after the anhydride intermediate has been formed.

Journal Article↗
PubMed1981

Effects of cathepsin B, H, and D in pectoral muscle of dystrophic chickens (line 413) of in vivo administration of E-64-c (N-[N-(L-3-transcarboxyoxirane-2-carbonyl)-L-leucyl]-3-methyl-butylamine).

The total activities of cathepsin B and cathepsin H in pectoral muscle of dystrophic chickens (Line 413) were about two times higher than in control chickens (Line 412), and cathepsin D activity was about 3 times higher in this muscle in the dystrophic chickens. When E-64-c, a synthesized potent thiol inhibitor was injected subcutaneously, in various doses, daily for 80 days into dystrophic chickens (L 413), the activities of cathepsin B and cathepsin H were reduced to the levels in control chickens (Line 412), but cathepsin D activity, which is insensitive to E-64-c in vitro, was not changed.

Animals↗
PubMed1982

Relationship between carcinogenicity and in vitro metabolism of nitrosomethylethylamine, nitrosomethyl-N-butylamine, and nitrosomethyl-(2-phenylethyl)amine labeled with deuterium in the methyl and alpha-methylene positions.

With the use of rat liver preparations, the in vitro microsomal metabolism of methylethylnitrosamine, methyl-n-butylnitrosamine, and methyl(2-phenylethyl)nitrosamine labeled with deuterium in the methyl and alpha-methylene positions has been compared with that of the parent (unlabeled) compounds. All three forms of the liver carcinogen methylethylnitrosamine are metabolized with two sets of kinetic constants. Examination of these kinetic constants suggests that both methylation and ethylation of cellular nucleophiles might be important in the carcinogenic action of these nitrosamines. The esophageal carcinogen, methyl(2-phenylethyl)nitrosamine, gave only one set of kinetic constants during metabolism. The metabolism of the three methylbutylnitrosamines gave results similar to that of the three methylethyl nitrosamines. Except for metabolism of d2-methylbutylnitrosamine to butyraldehyde, two sets of kinetic constants were found. Approximately equivalent amounts of methylating species were produced from d3-methylbutylnitrosamine and d0-methylbutylnitrosamine.

Animals↗
PubMed1985

Metabolic fate of omega-1 and omega-2 oxidized N-nitrosodibutylamines in the rat.

Of the three metabolic oxidation pathways of N-nitrosodibutylamine (NDBA) demonstrated in vivo, omega oxidation is responsible for the induction of bladder tumors, while omega-1 and omega-2 oxidations are considered to be associated with the induction of liver tumors by NDBA. The metabolic fate of the following five NDBA derivatives was investigated in the rat in order to elucidate further the metabolic characteristics of NDBA in relation to its hepatocarcinogenic activity: N-nitroso-N-(3-hydroxybutyl)butylamine (NHBBA-3), N-nitroso-N-(3-oxobutyl)butylamine (NOBBA-3), N-nitroso-N-(2-hydroxybutyl)butylamine (NHBBA-2) and N-nitroso-N-(2-oxobutyl)butylamine (NOBBA-2), which are involved in the omega-1 and omega-2 oxidation pathways of NDBA, and N-nitroso-N-(2-oxopropyl)butylamine (NOPBA), a minor urinary metabolite of NDBA. By characterization of the urinary metabolites, NHBBA-3 and NHBBA-2, primary metabolites of NDBA, were shown to undergo further oxidative metabolic transformation via NOBBA-3 and NOBBA-2, respectively, although conjugation with glucuronic acid to afford the glucuronides was demonstrated to be their principal metabolic pathway. The principal urinary metabolite of NOBBA-2 as well as NOBBA-3 was N-nitroso-N-(carboxymethyl)butylamine, while reduction of the oxo group followed by glucuronidation was found to be a minor metabolic pathway. The glucuronide of N-nitroso-N-(2-hydroxypropyl)butylamine was the principal metabolite of NOPBA, N-nitroso-N-(carboxymethyl)butylamine being a secondary metabolite. The hepatocarcinogenic activity of the three oxo compounds (NOBBA-3, NOBBA-2 and NOPBA) in relation to that of NDBA is discussed from the metabolic point of view.

Animals↗
PubMed1985

Biotransformation of terodiline I. Identification of metabolites in dog urine by mass spectrometry.

Nine metabolites of terodiline (N-tert-butyl-4,4-diphenyl-2-butylamine) have been identified in dog urine by various chromatographic techniques and mass spectrometry. The main metabolic pathway is aromatic hydroxylation, leading to the quantitatively most important metabolite, N-tert-butyl-4-(4-hydroxyphenyl)-4-phenyl-2-butylamine, and to two dihydroxylated metabolites, one mono substituted in both rings (N-tert-butyl-4,4'-bis(4-hydroxyphenyl)-2-butylamine), and one disubstituted in one ring (N-tert-butyl-4-(3,4-dihydroxyphenyl)-4-phenyl-2-butylamine). The latter is further metabolized by methylation, forming N-tert-butyl-4-(4-hydroxy-3-methoxyphenyl)-4-phenyl-2-butylamine, the second most abundant metabolite. Still another metabolite is formed by hydroxylation in the tert-butyl group to N-(2-hydroxymethyl-2-propyl)-4,4-diphenyl-2-butylamine. A very minor dihydroxylated metabolite results from oxidation both in an aromatic ring and in the tert-butyl group, giving N-(2-hydroxymethyl-2-propyl)-4-(4-hydroxyphenyl)-4-phenyl-2-butylamine. Oxidation of the carbon adjacent to the nitrogen and subsequent deamination gives the two ketones 4-(4-hydroxyphenyl)-4-phenyl-2-butanone and 4-(4-hydroxy-3-methoxyphenyl)-4-phenyl-2-butanone. Reduction of the carbonyl function in the former yields the corresponding alcohol, 4-(4-hydroxyphenyl)-4-phenyl-2-butanol. Some unchanged terodiline is also present. All metabolites formed by functionalization appear to be extensively conjugated, presumably with glucuronic acid.

Animals↗