SEARCH · PubMed Health

Results for “Benzphetamine”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2Linked to original sources

PubMed2001

Analysis of benzphetamine and its metabolites in rat urine by liquid chromatography-electrospray ionization mass spectrometry.

An analytical method to identify and determine benzphetamine (BMA) and its five metabolites in urine was developed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS) using the solid-phase extraction column Bond Elut SCX. Deuterium-labeled compounds, used as internal standards, were separated chromatographically from each corresponding unlabeled compound in the alkaline mobile phase with an alkaline-resistant ODS column. This method was applied to the identification and determination of BMA and its metabolites in rat urine collected after oral administration of BMA. Under the selected ion monitoring mode, the limit of quantitation (signal-to-noise ratio 10) for BMA, N-benzylamphetamine (BAM), p-hydroxybenzphetamine (p-HBMA), p-hydroxy-N-benzylamphetamine (p-HBAM), methamphetamine (MA) and amphetamine (AM) was 700 pg, 300 pg, 500 pg, 1.4 ng, 6 ng and 10 ng in 1 ml of urine, respectively. This analytical method for p-HBMA, structurally closer to the unchanged drug of all the metabolites, was very sensitive, making this a viable metabolite for discriminating the ingestion of BMA longer than the parent drug or other metabolites in rat.

Animals↗

PubMed1992

Cytochrome P450-benzphetamine interactions in the endoplasmic reticulum: studies using a monoclonal antibody to P450b.

A monoclonal antibody (MAb) to phenobarbital-induced rat cytochrome P450b was used to study the interaction of the substrate benzphetamine (Bz) with cytochromes P450 in liver microsomes. Binding of Bz to liver microsomes from phenobarbital-treated rats was monitored by the substrate-induced type I spectral change. The MAb maximally inhibited this spectral change by 49%, providing a probe to distinguish MAb-specific P450b from other Bz-binding P450s. Thermodynamic parameters of the interaction were determined in the absence and presence of MAb. The MAb did not influence the spin-state equilibrium of substrate-free P450b, but it increased the low spin content of substrate-bound P450b. The MAb also decreased the affinity of both high and low spin P450b for Bz. The temperature dependence of the Bz-binding interactions revealed a transition near 20 degrees C. Fluorescence polarization measurements of the membrane probe 1,6-diphenyl-1,3,5-hexatriene also revealed a transition at this temperature. The MAb comparably inhibited Bz binding to high spin P450b in the low and high temperature regions, whereas MAb inhibition of Bz binding to low spin P450b was greater in the low temperature region than in the high temperature region. These results indicate temperature-dependent changes in membrane structure that modulate both Bz binding to P450b and MAb-P450b-Bz interactions. These results also demonstrate the utility of MAbs for evaluating P450-substrate binding microequilibria of MAb-specific P450s in the presence of other P450s while in the natural membrane environment of the endoplasmic reticulum.

Animals↗

PubMed1997

Major role of the CYP2C isozymes in deamination of amphetamine and benzphetamine: evidence for the quinidine-specific inhibition of the reactions catalysed by rabbit enzyme.

1. The cytochrome P450 isozymes involved in the deamination of amphetamine (AP) and benzphetamine (BZP) have been studied in liver microsomes from rabbit and rat using isozyme-specific inhibitors. 2. Metabolism of BZP in rat yielding phenylacetone and formaldehyde was moderately inhibited by testosterone and chloramphenicol. N-Debenzylation was thought to be P450-dependent, but all inhibitors except for a non-specific inhibitor, SKF-525A, failed to inhibit this reaction. 3. In rabbit, quinidine and testosterone were potent inhibitors of both BZP deamination and dealkylation. Deamination of AP in rabbit was extensively inhibited only with quinidine. 4. AP deamination with purified rabbit CYP2C3, which was previously identified as the major isozyme responsible for this metabolism, was extensively inhibited with quinidine, previously thought to be a specific inhibitor of CYP2D. 5. These results strongly support the notion that the CYP2C isozymes play a major role in the deamination of both AP and BZP, but not for N-debenzylation of BZP in rat. However, on the basis of different sensitivities toward inhibitors, multiple isozymes seem to be involved in BZP deaminations in both species.

Amphetamine↗

PubMed1998

Simultaneous analysis of benzphetamine and its metabolites, and quantitation of urinary p-hydroxy-N-benzylamphetamine by micellar electrokinetic chromatography.

We developed a method for simultaneous analysis of benzphetamine (BZ) and its metabolites, p-hydroxy-N-benzylamphetamine (pHBA), p-hydroxybenzphetamine (pHBZ), amphetamine (AP), methamphetamine and p-hydroxymethamphetamine by micellar electrokinetic chromatography (MEKC). Urine samples from 0-15 h (3-h intervals) after oral administration of BZ (10 mg) were hydrolyzed with beta-glucuronidase (EC 3.2.1.31) at 37 degrees C overnight. The treated urine was applied to a solid phase extraction column Bond Elut Certify. After sequentially washing the column with water, 0.1 mol/l acetic acid and methanol, the samples were eluted with dichloromethane:isopropanol:28% ammonium hydroxide=78.4:19.6:2.0 (v/v %). The eluate was evaporated and the residue dissolved in running buffer was analyzed by MEKC. In urine from 0-3 h, AP, pHBZ and pHBA were detected. After that, only pHBA, which is one of the major metabolites of BZ in human urine, could be detected in the urine by the present method. A method for quantitation of pHBA by MEKC is described here. The effects of acetonitrile and sodium dodecyl sulfate in the running buffer of MEKC on the separation of BZ and its metabolites are also reported.

Acetonitriles↗

PubMed1996

Identification and characterization of cytochrome P4501A1 amino acid residues interacting with a radiolabeled photoaffinity diazido-benzphetamine analogue.

The photolabile benzphetamine analogue N-(p-azidobenzyl)-N-methyl-p-azidophenetylamine (N3-BP-N3) and its tritiated derivative were synthesized and used as photoaffinity ligands for P4501A1 substrate binding. The enzymatic activity of P4501A1 toward ethoxycoumarin was competitively inhibited by N3-BP-N3. After irradiation with UV light a radioactive photolysis product remained bound to P4501A1. After large scale labeling in the absence and in the presence of alpha-naphthoflavone, P-450 was digested with 1-p-tosyl-amino-2-phenylethyl chloromethyl ketone-treated trypsin and the resultant peptide fragments were separated with HPLC on a reverse-phase column. Six peptides with increased levels of incorporated radioactivity were detected and from a competition experiment in the presence of the inhibitor, four of them could be tentatively assigned as involved in substrate interaction. Amino acid sequences were determined and compared with the primary P-4501A1 sequence. N3-BP-N3 can bind amino acid residues through both ends of the molecule and, therefore, crosslinked peptides could be identified. Alignment of the primary structure of cytochrome P4501A1 with that of cytochrome P450102 revealed that two of the isolated crosslinked peptides can be placed in the vicinity of heme (in the L helix region and beta10-beta11 sheet region of cytochrome P450102) and could be involved in substrate binding. The other two peptides were located on the surface of the protein with the label bound specifically to Lys residues that were predicted to be involved in reductase-P450 interaction.

7-Alkoxycoumarin O-Dealkylase↗

PubMed1983

A kinetic study comparing the light-reversal properties of carbon monoxide inhibition of ethylmorphine, benzphetamine, and 7-ethoxycoumarin dealkylation with those of hydroxylation of 17-hydroxyprogesterone and testosterone.

The light-reversal properties of carbon monoxide (CO) inhibition of the dealkylation of benzphetamine, ethylmorphine, and 7-ethoxycoumarin by microsomes from phenobarbital (PB)-induced rat livers were compared with those of the 6 beta-, 7 alpha-, and 16 alpha-hydroxylations of testosterone by the same rat hepatic microsomes and C-21 hydroxylation of 17-OH progesterone by steer adrenal microsomes. CO inhibited all reactions studied to essentially the same degree. The significant finding was that the dealkylations were reversed most effectively by light of wavelengths between 440 and 445 nm, rather than around 450 nm, the optimal wavelength for steroid hydroxylations. Moreover, the dealkylations required several-fold higher light intensities for equivalent light reversal. These studies suggest that the heme protein-CO complex responsible for dealkylations has a spectrum corresponding to the shape of the pass band of the 445-nm filter, whereas that of the steroid hydroxylations has its light-reversal maximum at 450 nm and appears to be broader. The measurable differences in the light-reversal properties between the monooxygenations of two groups of substrates, (i) dealkylations and (ii) hydroxylations of lipid substrates, furnish biophysical properties that allow a better characterization of microsomal monooxygenases which should be of value in forwarding progress in the study of these systems.

17-alpha-Hydroxyprogesterone↗

PubMed1995

Different influences of two fractions of lung cytochrome b5 on reconstituted lung benzphetamine N-demethylase system.

Chromatography of lung microsomal cytochrome b5 obtained from DEAE-cellulose columns, yielded two distinct cytochrome b5 fractions. These cytochrome b5 fractions were further purified by Sephadex G-100 gel filtration chromatography. The specific cytochrome b5 content of fraction 1 and fraction 2 was found to be 16.5 and 16.4 nmol/mg protein respectively. Both fractions were free of cytochrome P-450, NADPH-cytochrome P-450 reductase and NADH-cytochrome b5 reductase activities. The effects of lung cytochrome b5 (fraction 1 and fraction 2) and liver cytochrome b5 on benzphetamine N-demethylase activity were examined. Four different reconstitution systems were used. Lung cytochrome b5 fraction 2 and liver cytochrome b5 stimulated N-demethylase activity in all four systems when b5:P-450 molar ratio was low, i.e. 0.25 or 0.5. Both cytochrome b5 samples inhibited N-demethylase activity when b5:P-450 ratio exceeded 1:1 molar ratio. In contrast lung cytochrome b5 fraction 1 stimulated N-demethylase activity in all four systems. Maximal enhancement of the activity was obtained when b5:P-450 ratio was 0.5. The greatest increase in N-demethylation activity was observed in the reconstitution system with the lowest concentration of cytochrome P-450 reductase, conditions which most closely resemble intact microsomes.

Animals↗

PubMedDate not supplied

Study of benzphetamine-N-demethylase in streptozotocin-diabetic mice and rats: evidence for the induction of catalytically and immunologically specific forms of cytochrome P450.

Phenobarbital treatment and streptozotocin-diabetes both increase, in mouse and rat microsomes, a benzphetamine-N-demethylase activity which can be inhibited by a specific antibody raised against purified rat phenobarbital-induced cytochrome P-450. However, similar studies performed on cytochrome P-450 A and B fractions separated by DEAE-cellulose chromatography, clearly proved that streptozotocin-diabetes promotes in mice the synthesis of two new species of cytochrome P-450 and that the streptozotocin diabetes-induced forms are different in mouse and rat. No such modifications were observed in the mixed-function oxidase system of congenitally diabetic mice.

Animals↗

PubMed1985

Activities of benzphetamine N-demethylase and aryl hydrocarbon hydroxylase in cells isolated from gamma-glutamyl transpeptidase-positive foci and surrounding liver.

The levels of two cytochrome P-450-linked enzymes of xenobiotic metabolism, benzphetamine N-demethylase and aryl hydrocarbon hydroxylase, were determined in cells isolated from gamma-glutamyl transpeptidase (GGT)-positive foci and in cells from surrounding liver obtained from carcinogen-treated inbred F344 rats. Rat liver foci were initiated with diethylnitrosamine (CAS: 55-18-5) and promoted with sodium phenobarbital [(PB) CAS: 64038-21-7] for 4 1/2 or 12 months. The levels of both enzymes were relatively low in the GGT-positive hepatocytes, while the GGT-negative hepatocytes from the surrounding liver had elevated levels of both enzymes comparable to levels seen in rats treated with PB alone. After 12 months of promotion the PB was removed from the diet and the activities of both enzymes fell below the control levels in the GGT-positive hepatocytes and returned to the control levels in the surrounding GGT-negative hepatocytes. Therefore, the cells in the GGT-positive foci contained low levels of these two cytochrome P-450 enzymes in relation to the levels in GGT-negative cells. These levels were responsive to phenobarbital induction, although the induced levels in the GGT-positive cells were much lower than the induced levels in GGT-negative hepatocytes. The liver surrounding the foci responded to phenobarbital induction to the same degree as did the liver of noninitiated rats.

Animals↗

PubMed1986

The effect of chronic ozone exposure on lung benzo(a)pyrene oxidase, benzphetamine demethylase and monoamine oxidase.

Adult male Fischer 344 rats were exposed either to clean air or to a mixture of clean air and 0.5ppm ozone for up to one year. These populations were sampled after three and six months and when the exposure was completed. The activity of several oxidative enzymes in these rat lungs were compared. Although there was no significant increase in the ability of pulmonary microsomes to oxidize benzo[alpha]pyrene after three months of exposure to ozone, this activity and the oxidative demethylation of benzphetamine were increased after six months and a year of exposure. Aside from these enzymatic changes, electrophoretic analysis indicated that the microsomes from ozone exposed rats were enriched with a protein with an apparent molecular weight of 68,000. The activity of the two isoenzymic forms of monoamine oxidase, MAO A and MAO B, were also measured, and neither activity was affected by the ozone exposure.

Animals↗

PubMed1983

Effect of cadmium in vitro on benzphetamine-N-demethylation and ethoxyresorufin-O-deethylation in rats of different age.

The in vitro influence of CdSO4 on the liver microsomal benzphetamine-N-demethylation and ethoxyresorufin-O-deethylation activities in male Wistar rats/age 10, 30, 60 and 240 days/as well as the type of inhibition were studied after phenobarbital or beta-naphthoflavone pretreatment. Both reactions were inhibited by CdSO4 in dependence on concentration in all age groups. After phenobarbital pretreatment the inhibition of N-demethylation was slightly pronounced in 10-day old rats. In 10 and 30-days old rats the type of inhibition was competitive while in 60 and 240-days old rats a non-competitive type of inhibition was observed. O-deethylation of ethoxyresorufin was inhibited also in 10-day old rats, the inhibition type was non-competitive in all age groups. After beta-naphthoflavone pretreatment N-demethylation was inhibited competitively in all age groups. The inhibition of O-deethylation was more pronounced in 30-day old rats, in other age groups the inhibition was weak but concentration dependent. The type of inhibition was noncompetitive for all age groups studied.

Aging↗

PubMedDate not supplied