In vitro microsomal [correction of mircosomal] metabolism of N-benzyl and N-benzoylnornicotine derivates by rat.

The in vitro hepatic microsomal metabolism of N-1'-benzylnornicotine, N-l'-(p-chlorobenzyl)nornicotine, N-1'-benzoylnornicotine and N-1'-(p-chlorobenzoyl) nornicotine was studied using hepatic washed rat microsomal preparations fortified with NADPH. Substrates and their potential metabolites were synthesized, characterised by spectral methods, and separated using a reverse phase HPLC system consisted of a C18 column and a mobile phase composition of acetonitrile: phosphate buffer. Substrates and their potential metabolites were extracted from biological systems with dichloromethane.

Molecular orbital calculations and nicotine metabolism: a rationale for experimentally observed metabolite ratios.

The results of molecular orbital calculations and molecular modelling studies on nicotine are reported. It is shown that the product ratio of nicotine metabolism can be directly related to HOMO electron densities on the relevant hydrogen atoms associated with oxidation sites in S-nicotine. In addition, molecular modelling of nicotine within the putative active site of CYP2A6, the enzyme most closely associated with nicotine metabolism, indicates that the substrate is orientated for oxidation at the 5'-position via a combination of hydrogen bonding and pi-pi stacking interactions.

Studies on the in vitro hepatic microsomal formation of amides during the metabolism of certain secondary and tertiary benzylic amines.

Part of our interest during the last few years has been to investigate the possible intermediate(s) and mechanism(s) involved in the formation of amides from N-benzylic amines. A number of benzylic amines with different aryl and alkyl moieties introduced onto the constituent nitrogen were prepared, thus creating a wide variety of secondary, tertiary and heterocyclic benzylic amines with different logP and pKa characteristics (Tables I & II). In some experiments, the possible intermediates of this reaction, i.

Evidence for the biosynthesis of A glucuronide conjugate of (S)-(-)-nicotine, but not (S)-(-)-cotinine or (+/-)-trans-3'-hydroxycotinine by marmoset hepatic microsomes.

Recently, the detection of urinary glucuronide conjugates of nicotine and its two major metabolites, trans-3'-hydroxycotinine and cotinine, showed that glucuronidation is an important pathway of nicotine metabolism in humans. (S)-(-)-Nicotine-N(+)-1-beta-glucuronide (quaternary N-glucuronide with linkage through the pyridino-nitrogen of nicotine) was shown to be an important nicotine metabolite of humans in vivo. The present study was undertaken to develop an animal model for this process, in order to ascertain the factors influencing quaternary N-glucuronide formation.

Comparison of metabolic rates of some 9-aralkyladenines obtained using hamster hepatic microsomes.

Previous investigations have revealed that N1-oxidation is a major metabolic pathway in vitro for some 9-aralkyladenines (AAs) such as 9-benzyladenine (BA). However, dealkylation and other metabolic pathways are also involved. In addition, various substituents on the benzyl moiety of BA seem to have a marked effect on the metabolic rate.

Induction and inhibition of the in vitro N1-oxidation of 9-benzyladenine and isomeric 9-(nitrobenzyl)adenines.

The present study investigated some aspects of the enzymology of the in vitro N1-oxidation of 9-benzyladenine (BA) and isomeric 9-(nitrobenzyl)adenines (NBAs) using various potential inducers and inhibitors of cytochrome P-450 (CYP). When incubated with phenobarbital-induced rabbit hepatic microsomes, the N1-oxidation rates of BA and 9-(4-nitrobenzyl)adenine were about 6- and 2-fold higher than that of the control, respectively; while the N1-oxidation of 9-(2-nitrobenzyl)adenine and 9-(3-nitrobenzyl)adenine was not markedly affected. In contrast, beta-naphthoflavone and Arochlor 1254 showed no inductive effects towards the N1-oxidation of any of these substrates.

The in vitro hepatic microsomal metabolism of N-benzyladamantanamine in rats.

The metabolism of N-benzyladamantanamine (NBAD) was studied in vitro using rat hepatic microsomal preparations. The substrate and proposed metabolites were synthesized and characterized using spectroscopic techniques and separated using a reverse phase HPLC system. NBAD was incubated with rat microsomal preparations, extracted into DCM in the presence of NaCl and evaporated under a stream of nitrogen.

In vitro metabolism of (S)-(-)-[2'-14C]nicotine, using various tissue preparations of marmoset.

The nicotine metabolite profile produced by marmoset liver, lung and kidney preparations was investigated after 30 minutes incubation of (S)-(-)-[2'-14C]nicotine. Cation-exchange high performance liquid radiochromatography was employed to separate and quantify nicotine and its metabolites. Cotinine-N-oxide (CNO, 0.

Effects of cAMP-dependent protein kinase and ATP on N1-oxidation of 9-benzyladenine by animal hepatic microsomes.

N1-Oxidation is a major metabolic pathway for 9-benzyladenine (BA) catalyzed by the cytochrome P450 system in animal hepatic microsomes. After normal hamster hepatic microsomes or phenobarbital induced rabbit hepatic microsomes were preincubated in the presence of cyclic AMP-dependent protein kinase catalytic subunit (PKA), MgCl2 and ATP, BA-N1-oxidation was significantly decreased. However, further investigation indicated that the decrease of BA-N1-oxidation seemed to be a combination of the effects of PKA and ATP, as ATP alone showed a biphasic regulatory effect on BA-N1-oxidation when microsomes were preincubated in the presence of various concentrations of ATP.

Effect of the nicotine metabolite 5'-hydroxycotinine on glucose transport and glycogen synthase activity in rat skeletal muscle.

Cigarette smoke contains many potentially harmful substances, including nicotine and nicotine metabolites, which are likely to contribute to altered glucose homeostasis. We determined the effects of nicotine and nicotine derivatives on glucose transport in skeletal muscle. Split rat soleus muscles were pre-incubated in the presence of nicotine (range 0.

In vitro hepatic microsomal metabolism of N-benzyl-N-methylaniline.

In the present study, the in vitro microsomal metabolism of a tertiary aniline, N-benzyl-N-methylaniline (NBNMA) was studied to determine whether this compound produces an amide derivative (benzoyl) together with N-dealkylation and C- and N-oxidation products as metabolites. The preparations of the corresponding potential metabolites were undertaken and were separated using TLC and HPLC. Incubations were performed using rat microsomal preparations fortified with NADPH.

Metabolism, pharmacogenetics, and metabolic drug-drug interactions of antipsychotic drugs.

1. Antipsychotic drugs are extensively metabolised by cytochrome P450 (CYP) enzymes. 2.

Metabolism of (-)-(S)-nicotine in the isolated perfused rabbit lung.

The metabolism of (-)-(S)-nicotine has been investigated following intratracheal administration to the recirculating perfused rabbit lung model. The metabolic products present in the perfusate were identified by co-chromatography (HPLC and GC) with authentic standards and quantified by HPLC. After the 180 min perfusion period, nicotine was found to be metabolically transformed to cotinine (33.

Metabolism of (-)-(S)-nicotine by guinea pig and rat brain: identification of cotinine.

Since the brain is the major site of pharmacological activity of nicotine, it was of interest to investigate the metabolism of nicotine by this organ. We now report our findings using guinea pig and rat brain as the enzyme source. Whole brains were removed and washed with isotonic KCl, blotted dry and cut into small pieces.

The in vitro metabolism of norcotinine and related biotransformation products by microsomal preparations.

Since norcotinine and 4-(3-pyridyl)-4-oxobutyramide (POBAM) are probable metabolites of nicotine and cotinine, it was of interest to investigate the further in vitro metabolism of these compounds. We now report our preliminary findings using rat microsomal preparations (induced and/or non-induced with phenobarbitone) fortified with NADPH. Following norcotinine metabolism, two compounds, i.

Studies on the relationship between in vitro metabolism and certain physicochemical characteristics of some 9-alkyl-/9-aralkyl adenines.

Previous studies demonstrated that biological N1-oxidation occurred for some 9-alkyl-/9-aralkyladenines, but not for others, when mammalian hepatic microsomal incubates were used as enzyme source. In order to understand the mechanisms controlling the metabolic fate of these compounds, the relationship between N1-oxidation and certain physicochemical characteristics of these substrates was studied. It was found that there was no marked link between N1-oxidation and the computer predicted pKa values of the substances studied.

Metabolism of 9-(2-chlorobenzyl)-, 9-(2-methylbenzyl)- and 9-(2-methoxybenzyl)-adenines by hamster hepatic microsomes.

It was previously found that 9-benzyladenine (BA) was extensively N1-oxidised by animal hepatic microsomes; further, mononitrosubstitution in the phenyl moiety of BA significantly modified the N1-oxidation rates of the corresponding substrates. In order to establish whether the electronic nature or a steric effect of the substituents in the phenyl moiety is the reason for the modification of N1-oxidation rate, the metabolism of some 2'-substituted 9-benzyladenines, i.e.

In vitro microsomal metabolism of nuclear chloro substituted secondary amines and imines.

The metabolism of N-(4-chlorobenzyl)-4-chloroaniline (CBCA), N-(4-chlorobenzyl)-4-chlorobenzylamine (CBCBA), and N-(4-chlorobenzylidene)-4-chlorobenzylamine (CBDCBA) were studied in vitro using rat liver microsomal preparations. The secondary amines produced the corresponding N-oxidation products (hydroxylamines and nitrones) and dealkylation products (4-chlorobenzaldehyde and primary amines). Both secondary amines failed to produce the corresponding amides, whilst the parent imine was detected as a metabonate.

In vitro metabolic N- and C-oxidation of phenanthridine.

The in vitro microsomal metabolism of phenanthridine has been studied to establish as to whether phenanthridine produces the corresponding N-oxide and lactam as metabolites and the mechanism involved. We now report our preliminary findings using rat hepatic microsomal preparations (control and induced with phenobarbitone) fortified with NADPH. The potential metabolite, phenanthridine-N-oxide, was prepared by m-CPBA oxidation of substrate; the lactam was commercially available.

Comutagenesis--V: rapid conversion of 2-hydroxyl-amino-3-methylpyridineto 2-amino-3-methylpyridine by a hepatic S9 preparation.

The in vitro metabolism of 2-hydroxylamino-3-methylpyridine has been investigated using arochlor 1254 pretreated rat S9 mixtures. 2-Hydroxylamino-3-methylpyridine is rapidly converted to the parent amine 2-amino-3-methylpyridine. No further oxidation products of 2-hydroxylamino-3-methylpyridine (i.

Comutagenesis-IV in vitro metabolism of the comutagen 2-amino-3-methylpyridine: species differences and metabolic interaction with norharman.

The metabolism of 2-amino-3-methylpyridine (2A3MP) in vitro has been investigated using the rat, rabbit, dog, marmoset, guinea pig and hamster hepatic microsomes and S9 supernatants (10,000 g fraction). Species differences were observed in the in vitro formation of 2-amino-3-methylpyridine-N-oxide (2A3MPNO), 2-amino-3-hydroxymethylpyridine (2A3HMP) and 2-amino-3-methyl-5-hydroxypyridine (2A3M5HP). The order of activity for 2A3MPNO using hepatic microsomes was dog > rat > rabbit > guinea pig > marmoset > hamster, for 2A3HMP dog > hamster > guinea pig > rat > rabbit > marmoset, for 2A3M5HP rabbit > hamster > dog > rat > guinea pig > marmoset.

In vitro microsomal metabolic studies on secondary aromatic amides.

Previous studies showed that amides are metabolites arising from certain secondary aromatic amines. However, some analogue amines did not lead to the formation of the corresponding amides when metabolised under identical conditions. We, therefore, wished to establish the factors preventing detection of amides.

Comutagenesis-III. In vitro metabolism of 2-amino-3-methylpyridine: the effect of various potential inhibitors, activators and inducers.

1. The effects of various potential inhibitors, activators and inducers on the metabolism of the comutagen 2-amino-3-methylpyridine (2A3MP) by rabbit hepatic microsomes and S9 supernatants have been studied. 2.

Comutagenesis-I: the in vitro metabolism of 2-amino-3-methylpyridine.

The metabolism of the comutagen 2-amino-3-methylpyridine has been studied in vitro using rat and rabbit hepatic preparations. 2-Amino-3-methylpyridine-N-oxide, 2-amino-3-hydroxymethylpyridine and 2-amino-5-hydroxy-3-methylpyridine were formed by both rat and rabbit hepatic preparations. No evidence was obtained for the formation of the corresponding 2-hydroxylamine, 2-nitroso, 2-nitro-3-methyl-pyridine or their condensation products i.

Solid phase extraction and HPLC determination of 9-benzyladenine and isomeric 9-(nitrobenzyl)adenines and their metabolic N1-oxides present in microsomal incubates.

9-Benzyladenine, 9-(2-nitrobenzyl)adenine, 9-(3-nitrobenzyl)adenine and 9-(4-nitrobenzyl)adenine were metabolized to 9-benzyladenine-N1-oxide, 9-(2-nitrobenzyl)adenine-n1-oxide, 9-(3-nitrobenzyl)adenine-N1-oxide and 9-(4-nitrobenzyl)adenine-N1-oxide, respectively, by animal hepatic microsomes. For the quantitative determination of the substrates and metabolites present in microsomal incubates, an off-line solid phase extraction procedure, using columns paced with C18 silica bonded phase, was developed. The extraction recovery for these 9-alkyladenines and their N1-oxides was in the range of 92-101%.