IN VITRO METABOLIC FATE OF N-SUBSTITUTED DIBENZYLAMINES : INVESTIGATION OF BIOLOGICAL OXIDATION SITE ON NITROGEN COMPOUNDS WITH DIFFERENT pKa

The in vitro rnicrosomal metabolism of four model tertiary amines ie. Nethyldibenzylamine (EDBA), tribenzylamine (TBA), N,N-dibenzylaniline(DBAN) and N,N-dibenzylbenzarnide (BZDBA) was studied to establish whetherthe corresponding N- and C-oxidation products such as the correspondingarnides, dealkylation products, N-oxides and phenols formed. These compoundswere selected as substrates to establish the effect of the varying pK, and logPcharacteristics on their iiz vitro metabolism. The substrates and their potentialmetabolites were synthesized and then separated using HPLC. Incubations wereperformed using rat microsomal preparations fortified with NADPH. The substrates and their potential metabolites were extracted into dichloromethane and examined by HPLC. Results from HPLC analysis indicated that all these substrates failed to produce the corresponding amides as metabolites. However, the dealkylation metabolites were observed with all the substrates used as major metabolites.The substrates EDBA and TBA produced the corresponding N-oxidemetabolites: Three phenolic. metabolites of DBAN were also demonstrated.These findings support the concept that nitrones are essential metabolic intermediates for the formation of arnides and this reaction reguees,a secondary mine as substrate. In addition, the metabolic N-oxidation of these substrates depends on the pKa of the constituent nitrogen of the molecule.Key words :Tertiary amines, in vitro metabolism, the effect of pKa.

Anahtar Kelimeler:

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IN VITRO METABOLIC FATE OF N-SUBSTITUTED DIBENZYLAMINES : INVESTIGATION OF BIOLOGICAL OXIDATION SITE ON NITROGEN COMPOUNDS WITH DIFFERENT pKa

The in vitro rnicrosomal metabolism of four model tertiary amines ie. Nethyldibenzylamine (EDBA), tribenzylamine (TBA), N,N-dibenzylaniline (DBAN) and N,N-dibenzylbenzarnide (BZDBA) was studied to establish whether the corresponding N- and C-oxidation products such as the corresponding arnides, dealkylation products, N-oxides and phenols formed. These compounds were selected as substrates to establish the effect of the varying pK, and logP characteristics on their iiz vitro metabolism. The substrates and their potential metabolites were synthesized and then separated using HPLC. Incubations were performed using rat microsomal preparations fortified with NADPH. The substrates and their potential metabolites were extracted into dichloromethane and examined by HPLC. Results from HPLC analysis indicated that all these substrates failed to produce the corresponding amides as metabolites. However, the dealkylation metabolites were observed with all the substrates used as major metabolites. The substrates EDBA and TBA produced the corresponding N-oxide metabolites: Three phenolic. metabolites of DBAN were also demonstrated. These findings support the concept that nitrones are essential metabolic intermediates for the formation of arnides and this reaction reguees,a secondary mine as substrate. ~n.addition, the metabolic N-oxidation of these substrates depends on the pKa of the constituent nitrogen of the molecule.

Keywords:

Tertiary amine, in vitl-o metabolism the effect of pK,

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