Alginic acid is a suitable material for modification to prepare new derivatives because of presence of its carboxyl groups. The high content of carboxyl groups over the entire length of its chain renders it an easily modifiable material with a possibility of achieving a high degree of substitution in the prepared derivatives. The salt of alginic acid (sodium alginate) is readily commercially available and is widely used in many branches of chemistry. Alginic acid was thus selected as the substrate for amidation. The amidation used two-steps: methyl esterification followed by amino-de-alkoxylation. The aim of this study was to prepare highly substituted derivatives with different polysaccharide chain characteristics. As such, the alginic acid was modified by the two-step amidation based on the esterification of the alginic acid carboxyl groups by reaction with methanol and further amino-de-alkoxylation (aminolysis) of the obtained methyl ester with amidation reagents (n-alkylamines, hydrazine and hydroxylamine). The purity and substitution degree of the prepared derivatives were monitored by vibration spectroscopic methods (FTIR and FT Raman) and organic elemental analysis. These analytical methods confirmed the preparation of highly or moderately substituted N-alkylamides, hydrazide and hydroxamic acid of alginic acid.
OBJECTIVES: N-(2-methoxyphenyl)hydroxylamine is a human metabolite of two industrial and environmental pollutants and bladder carcinogens 2-methoxyaniline (o-anisidine) and 2-methoxynitrobenzene (o-nitroanisole). Metabolism of N-(2-methoxyphenyl)hydroxylamine by rat hepatic microsomes and identification of the major microsomal enzymes participating in this process are aims of this study. METHODS: HPLC with UV detection was employed for the separation of N-(2-methoxyphenyl)hydroxylamine metabolites. Inducers and inhibitors of microsomal enzymes and rat recombinant CYPs were used to characterize the enzymes participating in N-(2-methoxyphenyl)hydroxylamine metabolism. RESULTS: N-(2-methoxyphenyl)hydroxylamine is metabolized by rat hepatic microsomes predominantly to o-anisidine, the parent carcinogen from which N-(2-methoxyphenyl)hydroxylamine is formed, while o-aminophenol and two N-(2-methoxyphenyl)hydroxylamine metabolites, whose exact structures have not been identified as yet, are minor products. Selective inhibitors of microsomal CYPs, NADPH:CYP reductase and NADH:cytochrome b5 reductase and hepatic microsomes of rats pre-treated with specific inducers of CYPs and NADPH:CYP reductase were used to characterize rat liver microsomal enzymes reducing N-(2-methoxyphenyl)hydroxylamine to o-anisidine. Based on these studies, we attribute most of N-(2-methoxyphenyl)hydroxylamine metabolism to o-anisidine in rat liver to CYP2C, followed by CYP2E1, 2D and 2A. Among recombinant rat CYP enzymes tested in this study, rat CYP2C11 and 2E1, followed by CYP2A2, 2D1/2, 2C12, 3A1/2 and 1A1/2 were the most efficient enzymes metabolizing N-(2-methoxyphenyl)hydroxylamine to o-anisidine. CONCLUSION: The results found in this study, the first report on the reduction of N-(2-methoxyphenyl)hydroxylamine by rat CYP enzymes, demonstrate that CYP2C, followed by CYP2E1, 2D and 2A are the major enzymes participating in this process in rat liver.
- MeSH
- aniliny metabolismus MeSH
- anisoly metabolismus MeSH
- aromatické hydroxylasy fyziologie MeSH
- cytochrom P-450 CYP2E1 fyziologie MeSH
- hydroxylamin metabolismus MeSH
- jaterní mikrozomy metabolismus MeSH
- karcinogeny metabolismus MeSH
- krysa rodu rattus MeSH
- látky znečišťující životní prostředí metabolismus MeSH
- modely u zvířat MeSH
- oxidace-redukce MeSH
- potkani Wistar MeSH
- steroidhydroxylasy fyziologie MeSH
- systém (enzymů) cytochromů P-450 fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- hydroxylamin aplikace a dávkování terapeutické užití MeSH
- nedostatek vitaminu B12 diagnóza komplikace terapie MeSH
- plošný screening metody MeSH
- příznaky a symptomy MeSH
- vitamin B 12 aplikace a dávkování fyziologie krev MeSH
- způsoby aplikace léků MeSH
- Publikační typ
- přehledy MeSH
- Geografické názvy
- Spojené státy americké MeSH
