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Metabolism of alpha-naphthoflavone by rat, mouse, rabbit, and hamster liver microsomes
Abstract:
The metabolism of alpha-naphthoflavone (ANF) was studied in hepatic microsomes from rats, mice, rabbits, and hamsters, species in which ANF exerts its biological activities. The major metabolites produced by all species were ANF-5,6-oxide, ANF-6-phenol, and ANF-7,8-dihydrodiol. Minor metabolites produced by all species were ANF-5,6-dihydrodiol, ANF-7-phenol, and ANF-9-phenol. In general, the total rates of metabolism were similar within all species: 22-32 nmol ANF metabolized/15 min/mg protein. Mouse liver microsomes were approximately 1.7 to 2.9 times as active as the other species on a nanomole of cytochrome P-450 basis. The major sites of enzymatic oxidation were the 5,6 and 7,8 bonds of ANF where for all species, 49-71% and 15-46% of the total metabolism occurred, respectively.
Insights
Alpha-naphthoflavone (ANF) metabolism was studied in four species. Major metabolites and oxidation sites were identified, with mouse liver microsomes showing higher activity.
Area of Science:
- Pharmacology and Toxicology
- Drug Metabolism
- Enzymology
Background:
- Alpha-naphthoflavone (ANF) is a compound with known biological activities.
- Understanding its metabolic pathways is crucial for its application and safety.
- Hepatic microsomes are key sites for drug metabolism.
Purpose of the Study:
- To investigate and compare the metabolism of alpha-naphthoflavone (ANF) across different animal species.
- To identify the major and minor metabolites of ANF.
- To determine the primary sites of enzymatic oxidation on the ANF molecule.
Main Methods:
- Incubation of ANF with hepatic microsomes from rats, mice, rabbits, and hamsters.
- Analysis of metabolic products using biochemical assays.
- Quantification of metabolic rates and identification of metabolites.
- Enzyme kinetic studies, including cytochrome P-450 basis comparisons.
Main Results:
- The major metabolites identified across all species were ANF-5,6-oxide, ANF-6-phenol, and ANF-7,8-dihydrodiol.
- Minor metabolites included ANF-5,6-dihydrodiol, ANF-7-phenol, and ANF-9-phenol.
- Metabolism rates were generally similar across species (22-32 nmol ANF/15 min/mg protein), but mouse liver microsomes exhibited 1.7-2.9 times higher activity per nanomole of cytochrome P-450.
- The primary sites of oxidation were the 5,6 (49-71% of metabolism) and 7,8 (15-46% of metabolism) bonds of ANF.
Conclusions:
- ANF undergoes consistent metabolism across rats, mice, rabbits, and hamsters, yielding similar major and minor products.
- The 5,6 and 7,8 positions are the principal sites of ANF enzymatic oxidation.
- Mouse liver microsomes demonstrate significantly higher metabolic capacity for ANF compared to other species studied, particularly on a cytochrome P-450 basis.