Formation of dimethyl selenide and trimethylselenonium from selenobetaine in the rat
The 24-h respiratory excretion of dimethyl selenide (DMSe) and urinary excretion of trimethylselenonium (TMSe) were studied in adult male rats injected with 2 mg Se/kg as selenobetaine ((CH/sub 3/)2Se+CH/sub 2/COOH) or its methyl ester, labeled with /sup 75/Se and /sup 14/C. The DMSe was trapped by means of 20% benzyl chloride in xylene. TMSe was measured by cation exchange high performance liquid chromatography. There was extensive respiratory excretion of DMSe from selenobetaine methyl ester (about 50% of the dose) and from selenobetaine (about 25%). About 12% of the dose was converted to TMSe for both compounds. When the Se-methyl carbons were labeled with /sup 14/C and the selenium with /sup 75/Se, doubly labeled DMSe and TMSe were formed; the /sup 14/C//sup 75/Se ratio in DMSe formed from selenobetaine methyl ester was almost unchanged from that administered, and the ratio in TMSe was only slightly lower than in DMSe. In contrast to its ester, doubly labeled selenobetaine yielded DMSe having a lower /sup 14/C//sup 75/Se ratio (approximately one-half of that administered) and a further decrease was observed between DMSe and TMSe. These data indicate that the (CH3)2Se moiety in selenobetaine methyl ester undergoes facile release to form DMSe, which is directly methylated to form TMSe. Selenobetaine, however, appears to lose a methyl group prior to scission of the Se-CH2COOH bond. The results with selenobetaine also suggest that TMSe generated metabolically is not inert, and can undergo demethylation followed by remethylation; confirmatory evidence for this metabolic instability is provided by the exhalation of (/sup 75/Se)DMSe after the direct administration of (/sup 75/Se)TMSe. When (/sup 75/Se)selenobetaine or its ester was given with the methylene carbon in the acetic acid molabeled with /sup 14/C, only /sup 75/Se was present in the DMSe and TMSe.
- Research Organization:
- Univ. of Wisconsin, Madison
- OSTI ID:
- 5623156
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 1
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
SELENIDES
EXCRETION
METABOLISM
BETAINE
CARBON 14
DECARBOXYLATION
DOUBLE LABELLING
ION EXCHANGE CHROMATOGRAPHY
ISOTOPE RATIO
METHYLATION
ORGANOMETALLIC COMPOUNDS
RATS
SELENIUM 75
AMINES
AMINO ACIDS
AMMONIUM COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBON ISOTOPES
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMATOGRAPHY
CLEARANCE
DAYS LIVING RADIOISOTOPES
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
EVEN-EVEN NUCLEI
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
ISOTOPES
LABELLING
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
QUATERNARY COMPOUNDS
RADIOISOTOPES
RODENTS
SELENIUM COMPOUNDS
SELENIUM ISOTOPES
SEPARATION PROCESSES
VERTEBRATES
YEARS LIVING RADIOISOTOPES
550501* - Metabolism- Tracer Techniques