Biotransformation of N-substituted aromatic compounds in mammalian spermatozoa. Nonoxidative formation of N-hydroxy-N-arylacetamides from nitroso aromatic compounds.
The metabolism of N-substituted aromatic compounds, i.e. aniline, acetanilide, N-hydroxyacetanilide, nitrosobenzene, and nitrobenzene in mammalian spermatozoa was investigated. In boar spermatozoa fortified with glucose, no acetylation, deacetylation, and monooxygenation of these compounds were found. Nitrobenzene was reduced slowly, but nitrosobenzene was a good substrate for this reductive activity. In the latter reaction, the products were N-hydroxyacetanilide, azoxybenzene, and an organic phase-nonextractable metabolite(s). Pyruvate was found to be involved in the formation of N-hydroxyacetanilide from nitrosobenzene, and the reaction occurred through a ping-pong mechanism. This enzymatic activity, located in the mid-piece fraction of spermatozoa, was enhanced by thiamine pyrophosphate and Mg2+ and inhibited by thiamine thiazolone pyrophosphate. N-Hydroxyacetanilide formed from [3(-13)C]pyruvate showed complete retention of the isotope at the methyl carbon of the molecule. 2-Nitrosofluorene and 4-nitrosobiphenyl were also transformed into the corresponding N-hydroxy-N-arylacetamides. N-Hydroxyacetanilide was also formed in rat and human spermatozoa. These facts suggest that the formation of N-hydroxy-N-arylacetamides from the nitroso aromatic compounds and pyruvate is mediated by a pyruvate dehydrogenase complex located in the mitochondria of spermatozoa. The formation of both azoxybenzene and the organic phase-nonextractable metabolite(s) was found to be a pyruvate-independent nonenzymatic reaction.
Yoshioka
T
T
Department of Chemical Hygiene, Hokkaido Institute of Pharmaceutical Sciences, Otaru, Japan.
Suzuki
T
T
Uematsu
T
T
D000588:Amines / Q000378:metabolism*; D000818:Animals; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D009603:Nitroso Compounds / Q000378:metabolism*; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity; D013094:Spermatozoa / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D013552:Swine
D000588:Amines; D009603:Nitroso Compounds; D011773:Pyruvates; D019289:Pyruvic Acid