No abstract

A bstmct: The metabolic conversion of biphenyl to phenolic metabolites was studied in the rat. The metabolites were identified by mass spectrometry and quantified by gas chromatography following conversion to their trimethylsilyl (TMS) ether\. The main route of excretion was via the urine, and the major part (22.3 %) of the biphenyl metabolites was excreted in the first 24 hrs. The total urinary recovery 96 hrs after administration was 29.5 % of the dose and the metabolites detected were conjugates of mono-, di-and tri-hydroxy derivatives o f biphenyl as well as the meta-and para-methyl ethers of the catecholic compounds. The two main urinary metabolites were 4-hydroxybiphenyl (7.7 76) and 4,4'-dihydroxybiphenyl (11.4 %). The experiments also showed that biphenyl has to be hydroxylated and then conjugated before it appears in the rat bile. Thus, 5.2 % of the dose was found in the 24 hrs bile as conjugates, mainly of 4-hydroxy-, 4,4'-dihydroxy-and 3,4,4'-trihydroxy-biphenyl. Faecal excretion of phenolic biphenyl derivatives was found to be of minor importance, but 4.7 70 of the dose was detected during the first 24 hrs after dosing. The following previously undetected metabolites of biphenyl were found: 3,4'dihydroxy-, 3,4,4'-trihydroxy-, 3,4'-dihydroxy-4-methoxyand 4,4'-dihydroxy-3rnethoxy-biphenyl. Kry-words:Biphenylmetabolismphenolsrat.Metabolic experiments with biphenyl in several laboratory animal species have revealed a series of phenolic metabolites. An early report by KLINGEN-BERG (1 89 1) indicated that biphenyl was converted into 4-hydroxybiphenyl in the dog. The same metabolic conversion has been demonstrated in the rabbit (STROUD 1940;BLOCK & CORNISH 1959).

The storage of blood alcohol samples was studied. The samples were analysed and then frozen and kept at — 20° for 6 months before reanalysis. The results from this reanalysis did not deviate to any significant extent from those originally obtained. The process of freezing and thawing the same samples before analysis was repeated three times without any significant difference from the results obtained with the fresh blood samples.

The degradation of Fast Red E, Amaranth, Ponceau 4R and Ponceau 6R in anaerobic incubates of rat caecal extract was studied by spectrophotometric scanning. The compounds underwent reduction of the azo linkage and thus loss of colour. The reaction rates seem to depend on the number rather than position of the sulphonate groups in the molecule.