Metabolism of surfactants sodium undecyltriethoxy sulphate and sodium dodecyltriethoxy sulphate in the rat

Abstract

The metabolic fates of the synthetic surfactants, sodium [1-14C]undecyltriethoxy sulphate and sodium [1-14C]dodecyltriethoxy sulphate were studied in the rat. Both compounds were extensively metabolized regardless of the route of administration, oral, intraperitoneal or intravenous. Short-chain radioactive products were eliminated in the urine: the major metabolite of the dodecyl homologue in the urine was identified as −O2C14CH2- (OC2H4)3OSO3− by n.m.r. and g.l.c.–mass spectrometry, whereas the major metabolite of the undecyl homologue in the urine was tentatively identified as −O2CCH214CH2- (OC2H4)3OSO3−. In contrast with experiments with the dodecyl derivative, when [1-14C]undecyltriethoxy sulphate was administered to rats, appreciable amounts of radioactivity were recovered as 14CO2 in expired air. Whole-body radioautography implicated the liver as the major site of metabolism of both surfactants. The nature of the metabolic products establishes that both compounds are degraded by ω,β-oxidation. Cleavage of the ether linkage proximal to the sulphate moiety may account for the small amounts of 14CO2 recovered in expired air after the administration of [1-14C]dodecyltriethoxy sulphate. It is suggested the substantial amounts of 14CO2 recovered after [1-14C]-undecyltriethoxy sulphate administration originate from −O214C(OC2H4)3 OSO3−, an unstable product of ω,β-oxidation. An n.m.r. spectrum of the metabolite identified as 2-(triethoxy sulphate)acetic acid and a mass spectrum of the trimethylsilyl derivative of the parent alcohol of that metabolite have been deposited as Supplementary Publication SUP50086 (5 pages) at the British Library Lending Division, Boston Spa, Wetherby, West Yorkshire LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1978) 169, 5.