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Administrative data

Link to relevant study record(s)

Description of key information

There is no specific study on DIPB, but there are data on cumene (isopropylbenzene) as well on diethyl benezene, which are close related compounds and which metabolised by alkyl chain hydroxylation; leading to corresponding alcohol metabolites.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

According to CICAD (2005)

Cumene (CAS no. 98-82-8; C9H12; 2-phenylpropane, isopropylbenzene, (1-methylethyl)-benzene) : Metabolism of cumene by cytochrome P-450 is extensive and takes place within hepatic and extrahepatic tissues, including lung (Sato & Nakajima, 1987), with the secondary alcohol 2-phenyl-2-propanol being a principal metabolite. Metabolites excreted in urine of rats and rabbits include 2-phenyl-2-propanol and its glucuronide or sulfate conjugates, conjugates of 2-phenyl-1,2-propanediol, and an unknown metabolite, possibly the dicarboxylic acid that would result from complete oxidation of the 1- and 3-alkyl carbons of phenylmalonic acid (Research Triangle Institute, 1989; Ishida & Matsumoto, 1992; MAK, 1996). According to SIDS INITIAL ASSESSMENT PROFILE CAS No. 105-05-5 Chemical Name Benzene, 1,4-diethyl-: Drug Metab Dispos. 2001 Jun;29(6):868-76. Abstract In a previous study, it was shown that the neurotoxic compound 1,2-diethylbenzene (1,2-DEB) is mainly hydroxylated in the alkyl chain to give 1-(2'-ethylphenyl)ethanol (1,2-EPE) and excreted in urine of rats as two glucuronide compounds (GA1 and GA2). Some findings have suggested that the two enantiomers of 1,2-EPE are formed in vivo. In the present study, a chiral high-performance liquid chromatography method was developed to separate the two enantiomers of 1,2-EPE from a synthesized racemic mixture. Absolute configuration of both enantiomers was determined after esterification with (R)-(+)-alpha-methoxy-alpha-(trifluoromethyl)phenylacetic acid and analysis of their (1)H NMR spectra in CCl(4) added with Eu (fod)(3). The two main urinary metabolites, GA1 and GA2, from [(14)C]1,2-DEB-treated Sprague-Dawley rats (80 mg/kg, i.p.) were identified, after hydrolysis with beta-glucuronidase from Escherichia coli, as (R) and (S) glucuronide conjugates of 1,2-EPE, respectively. In vitro hydroxylation of 1,2-DEB and glucuroconjugation of 1,2-EPE were under stereoselective control in S9 fraction or microsomes from male Sprague-Dawley rat liver. The V(max) and K(m) constants for (R)1,2-EPE enantiomer formation determined in S9 fraction were greater than those for the (S) enantiomer. In the plasma of bile duct-cannulated rats, the ratio was 1.2 +/- 0.02 over the 1- to 4-h period after oral administration of [(14)C]1,2-DEB (100 mg/kg). In contrast, the glucuroconjugation rate of (S)1,2-DEB enantiomer was 4 times that of (R)1,2-EPE glucuroconjugation. A similar ratio of (R) to (S)1,2-EPE glucuronide conjugates was obtained in the plasma of bile duct-cannulated rats.