HYDROCARBONS 353 



from the urine of rats and rabbits which had received anthracene. It is 

 not known as yet whether or not the anthraquinone is a true metabolic 

 product of the anthracene, or whether it was a contaminant present in 

 the anthracene administered. 



(6) Phenanihrene. Phenanthrene is an isomer of anthracene in which 

 no carbons separate the attachment of the two benzene groups to the 

 central ring, in contrast to the separation of these two rings by one carbon 

 in the case of anthracene. 



Phenanthrene 



However, little is known about the metabolism of phenanthrene, other 

 than that it yields a phenanthrol which is excreted as a strongly levorota- 

 tory glucuronide ([ajo = —35°).-^* Elson et al.-'" observed that, in rats, 

 a metabolic product (presumably a phenanthrol) results, which increases 

 the ethereal sulfate fraction of the urine. 



(c) Acenaphthene. Acenaphthene differs from anthracene and phen- 

 anthrene in that the third ring is a partially saturated five-carbon ring 

 which is similar to that present in such powerful carcinogenic agents as 

 cholanthrene and 20-methylcholanthrene. 



Chang and Young-" observed that, when acenaphthene was given orally 

 to rats, its five-carbon ring underwent fission, with the formation of naph- 

 thalic anhydride, which was eliminated in the urine. A similar metabolic 

 fate resulted when acenaphthene was given by subcutaneous injection.^*'* 

 Since naphthalic acid (naphthalene-l,8-dicarboxylic acid) is readily con- 

 vertible to its anhydride,-*" it is only reasonable to suppose that the acid 

 is an intermediate in the oxidation of acenaphthene. Young^^'' suggests 

 the possibility that the dicarboxylic acid is the true metabolic product 

 formed in these cases, and that the anhydride originates during its separa- 

 tion from the urine. 



2" P. Bergell and R. Pschorr, Z. physiol Chem., 38, 16-38 (1903). 



"9 L. H. Chang and L. Young, J. Bwl. Chem., 151, 87-91 (1943). 



"*« L. Young and A. R. Morrison, unpublished observations, 1949; cited by L. Young, 

 The Oxidation of Polycyclic Hydrocarbons in the Animal Body, in R. T. WilUams, Bio- 

 logical Oxidation of Aromatic Rings, Biochem. Soc. Symposia No. 5. Cambridge Univ. 

 Press, 27-39 (1950), p. 29. 



