This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Prough, R. A. Articles by Estabrook, R. W. Search for Related Content PubMed PubMed Citation Articles by Prough, R. A. Articles by Estabrook, R. W.

The Direct Spectrophotometric Observation of Benzo(a)pyrene Phenol Formation by Liver Microsomes¹

Department of Biochemistry and the Cancer Center, The University of Texas Health Science Center at Dallas, Dallas, Texas 75235

Optical spectral repetitive scan analysis during the oxidative metabolism of benzo(a)pyrene by liver microsomal suspensions reveals the time-dependent formation of an intermediate(s) of which the visible spectra resemble those of several benzo(a)pyrene phenols. Liver microsomes from 3-methylcholanthrene-treated rats showed a greater rate of formation of the phenols than did microsomes from control animals; the rate of formation catalyzed by liver microsomes from phenobarbital-pretreated rats was intermediate. When 3-hydroxybenzo(a)pyrene was used as a standard for comparison of activity, the rates of formation of phenols were compared when measured by fluorometric, spectrophotometric, or high-pressure liquid chromatographic analytical techniques. An epoxide hydrase inhibitor, 1,1,1-trichloropropene-2,3-oxide, enhanced phenol formation regardless of the source of liver microsomes, and 7,8-benzoflavone inhibited control and 3-methylcholanthrene-induced microsomal metabolism of benzo(a)pyrene. 7,8-Benzoflavone did not effect benzo(a)pyrene metabolism by liver microsomes from phenobarbital-pretreated rats. The effect of inhibitors on the spectrophotometric assay correlates well with the results obtained from benzo(a)pyrene metabolite analysis using high-pressure liquid chromatography.

¹ Supported in part by National Cancer Institute Contract NO1-CP-33362, USPHS Young Investigators Pulmonary Research Grant HL 17134, and National Cancer Institute Specialized Cancer Center Grant CA 17065. A preliminary report was made at the 1976 Miami Winter Symposium, Papanicolaou Cancer Research Institute, Miami, Florida, January 12 to 16, 1976.

Received 6/21/76. Accepted 8/26/76.