A NEW SENSITIVE FLUOROMETRIC ASSAY FOR THE METABOLISM OF (-)-7,8-DIHYDROXY-7,8-DIHYDROBENZO[A]PYRENE BY HUMAN HAIR-FOLLICLES

A new sensitive fluorometric assay was established to measure the stereospecific formation of benzo[a]pyrene tetrols formed after cytochrome P450-dependent metabolism of (-)-7,8-dihydroxy-7,8-dihydrobenzo[a]pryene by human hair follicles. This simple assay requires three human hair follicles and a low (0.5-2.0 mu-M) substrate concentration and has a limit of detection of approximately 0.3 fmol of tetrols. Freshly isolated human hair follicles from 20 adult volunteers (10 non-smokers and 10 smokers) were assayed. While intersubject and seasonal variations were observed, the assay was found to be reproducible for a given subject. This rapid and non-invasive assay provides a new means for metabolic phenotyping of human subjects for their capacity to metabolize (-)-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene to its carcinogenic form (+)anti-benzo[a]pyrene diolepoxide.