Biotransformation of deoxypodophyllotoxin to epipodophyllotoxin by three major human hepatic enzymes, CYP1A2, CYP2C9 and CYP3A4, heterologously expressed in E coli DH5 alpha, was investigated. It was shown that CYP3A4 catalysed the hydroxylation of deoxypodophyllotoxin into epipodophyllotoxin in yields up to 90%. The structure of the metabolite was determined using HPLC-MS and HPLC-SPE-NMR. techniques. There was no detectable production of epipodophyllotoxin or podophyllotoxin by CYP1A2 and CYP2C9 enzymes. The CYP3A4 enzyme shows a distinctly different reactivity to deoxypodophyllotoxin compared to the semi-synthetic derivatives etoposide and teniposide, which are degraded by 3-O-demethylation. These findings demonstrate a novel system for the production of 2,7'-cyclolignans, starting from the easily accessible deoxypodophyllotoxin. (c) 2006 Elsevier B.V. All rights reserved.
- cytochrome p450