Microbial flavoprotein monooxygenases as mimics of mammalian flavin-containing monooxygenases for the enantioselective preparation of drug metabolites

摘要

Mammalian flavin-containing monooxygenases are difficult to obtain and study while they play a major role in detoxifying various xenobiotics. In order to provide alternative biocatalytic tools to generate FMO-derived drug metabolites, a collection of microbial flavoprotein monooxygenases, sequence-related to human flavin-containing monooxygenases (FMOs), was tested for their ability to oxidize a set of xenobiotic compounds. For all tested xenobiotics (nicotine, lidocaine, 3-(methylthio)aniline, albendazole, and fenbendazole), one or more monooxygenases were identified capable of converting the target compound. Chiral LC-MS/MS analyses of the conversions of 3-(methylthio)aniline, albendazole and fenbendazole revealed that the respective sulfoxides are formed in good to excellent enantiomeric excess by several of the tested monooxygenases. Intriguingly, depending on the chosen microbial monooxygenase, either the (R)- or (S)-sulfoxide was formed. For example, when using a monooxygenase from Rhodococcus jostii the (S)-sulfoxide of albendazole (ricobendazole) was obtained with an e.e. of 95%, while a fungal monooxygenase yielded the respective (R)-sulfoxide in 57% e.e. For nicotine and lidocaine, monooxygenases could be identified that convert the amines into their respective N-oxides. This study shows that recombinantly expressed microbial monooxygenases represent a valuable toolbox of mammalian FMO mimics that can be exploited for the production of FMO-associated xenobiotic metabolites.