title: Biotransformation of prednisone and dexamethasone by cytochrome P450 based systems - Identification of new potential drug candidates.
abstract: Prednisone and dexamethasone are synthetic glucocorticoids widely used as anti-inflammatory and immunosuppressive drugs. Since their hydroxylated derivatives could serve as novel potential drug candidates, our aim was to investigate their biotransformation by the steroid hydroxylase CYP106A2 from Bacillus megaterium ATCC13368. In vitro we were able to demonstrate highly selective 15β-hydroxylation of the steroids with a reconstituted CYP106A2 system. The reactions were thoroughly characterized, determining the kinetic parameters and the equilibrium dissociation constant. The observed lower conversion rate in the case of dexamethasone hydroxylation was clarified by quantum chemical calculations, which suggest a rearrangement of the intermediately formed radical species. To identify the obtained conversion products with NMR, CYP106A2-based Bacillus megaterium whole-cell systems were applied resulting in an altered product pattern for prednisone, yet no significant change for dexamethasone conversion compared to in vitro. Even the MS941 control strain performed a highly selective biotransformation of prednisone producing the known metabolite 20β-dihydrocortisone. The identified novel prednisone derivatives 15β, 17, 20β, 21-tetrahydroxy-preg-4-en-3,11-dione and 15β, 17, 20β, 21-tetrahydroxy-preg-1,4-dien-3,11-dione as well as the 15β-hydroxylated variants of both drugs are promising candidates for drug-design and development approaches.
authors.affiliation: Institute of Biochemistry, Saarland University, D-66123 Saarbruecken, Germany.
authors.forename: Natalia
authors.initials: N
authors.lastname: Putkaradze
authors.affiliation: Institute of Biochemistry, Saarland University, D-66123 Saarbruecken, Germany.
authors.forename: Flora Marta
authors.initials: FM
authors.lastname: Kiss
authors.affiliation: Institute of Biochemistry, Saarland University, D-66123 Saarbruecken, Germany.
authors.forename: Daniela
authors.initials: D
authors.lastname: Schmitz
authors.affiliation: Institute of Pharmaceutical Biology, Saarland University, D-66123 Saarbruecken, Germany.
authors.forename: Josef
authors.initials: J
authors.lastname: Zapp
authors.affiliation: Center for Bioinformatics, Saarland University, D-66123 Saarbruecken, Germany.
authors.forename: Michael C
authors.initials: MC
authors.lastname: Hutter
authors.affiliation: Institute of Biochemistry, Saarland University, D-66123 Saarbruecken, Germany. Electronic address: ritabern@mx.uni-saarland.de.
authors.forename: Rita
authors.initials: R
authors.lastname: Bernhardt
mesh_terms: D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D001410:Bacillus megaterium / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001711:Biotransformation; D003348:Cortisone / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D003907:Dexamethasone / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology; D004789:Enzyme Activation; D007166:Immunosuppressive Agents / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D062105:Molecular Docking Simulation; D010084:Oxidation-Reduction; D011241:Prednisone / Q000737:chemistry / Q000493:pharmacokinetics* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000096:biosynthesis
chemical_list: D000893:Anti-Inflammatory Agents; D001426:Bacterial Proteins; D007166:Immunosuppressive Agents; D011994:Recombinant Proteins; D003907:Dexamethasone; D003577:Cytochrome P-450 Enzyme System; C517094:15beta-hydroxylase CYP106A2, Bacillus megaterium; D003348:Cortisone; D011241:Prednisone
keywords: Bacillus megaterium; Biocatalysis; CYP106A2; Dexamethasone; Hydroxylation; Prednisone