Microbial Transformation In The Drug Aromatic Ring Hydroxylated Metabolite

Microbial transformation and LC/MS~ analysis technology were used in this study. Hydroxylation studies on aromatic ring of propafenone, benproperine and propranolol by Cunninghamella blakesleana AS 3. 153 in vitro were conducted. Structure-site selectivity of Cunninghamella blakesleana AS 3.153 is very strong. It had been discovered that propafenone could be transformed to mono-hydroxypropafenone (81.8 %); benproperine could be transformed to mono-hydroxybenproperine (69.4 %), di-hydroxybenproperine (7.5 %) and sulfate conjugation of mono-hydroxybenproperine (2.8 %) and propranolol could be transformed to mono-hydroxypropranolol (71.6 %), sulfate conjugation of propranolol (15.9 %) and sulfate conjugation of mono-hydroxypropranolol (11.4%) by strain AS 3.153. It was shown that major metabolic profiles and capacities of three drugs were almost identical by strain AS 3.153. Furthefmore, some similarities were found about metabolic profiles of three drugs between microorganisms and humans. Semipreparative HPLC was utilized to isolate major transformed 3 ABSTRACT products of three drugs, and their structures were then identified as 4? hydroxypropafenone; 4-hydroxybenproperine and 4?-hydroxy- benproperine and 5-hydroxypropranolol by NMR, respectively. Except for 5-hydroxypropranolol, they all were used to as reference compounds correspond to metabolites in humans. They played an important role in inferring partly metabolism pathways of drugs in humans. Optimized systems on aromatic ring hydroxylation of three drugs were established by strain AS 3.153. Significant effect factors were found on cumulation of major metabolites. They were concentration of solvent which was used to aid drugs solubility, substrate concentration (corresponding drug concentration ), transformation time and initial transformation medium pH. On optimized conditions, yields of mono- hydroxyp ropafenone, mono-hydroxyb enproperine and mono-hydroxy- propranolol were approximately 94 %, 70 % and 99 %, respectively. Based on three optimized system, basic transformation conditions were 0.050% of substrate concentration, initial transformation medium pH 6.5 and 72 hours of incubation. Seven selective inhibitors and specific substrates for cytochrome P450 isozyme isoforms of humans and animals were used to as probes. Cytochrome P450 isozyme isoforms responsible for formation of 4? hydroxypropafenone were proved to be possibly CYP2D6 and 2C9 isozyme in strain AS 3.153. It offered a reference to studies on cytochrome P450 isozyme isoforms involving in such metabolic profile in humans. Studies on aromatic ring hydroxylation of three drugs had been carried out by microbial transformation model. It proved that Cunning- hamella blakesleana AS 3. 153 was a good transformation strain with 4 ABSTRACT powerfiul structure-site selectivity and high hydroxylation ratio. Such microbial transformation model was shown to be a suitable in vitro studies on aromatic ring hydroxylated metabolism of drugs in humans.