Avaliação de fungos na biotransformação estereosseletiva da Hidroxizina e obtenção do metabólito quiral e ativo Cetirizina
FORTES, S. S. Evaluation of fungi in the stereoselective biotransformation of hydroxyzine and obtention of the active and chiral metabolite cetirizine. 2013. 103 f. Thesis (Master). Faculty of Philosophy, Sciences and Letters of Ribeirão Preto -University of São Paulo, Ribeirão Preto, 2013. Microbial models have been used in biotransformation studies of many drugs aiming their metabolite production. Fungi of various genera have been extensively used to mimic the mammals' hepatic metabolism. The
... tic metabolism. The use of fungi is advantageous because they present fast growth and easy formation of the multienzymatic system. Moreover, the biotransformation is, nowadays, considered an economically and competitive technology, in the search of new production routes for fine chemical, pharmaceutical and agrochemical compounds. In many cases, the biological transformation is enantioselective, allowing the production of pure enantiomers from racemic mixtures. In light of the above considerations and due to the absence of a low consuming organic solvent extraction method for the enantioselective determination of hydroxyzine (HZ) and cetirizine (CTZ), it was developed a method combining dispersive liquid-liquid microextraction (DLLME) and capillary electrophoresis (CE) to study the enantioselective biotransformation of HZ through the fungi Penicillium crustosum, Mucor rouxii, Cunnonghamella echinulata var. elegans ATCC 8688, Cunnonghamella echinulata var. elegans ATCC 10028, Nigrospora sphaerica e Fusarium oxysporum. A CE method was developed for the enantioselective analysis of hydroxyzine (HZ) and cetirizine (CTZ) in Czapek liquid culture medium. The CE analyses were performed using an uncoated fused-silica capillary and 50 mmol/L sodium borate buffer (pH 9.0) containing 0.8% (w/v) sulfated-β-cyclodextrin. The applied voltage and temperature used were +6 kV and 15 °C, respectively. The UV detector was set at 214 nm. The DLLME conditions involved: chloroform (300 µL) as extraction solvent and ethanol (400 µL) as dispersive solvent. After the formation of the cloudy solution, the samples were subjected to vortex agitation during 30 s at 2000 rpm and centrifugation for 5 min at 3000 rpm. The recoveries were in the range of 87.4 -91.7%. The method was linear over the concentration range of 250 -12500 ng/mL for each enantiomer of HZ (r > 0.998) and of 125 -6250 ng/mL for each enantiomer of CTZ (r > 0.998). The quantification limits were 125 and 250 ng/mL for CTZ and HZ, respectively. Among the six studied fungi three were able to convert HZ to CTZ enantioselectively, especially the fungus Cunninghamella elegans ATCC 10028B that converted 19% of (E1)-HZ to (S)-CTZ with an enantiomeric excess of 65%.