Microbial transformation of naproxen by Cunninghamella species.

AIM: The metabolites of naproxen produced by Cunninghamella species were isolated and identified, and further to compare the similarities between microbial transformation and mammalian metabolism. METHODS: Naproxen was transformed by three strains of Cunninghammella species (Cunninghamella blakeslesna AS 3.153, Cunninghamella echinulata AS 3.2004, and Cunninghamella elegans AS 3.156). The metabolites of naproxen were separated and assayed by liquid chromatography-mass spectrometry method. Semi-preparative HPLC was used to isolate the major metabolite, and the structure was identified by nuclear magnetic resonance (NMR) and mass spectrometry. RESULTS: Naproxen was transformed into 2 metabolites, desmethylnaproxen and desmethylnaproxen-6-O-sulfate, both were the known mammalian metabolites. The conjugated metabolite was newly detected in microbial transformation samples. CONCLUSION: The microbial transformation of naproxen has some similarities with the metabolism of naproxen in mammals. The fungi belonging to Cunninghamella species could be used as complementary in vitro models for drug metabolism to predict and produce the metabolites of drugs in mammals.