Biodegradation of the analgesic naproxen by Trametes versicolor and identification of intermediates using HPLC-DAD-MS and NMR

The white-rot fungus Trametes vesicolor degraded naproxen (10 mg L−1) in a liquid medium to non-detectable levels after 6 h. When naproxen was added in the range of concentrations typically found in the environment (55 μg L−1), it was almost completely degraded (95%) after 5 h. In vitro degradation experiments with purified laccase and purified laccase plus mediator 1-hydroxybenzotriazol showed slight and almost complete naproxen degradation, respectively. A noticeable inhibition on naproxen degradation was also observed when the cytochrome P450 inhibitor 1-aminobenzotriazole was added to the fungal cultures. These data suggest that both enzymatic systems could play a role in naproxen degradation. 2-(6-hydroxynaphthalen-2-yl)propanoic acid and 1-(6-methoxynaphthalen-2-yl)ethanone were structurally elucidated by HPLC-DAD-MS and NMR as degradation intermediates of naproxen. After 6 h of incubation, both parent compound and intermediates disappeared from the medium. The non-toxicity of the treated medium was confirmed by Microtox test.