Biotransformation of common NSAIDs by Cunninghamella species and resulting metabolite toxicity

Abstract Nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac (DCF), ibuprofen (IBU), and ketoprofen (KET) are commonly found in the environment and pose potential toxicological risks. This study investigates the microbial biotransformation of these NSAIDs by Cunninghamella spp. and evaluates the toxicity of the Cunninghamella -processed samples. The results demonstrate that Cunninghamella efficiently biotransformed DCF and IBU into multiple metabolites, whereas the biotransformation of KET was negligible. Microbial treatment reduced the ecotoxicity of IBU and DCF, as confirmed by Microtox ® and algal growth inhibition assays. In vitro cytotoxicity tests using human hepatocytes (HepG2), neuroblastoma cells (SH-SY5Y), astrocytes, and rat cardiomyocytes (H9c2) showed lower toxicity of the biotransformation products compared to the parent compounds. The Ames assay revealed no mutagenicity for any of the samples. Endocrine disruption assays indicated a loss of antagonistic estrogenic and androgenic effects post-biotransformation, with minor estrogenic agonistic activity observed. In conclusion, fungal biotransformation by Cunninghamella appears to be a promising strategy for reducing the environmental toxicity of NSAIDs. However, the generation of transformation products with altered biological activity underscores the importance of combining analytical identification with comprehensive toxicological assessment.