Biotransformation of Coumarins: Mechanisms and Pharmaceutical Potential

Coumarins are compounds that are naturally found in various plants and are known for their potential pharmacological characteristics, such as anti-inflammatory, antibacterial, antiparasitic, and anticoagulant activities. Despite the potential pharmacological properties, structural modification of coumarins is important to enhance the biological activity, solubility, bioavailability, and various therapeutic characteristics. Microbial transformation is a promising method to modify coumarins since this method offers regioselective and stereospecific transformation, which is challenging to obtain through chemical synthesis. Various microorganisms, including bacteria and fungi, play an essential role in the microbial transformation of coumarins. These microorganisms employ enzymatic mechanisms involving various enzymes to catalyze several reactions, such as hydroxylation, oxidation, reduction, and demethylation. Among these microbial transformation processes, the demethylation process is a significant mechanism for altering the bioactivity of coumarins by converting methoxy groups into hydroxyl groups. Despite all the advantages, microbial transformation also has limitations such as low substrate specificity, contamination during inoculation, variable enzymatic activity, and challenges to scale up the production of bioactive coumarins. These challenges can be addressed through the optimization of the bioprocess to enhance the efficiency of microbial coumarin metabolism. This review provides a comprehensive overview of the microbial transformation of coumarins, highlighting the role of various microorganisms, enzymatic mechanisms, and the transformation processes.