High-throughput screening technologies for drug glucuronidation profiling

A significant number of endogenous and exogenous compounds, including many therapeutic agents, are metabolized in humans via glucuronidation, catalysed by uridine diphosphoglucuronosyltransferases (UGTs). The study of the UGTs is a growing field of research, with constantly accumulated and updated information regarding UGT structure, purification, substrate specificity and inhibition, including clinically relevant drug interactions. Development of reliable UGT assays for the assessment of individual isoform substrate specificity and for the discovery of novel isoformspecific substrates and inhibitors is crucial for understanding the function and regulation of the UGT enzyme family and its clinical and pharmacological relevance. High-throughput screening (HTS) is a powerful technology used to search for novel substrates and inhibitors for a wide variety of targets. However, application of HTS in the context of UGTs is complicated because of the poor stability, low levels of expression, low affinity and broad substrate specificity of the enzymes, combined with difficulties in obtaining individual UGT isoforms in purified format, and insufficient information regarding isoform-specific substrates and inhibitors. This review examines the current status of HTS assays used in the search for novel UGT substrates and inhibitors, emphasizing advancements and challenges in HTS technologies for drug glucuroniclation profiling, and discusses possible avenues for future advancement of the field.