A Practical and High-Affinity Fluorescent Probe for Uridine Diphosphate Glucuronosyltransferase 1A1: A Good Surrogate for Bilirubin

This
study aimed to develop a practical and high-affinity fluorescent
probe for uridine diphosphate glucuronosyltransferase 1A1 (UGT1A1),
a key conjugative enzyme responsible for the elimination and detoxification
of many potentially harmful compounds. Several substrates derived
from N-butyl-4-phenyl-1,8-naphthalimide were designed
and synthesized on the basis of the substrate preference of UGT1A1
and the principle of photoinduced electron transfer (PET). Following
the preliminary screening, substrate 2 was found with
a high specificity and high affinity toward UGT1A1, while such biotransformation
brought remarkable changes in fluorescence emission. Both inhibition
kinetic analyses and molecular docking simulations demonstrated that 2 could bind on UGT1A1 at the same ligand-binding site as
bilirubin. Furthermore, this newly developed probe was successfully
used for sensing UGT1A1 activities and the high-throughput screening
of UGT1A1 modulators in complex biological samples. In conclusion,
a practical and high-affinity fluorescent probe for UGT1A1 was designed
and well-characterized, which could serve as a good surrogate for
bilirubin to investigate UGT1A1-ligand interactions.