Enzymatic Synthesis of Bioactive O-Glucuronides Using Plant Glucuronosyltransferases

Abstract

Many O-glucuronides exhibiting various pharmacological activities have been found in nature and in drug metabolism. The glucuronidation of bioactive natural products or drugs to generate glucuronides with better activity and druggability is important in drug discovery and research. In this study, by using two uridine diphosphate (UDP)-dependent glucuronosyltransferases (GATs, UGT88D4 and UGT88D7) from plants, we developed two glucuronidation approaches, pure enzyme catalysis in vitro and recombinant whole-cell catalysis in vivo, to efficiently synthesize bioactive O-glucuronides by the glucuronidation of natural products. In total, 14 O-glucuronides with different structures, including flavonoids, anthraquinones, coumarins, and lignans, were obtained, 7 of which were new compounds. Furthermore, one of the biosynthesized O-glucuronides, kaempferol-7-O-β-d-glucuronide (3a), potently inhibited protein tyrosine phosphatase (PTP) 1B with an IC50 value of 8.02 × 10–6 M. Some of the biosynthesized O-glucuronides also exhibited significant antioxidant activities.

Efficient Production of Flavonoid Glucuronides in Escherichia coli Using Flavonoid O-Glucuronosyltransferases Characterized from Marchantia polymorpha

“…In another related study, the employed UGATs produced several products in vitro but only one product in vivo . The reason for the generation of only one dominant product could be attributed to the varying internal and external environments of the cells, as well as the relatively low concentration level of sugar donors in vivo .…”

“…Applying UGATs from plants, some studies have constructed engineered Escherichia coli to synthesize flavonoid glucuronides in vivo . With UDP-glucose dehydrogenase ( ugd ) and UGT88D4 (or UGT88D7 ) coexpressed in E. coli , several flavonoid-7- O -glucuronides were prepared by Tian et al Mutation of the UGT from Scutellaria baicalensis increased the production of baicalein-7- O -glucuronic acid . With knockout of the arnA gene that metabolizes UDP-GA in E. coli , AmUGT10 from Antirrhinum majus and VvUGT from V. vinifera were applied to produce luteolin-7- O -glucuronide and quercetin-3- O -glucuronide, respectively .…”

Efficient Chemical Synthesis of (Epi)catechin Glucuronides: Brain-Targeted Metabolites for Treatment of Alzheimer’s Disease and Other Neurological Disorders

“…In part, this reflects the lack of good synthetic strategies to furnish all possible (epi)­catechin-glucuronide regioisomers. In particular, the chemical synthesis of glucuronide derivatives of catechin is underexplored when compared with the chemical/enzymatic synthesis of the corresponding conjugates of epicatechin. − For the series of (epi)­catechin glucuronides shown in Figure , the synthesis of glucuronides 7 , , 8 , , 10 , ,, and 11 ,, has been reported elsewhere, while the chemical synthesis of glucuronides 8 and 9 is described here for the first time. In this context, authentic standards of (+) catechin and (−) epicatechin metabolites 3 – 12 (Figure ) were prepared by a chemically unambiguous synthetic approach for the further mechanism of action studies.…”

The sugar donor specificity of plant family 1 glycosyltransferases

“…Glucuronosyltransferases play a vital role in the phase II metabolism of exogenous compounds in mammals ( Mazerska et al, 2016 ). In addition, natural glucuronides are found in plants where some isolated glucuronides such as scutallerin-7- O -glucuronide ( Guo et al, 2014 ) and apigenin-7- O -glucuronide ( Ma et al, 2017 ; Yue et al, 2019 ) display pharmacological activity. Even though there is a wide variety of glucuronides identified in plants ( Yue et al, 2019 ), only a few plant glucuronosyltransferases have been discovered and characterised.…”