Assessment Of The Inhibition Of Myricetin Towards Human UDP-glucronosyltransferases

Myricetin（3,5,7,3’,4’,5’-hexahydroxy flavonol）is a natural flavonol extracted from the Myrica rubra.Myricetin has multiple biological properties.As one of the most well-studied polyphenols,myricetin boasts diverse pharmacological activities:antimicrobial,antidiabetic,anticancer,etc.It also has many therapeutic effects:It can be used on immunomodulatory and cardiovascular and analgesic treatments.Moreover,Myricetin won’t affect normal cellular functions,which inspired researchers with new treatment ideas.It has great potential to become competitive pharmaceutical integrands for new medicine in the treatment of tumor,inflammation and endocrine diseases.UDP-glucuronosyltransferases（UGTs）will metabolise and decompose a range of small molecule endogenous substances like bilirubin.It is conjointly involved within the breakdown of alternative exogenous substances including medicine.Therefore,inhibition of metabolic enzymes will lead to the disorder of toxic endogenous substances and drug metabolism,and even induce Drug-Drug interactions（DDIs）.It will severely limit the research and application of new compounds,or maybe the clinical application of these new compounds.There are enough evidence proving that Myricetin can produce inhibitory effect to a variety of phaseⅠmetabolizing enzyme,thus cause adverse reactions.But,there square measure comparatively few studies on the inhibition of UGTs by myricetin.However,whether or not Myricetin will have an effect on the activities of UGTs and cause drug-drug interactions remains unclear.This analysis aims to check investigate the impact of Myricetin on 11 major human UGTs isoforms,and to evaluate the potential drug-drug interactions.At the same time,whether other flavonols have an effect on the main subtypes of UGTs was also explored.In this study,the environment of UGTs metabolize compounds will be simulated in vivo the control group（solvent group）and the experimental group（inhibitor group）will be set up under a 37℃constant temperature incubation system in vitro.In order to ascertain inhibition of Myricetin.4-MU,a nonselective substrate of UGTs,was incubated with recombinant UGTs in the absence and presence of different concentration of.The in vitro culture mixture was accustomed study the glucuronidation metabolism of 4-methylumbelliferone（4-MU）catalyzed by recombinant UGTs,and therefore the yield of substance 4-MU-β-D-glucuronide（4-MUG）was quantified to check the repressive potential of Myricetin.Based on the initial screening,further experiments were conducted to determine the inhibition types and kinetics towards UGTs isoforms when the inhibition was up to 80%.The half-maximal inhibitory concentration(IC₅₀)values were determined.Lineweaver–Burk plot was drawn using 1/reaction velocity（v）versus 1/the concentration of 4-MU（[4-MU]）,and it was used to determine the inhibition kinetic type.The K_i value was calculated by using the slope of the line and compound concentration in the Lineweaver-Burk diagram.The K_i value was calculated by using the slope of the line and compound concentration in the Lineweaver-Burk diagram.The in vitro and in vivo extrapolation method was used to evaluate and calculate the thresholds for the inhibition of endogenous substance metabolism in vivo by exposure of Myricetin.Finally,in this study,in order to compare the mechanism of the interaction between myricetin with UGTs isoforms with other UGTs,the in silico docking method was performed.Initial screening experiment showed that Myricetin exhibited inhibition against the majority the tested UGTs isoforms at a degree of 100μM.Additional kinetic investigation incontestable that myricetin competitively restrained UGT1A9,with IC₅₀ and K_i values of 29.46μM and 35.55μM,severally.Meanwhile,myricetin uncompetitively inhibited UGT1A1,UGT1A3,UGT1A6,UGT1A7,UGT1A10,UGT2B7 with an IC₅₀ value of2.07,8.89,5.31,4.32,3.08,25.74μM,and a K_i value of 4.71,18.81,1.96,3.96,1.49,20.92μM,severally.According to the inhibition analysis commonplace（0.1<[I]/K_i,medium possibility）,associate in vivo drug–drug interactions between Myricetin and medicines in the main undergoing UGT1A1,UGT1A3,UGT1A6,UGT1A9,UGT1A10 or UGT2B7 catalyzed metabolism may occur once the plasma concentration of Myricetin is higher than 0.47,1.88,0.20,0.40,3.56,0.15,2.09μM,severally.The binding free energies of myricetin to UGT1A1,1A3,1A6,1A7,1A9 and 2B7 were-6.35,-7.4,-6.91,-7.69,-7.06 and-4.0 kcal/mol,severally.Finally,except galangin had promoting effects on UGT1A1 and UGT1A10,other flavonols had inhibitory effects on UGTs.The follow-up findings showed that flavonols were broad-spectrum inhibitors of human UGTs.Even though myricetin is unlikely to cause drug-drug interactions in common foods,precautions should be taken when co-administration of flavonol supplements with drugs.we have a tendency to conjointly evaluated the consequences of alternative flavonols on human UGTs.To provide a theoretical basis for further study on the safety of flavonols represented by Myricetin in clinical application.