The Environmental Pollutant Bromophenols Interfere With Sulfotransferase That Mediates Endocrine Hormones

Bromophenols (BPs), known as an important environmental contaminant, can cause endocrine disruption and other chronic toxicity. The study aimed to investigate the potential inhibitory capability of BPs on four human sulfotransferase isoforms (SULT1A1, SULT1A3, SULT1B1 and SULT1E1) and interpret how to interfere with endocrine hormone metabolism. P-nitrophenol(PNP) was utilized as a nonselective probe substrate, and recombinant SULT isoforms were utilized as the enzyme resources. PNP and its metabolite PNP-sulfate were analyzed using a UPLC-UV detecting system. SULT1A1 and SULT1B1 were demonstrated to be the most vulnerable SULT isoforms towards BPs’ inhibition. To determine the inhibition kinetics, 2,4,6-TBP and SULT1A3 were selected as the representative BPs and SULT isoform respectively. The competitive inhibition of 2,4,6-TBP on SULT1A3. The fitting equation was y=90.065x+1466.7, and the inhibition kinetic parameter (Ki) was 16.28 µM. In vitro-in vivo extrapolation (IVIVE) showed that the threshold concentration of 2,4,6-TBP to induce inhibition of SULT1A3 was 1.628 µM. In silico docking, the method utilized indicated that more hydrogen bonds formation contributed to the stronger inhibition of 3,5-DBP than 3-BP. In conclusion, our study gave the full description of the inhibition of BPs towards four SULT isoforms, which may provide a new perspective on the toxicity mechanism of BPs and further explain the interference of BPs on endocrine hormone metabolism.

Synthesis and Enzymological Characterization of Some 2- (Substitutedphenylamino)quinazolin-4(3H)-one Derivatives as Potent αGlucosidase Inhibitors In vitro

Background: α-Glucosidase is an important hydrolytic enzyme playing a vital role in digestion of carbohydrates. It catalyzes the final step of carbohydrates digestion in biological systems and converts unabsorbed oligosaccharides and disaccharides into monosaccharides, thus resulting in hyperglycemia for diabetic patients. In this respect, it has been considered as a therapeutic target for the treatment of type 2 diabetes since the enzyme inhibition delays carbohydrate digestion and monosaccharide absorption and subsequently reduces postprandial plasma glucose levels.Objective: In this study, fourteen 2-(substitutedphenylamino)quinazolin-4(3H)-one derivatives were synthesized and evaluated for their αglucosidase inhibitory activities. Methods: The structures of the synthesized compounds were confirmed by spectral and elemental analyses. The biological activity and enzyme inhibition kinetic studies were performed by spectrophotometrical method using microplate reader. Physicochemical and drug-likeness properties of selected compounds were predicted by in silico method. Result: The biological activity results revealed that all of the synthesized compounds showed more potent αglucosidase inhibitory activity in the range of IC50= 57.81±2.16-374.68±15.48 μM when compared to the standard drug acarbose (IC50= 891.79±6.87 μM). Among the tested compounds, compound 12 bearing chlorine substituent at ortho position on N-phenyl ring displayed the highest inhibition with an IC50 value of 57.81±2.16 μM against α-glucosidase. Furthermore, the enzyme inhibition kinetic study of the most active compound 12 indicated that the compound inhibited the α-glucosidase enzyme as uncompetitive with a Ki value of 63.46 μM. On the other hand, physicochemical and drug-likeness properties of selected compounds were predicted by in silico method. According to the results, it can be speculated that synthesized 2-phenylaminoquinazolin-4(3H)-one derivatives possessed favorable drug-likeness and pharmacokinetic profiles. Conclusion: In the light of results, 2 (substitutedphenylamino)quinazolin-4(3H)-one derivatives may serve as lead compounds to develop novel α-glucosidase inhibitors.

Characterization of Maltase and Sucrase Inhibitory Constituents from Rhodiola crenulata

The inhibitory properties of epicatechin-(4β,8)-epicatechingallate (B2-3’-O-gallate), epicatechin gallate (ECG), and epicatechin (EC) isolated from Rhodiola crenulata toward maltase and sucrase were investigated. The half-maximal inhibitory concentration (IC50) values for maltase were as follows: B2-3’-O-gallate (1.73 ± 1.37 μM), ECG (3.64 ± 2.99 μM), and EC (6.25 ± 1.84 μM). Inhibition kinetic assays revealed the inhibition constants (Ki) of the mixed-competitive inhibitors of maltase, as follows: B2-3’-O-gallate (1.99 ± 0.02 μM), ECG (3.14 ± 0.04 μM), and EC (7.02 ± 0.26 μM). These compounds also showed a strong inhibitory activity toward sucrase, and the IC50 values of B2-3’-O-gallate, ECG, and EC were 6.91 ± 3.41, 18.27 ± 3.99, and 18.91 ± 3.66 μM, respectively. Inhibition kinetic assays revealed the inhibition constants (Ki) of the mixed-competitive inhibitors of sucrase as follows: B2-3’-O-gallate (6.05 ± 0.04 μM), ECG (8.58 ± 0.08 μM), and EC (13.72 ± 0.15 μM). Overall, these results suggest that B2-3’-O-gallate, ECG, and EC are potent maltase and sucrase inhibitors.

An Improved Method for the Synthesis of Butein Using SOCl2/EtOH as Catalyst and Deciphering Its Inhibition Mechanism on Xanthine Oxidase

Butein (3,4,2′,4′-tetrahydroxychalcone) belongs to the chalcone family of flavonoids and possesses various biological activities. In this study, butein was synthesized through aldol condensation catalyzed by thionyl chloride (SOCl2)/ethyl alcohol (EtOH) for the first time. The optimal reaction conditions including the molar ratio of reactants, the dosage of catalyst, and the reaction time on the yield of product were investigated, and the straightforward strategy assembles the yield of butein up to 88%. Butein has been found to inhibit xanthine oxidase (XO) activity. Herein, the inhibitory mechanism of butein against XO was discussed in aspects of inhibition kinetic, fluorescence titration, synchronous fluorescence spectroscopy, and molecular docking. The inhibition kinetic analysis showed that butein possessed a stronger inhibition on XO in an irreversible competitive manner with IC50 value of 2.93 × 10−6 mol L−1. The results of fluorescence titrations and synchronous fluorescence spectroscopy indicated that butein was able to interact with XO at one binding site, and the fluorophores of XO were placed in a more hydrophobic environment with the addition of butein. Subsequently, the result of molecular docking between butein and XO protein revealed that butein formed hydrogen bonding with the amino acid residues located in the hydrophobic cavity of XO. All the results suggested that the inhibitory mechanism of butein on XO may be the insertion of butein into the active site occupying the catalytic center of XO to avoid the entrance of xanthine and inducing conformational changes in XO.