Tetrabutylammonium bromide-based hydrophobic deep eutectic solvent for the extraction and separation of dihydromyricetin from vine tea and its inhibitory efficiency against xanthine oxidase

Identification and molecular docking of xanthine oxidase and α-glucosidase inhibitors in Opuntia ficus-indica fruit

Opuntia ficus-indica fruit (OFI) is rich in bioactive compounds, which can promote human health. In this work, the purified OFI extract was prepared from OFI and its bioactivities were investigated. Xanthine oxidase (XOD) and α-glucosidase (α-Glu) inhibitors of the purified OFI extract were screened and identified by bio-affinity ultrafiltration combined with UPLC-QTRAP-MS/MS technology. The inhibitory effect of these inhibitors on enzymes were verified, and the potential mechanism of action and binding sites of inhibitors with enzymes were revealed based on molecular docking. The results showed that the total phenolic content of the purified OFI extract was 355.03 mg GAE/g DW, which had excellent antioxidant activity. Additionally, the extract had a certain inhibitory effect on XOD (IC50 = 199.00 ± 0.14 µg/mL) and α-Glu (IC50 = 159.67 ± 0.01 µg/mL). Seven XOD inhibitors and eight α-Glu inhibitors were identified. Furthermore, XOD and α-Glu inhibition experiments in vitro confirmed that inhibitors such as chlorogenic acid, taxifolin, and naringenin had significant inhibitory effects on XOD and α-Glu. The molecular docking results indicated that inhibitors could bind to the corresponding enzymes and had strong binding force. These findings demonstrate that OFI contains potential substances for the treatment of hyperuricemia and hyperglycemia.

Deep eutectic solvent extraction of myricetin and antioxidant properties

In this study, a response surface method (RSM) was used to optimise the ultrasonic-assisted deep eutectic solvent (DES) extraction of myricetin from myricetin leaves. The results demonstrated that the DES-5 (choline chloride-oxalic acid) system exhibited better extraction results than the other seven DESs prepared. The optimum extraction conditions for myricetin were a DES-5 system with 19% water content of DES, a liquid-to-solid ratio of 37 : 1 mL g-1, an extraction time of 45 min, and an extraction temperature of 72 °C. Under these conditions, the extraction amount of myricetin was 22.47 mg g-1. To optimise the extraction process, the crude myricetin extract was purified, and the optimal conditions were as follows: an AB-8 macroporous adsorption resin was used with an anhydrous ethanol desorption agent. The adsorption rate was 1 BV per h (bed volume per hour), the desorption rate was 1 BV per h, and the desorption capacity was 2 BV (bed volume). The antioxidant properties of the myricetin were also investigated. The results demonstrated that, with an increase in concentration, the scavenging rates of DPPH and ˙OH free radicals increased. Compared to Vc, myricetin had a better scavenging ability for DPPH free radicals, whereas purified myricetin had a better antioxidant effect. At the same concentration, the radical-scavenging rate of the ˙OH radical was slightly higher in myricetin purified by the macroporous adsorption resin than in Vc, and that of the unpurified myricetin was the smallest. Myricetin was purified using a macroporous adsorption resin to improve its antioxidant properties.

Integrating Network Pharmacology and Experimental Validation to Reveal the Mechanism of Vine Grape Tea Polyphenols on Hyperuricemia-Induced Renal Injury in Mice

Hyperuricemia (HUA) is a metabolic disease and contributes to renal injury (RI). Vine grape tea polyphenols (VGTP) have been widely used to treat HUA and RI. However, the potential mechanism of VGTP activity remains unclear. To explore the underlying mechanism of VGTP treatment for HUA-induced RI based on network pharmacology that is confirmed by an in vivo study. All ingredients of VGTP were retrieved using a Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform and Comparative Toxicogenomics Database systems. The related targets of HUA and RI were obtained from GeneCards and National Center for Biotechnology Information (NCBI) databases. Some ingredients and targets were selected for molecular docking verification. One hour after administering potassium oxonate (300 mg/kg), VGTP (50, 100, and 200 mg/kg/d) was orally administered to HUA mice for 4 weeks. Histopathology and western blotting were performed in renal tissue. Our results showed that VGTP significantly reduced blood urea nitrogen, creatinine, uric acid, and significantly improved the RI and fibrosis of HUA mice. There were 54 active ingredients and 62 targets of HUA-induced RI. Further studies showed that VGTP decreased the expression of Bax, cleaved caspase 3, transforming growth factor-β (TGF-β1), CHOP, p-STAT3, and P53, and increased Bcl-2 expression in renal tissue. The related signaling pathways have apoptosis, TGF-β1, P53 and STAT, and endoplasmic reticulum stress (ERS). In this study, VGTP exerted antihyperuricemic and anti fibrosis effects by regulating the apoptosis and ERS signaling pathways. VGTP is expected to become a drug for combating HUA and RI.

Identification of natural xanthine oxidase inhibitors: Virtual screening, anti-xanthine oxidase activity, and interaction mechanism

Xanthine oxidase (XO) is a crucial target for hyperuricemia treatment(s). Naturally occurred XO inhibitors with minimal toxicity and high efficacy have attracted researchers' attention. With the goal of quickly identifying natural XO inhibitors, an integrated computational screening strategy was constructed by molecular docking and calculating the free energy of binding. Twenty-seven hits were achieved from a database containing 19,377 natural molecules. This includes fourteen known XO inhibitors and four firstly-reported inhibitors (isolicoflavonol, 5,7-dihydroxycoumarin, parvifolol D and clauszoline M, IC50 < 40 μM). Iolicoflavonol (hit 8, IC50 = 8.45 ± 0.68 μM) and 5,7-dihydroxycoumarin (hit 25, IC50 = 10.91 ± 0.71 μM) displayed the great potency as mixed-type inhibitors. Docking study and molecular dynamics simulation revealed that both hits could interact with XO's primarily active site residues ARG880, MOS1328, and ASN768 of XO. Fluorescence spectroscopy studies showed that hit 8 bound to the active cavity region of XO, causing changes in XO's conformation and hydrophobicity. Hits 8 and 25 exhibit favorable Absorption, Distribution, Metabolism, and Excretion (ADME) properties. Additionally, no cytotoxicity against human liver cells was observed at their median inhibition concentrations against XO. Therefore, the present study offers isolicoflavonol and 5,7-dihydroxycoumarin with the potential to be disease-modifying agents for hyperuricemia.

Selective extraction of plant bioactive compounds with deep eutectic solvents: Iris sibirica L. as example

INTRODUCTION

Deep eutectic solvents (DESs) are promising extractants with tuneable properties. However, there is a lack of reports about the influence of the nature of the original DES on obtaining the metabolomic profile of a plant.

OBJECTIVE

The aim of this study is to investigate the possibility of obtaining Iris sibirica L. chromatographical profiles with DESs based on various hydrogen bond donors and acceptors as extraction solvents.

METHODOLOGY

DESs were prepared by mixing choline chloride or tetrabutylammonium bromide with various hydrogen bond donors and investigated for the extraction of bioactive substances from biotechnological raw materials of I. sibirica L. The obtained extracts were analysed by HPLC with diode array detector (DAD) and Q-MS.

RESULTS

Chromatographic profiles for I. sibirica L. extracts by eight choline chloride DESs and six tetrabutylammonium DESs have been obtained. It has been found that selective recovery of bioactive substances can be achieved by varying the composition of DESs. Eleven phenolic compounds were identified in I. sibirica L. using HPLC-MS. Phase separation was observed with acetonitrile for four DESs. New flavonoid derivatives have been found in DES extracts compared with methanol extracts.

CONCLUSION

The results showed the possibility of DES usage for extraction without water addition. Selectivity of DESs varies depending on the chemical composition of hydrogen bond donors and acceptors. Choline chloride is a more suitable hydrogen bond acceptor for the flavonoid extraction. Choline chloride-lactic acid (1:1) DES has demonstrated a metabolic profile that was the closest to the methanol one and enhanced the extraction up to 2.6-fold.