Evaluation of Enzyme Inhibitory Activity of Flavonoids by Polydopamine-Modified Hollow Fiber-Immobilized Xanthine Oxidase

Recent advances in green solvents-based liquid-phase microextraction techniques for chromatographic analysis of active components in traditional Chinese medicine

Traditional Chinese medicine (TCM) is a treasure of China and a crucial part of traditional medicine in the world, particularly in many oriental countries. TCM is the core and basis of traditional medicine in clinical practice for numerous diseases, and performs important function in nutraceuticals and dietary supplements. However, it is extremely difficult to extract each active ingredient from TCM to elucidate the mechanism of TCM clinical efficacy due to numerous compounds in TCM, especially trace compounds. Consequently, liquid-phase microextraction (LPME) techniques, one of the main extraction methods of active ingredients in TCM, have attracted a considerable attention from researchers. In recent years, many novel green solvents based-LPME methods have been reported, such as single-drop microextraction (SDME), hollow-fiber liquid-phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME), and electro-membrane extraction (EME). Therefore, in this review, we present an up-to-date and comprehensive summary of various LPME techniques, novel green solvents, and their applications in the analysis of active ingredients within the complex TCM samples. We provide a detailed overview of the fundamental principles, modes, and the critical process parameters of the LPME techniques. In addition, we compare different types of green solvents (i.e., deep eutectic solvents, ionic liquids, magnetic ionic liquids, supramolecular solvents, switchable solvents, among others), and the advantages and disadvantages of these solvents are critically evaluated, highlighting their suitability for various applications. Finally, we elucidate the merits and demerits of different LPME methods, discuss their practical applications, and explore their future research directions. This review aims to provide a valuable resource for researchers and practitioners in the field of TCM, promoting research development and application of the advanced and environmentally friendly sample pretreatment techniques.

Rapid screening of xanthine oxidase inhibitors from Ligusticum wallichii by using xanthine oxidase functionalized magnetic metal-organic framework

In this study, xanthine oxidase was immobilized for the first time using a novel magnetic metal-organic framework material (Fe3O4-SiO2-NH2@MnO2@ZIF-8-NH2). A ligand fishing method was established to rapidly screen XOD inhibitors from Ligusticum wallichii based on the immobilized XOD. Characterization and properties of the immobilized enzyme revealed its excellent stability and reusability. A ligand was screened from Ligusticum wallichii and identified as ligustilide by ultra-high performance liquid chromatography tandem mass spectrometry. The IC50 value of ligustilide was determined to be 27.70 ± 0.13 μM through in vitro inhibition testing. Furthermore, molecular docking verified that ligustilide could bind to amino acid residues at the active site of XOD. This study provides a rapid and effective method for the preliminary screening of XOD inhibitors from complex natural products and has great potential for further discovery of anti-hyperuricemic compounds.

Screening and Elucidation of Chemical Structures of Novel Mammalian α-Glucosidase Inhibitors Targeting Anti-Diabetes Drug from Herbals Used by E De Ethnic Tribe in Vietnam

Among ten extracts of indigenous medicinal plants, the MeOH extract of Terminalia triptera Stapf. (TTS) showed the most efficient mammalian α-glucosidase inhibition for the first time. The data of screening bioactive parts used indicated that the TTS trunk bark and leaves extracts demonstrated comparable and higher effects compared to acarbose, a commercial anti-diabetic drug, with half-maximal inhibitory concentration (IC50) values of 181, 331, and 309 µg/mL, respectively. Further bioassay-guided purification led to the isolation of three active compounds from the TTS trunk bark extract and identified as (-)-epicatechin (1), eschweilenol C (2), and gallic acid (3). Of these, compounds 1 and 2 were determined as novel and potent mammalian α-glucosidase inhibitors. The virtual study indicated that these compounds bind to α-glucosidase (Q6P7A9) with acceptable RMSD values (1.16-1.56 Å) and good binding energy (DS values in the range of -11.4 to -12.8 kcal/mol) by interacting with various prominent amino acids to generate five and six linkages, respectively. The data of Lipinski's rule of five and absorption, distribution, metabolism, excretion and toxicity (ADMET)-based pharmacokinetics and pharmacology revealed that these purified compounds possess anti-diabetic drug properties, and the compounds are almost not toxic for human use. Thus, the findings of this work suggested that (-)-epicatechin and eschweilenol C are novel potential mammalian α-glucosidase inhibitor candidates for type 2 diabetes treatment.

Neuroprotective Potentials of Flavonoids: Experimental Studies and Mechanisms of Action

Neurological and neurodegenerative diseases, particularly those related to aging, are on the rise, but drug therapies are rarely curative. Functional disorders and the organic degeneration of nervous tissue often have complex causes, in which phenomena of oxidative stress, inflammation and cytotoxicity are intertwined. For these reasons, the search for natural substances that can slow down or counteract these pathologies has increased rapidly over the last two decades. In this paper, studies on the neuroprotective effects of flavonoids (especially the two most widely used, hesperidin and quercetin) on animal models of depression, neurotoxicity, Alzheimer's disease (AD) and Parkinson's disease are reviewed. The literature on these topics amounts to a few hundred publications on in vitro and in vivo models (notably in rodents) and provides us with a very detailed picture of the action mechanisms and targets of these substances. These include the decrease in enzymes that produce reactive oxygen and ferroptosis, the inhibition of mono-amine oxidases, the stimulation of the Nrf2/ARE system, the induction of brain-derived neurotrophic factor production and, in the case of AD, the prevention of amyloid-beta aggregation. The inhibition of neuroinflammatory processes has been documented as a decrease in cytokine formation (mainly TNF-alpha and IL-1beta) by microglia and astrocytes, by modulating a number of regulatory proteins such as Nf-kB and NLRP3/inflammasome. Although clinical trials on humans are still scarce, preclinical studies allow us to consider hesperidin, quercetin, and other flavonoids as very interesting and safe dietary molecules to be further investigated as complementary treatments in order to prevent neurodegenerative diseases or to moderate their deleterious effects.

Probiotics, bioactive compounds and dietary patterns for the effective management of hyperuricemia: a review

Hyperuricemia is closely linked with an increased risk of developing hypertension, diabetes, renal failure and other metabolic syndromes. Probiotics, bioactive compounds and dietary patterns are safe cost-efficient ways to control hyperuricemia, whereas comprehensive reviews of their anti-hyperuricemic mechanisms are limited. This review summarizes the roles of probiotics, bioactive compounds and dietary patterns in treating hyperuricemia and critically reviews the possible mechanisms by which these interventions exert their activities. The dietary patterns are closely related to the occurrence of hyperuricemia through the indirect action of gut microbiota or the direct effects of host purine metabolism. The Mediterranean and Dietary Approaches to Stop Hypertension diets help reduce serum uric acid concentrations and thus prevent hyperuricemia. Meanwhile, probiotics alleviate hyperuricemia by ways of absorbing purine, restoring gut microbiota dysbiosis and inhibiting xanthine oxidase (XO) activity. Bioactive compounds such as polyphenols, peptides and alkaloids exert various anti-hyperuricemic effects, by regulating urate transporters, blocking the active sites of XO and inhibiting the toll-like receptor 4/nuclear factor kappa B signaling pathway and NOD-, LRR- and pyrin domain-containing protein 3 signaling pathway. This review will assist people with hyperuricemia to adopt a healthy diet and contribute to the application of natural products with anti-hyperuricemic activity.

Nanozyme based on ZIF-8 for the colorimetric detection of sulfonamides in cow milk

A simple and time-saving colorimetric method was developed to quantify sulfonamides (SAAs) in milk via inhibition of the human carbonic anhydrase II (hCAII)-like activity of ZIF-8 that can hydrolyze p-nitrophenyl acetate (pNPA) to p-nitrophenol (pNP), following the color change from yellow to colorless. Effects of different reaction conditions, including pH, temperature, amount of ZIF-8, and incubation time, were investigated. The value of Michaelis-Menten constant (K_m) is measured to be 0.15 mM, which exhibits high affinity to pNPA. The IC₅₀ (0.17, 0.24, and 0.60 mM) and inhibition constant (K_i) (0.09, 0.13, and 0.33 mM) of sulfamethazine (SD), sulfadimethoxine (SDM), and sulfathiazole (ST) on ZIF-8 were measured, respectively. Moreover, the activity of ZIF-8 remains more than 90.0% of its initial activity after 30 days' storage. The colorimetric method for SD, SDM, and ST determination was established at the linear ranges of 6.3-750.0 μM (1.75-208.75 mg/kg), 6.3-750.0 μM (1.96-232.75 mg/kg), and 5.0-1250.0 μM (1.28-319.15 mg/kg) with limit of detection of 4.3, 3.2, and 3.9 mΜ (1.2, 0.99, and 0.96 mg/kg), respectively. In addition, the spiked recoveries of SAAs in milk sample are in the range of 81.6%-106.7% with RSD less than 6.5%. In short, the developed colorimetric method can achieve rapid analysis of SAAs in milk with simple operations.