•PPO was more active in catalysing flavonol glycosides than POD and β-glucosidase.•PPO activity was greatly influenced by pH but moderately impacted by temperature.•POD strongly promoted the ...PPO-induced oxidation of flavonol glycosides.•Aglycone was the dominant moiety for the sensitivity of flavonol glycosides to PPO.•Sugar moiety promoted the better docking between flavonol glycosides and PPO.
Flavonol glycosides are associated with astringency and bitterness of teas. To clarify the dominant enzymatic reaction of flavonol glycosides in tea leaves, the catalytic effects of polyphenol oxidase (PPO), peroxidase (POD) and β-glucosidase were studied, with the maintaining rates of total flavonol glycosides (TFG) being 73.0%, 99.8% and 94.3%. PPO was selected for further investigations, including the effects of pH value (3.5 ~ 6.5), temperature (25 °C ~ 55 °C) and dosage (39 ~ 72 U/mL PPO and 36 U/mL PPO, 3 ~ 36 U/mL POD). The oxidation of flavonol glycosides were intensified at pH 6.5, with 51.8% and 15.4% of TFG maintained after PPO and PPO + POD treatments, suggesting an enhancement from POD. The sensitivity ranking to PPO was: myricetin glycosides > quercetin glycosides > kaempferol glycosides. The inhibitor treatment testified the leading role of PPO in catalyzing flavonol glycosides in tea leaves. Sugar moiety enhanced the docking affinity of flavonol glycosides for PPO. PPO shows the potential of modifying flavonol glycoside composition.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This work describes a simple and sensitive fluorescent method for detection of hydroquinone utilizing conjugated polymer nanoparticles (CPNs). The CPNs serve both as a catalyst to accelerate the ...conversion of hydroquinone to benzoquinone and a fluorescent probe. In the presence of hydroquinone, the fluorescence of CPNs can be effectively quenched by benzoquinone. The detection limit of hydroquinone was down to 5 nM and excellent selectivity toward possible interferences was obtained. This method was successfully applied for hydroquinone detection in lake water and satisfactory results were achieved.
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•Fluorescent conjugated polymer nanoparticles have been synthesized via a facile nano-precipitation method.•The conjugated polymer nanoparticles functionalized both as catalystand the fluorescent probe for biosensor construction.•The biosensor demonstrated significant improvement in detection sensitivity compared to previous hydroquinone assay.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Although metal–organic frameworks (MOFs) have been reported as important porous materials for the potential utility in metal ion separation, coordinating the functionality, structure, and component ...of MOFs remains a great challenge. Herein, a series of anionic rare earth MOFs (RE-MOFs) were synthesized via a solvothermal template reaction and for the first time explored for uranium(VI) capture from an acidic medium. The unusually high extraction capacity of UO2 2+ (e.g., 538 mg U per g of Y-MOF) was achieved through ion-exchange with the concomitant release of Me2NH2 +, during which the uranium(VI) extraction in the series of isostructural RE-MOFs was found to be highly sensitive to the ionic radii of the metal nodes. That is, the uranium(VI) adsorption capacities continuously increased as the ionic radii decreased. In-depth mechanism insight was obtained from molecular dynamics simulations, suggesting that both the accessible pore volume of the MOFs and hydrogen-bonding interactions contribute to the strong periodic tendency of uranium(VI) extraction.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
Methylglyoxal (MG) is a byproduct of glycolysis that functions in diverse mammalian developmental processes and diseases and in plant responses to various stresses, including salt stress. ...However, it is unknown whether MG-regulated gene expression is associated with an epigenetic modification. Here we report that MG methylglyoxalates H3 including H3K4 and increases chromatin accessibility, consistent with the result that H3 methylglyoxalation positively correlates with gene expression. Salt stress also increases H3 methylglyoxalation at salt stress responsive genes correlated to their higher expression. Following exposure to salt stress, salt stress responsive genes were expressed at higher levels in the Arabidopsis glyI2 mutant than in wild-type plants, but at lower levels in 35S::GLYI2 35S::GLYII4 plants, consistent with the higher and lower MG accumulation and H3 methylglyoxalation of target genes in glyI2 and 35S::GLYI2 35S::GLYII4, respectively. Further, ABI3 and MYC2, regulators of salt stress responsive genes, affect the distribution of H3 methylglyoxalation at salt stress responsive genes. Thus, MG functions as a histone-modifying group associated with gene expression that links glucose metabolism and epigenetic regulation.
Salt-induced hydrogen peroxide promotes methylglyoxal accumulation to inhibit plant growth and stimulates sulfenylation of plastid triose phosphate isomerase.
Abstract
High salinity, an adverse ...environmental factor affecting about 20% of irrigated arable land worldwide, inhibits plant growth and development by causing oxidative stress, damaging cellular components, and disturbing global metabolism. However, whether and how reactive oxygen species disturb the metabolism of salt-stressed plants remain elusive. Here, we report that salt-induced hydrogen peroxide (H2O2) inhibits the activity of plastid triose phosphate isomerase (pdTPI) to promote methylglyoxal (MG) accumulation and stimulates the sulfenylation of pdTPI at cysteine 74. We also show that MG is a key factor limiting the plant growth, as a decrease in MG levels completely rescued the stunted growth and repressed salt stress tolerance of the pdtpi mutant. Furthermore, targeting CATALASE 2 into chloroplasts to prevent salt-induced overaccumulation of H2O2 conferred salt stress tolerance, revealing a role for chloroplastic H2O2 in salt-caused plant damage. In addition, we demonstrate that the H2O2-mediated accumulation of MG in turn induces H2O2 production, thus forming a regulatory loop that further inhibits the pdTPI activity in salt-stressed plants. Our findings, therefore, illustrate how salt stress induces MG production to inhibit the plant growth.
Given its promising electron transportation ability, excellent electrical conductivity, and larger work function (6.2 eV) disclosed by density functional theory calculations, MXene material, ...O-terminated Ti3C2 has the potential to serve as a perfect cocatalyst. Herein, a novel Ti3C2/SrTiO3 heterostructure based on partly superficial oxidation from precursor multilayered Ti3C2 is developed as a photocatalyst for efficiently photocatalytic reduction and removal of U(VI). Specifically, the composite of 2 wt % Ti3C2/SrTiO3 (0.02 Ti3C2/SrTiO3) exhibits an excellent photocatalytic UO2 2+ removal rate of 77%, which is nearly 38 times higher than that of the pristine SrTiO3. The enhanced photocatalytic performance of 0.02 Ti3C2/SrTiO3 is systematically identified by photoluminescence spectroscopy, UV–vis diffuse reflectance spectroscopy, Raman spectroscopy, and electrochemical characterizations. The multilayered Ti3C2 as a cocatalyst can facilitate the charge transportation and inhibit the recombination of electrons in the conduction band. This work establishes the enticing potential for developing doped perovskite oxide crystals based on the MXene Ti3C2 with sun-light responsivity for improving solar energy utilization.
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IJS, KILJ, NUK, PNG, UL, UM
Aging is an important risk factor in the occurrence of many chronic diseases. Senescence and exhaustion of adult stem cells are considered as a hallmark of aging in organisms. In this study, a ...senescent human amniotic mesenchymal stem cell (hAMSC) model subjected to oxidative stress was established in vitro using hydrogen peroxide. We investigated the effects of ganoderic acid D (GA-D), a natural triterpenoid compound produced from Ganoderma lucidum, on hAMSC senescence. GA-D significantly inhibited β-galactosidase (a senescence-associated marker) formation, in a dose-dependent manner, with doses ranging from 0.1 μM to 10 μM, without inducing cytotoxic side-effects. Furthermore, GA-D markedly inhibited the generation of reactive oxygen species (ROS) and the expression of p21 and p16 proteins, relieved the cell cycle arrest, and enhanced telomerase activity in senescent hAMSCs. Furthermore, GA-D upregulated the expression of phosphorylated protein kinase R- (PKR-) like endoplasmic reticulum kinase (PERK), peroxidase III (PRDX3), and nuclear factor-erythroid 2-related factor (NRF2) and promoted intranuclear transfer of NRF2 in senescent cells. The PERK inhibitor GSK2656157 and/or the NRF2 inhibitor ML385 suppressed the PERK/NRF2 signaling, which was activated by GA-D. They induced a rebound for the generation of ROS and β-galactosidase-positive cells and attenuated the differentiation capacity. These findings suggest that GA-D retards hAMSC senescence through activation of the PERK/NRF2 signaling pathway and may be a promising candidate for the discovery of antiaging agents.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Leveraging on the orchestrated application of both Schmidt and Yu glycosylations, the first total syntheses of the echinocystic acid saponins pithedulosides D and E, the two antitumoral and ...representative D‐ring‐functionalized oleanane‐type saponins, were achieved. Benefitting from the applied convergent synthetic strategy, the echinocystic acids could be synthesized in overall yields of as high as 71 and 76 % through four linear steps.
The first total syntheses of the bioactive echinocystic acid saponins pithedulosides D and E are achieved by a convergent strategy using glycoysyl trichloroacetimidate and a glycosyl ortho‐alkynylbenzoate as donors.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Objective * To investigate the effects of Moringa Oleifera Leaf Extract (MOLE) plus rosiglitazone (RSG) on glucose and lipid metabolism, serum leptin, and the Akt/GSK3β/β-Catenin signaling pathway in ...type 2 diabetic (T2D) rats. Methods * Sixty male Sprague-Dawley (SD) rats were randomly divided into six groups: the normal group, the model group, the RSG group, the low- and high-dose MOLE group, and the MOLE+RSG group. The normal group was fed a standard rat diet, while the other groups were given a single intraperitoneal injection of low-dose streptozomycin (STZ) (35 mg/kg) and fed a high-sugar and high-fat diet. After 8 weeks, the treatment outcomes were evaluated by measuring key parameters of blood glucose and lipid metabolism and the protein kinase B (AKT) / Glycogen synthase kinase 3beta (GSK3β /β-Catenin signaling pathway in the T2D rats. Results * Compared with the normal group, the model group showed significantly increased levels of blood glucose, blood lipids, serum leptin, free fatty acid (FFA), and tumor necrosis factor-α (TNF-α). Compared with the model group, the RSG, low-dose MOLE, and high-dose MOLE groups displayed effective control of blood glucose, blood lipids, serum leptin, FFA, and TNF-α. The MOLE+RSG group surpassed the RSG group in regulating glucose, lipid metabolism, and serum leptin levels in T2D rats. In addition, the MOLE+RSG group also had superiority over the RSG group in activating the AKT/ GSK3β/β-Catenin pathway. Conclusion * MOLE plus RSG can effectively reduce blood glucose and blood lipids in T2DM rats. (Altern Ther Health Med. 2023;29(8):650-655).
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