Chemical stability of carboxylpyranocyanidin-3-O-glucoside under ß-glucosidase treatment and description of their interaction.

Anthocyanins are susceptible to degradation by ß-glycosidase, resulting in color loss. This study analyzed the impact of ß-glycosidase on carboxylpyranocyanidin-3-O-glucoside (Carboxyl-pycy-3-gluc) and its precursor cyanidin-3-O-glucoside (Cy-3-gluc). Carboxyl-pycy-3-gluc exhibited enhanced stability upon treatment with ß-glucosidase. Ultraviolet-visible and circular dichroism spectroscopy revealed slight changes in the microenvironment and secondary structure of ß-glycosidase when carboxyl-pycy-3-gluc was present. The fluorescence experiment indicated that anthocyanins quench the fluorescence of ß-glycosidase through static quenching via hydrophobic interactions. Molecular docking of six types of carboxylpyranoanthocyanins and their precursors with ß-glycosidase revealed that carboxylpyranoanthocyanins exhibited lower binding affinity than their precursors, consistent with the enzyme kinetic experiment results. The incorporation carboxyl-pycy-3-gluc into Sanhua Plum Juice and Wine endowed them with vivid and stable coloration. The study illustrated that carboxyl-pycy-3-gluc exhibits low binding affinity with ß-glycosidase, thereby maintaining stability and confirming its potential as a colorant.

Vitisin A, as a Type of Pyranoanthocyanin, Suppresses Inflammation by Restricting Hematopoietic Stem Cell Differentiation toward Monocytes in Bone Marrow.

Hematopoietic stem and progenitor cells (HSPCs) could be differentiated into mature myeloid and lymphoid cells, maintaining the requirements of immune cells. Atherosclerosis and ulcerative colitis (UC) drive HSPC homeostasis destruction, which triggers expansive HSPC proliferation and Ly6Chi monocyte production, contributing to aggravated inflammation. Vitisin A belongs to the anthocyanin derivatives with excellent stability and bioactivity in vitro. However, there is no report about the anti-inflammation of Vitisin A via reprogramming HSPC differentiation toward monocytes. In this study, we found that Vitisin A presents anti-inflammatory ability during the development of atherosclerosis and UC by depressing Ly6Chi monocyte production from bone marrow. This performance depended on restricted HSPC differentiation, which suggested that Vitisin A participated in monocyte generation and carried out the immunomodulation. Together, Vitisin A ameliorates inflammation during atherosclerosis and UC via the suppressed differentiation of HSPCs toward monocytes, which could be considered an ideal functional component with immunomodulatory effects.

Theabrownin from Dark Tea Ameliorates Insulin Resistance via Attenuating Oxidative Stress and Modulating IRS-1/PI3K/Akt Pathway in HepG2 Cells.

Dark tea has great potential in regulating glycolipid metabolism, and theabrownin (TB) is considered to be the characteristic and bioactive constituent of dark tea. This study evaluated the ability of TB1 (fermented for 7 days) and TB2 (fermented for 14 days) isolated from dark tea to reverse insulin resistance (IR) in HepG2 cells. The results indicated that TB significantly ameliorated oxidative stress by improving mitochondrial function. In addition, TB improved glycogen synthesis and glucose consumption, and inhibited gluconeogenesis and fatty acid synthesis, by regulating GSK3ß (Glycogen synthase kinase 3ß), G6Pase (Glucose-6-phosphatase), GCK (Glucokinase), PEPCK1 (Phosphoenolpyruvate carboxy kinase 1), SREBP-1C (sterol regulatory element-binding protein 1C), FASN (fatty acid synthase), and ACC (Acetyl-CoA carboxylase). Additionally, the results of Western blot and real-time PCR experiments demonstrated that TB modulated glucolipid metabolism through the IRS-1 (Insulin receptor substrate 1)/PI3K (phosphatidylinositol-3 kinase)/Akt (protein kinase B) signaling pathway. Treatment with the PI3K inhibitor demonstrated a favorable correlation between PI3K activation and TB action on glycolipid metabolism. Notably, we observed that TB2 had a greater effect on improving insulin resistance compared with TB1, which, due to its prolonged fermentation time, increased the degree of oxidative polymerization of TB.

Cholesterol-Lowering Activity of Vitisin A Is Mediated by Inhibiting Cholesterol Biosynthesis and Enhancing LDL Uptake in HepG2 Cells.

Pyranoanthocyanins have been reported to possess better chemical stability and bioactivities than monomeric anthocyanins in some aspects. The hypocholesterolemic activity of pyranoanthocyanins is unclear. In view of this, this study was conducted to compare the cholesterol-lowering activities of Vitisin A with the anthocyanin counterpart Cyanidin-3-O-glucoside(C3G) in HepG2 cells and to investigate the interaction of Vitisin A with the expression of genes and proteins associated with cholesterol metabolism. HepG2 cells were incubated with 40 µM cholesterol and 4 µM 25-hydroxycholeterol with various concentrations of Vitisin A or C3G for 24 h. It was found that Vitisin A decreased the cholesterol levels at the concentrations of 100 µM and 200 µM with a dose-response relationship, while C3G exhibited no significant effect on cellular cholesterol. Furthermore, Vitisin A could down-regulate 3-hydroxy-3-methyl-glutaryl coenzyme A reductase (HMGCR) to inhibit cholesterol biosynthesis through a sterol regulatory element-binding protein 2 (SREBP2)-dependent mechanism, and up-regulate low-density lipoprotein receptor (LDLR) and blunt the secretion of proprotein convertase subtilisin/kexin type 9 (PCSK9) protein to promote intracellular LDL uptake without LDLR degradation. In conclusion, Vitisin A demonstrated hypocholesterolemic activity, by inhibiting cholesterol biosynthesis and enhancing LDL uptake in HepG2 cells.

Platinum atomic clusters embedded in polyoxometalates-carbon black as an efficient and durable catalyst for hydrogen evolution reaction.

Platinum-based catalysts are regarded as the Holy Grail of hydrogen evolution reaction (HER). As a benchmark catalyst for HER, the commercial Pt/C catalyst has low Pt utilization efficiency and high cost, which hinders its commercialization. Atomic clusters-based catalysts show high efficiency of atom utilization and high performance toward electrocatalysis. Herein, an environmentally friendly preparation strategy is proposed to construct Pt atomic clusters on the polyoxometalates-carbon black (Pt-POMs-CB) support. Density functional theory (DFT) calculations reveal that the Pt clusters can be stably anchored on the surface with the driving force arising from the charge transfer from Pt atoms to O atoms of the POMs. Benefiting from metal-support interaction, Pt atomic clusters embedded in silicotungstic acid-carbon black (Pt-STA-CB) exhibit excellent HER activity with an overpotential of 33.8 mV at 10 mA cm-2, and high mass activity is 1.62 A mg-1Pt at 33.8 mV, which is 5.4 times that of the commercial Pt/C. In addition, the catalyst displays high stability of 800 h at current density of 500 mA cm-2. It provides a platform for facile and low-cost preparation of stable Pt-based catalysts, which is crucial for their large-scale production and practical application in the industry.

FeCo Nanoparticles Encapsulated in N-Doped Carbon Nanotubes Coupled with Layered Double (Co, Fe) Hydroxide as an Efficient Bifunctional Catalyst for Rechargeable Zinc-Air Batteries.

Low-cost bifunctional nonprecious metal catalysts toward oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are critical for the commercialization of rechargeable zinc-air batteries (ZABs). However, the preparation of highly active and durable bifunctional catalysts is still challenging. Herein, an efficient catalyst is reported consisting of FeCo nanoparticles embedded in N-doped carbon nanotubes (FeCo NPs-N-CNTs) by an in situ catalytic strategy. Due to the encapsulation and porous structure of N-doped carbon nanotubes, the catalyst shows high activity toward ORR and excellent durability. Furthermore, to enhance the OER activity, CoFe-layer double hydroxide (CoFe-LDH) is coupled with FeCo NPs-N-CNTs by in situ reaction approach. As the air electrode for rechargeable ZABs, the cell with CoFe-LDH@FeCo NPs-N-CNTs catalyst exhibits high open-circuit potential (OCP) of 1.51 V, high power density of 116 mW cm-2 , and remarkable durability up to 100 h, demonstrating its great promise for the practical application of the rechargeable ZABs.

Pyrene derivative-functionalized mesoporous silica-Cu2+ hybrid ensemble for fluorescence "turn-on" detection of H2S and logic gate application in aqueous media.

The ensemble system PyH-SBA-15-Cu2+ was obtained via coordination interaction of pyrene derivative-functionalized mesoporous SBA-15 and Cu2+, and applied for the selective and sensitive detection of H2S over pH 6.0-12.0 in aqueous media. The sensing strategy was designed on the basis of the H2S-induced dissolution of Cu2+ from PyH-SBA-15-Cu2+. Cu2+ has good binding affinity to N atoms in PyH-SBA-15; therefore, the organic-inorganic hybrid ensemble PyH-SBA-15-Cu2+ was formed, which is nonfluorescent in aqueous solution because of the Cu2+-promoted emission quenching of PyH-SBA-15. The addition of H2S induces the dissolution of PyH-SBA-15-Cu2+ by the formation of stable CuS, thereby producing fluorescence revival of PyH-SBA-15. The correlative "turn-on" fluorescence signals of this ensemble system are linearly proportional to [H2S] in the concentration region of 0-1.0 × 10-4 M, showing a low detection limit of 3.7 × 10-7 M. Other common anions do not induce distinct fluorescence changes. When using the fluorescence intensity signal changes of PyH-SBA-15 as outputs and Cu2+ and S2- as inputs, PyH-SBA-15 can act as an XNOR logic gate.

A green and efficient technology for the degradation of cellulosic materials: structure changes and enhanced enzymatic hydrolysis of natural cellulose pretreated by synergistic interaction of mechanical activation and metal salt.

A new technology for the pretreatment of natural cellulose was developed, which combined mechanical activation (MA) and metal salt treatments in a stirring ball mill. Different valent metal nitrates were used to investigate the changes in degree of polymerization (DP) and crystallinity index (CrI) of cellulose after MA+metal salt (MAMS) pretreatment, and Al(NO3)3 showed better pretreatment effect than NaNO3 and Zn(NO3)2. The destruction of morphological structure of cellulose was mainly resulted from intense ball milling, and the comparative studies on the changes of DP and crystal structure of MA and MA+Al(NO3)3 pretreated cellulose samples showed a synergistic interaction of MA and Al(NO3)3 treatments with more effective changes of structural characteristics of MA+Al(NO3)3 pretreated cellulose and substantial increase of reducing sugar yield in enzymatic hydrolysis of cellulose. In addition, the results indicated that the presence of Al(NO3)3 had significant enhancement for the enzymatic hydrolysis of cellulose.

Novel crosslinked membranes based on sulfonated poly(ether ether ketone) for direct methanol fuel cells.

Novel covalently crosslinked membranes based on sulfonated poly(ether ether ketone) and carboxylated polysulfone exhibit much lower methanol crossover and better performance in direct methanol fuel cells at 65 °C in 1 and 2 M methanol solutions compared to Nafion 115 membranes.