Monomeric Compounds Research Articles

Mechanism of miRNA-based Aconitum leucostomum Worosch. Monomer inhibition of bone marrow-derived dendritic cell maturation

Delvestidine (DLTD) is a monomeric compound isolated from Aconitum leucostomum Worosch, a widely used medicine for local treatment of rheumatoid arthritis (RA). Studies have shown that Aconitum leucostomum Worosch. can inhibit maturation of bone marrow-derived dendritic cells (BMDCs). Further, microRNAs (miRNAs) have regulatory effects on DC maturity and function. However, the mechanism underlying DLTD effects on DC maturity and RA remains to be elucidated. This study investigated whether DLTD-mediated inhibition of DC maturation is regulated by miRNAs. LPS-induced mature BMDCs were treated with DLTD for 48 h. CD80 and CD86 expression on BMDCs was detected by flow cytometry, and levels of inflammatory factors IL-6, IL-23, IL-1β, and TNF-α were detected by ELISA and PCR. Further, gene expression and miRNA expression profiles were investigated by bioinformatics analysis and verified by PCR. DLTD was found to inhibit CD80 and CD86 expression on the surface of BMDCs and secretion of inflammatory factors IL-6, IL-23, IL-1β, and TNF-α. In total, 54 differentially expressed miRNAs were detected, including 29 up-regulated and 25 down-regulated miRNAs after DLTD treatment. Analysis of biological information revealed that the differentially expressed target genes mainly regulated biological processes, including cell differentiation, cell cycle, and protein kinase complexes. Additionally, miR-511-3p downstream targets Calcr, Fzd10, and Eps8, were closely related to BMDCs maturation. DLTD may induce BMDCs maturity through regulation of miRNAs that affect Calcr, Fzd10, and Eps8 gene signals.

Selective cleavage of ether C-O bond in lignin-derived compounds over Ru system under different H-sources

Selective hydrogenolysis, the aromatic ether C-O bonds under mild conditions, is crucial for the valorization of lignin. In this context, the effects of H2 and solvent on the hydrogenolysis of lignin model compounds over Ru catalysts were explored. With H2 as hydrogen donor, the Ru/AC exhibited the highest activity for converting lignin model compounds into monomeric compounds, whereas H2 led to low selectivity of aromatics. However, isopropanol was the good H-donor solvent, which could provide a large amount of active hydrogen to promote the cleavage of C-O bonds. Additionally, the yield of aromatics in isopropanol was higher than that under H2 atmosphere. It could be ascribed to the fact that isopropanol is the protic solvent which displays Lewis basicity, and is a good H-bond donor and a good H-bond acceptor. The higher electron-releasing inductive effect of isopropanol made it easier to provide active hydrogen. Based on the experiments, the mechanism of benzyl phenyl ether hydrogenolysis in H2 and isopropanol system was presented.

Efficient energy transfer in phenyl-ethynyl-linked asymmetric BODIPY dimers

Abstract Three asymmetric boron dipyrromethene (BODIPY) dimers were synthesized via coupling of a BODIPY monomer with a meso-phenyl ethynyl group substituent to the different monomers with an iodine atom at the second position of the BODIPY core. The dimers were characterized by 1H, 13C, and 11B, 19F NMR spectroscopy and high-resolution mass spectrometry. Density functional theory calculations show minimal conjugation between the two BODIPY units in the dimers due to a large dihedral angle between the BODIPYs and the linker. Absorption and fluorescence measurements of monomeric and dimeric compounds in dichloromethane indicated highly efficient singlet-singlet energy transfer between two BODIPY units (in which the meso-phenyl containing BODIPY unit act as the donor while the other BODIPY unit is the acceptor) and large Stokes shifts. In particular, the dimer with the styryl BODIPY unit absorbs light in a wide range of the spectrum (325 nm–690 nm) with emission in the near IR region. The ethynyl thiophene linked dimer showed the highest fluorescence quantum yield (76%) of all three dimers investigated in this study.

The Influence of Redox-Active Linkers on the Stability and Physical Properties of a Highly Electroactive Porphyrin Nanoprism.

Redox-active metal-organic nanocages are of interest for many applications, but the development of cages with extensive redox activity is often hindered by their limited stability and solubility across multiple charge states. This report reveals that these properties can be tuned for cages with redox-active walls by incorporating additional redox activity into the linkers. In particular, new +12 charged triangular nanoprisms 1a,b were formed from three electroactive tetrakis(3-pyridyl)porphyrin walls linked by six [(TMEDA)Pt]2+ (for 1a) or [(2,2'-bipy)Pt]2+ (for 1b) vertices, the latter of which are also electroactive. Thus, 1b exhibits extensive redox activity, consisting of two porphyrin-centered (x3) and two 2,2'-bipy-centered (x6) reductions that provide reversible access to +12, +9, +3, 0, and -6 charge states, whereas 1a undergoes only two, porphyrin-centered (x3) reversible reductions. Comparisons of 1a and 1b (and monomeric control compounds) by cyclic voltammetry and UV-vis-NIR spectroelectrochemistry show that the redox-activity of the linkers in 1b lowers the second reduction potential of the porphyrins by 100 mV and improves the stability and solubility of this structure under highly reducing conditions (e.g., -2.25 V vs Fc+/0 in MeCN). These findings reveal new principles for controlling the properties of highly electroactive molecular nanostructures. Anion exchange rates (≫103 s-1) were also probed, showing that the narrow apertures (≤3 Å van der Waals width) of 1a,b do not impede the loss/gain of PF6- anions during redox processes.

Study of a renewable capping agent addition in lignin base catalyzed depolymerization process

The aim of this work was to study the influence of a renewable capping agent (CA) in the production of monomeric compounds from the depolymerization of an organosolv lignin (Pinus radiata) by a base catalyzed depolymerization (BCD) process. After the delignification process of the Pinus radiata sawdust, the lignin contained in the black liquor was subjected to a first mild depolymerization process, without using any catalyst, in order to obtain two different products: a lignin which was the feed in the subsequent BCD process and a phenolic oil which was used as CA in the same BCD process. This process was carried out at 230 °C in three consecutive cycles of 20 min using different amounts of capping agent dissolved in a 4% wt. NaOH solution with a lignin:solvent ratio of 1:20. The use of a renewable capping agent derived from lignin was effective not only in terms of phenolic oil production increasing but also in maximizing the monomeric phenolic compounds concentration. The use of CA: lignin ratio of 1:1 resulted the most effective with 10.64% of oil yield and almost 44% of monomeric phenolic compounds concentration while minimizing de undesired by-products yield.

Mechanochemical and Conventional Synthesis of Copper(II) Coordination Polymers Bearing Arylhydrazone of Acetoacetanilide and Their Catalytic Activity in Conversion of Acetone to Acetic Acid

AbstractCopper(II) coordination polymers, [Cu(μ2‐HL)]n⋅n(CH3)2C=O (1), [Cu(μ1‐HL)(CH3OH)]n (2) and [Cu(μ1‐HL)(H2O)]n (3) were isolated by recrystallization (in acetone, methanol and dimethylformamide, respectively) of an intermediate produced by a solid state ball milling reaction of CuCl2⋅2H2O with 2‐(2‐(1,3‐dioxo‐1‐(phenylamino)butan‐2‐ylidene)hydrazinyl)benzoic acid (H3L). Reaction under conventional fully solution‐based conditions of CuCl2⋅2H2O with H3L in acetone and dimethylformamide leads to 3, and in methanol to the known monomeric compound [Cu(HL1)(H2O)(CH3OH)] (4). All the coordination polymers 1−3 act as homogenous catalysts for the peroxidative (H2O2) oxidation of acetone to acetic acid with yields up to 50% and at room temperature.

Physicochemical and solution properties of quaternary-ammonium-salt-type amphiphilic gemini ionic liquids with spacers containing oxygen or nitrogen

Quaternary-ammonium-salt-type amphiphilic gemini compounds 2Cn(Spacer) NTf2 were synthesized by the quaternization of a tertiary diamine and an n-alkyl bromide, followed by an ion-exchange reaction with potassium bis(trifluoromethanesulfonyl)imide [(Spacer) = (2-O-2), (2-O-2-O-2), (2-N-2), (2/2-N-2), (2/2)-OH, (5), (6), and n represents the alkyl chain lengths; n = 10, 12, 14 for the 2-O-2 spacer, and n = 12 for all others]. The compounds with melting points below 100 °C were treated as ionic liquids during the subsequent measurements. The melting points of the amphiphilic gemini compounds could be arranged in the following order, based on the spacer present: (2/2)-OH >> 2/2-N-2 > (2-N-2) > (2-O-2) > (5) > (6) > (2-O-2-O-2). The melting points for 2Cn(2-O-2) NTf2 (n = 10, 12), 2C12(2-O-2-O-2) NTf2, and 2C12(2-N-2) NTf2 could be reduced to <0 °C. The amphiphilic gemini ionic liquids exhibited significantly lower conductivities and higher viscosities than the corresponding monomeric ionic liquids. This was attributed to a decrease in the mobility of the cationic molecules caused by the gemini structure, in which the two monomeric compounds are connected by a spacer. Furthermore, the amphiphilic gemini ionic liquids, particularly those containing oxygen in the spacer, exhibited efficient adsorption at the air/water interface.

Unlocking Structure-Reactivity Relationships for Catalytic Hydrogenolysis of Lignin into Phenolic Monomers.

Lignin depolymerization into aromatic monomers with high yields and selectivity is essential for the economic feasibility of biorefinery. However, the relationship between lignin structure and its reactivity for upgradeability is still poorly understood, in large part owing to the difficulty in quantitative characterization of lignin structural properties. To overcome these shortcomings, advanced NMR technologies [2D HSQC (heteronuclear single quantum coherence) and 31 P] were used to accurately quantify lignin functionalities. Diverse lignin samples prepared from Eucalyptus grandis with varying β-O-4 linkages were subjected to Pd/C-catalyzed hydrogenolysis for efficient C-O bond cleavage to achieve theoretical monomer yields. Strong correlations were observed between the yield of monomeric aromatic compounds and the structural features of lignin, including the contents of β-O-4 linkages and phenolic hydroxyl groups. Notably, a combined yield of up to 44.1 wt % was obtained from β-aryl ether rich in native lignin, whereas much lower yields were obtained from technical lignins low in β-aryl ether content. This work quantitatively demonstrates that the lignin reactivity for acquiring aromatic monomer yields varies depending on the lignin fractionation processes.

Catalytic hydrogenolysis of native and organosolv lignins of aspen wood to liquid products in supercritical ethanol medium

Catalytic hydrogenolysis in the medium of supercritical organic solvents is a promising way of wood lignins depolymerization into liquid products.In this study, for the first time, the catalytic properties of bifunctional catalysts Ru/C, Pt/ZrO2, NiCuMo/SiO2, containing nanosized metal particles on acidic groups are compared in the processes of aspen wood and ethanol lignin hydrogenolysis in supercritical ethanol.The most active catalysts are Ru/C and Pt/ZrO2 which provide the high conversion of wood (to 78.0 wt%), significant yield of liquid products (to 50.6 wt%) and low yield of solid rest (to 22.0 wt%) at temperature 250 °C and H2 pressure 9.0 MPa. These catalysts increase the yield of monomeric compounds in liquid products from 10.5 % to 50.4 % on mass of lignin.GC–MS analysis shows that alkyl derivatives of methoxyphenols (mainly propyl syringol and propyl guaiacol) are dominated in liquid products. Solid products of aspen wood catalytic hydrogenolysis contain mainly cellulose (to 82.2 wt%). Therefore, the catalytic hydrogenolysis in supercritical ethanol in the presence of by functional catalysts Ru/C and Pt/ZrO2 allows to fractionate the aspen wood biomass on cellulose and liquid products enriched with propyl syringol and propyl guaiacol.In catalytic hydrogenolysis of ethanol lignin the yield of alkyl derivatives of methoxyphenols is lower compared to wood. This is probably due to the reduced content of reactive β-O-4 bonds in the structure of ethanol lignin compared to native lignin of aspen wood. As follows from the results obtained, native lignin of wood is easier depolymerized to monomeric compounds in the process of catalytic hydrogenolysis than ethanol lignin, isolated from wood.According to GPC data, the catalysts shift to the region of lower molecular mass the molecular mass distribution of liquid products of aspen wood and ethanol lignin hydrogenolysis.

Production of phenolic chemicals from hydrolysis lignin via catalytic fast pyrolysis

Catalytic fast pyrolysis of hydrolysis lignin was investigated in a drop-tube fixed bed reactor at different temperatures ranging between 400–800 °C using zeolite X as a catalyst for the production of phenolic chemicals. The yield of low molecular weight monomeric phenolics increased considerably while increasing the pyrolysis temperature from 400 °C to 450 °C, but decreased with further increasing the pyrolysis temperature. Zeolite X remarkably increased the yield of monomeric phenolic compounds in the catalytic fast pyrolysis of hydrolysis lignin at all temperatures (400–800 °C) compared to fast pyrolysis. No significant changes were observed in the catalyst properties (crystallinity and textural structure) during fast pyrolysis of lignin. The superb activity of the zeolite X catalyst might be owing to its strong acidity and low pore volume. Under the best reaction conditions tested in this study (450 °C, with zeolite X catalyst), the bio-oil yield was 50.5% in relation to the dry lignin, and the content of monomeric phenolics (mainly guaiacol, syringol, 4-methoxy-3-(methoxymethyl) phenol and metoxyeugenol) was 146.2 mg/g of bio-oil.

Light induced intramolecular energy and electron transfer events in carbazole–corrole and phenothiazine-corrole dyads

We report two corrole based donor–acceptor (D–A) dyads, Cbz-Cor and Ptz-Cor to understand the energy/electron transfer reactions. In these D–A systems, the donor, either carbazole (Cbz) or phenothiazine (Ptz), is covalently connected at the meso-phenyl position of 10-(phenyl)-5,15-bis-(pentafluorophenyl)corrole (Ph-Cor) by C–N linkage. Both the dyads were characterized by 1H NMR, MALDI-TOF MS, UV-vis, electrochemical, computational methods, study state fluorescence and TCSPC techniques. A comparison of absorption spectra with their reference monomeric compounds (Cbz-Ph, Ptz-Ph and Ph-Cor) revealed minimal ground-state interactions between chromophores in both dyads. Fluorescence studies suggested that singlet–singlet energy transfer from 1Cbz* to corrole is the major photochemical pathway in the Cbz-Cor dyad with a quenching efficiency of [Formula: see text]99%. Detailed analysis of the data suggests that Forster’s dipole–dipole mechanism does not adequately explain this energy transfer. However, at a 410 nm excitation, florescence quenching is detected in Ptz-Cor (49%) supporting a photo induced electron transfer (PET) process from the ground state of PTZ to the excited state of corrole macrocycle. The electron-transfer rates ([Formula: see text] of Ptz-Cor are found in the range [Formula: see text] to [Formula: see text] and are concluded to be solvent dependent.

Electrochemical Polymer and Polymer Additive Synthesis from Biobased Vanillin and Syringaldehyde

In recent years the field of biobased polymers and materials has drawn much attention due to oil depletion and environmental concerns regarding petrochemical processes [1, 2]. Lignin is the world’s second most abundant renewable biopolymer. In comparison to cellulose, the most abundant biopolymer, the potential of lignin is sparsely valorized. Currently, lignin is considered as a waste stream in the pulp and paper industry and is used almost only energetically on a 107 ton per year scale [3, 4]. However, recent findings showed that lignin can be electrochemically depolymerized selectively to the monomeric compounds vanillin and syringaldehyde [5]. Due to lignin’s abundance and good mechanical as well as thermal behavior of the depolymerization products, they have the potential to become key intermediates in the field of high performance biobased polymers and polymer additives [6].Cathodic pinacolization of these monomers offers a green and CO2-neutral pathway for controlled molecular weight increase, leading to attractive bi- or multifunctional phenolic compounds for polymeric applications [7]. Feasibility studies of the electrochemical synthesis of hydrovanilloin [8] and polyvanillin [9] at lead electrodes by pinacolization of vanillin and divanillin showed already promising results. Herein, we investigated the cathodic pinacolization of the lignin monomers vanillin and syringaldehyde as well as polyvanillin synthesis from divanillin in detail.First, the electrochemical hydrodimerization of vanillin and syringaldehyde (equation 1) in alkaline aqueous solution was studied in an H-type cell investigating electrode material, current density and applied charge. The electrochemical reduction of vanillin was monitored by capillary electrophoresis with diode array detection (CE-DAD). The electrode materials lead, zinc and glassy carbon were investigated. We found that zinc can replace the currently used toxic electrode material lead with almost same reaction rates, product distribution and yields up to 72 % of isolated dimer. Electrode degradation was found for lead, whereas zinc and glassy carbon remained stable. The pinacolization product hydrovanilloin was found as the main product for all three electrode materials at current densities of 30 mA cm-2 in alkaline aqueous solution. However, also significant amount of vanillyl alcohol production was found at glassy carbon at 30 mA cm-2 increasing with higher current densities. Only a slight increase of vanillyl alcohol production was found at lead at higher current densities and no increase was found at zinc. We assume cathodic depolarization at zinc and lead electrodes by the competing hydrogen evolution reaction, hindering the potential to drop lower and thus suppressing vanillyl alcohol production. For syringaldehyde equal yields of 72 % were obtained for the dimeric pinacolization product 1,2-Bis(4-hydroxy-3,5-dimethoxyphenyl)glykol. However, the reaction temperature had to be increased from room temperature to 60 °C due to solubility reasons. Solid products were characterized via several methods, e.g. HPLC-DAD-MS, FT-IR, 1H-NMR and 13C-NMR.Further, polyvanillin was electrochemically synthesized at zinc electrodes by pinacolization of divanillin, which had been produced by enzymatic conversion of vanillin with horse-radish peroxidase (equation 2). The degree of polymerization of the isolated biopolymer was monitored via gel permeation chromatography (GPC). Weight average molecular weights up to 3292 g mol-1 were achieved. Changing the current densities for the polymerization showed no difference in the molecular weight distribution upon full divanillin conversion. The polymer was further characterized by several methods, e.g. FT-IR, TGA and DSC, confirming its structure and good thermal behavior.

Exploring the reactivity of α-Acetamidocinnamic acid and 4-Phenylpyridine with Zn(II) and Cd(II)

The synthesis and characterization of four new coordination complexes is presented. Two of them have been obtained by reaction between M(OAc)2·2H2O (M = Zn(II), Cd(II)) and α-acetamidocinnamic acid (HACA) yielding two isostructural monomeric compounds with general formula [M(ACA)2(H2O)2] (M = Zn(II) (1), Cd(II) (2)). In opposite, the reactivity of 1 and 2 with 4-phenylpyridine (4-Phpy) leads to a monomeric [Zn(4-Phpy)2(ACA)2(H2O)2]·3H2O (3) or a dimeric compound [Cd(4-Phpy)2(µ-ACA)(ACA)]2·2EtOH (4). All of them have been characterised by analytical and spectroscopic techniques. In addition, single crystals of 1–4 for X-ray diffraction analysis have been obtained and their intra- and intermolecular interactions have been discussed and studied by Hirshfeld surface analysis, showing 3D supramolecular networks for all the compounds. In addition, the thermal stability of 3 and 4 has been studied. Finally, the photoluminescence properties of 1–4 have been examined, and their quantum yields calculated.

Optimization of extraction for Anemarrhena asphodeloides Bge. using silica gel-based vortex-homogenized matrix solid-phase dispersion and rapid identification of antioxidant substances.

A novel and simple method was established for the extraction and determination of seven compounds in Anemarrhena asphodeloides Bge. using silica gel-based vortex-homogenized matrix solid-phase dispersion and ultra-high performance liquid chromatography quadrupole-time of-flight mass spectrometer. The conditions for the extraction were optimized. Silica gel was used as the dispersant, 50% methanol-water was selected as an elution solvent and the grinding time was 3min. Compared with the traditional ultrasonic-assisted extraction, the developed method was rapid and efficient. In order to screen potential antioxidants, extract dealing with the optimized method was applied to a polyamide chromatography column and a D-101 macroporous resin column. Fr.2.2 showed the highest antioxidant activities with the most content of flavonoid. A total of 25 peaks were identified from the active fraction. A 2,2'-diphenyl-1-picrylhydrazyl ultra-high performance liquid chromatography coupled with mass spectrometry approach was adopted for the rapid and exact screening and identification of antioxidant compounds. It indicated that flavonoids exhibited potential antioxidant activities. The antioxidant activities of nine monomeric compounds in vivo were tested. Structure-activity relationships were discussed. Five flavonoids with the concentration of 500 µg/mL would reduce the oxidative stress of PC12 cells that were induced with 2,2'-azobis[2-methylpropionamidine] dihydrochloride.

Solvent-triggered single-crystal-to-single-crystal transformation from a monomeric to polymeric copper(II) complex based on an aza macrocyclic ligand.

Reversible solvent-triggered single-crystal-to-single-crystal (SCSC) transformations are observed between two copper(II) azamacrocyclic complexes: [Cu(C16H38N6)(H2O)2](C12H6O4) (1) and [Cu(C16H38N6)(C12H6O4)] (2). Complex (1) was prepared via self-assembly of a copper(II) azamacrocyclic complex containing butyl pendant groups, [Cu(C16H38N6)(ClO4)2], with 2,7-naphthalenedicarboxylic acid. When monomeric compound (1) was immersed in CH3OH, coordination polymer (2) was obtained, indicating a solvent-triggered SCSC transformation. Furthermore, when (2) was immersed in water, an reverse SCSC transformation from (2) to (1) occurred. Complex (1) presents a 3D supramolecular structure formed via intermolecular hydrogen-bonding interactions, whereas complex (2) features a 1D zigzag coordination polymer. The reversible SCSC transformation of (1) and (2) was characterized using single-crystal X-ray diffraction and in situ powder X-ray diffraction techniques. Despite its poor porosity, complex (2) displayed interesting CO2 adsorption behaviour under CO2 gas.

β-elemene suppresses the malignant behavior of esophageal cancer cells by regulating the phosphorylation of AKT

BackgroundEsophageal cancer is a digestive tract malignancy, ranking sixth among the world's deadliest tumor incidence. However, the pathogenesis of esophageal cancer is complex and the prognosis remains poor. Therefore, in-depth study of the pathogenesis and developing effective treatments are of great value for esophageal cancer. β-elemene is a natural monomeric compound derived from the Chinese herbal Curcuma wenyujin. β-elemene has been reported to have anti-tumor effects and used as an adjunct to clinical therapy for multiple cancers. This study aims to explore the effects of β-elemene on esophageal cancer and its related molecular mechanisms. MethodsTE-1 and KYSE-150 cells were used to evaluate the activity of β-elemene on esophageal cancerin vitro and in vivo. Western blot was performed for protein expression assessment. CCK8 assay and cell cycle analysis were used for proliferation testing. Flow cytometry was performed for apoptosis detection. Wound healing assay was subjected to assess the migration ability. Transwell chamber assay was applied to assess the invasion ability. HE staining, TUNEL staining and immunohistochemical staining were used to evaluate the changes in tumor tissues. ResultsWe found that β-elemene treatment suppressed proliferation, as well as induced apoptosis of esophageal cancer cells. In addition, β-elemene inhibited the migration and invasion ability of esophageal cancer cells. Furthermore, β-elemene exerted its effects against esophageal cancer by specifically regulating AKT signaling, thereby controlling the expression of PD-L1. Conclusionβ-elemene inhibits proliferation and metastasis of esophageal cancer cells by regulating the phosphorylation of AKT.

Panaxadiol inhibits programmed cell death-ligand 1 expression and tumour proliferation via hypoxia-inducible factor (HIF)-1α and STAT3 in human colon cancer cells

Panaxadiol is a triterpenoid sapogenin monomeric compound found in the roots of Panax ginseng and has a variety of biological activities such as neuroprotective and anti-tumour functions. However, the mechanisms how panaxadiol exerts the anticancer effects remain unknown. The current study aimed to investigate the potential activity of panaxadiol on programmed cell death-ligand 1 (PD-L1) expression and tumour proliferation in human colon cancer cells and to identify the underlying mechanism. Results showed that panaxadiol showed little cytotoxicity as assessed by a cytotoxicity assay and significantly inhibited PD-L1 expression at the protein and mRNA level in a dose-dependent manner. Furthermore, panaxadiol supressed the hypoxia-induced synthesis of hypoxia-inducible factor (HIF)-1α via the phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways without affecting HIF-1α degradation. Simultaneously, panaxadiol inhibited STAT3 activation through the JAK1, JAK2, and Src pathways. Moreover, pre-treatment with panaxadiol enhanced the activity of cytotoxic T lymphocytes (CTL) and regained their capacity of tumour cell killing in a T cell and tumour cell co-culture system. Immunoprecipitation showed that panaxadiol inhibited PD-L1 expression by blocking the interaction between HIF-1α and STAT3. The inhibitory effect of panaxadiol on tumour proliferation was further demonstrated by colony formation and EdU labelling assays. The anti-proliferative effect of panaxadiol was also proved by a xenograft assay in vivo. Taken together, the current work highlights the anti-tumour effect of panaxadiol, providing insights into development of cancer therapeutic through PD-L1 inhibition.

Monomeric and dimeric nitrate lanthanide(III) and yttrium(III) coordination compounds of (2 + 2) imine macrocycle derived from 2,6-diformylpyridine and trans-1,2-diaminocyclopentane

Monomeric nitrate coordination compounds [Ln(L1)](NO3)3·nH2O (Ln = Y(III), Tm(III), Yb(III) and Lu(III)); n = 0, 0.75 or 3)11For simplicity of description we included the Y(III) in the abbreviation of Ln(III), commonly reserved for lanthanide(III) ions. It is well known that although yttrium does not belong to the lanthanides, the ionic radius of the Y(III) cation is similar to ionic radii of lanthanide(III) cations. Y(III) coordination compounds resemble very much in their chemical properties those of the respective lanthanide(III) coordination compounds. of the chiral macrocyclic (2 + 2) imine L1 (L1RRRR, L1SSSS and/or L1rac), derived from enantiomerically pure or racemic trans-1,2-diaminocyclopentane (DACP) and 2,6-diformylpyridine (DFP), have been synthesized in the templated condensation of precursors in the presence of appropriate metal salts. From these monomers their homochiral μ-hydroxodimers [Ln2(L1)2(μ-OH)2](NO3)4·nH2O (Ln = Y(III), Tm(III), Yb(III) and Lu(III)); n = 4, 5 or 7) have been obtained and isolated by addition of NaOH to the respective monomeric form of coordination compound solution. All synthesized coordination compounds have been characterized by NMR spectroscopy, mass spectrometry, elemental analyses and/or circular dichroism (CD). 1H NMR signals of CDCl3/CD3OD solutions of the diamagnetic Y(III) and Lu(III) monomers have been assigned on the basis of their COSY and HMQC spectra, and for the remaining paramagnetic lanthanide coordination compounds (Tm(III) and Yb(III)) the signals were tentatively assigned on the basis of linewidths analyses. 1H NMR signals of D2O solutions of diamagnetic Y(III) and Lu(III) representatives of dimeric species have been established taking into account their COSY, HMQC, HMBC and NOESY spectra. The NOESY spectra confirm that the structure of the dimmers observed in solids is also maintained in a solution.The axial ligand exchange in all monomeric coordination compounds was investigated by 1H NMR titration experiments with acetate and chloride anions in organic solvents as well as with hydroxide anion in D2O. The formation of homochiral heterobimetallic μ-hydroxodimers [Ln’Ln”(L1)2(μ-OH)2](NO3)4 was investigated in a solution by mixing the solutions of two different [Ln’2(L1)2(μ-OH)2](NO3)4·nH2O and [Ln”2(L1)2(μ-OH)2](NO3)4·nH2O homochiral homobimetallic precursors. This experiment proves the chiral recognition between two macrocyclic units of the same chirality in a solution. The μ-hydroxodimers may convert with time to the corresponding peroxo-dimers of the general formula [Ln2(L1)2(μ-η2: η2-O2)](NO3)4.The X-ray crystal structures of the representative monomeric and dimeric coordination compounds [Yb(L1RRRR)(NO3)2]NO3, [Yb2(L1SSSS)2(OH)2(H2O)2](NO3)4·2MeOH·2H2O, [Yb2(L1RRRR)2(OH)2(H2O)2][Yb2(L1SSSS)2(OH)2(H2O)2](NO3)8·1.5MeOH·5H2O and [Y2(L1SSSS)2(O2)(NO3)2](NO3)2·2MeOH with enantiomerically pure or racemic ligand L1 have been determined. The structure of [Yb2(L1RRRR)2(OH)2(H2O)2][Yb2(L1SSSS)2(OH)2(H2O)2] (NO3)8·1.5MeOH·5H2O crystal confirms chiral recognition of macrocyclic units of the same chirality in solids.

Comparison of phenolic substances and antioxidant activities in different varieties of chrysanthemum flower under simulated tea making conditions

Chrysanthemum flowers are rich in phenolic substances. The chrysanthemum flower tea (CT) obtained by simulating the process of hot water brewing as the research object and 80% methanol aqueous extract (ME) as the controls to explore the composition of phenolic compounds and antioxidant capacities of five varieties of chrysanthemum flowers including Xueju, Taiju, Hangbaiju, Gongju and Jinzhanju. Nine phenolic compounds including p-hydroxybenzoic acid, catechin, vanillic acid, caffeic acid, syringic acid, epicatechin, p-coumaric acid, ferulic acid and sinapic acid were initially identified and quantified by using high-performance liquid chromatography with diode-array detection (HPLC-DAD). The content of catechin in Xueju, Taiju, Hangbaiju, Gongju and Jinzhanju was 45.6, 50.9, 51.8, 55.0 and 53.2 µg/g, respectively, which is the highest among the nine monomeric phenolic compounds. The Xueju variant had the largest total phenolic content of 123.7 mg gallic acid equivalent (GAE)/g and total flavonoid content of 92.5 catechin equivalent (CE)/g when compared to other cultivars, which was also consistent with the results from the HPLC-DAD measurements. After 15 min of simulated brewing, the DPPH radical eliminating ability of different varieties of CT was higher than that of the ME which corresponded with the FRAP results. The process of tea making improves the bioactive component and antioxidant activity of the chrysanthemum flower.

Nostotrebin 6 Related Cyclopentenediones and δ-Lactones with Broad Activity Spectrum Isolated from the Cultivation Medium of the Cyanobacterium Nostoc sp. CBT1153

Cyanobacteria are an interesting source of biologically active natural products, especially chemically diverse and potent protease inhibitors. On our search for inhibitors of the trypanosomal cysteine protease rhodesain, we identified the homodimeric cyclopentenedione (CPD) nostotrebin 6 (1) and new related monomeric, dimeric, and higher oligomeric compounds as the active substances in the medium extract of Nostoc sp. CBT1153. The oligomeric compounds are composed of two core monomeric structures, a trisubstituted CPD or a trisubstituted unsaturated δ-lactone. Nostotrebin 6 thus far has been the only known cyanobacterial CPD. It has been found to be active in a broad variety of assays, indicating that it might be a pan-assay interference compound (PAIN). Thus, we compared the antibacterial and cytotoxic activities as well as the rhodesain inhibition of selected compounds. Because a compound with a δ-lactone instead of a CPD core structure was equally active as nostotrebin 6, the bioactivities of these compounds seem to be based on the phenolic substructures rather than the CPD moiety. While the dimers were roughly equally potent, the monomer displayed slightly weaker activity, suggesting that the compounds show unspecific activity depending upon the number of free phenolic hydroxy groups per molecule.