A Novel Polyfunctional Polyurethane Acrylate Derived from Castor Oil-Based Polyols for Waterborne UV-Curable Coating Application.

Because of its unique molecular structure and renewable properties, vegetable oil has gradually become the focus of researchers. In this work, castor oil was first transformed into a castor oil-based triacrylate structure (MACOG) using two steps of chemical modification, then it was prepared into castor oil-based waterborne polyurethane acrylate emulsion, and finally, a series of coating materials were prepared under UV curing. The results showed that with the increase in MACOG content, the glass transition temperature of the sample was increased from 20.3 °C to 46.6 °C, and the water contact angle of its surface was increased from 73.85 °C to 90.57 °C. In addition, the thermal decomposition temperature, mechanical strength, and water resistance of the samples were also greatly improved. This study not only provides a new idea for the preparation of waterborne polyurethane coatings with excellent comprehensive properties but also expands the application of biomass material castor oil in the field of coating.

Assessment of the Binding of Pseudallecin A to Human Serum Albumin with Multi-Spectroscopic Analysis, Molecular Docking and Molecular Dynamic Simulation.

The binding of pseudallecin A (PA), a potential antibiotic with strong inhibitory activities against Gram-positive Escherichia coli and Gram-negative Staphylococcus aureus, to human serum albumin (HSA) was explored. The interaction between them was assessed by multi-spectroscopic analysis, binding site competitive analysis, molecular docking and molecular dynamic simulation, showing the results as follows: PA effectively quenched the innate fluorescence of HSA by a static quenching process, formed a complex at a molar ratio of approximately 1 : 1 and performed an effective non-radiative energy transfer; the binding of PA to HSA was a spontaneous exothermic reaction driven by enthalpy with strong affinity and had a slight effect on the conformation of HSA; PA bound at site III of HSA and hydrogen bonds were the major binding forces to maintain the stability of the PA-HSA complex. Molecular dynamic simulation was performed to calculate the root mean square deviation (RMSD), root mean square fluctuation (RMSF) and radius of gyration (Rg) for this complex and effectively supported the spectroscopic outcome. These results meant that the delivery and distribution of PA as a water-insoluble molecule can be efficiently accomplished via HSA in human blood and, it has a good potential for future drug application and pharmacological development.

[Metabolites of endophytic fungus Nigrospora sphaerica S5 from Myoporum bontioides].

The endophytic fungus Nigrospora sphaerica S5 derived from the semi-mangrove plant Myoporum bontioides was fermented. Its metabolites were purified by column chromatography. Nine compounds were obtained and identified as terezine P(1), 3-(1-hydroxyethyl)-4-methyl dihydrofuran-2(3H)-one(2), methylhydroheptelidate(3), hydroheptelidic acid(4), 5, 7-dimethoxy-4, 6-dimethylphthalide(5),(3R,4S)-(-)-4-hydroxymellein(6), pestalopyrone(7), indole-3-formaldehyde(8) and p-hydroxybenzaldehyde(9) by spectroscopic techniques. Terezine P(1) was a new alkaloid belonging to the terezine class with a pyrazine ring. Compounds 2-7 were lactones, of which 3 and 4 belonged to sesquiterpenes. Compounds 8 and 9 were indole alkaloids and phenols, respectively. Compounds 3-6 were purified from Nigrospora sp. for the first time. These compounds showed different degrees of antibacterial activity against Staphylococcus aureus, Escherichia coli of O6 serotype and E. coli of O78 serotype.

Four new diphenyl ether derivatives from a mangrove endophytic fungus Epicoccum sorghinum.

Four new diphenyl ethers, named epicoccethers K-N (1-4), were purified from the fermentation medium of a fungus Epicoccum sorghinum derived from Myoporum bontioides, and identified through HR-ESI-MS and NMR spectral analysis. Except that compound 1 showed moderate antifungal activity against Penicillium italicum and Fusarium graminearum, the other three compounds showed stronger activity against them than triadimefon. All of them showed moderate or weak antibacterial activity towards Staphylococcus aureus and Escherichia coli with O6 and O78 serotypes except that 3 was inactive to E. coli O6.

A novel antibacterial tyroscherin derivative with a natural unprecedented morpholine-2, 3-dione structural unit from the fungus Pseudallescheria boydii.

A novel tyroscherin derivative named pseudallecin A (1) with a natural unprecedented morpholine-2, 3-dione structural unit, and a new biogenic synthesis related organic acid named pseudallecin B (2) were purified from a symbiotic fungus Pseudallescheria boydii derived from Pomacea canaliculata. Their structures were elucidated via spectroscopic analyses and ECD calculation. Pseudallecin A exhibited strong inhibitory activities against both Gram-positive Escherichia coli and Gram-negative Staphylococcus aureus.

Antifungal sesquiterpenes with post-harvest anthracnose control effect on bananas from the fungus Fusarium lateritium.

To search for antifungal leads, the metabolites of an insect-derived fungus Fusarium lateritium ZMT01 were investigated, providing five sesquiterpenes (1-5), including new molecules microsphaeropsisins D and E (1 and 2). The evaluated antifungal activities in vitro which are higher than the positive control triadimefon include: 1 and 2 towards Fusarium oxysporum (MICs 50, 25 mg L-1; triadimefon 100 mg L-1); 1, 2, 4 and 5 towards Penicillium italicum (MICs 25, 12.5, 25, 25; triadimefon 50 mg L-1), 1, 2 and 4 towards Colletotrichum musae (MICs 25, 12.5, 25; triadimefon 80 mg L-1), 2 and 4 towards Fusarium graminearum (MICs 100, 100; triadimefon 150 mg L-1). The bioassay in vivo displayed that the banana anthracnose control effect of 2 (100 mg L-1) was also higher than that of triadimefon (Inhibition ratios 27.5 ± 2.5%, 55.3 ± 1.4%, 52.1 ± 1.3% for 2, 22.5 ± 2.1%, 47.2 ± 2.0%, 36.6 ± 2.2% for triadimefon at 4 d, 8 d and 12 d, respectively).[Formula: see text].

New diphenyl ethers from a fungus Epicoccum sorghinum L28 and their antifungal activity against phytopathogens.

The strategy "IEMAHC" (Induction of Endophyte Metabolism by Adding Host Components) was applied to the fermentation of the endophytic fungus Epicoccum sorghinum L28 from Myoporum bontioides by introducing guaiol, an ingredient of M. bontioides, into the cultivation medium, which resulted in the purification of nine new diphenyl ethers, epicoccethers A-I (1-9). Their structures were determined by overall spectroscopic analysis. HPLC-MS analysis revealed that compounds 5-7 were products generated by induction of guaiol. Compounds 6 and 7 are the first members containing an ester moiety formed by the natural long-chain fatty acid and the hydroxyl group in the phenylmethanol unit of the diphenyl ether class. The antifungal activities of compounds 1, 2, and 4-7 against Fusarium oxysporum were 1, 1, 2, 1, 2 and 4 times as high as those of the positive control triadimefon, respectively. Compounds 4 and 5 showed 1.6 times the antifungal activities of triadimefon towards Colletotrichum musae.

Synthesis, DNA binding, antibacterial and anticancer properties of two novel water-soluble copper(II) complexes containing gluconate.

In this paper, two new Cu(II) complexes, [Cu(Gluc)(HPB)(H2O)]Gluc (CuG1) and [Cu(Gluc)(HPBC)(H2O)]Gluc (CuG2) (where HPB = 2-(2'-pyridyl)benzimidazole, HPBC = 5-chloro-2-(2'-pyridyl)benzimidazole, Gluc = d-Gluconic acid), with good water solubility were synthesized and characterized. These complexes exhibited a five-coordinated tetragonal pyramidal geometry. The DNA binding and cleavage properties of the complexes were investigated using multi-spectroscopy, viscosity measurement, molecular docking and gel electrophoresis analysis methods. The results showed that the complexes could interact with DNA by insertion and groove binding, and cleave CT-DNA through a singlet oxygen-dependent pathway in the presence of ascorbic acid. The studies on antibacterial and anticancer activities in vitro demonstrated that both complexes had good inhibitory activity against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Listeria monocytogenes) and one Gram-negative bacterium (Escherichia coli) and good cytotoxic activity toward the tested cancer cells (A549, HeLa and SGC-7901). CuG2 showed higher antimicrobial and cytotoxic activities than CuG1, which was consistent with their binding strength and cleavage ability to DNA, indicating that their antimicrobial and cytotoxic activities may be related to the DNA interaction. Moreover, the cell-based mechanism studies have indicated that CuG1 and CuG2 could arrest the cell cycle at G2/M phase, elevate the levels of intracellular reactive oxygen species (ROS) and decrease the mitochondrial membrane potential (MMP). The results showed that the complexes could induce apoptosis through DNA-damaged and ROS-mediated mitochondrial dysfunction pathways. Finally, the in vivo antitumor study revealed that CuG2 inhibited tumor growth by 50.44%, which is better than that of cisplatin (40.94%).

PET imaging of occult tumours by temporal integration of tumour-acidosis signals from pH-sensitive 64Cu-labelled polymers.

Owing to the diversity of cancer types and the spatiotemporal heterogeneity of tumour signals, high-resolution imaging of occult malignancy is challenging. 18F-fluorodeoxyglucose positron emission tomography allows for near-universal cancer detection, yet in many clinical scenarios it is hampered by false positives. Here, we report a method for the amplification of imaging contrast in tumours via the temporal integration of the imaging signals triggered by tumour acidosis. This method exploits the catastrophic disassembly, at the acidic pH of the tumour milieu, of pH-sensitive positron-emitting neutral copolymer micelles into polycationic polymers, which are then internalized and retained by the cancer cells. Positron emission tomography imaging of the 64Cu-labelled polymers detected small occult tumours (10-20 mm3) in the brain, head, neck and breast of mice at much higher contrast than 18F-fluorodeoxyglucose, 11C-methionine and pH-insensitive 64Cu-labelled nanoparticles. We also show that the pH-sensitive probes reduce false positive detection rates in a mouse model of non-cancerous lipopolysaccharide-induced inflammation. This macromolecular strategy for integrating tumour acidosis should enable improved cancer detection, surveillance and staging.

Synthesis, characterization, DNA/HSA interactions and in vitro cytotoxic activities of two novel water-soluble copper(II) complexes with 1,3,5-triazine derivative ligand and amino acids.

Two water-soluble copper(II) complexes of 6-(pyrazin-2-yl)-1,3,5-triazine-2,4-diamine (pzta) and amino acids, [Cu(pzta)(L-ArgH)(H2O)](ClO4)2 (1) and [Cu(pzta)(L-Met)(H2O)]ClO4·3H2O (2) (L-ArgH: protonated L-Argininate; L-Met: L-Methioninate), were synthesized and characterized. The determined X-ray crystallographic structures of 1 and 2 exhibited distorted square-pyramidal coordination geometries. Their binding properties toward calf thymus DNA (CT-DNA) and human serum protein (HSA) were measured by spectroscopic (UV-Vis, fluorescence, circular dichroism (CD)), calorimetric (isothermal titration calorimetry (ITC)) and molecular docking technology. DNA binding experiments showed that the complexes bound to DNA through a groove binding mode, the positive ΔH and ΔS values indicated that the hydrophobic interaction was the main force in the binding between the complexes and DNA. Besides, the complexes caused the fluorescence quenching of HSA through a static quenching procedure, changed the secondary structure and microenvironment of the Trp-214 residue, and preferably bound to subdomain IIA of HSA driven by hydrophobic and hydrogen-bond interactions. These results were further verified by the molecular docking technology. Furthermore, the in vitro cytotoxicities of the complexes against three human carcinoma cell lines (A549, PC-3 and HeLa) were evaluated, which confirmed that the complexation improved the anticancer activity of the pzta ligand significantly.

Ovalbumin as a carrier to significantly enhance the aqueous solubility and photostability of curcumin: Interaction and binding mechanism study.

Egg ovalbumin (OVA) as a macromolecular carrier has the potential to improve the solubility and stability of insolubility bioactive molecules, however, their binding behavior and the mechanism is still ambiguous. In this work, the curcumin was selected as the target to study the interaction and binding mechanism between curcumin and OVA by thermodynamic titration technique in combination with molecular dynamic simulation. The results suggested that the binding included two steps: first, curcumin molecule entered into the hydrophobic pocket of OVA by hydrophobic interaction; and second the interaction was enhanced via hydrogen bonds, resulting in static fluorescence quenching and secondary structural change of OVA. This study provided further evidence in support of the proposed mechanism of the polyphenol-protein binding by the "Hands-gloves" model. Furthermore, when the OVA was as a carrier, the solubility of curcumin has been increased ~370 times to 32.73 µg/mL compared to that of free curcumin at pH 7.0. The photostability was enhanced significantly indicating that it is an efficient way to improve the stability of curcumin in contributing to its application in nutritional supplements or functional foods.

Two new Cu(II) dipeptide complexes based on 5-methyl-2-(2'-pyridyl)benzimidazole as potential antimicrobial and anticancer drugs: Special exploration of their possible anticancer mechanism.

In the search for more effective anticancer drugs with less toxic side effects, dipeptides were introduced into the Cu(II) complex of 5-methyl-2-(2'-pyridyl)benzimidazole (HPBM). Analytical and spectroscopic techniques were employed to thoroughly characterize complexes [Cu(Gly-gly)(HPBM)(H2O)]ClO4·0.5H2O (1) and [Cu(Gly-L-leu)(HPBM)(H2O)]ClO4 (2) (where Gly-gly = Glycyl-glycine anion, Gly-L-leu = Glycyl-l-leucine anion). The solution stability studies performed by ultraviolet-visible (UV-Vis) spectroscopy confirmed the stability of the complexes in the buffer solutions. The DNA binding affinity was evaluated using multi-spectroscopy, viscosity measurement and molecular docking methods and further quantified by Kb and Kapp values, revealing an intercalative mode. Moreover, gel electrophoresis analysis revealed that the complexes could damage CT DNA through a hydroxyl radical pathway in the presence of ascorbic acid. All the complexes displayed favorable antimicrobial and cytotoxic activities toward the tested microorganisms (Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) and cancer cells (A549, HeLa and PC-3). Most importantly, the possible anticancer mechanism of the complexes was explored by determining the cells morphological changes, intracellular reactive oxygen species (ROS) levels, location in mitochondria, mitochondrial membrane potentials and the expression of Bcl-2 family proteins. The results showed that the complexes could induce apoptosis in HeLa cells through an ROS-mediated mitochondrial dysfunction pathway, which was accompanied by the regulation of Bcl-2 family proteins.

PD-L1 on host cells is essential for PD-L1 blockade-mediated tumor regression.

Programmed death-ligand 1 (PD-L1) expression on tumor cells is essential for T cell impairment, and PD-L1 blockade therapy has shown unprecedented durable responses in several clinical studies. Although higher expression of PD-L1 on tumor cells is associated with a better immune response after Ab blockade, some PD-L1-negative patients also respond to this therapy. In the current study, we explored whether PD-L1 on tumor or host cells was essential for anti-PD-L1-mediated therapy in 2 different murine tumor models. Using real-time imaging in whole tumor tissues, we found that anti-PD-L1 Ab accumulates in tumor tissues, regardless of the status of PD-L1 expression on tumor cells. We further observed that, while PD-L1 on tumor cells was largely dispensable for the response to checkpoint blockade, PD-L1 in host myeloid cells was essential for this response. Additionally, PD-L1 signaling in defined antigen-presenting cells (APCs) negatively regulated and inhibited T cell activation. PD-L1 blockade inside tumors was not sufficient to mediate regression, as limiting T cell trafficking reduced the efficacy of the blockade. Together, these findings demonstrate that PD-L1 expressed in APCs, rather than on tumor cells, plays an essential role in checkpoint blockade therapy, providing an insight into the mechanisms of this therapy.

Two New Mononuclear Copper(II)-Dipeptide Complexes of 2-(2'-Pyridyl)Benzoxazole: DNA Interaction, Antioxidation and in Vitro Cytotoxicity Studies.

Two new mononuclear mixed ligand copper(II) complexes [Cu(PBO)(Gly-gly)(H2O)]·ClO4·1.5H2O (1) and [Cu(PBO)(Gly-L-leu)(H2O)]·ClO4 (2) (PBO is 2-(2'-pyridyl)benzoxazole, Gly-gly and Gly-L-leu are Glycyl-glycine anion and Glycyl-L-leucine anion, respectively), have been prepared and characterized by various analytical and spectral techniques. The interactions of the complexes with DNA were investigated using multi-spectroscopic methods (absorption, emission, circular dichroism), viscometry and electrochemical titration as well as molecular docking technique. The results indicated that 1 and 2 are bound to calf thymus DNA (CT-DNA) through an intercalative mode. The thermodynamic analyses revealed that the reactions between the Cu(II) complexes with DNA are spontaneous with negative Gibbs free energy (ΔG). The positive changes of enthalpy (ΔH) and entropy (ΔS) suggested that the binding processes are dominated by hydrophobic interaction accompanying with endothermic. Also, the complexes exhibited efficient oxidative cleavage of pBR322 plasmid DNA in the presence of ascorbic acid, probably induced by •OH as reactive oxygen species. In addition, 1 and 2 displayed excellent antioxidant activities with the IC50 values of 0.112 and 0.191 µM, respectively, using the mean of nitroblue tetrazolium (NBT) photochemical reduction under a nonenzymatic condition. Moreover, the complexes were screened for their in vitro cytotoxicity against three human carcinoma cell lines (HeLa, PC-3 and A549), in which 2 owns higher cytotoxicity, which was consistent with DNA binding and cleavage ability order of the complexes. This results showed the in vitro biochemical potentials of the Cu(II)-dipeptide complexes with aromatic heterocyclic, viz. effective metallopeptide-nucleases, SOD mimics and non-platinum chemotherapeutic metallopharmaceuticals and their structure-activity relationship, which may contribute to the rational molecular design of new metallopeptide based chemotherapeutic agents.

Synthesis, DNA/HSA Interaction Spectroscopic Studies and In Vitro Cytotoxicity of a New Mixed Ligand Cu(II) Complex.

A new mixed ligand copper(II)-dipeptide complex with 2-(2'-pyridyl)benzothiazole (pbt), [Cu(Gly-L-leu)(pbt)(H2O)]·ClO4 (Gly-L-leu = Glycyl-L-leucine anion) was synthesized and characterized by various physico-chemical means. The DNA binding and cleavage properties of the complex investigated by viscosity, agarose gel electrophoresis and multi-spectroscopic techniques (UV, circular dichroism (CD) and fluorescence) showed that the complex was bound to CT-DNA through intercalation mode with moderate binding constant (K b = 3.132 × 10(4) M(-1)), and cleaved pBR322 DNA efficiently (~ 5 µM) in the presence of Vc, probably via an oxidative mechanism induced by •OH. Additionally, the interaction of the complex with human serum albumin (HSA) was explored by UV-visible, CD, fluorescence, synchronous fluorescence and 3D fluorescence spectroscopy. The complex exhibits desired affinity to HSA through hydrophobic interaction. Moreover, the cytotoxicity of the complex against three human carcinoma cell lines (HeLa, HepG2 and A549) was evaluated by MTT assay, which showed that the complex had effective cytotoxicity and higher inhibition toward A549 cell lines with IC50 of 38.0 ± 3.2 µM.

Purification, kinetic and thermodynamic studies of a new ribonuclease from a mutant of Aspergillus niger.

Ribonuclease was purified from Aspergillus niger SA-13-20 to homogeneity level by using (NH(4))(2)SO(4) precipitation, DEAE-cellulose anion-exchange chromatography, ultrafiltration and Sephacryl HR-200 chromatography. The molecular weight and isoelectric point of the enzyme was 40.1kDa and 5.3, respectively. The pH- and temperature-dependent kinetic parameters were determined. The RNase showed the strongest affinity with RNA as the substrate, and the highest catalytic efficiency for hydrolysis of the substrate at pH 3.5 and 65 degrees C. It exhibited Michaelis-Menten Kinetics with k(cat) of 118.1s(-1) and K(m) of 57.0 microg ml(-1), respectively. Thermodynamic parameters for catalysis and thermal denaturation were also determined. Activation energy (E(a)) for catalysis of A. niger SA-13-20 RNase was 50.31 kJ mol(-1) and free energy (DeltaG(#)), enthalpy (DeltaH(#)) and entropy (DeltaS(#)) of activation for catalysis of the enzyme at 65 degrees C were 69.76, 47.50 and -65.83 Jmol(-1)K(-1), respectively. Activation energy (E(a,d)) for denaturation of the enzyme was 200.53 kJ mol(-1) and free energy (DeltaG(d)(#)), enthalpy (DeltaH(d)(#)) and entropy (DeltaS(d)(#)) of activation for denaturation of the enzyme at 45 degrees C were 79.18 kJ mol(-1), 197.88 and 373.09 Jmol(-1)K(-1), respectively.

Purification and partial characterization of an extracellular ribonuclease from a mutant of Aspergillus niger.

A new extracellular ribonuclease (RNase) from a mutant of Aspergillus niger, named A. niger SA-13-20 RNase, was purified to homogeneity by (NH4)2SO4 fractionation (50-85%), DEAE-cellulose anion-exchange chromatography, ultrafiltration and Sephacryl HR-200 chromatography. The enzyme was purified up to 54.4-fold with a final yield of 24.5%. There were differences in the molecular weight, pI value and some physico-chemical properties between A. niger SA-13-20 RNase and that from the parent strain. The enzyme is monomeric and its molecular weight and isoelectric point were 40.1 kDa and 5.3, respectively. The N-terminal amino acid sequence of A. niger SA-13-20 RNase was TIDTYSSDSP. The optimum pH, temperature and buffer concentration for the enzymatic reaction were 3.5, 65 degrees C, and 0.175 M, respectively. Metal ions, such as K+, NH4+, Mg2+, and Ca2+ at the concentration of 1.0 mM had a slight activation effect on the enzyme activity and (NH4)2SO4 activated the enzyme significantly. The enzyme was stable at pH lower than 8.5 and was easy to inactivate in strong alkali solution.