CHEN Meng-han, Amel Mohamed, XU Ying-shu, YANG Zi-fan, JIA Hong-bing*
"Rubber blending was an effective way to develop new rubber materials that could achieve better properties than those of single components. The properties of blend could be precisely controlled by using different types of rubbers. However, most blends tended to phase separation, which led to deterioration in mechanical properties. Graphene oxide (GO) could be used as a novel compatibilizer to improve compatibility between rubbers［1-2］.
In this work, GO was added to the blends of carboxylated nitrile butadiene rubber (XNBR) and styrene-butadiene rub-ber (SBR). The XNBR/SBR blend with different blend ratios were designed, and the effect of GO on the mechanical properties of GO/XNBR/SBR blended systems was analyzed in detail by a combination of molecular dynamics (MD) simulations and experiments. The formulation of rubber compounds was XNBR/SBR 100 phr (in mass, the same below), GO 0 or 3.0 phr, antideteriorant 4010 NA 2.0 phr, zinc oxide 2.0 phr, stearic acid 2.4 phr, accelerator CZ 2.2 phr and sulfur 1.5 phr. The mass ratios of XNBR/SBR were 25/75, 50/50 and 75/25, respectively.
Through MD simulation, the number of hydrogen bonds of GO/XNBR/SBR blends was shown in Fig 1. The results showed that plenty of hydrogen bonds existed in GO/XNBR/SBR blends, and both the total number of hydrogen bonds and the number of interfacial hydrogen bonds increased with increasing XNBR content, indicating that the interfacial interaction of GO/XNBR/SBR blends was enhanced. After adding 75 phr of XNBR, the number of hydrogen bonds was the highest［3］.
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Fig 1 Number of hydrogen bonds of GO/XNBR/SBR blends
Tensile strength of XNBR/SBR and GO/XNBR/SBR blends were shown in Fig 2. It could be seen that the tensile strength of XNBR/SBR blend increased gradually with the growing of XNBR content, mainly due to the higher strength of XNBR compared to SBR. The higher the proportion of XNBR rubber was, the better the mechanical properties of the blends were. Compared to that of XNBR/SBR blend, the tensile strength of GO/XNBR/SBR blend increased by 86% when adding XNBR of 75 phr. The strong interfacial interactions, such as hydrogen bonds, may lead to a remarkable increase in the mechanical properties of the blend.
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Fig 2 Tensile strength of XNBR/SBR and GO/XNBR/SBR blends"
Hayet Elkolli, Meriem Elkolli, Farid S. Ataya
et al.
<i>Eucalyptus</i>, a therapeutic plant mentioned in the ancient Algerian pharmacopeia, specifically two species belonging to the <i>Myrtaceae</i> family, <i>E</i>. <i>radiata</i> and <i>E</i>. <i>cinerea</i>, were investigated in this study for their antibacterial, antioxidant, and anti-inflammatory properties. The study used aqueous extracts (AE) obtained from these plants, and the extraction yields were found to be different. The in vitro antibacterial activity was evaluated using a disc diffusion assay against three typical bacterial strains. The results showed that the two extracts were effective against all three strains. Both extracts displayed significant antioxidant activity compared to BHT. The anti-inflammatory impact was evaluated using a protein (BSA) inhibition denaturation test. The <i>E</i>. <i>radiata</i> extract was found to inhibit inflammation by 85% at a concentration of 250 µg/mL, significantly higher than the Aspirin. All phytoconstituents present good pharmacokinetic characteristics without toxicity except very slight toxicity of terpineol and cineol and a maximum binding energy of −7.53 kcal/mol for its anti-TyrRS activity in silico. The study suggests that the extracts and their primary phytochemicals could enhance the efficacy of antibiotics, antioxidants, and non-steroidal anti-inflammatory drugs (NSAIDs). As pharmaceutical engineering experts, we believe this research contributes to developing natural-based drugs with potential therapeutic benefits.
Given the fossil fuel crisis and the steady consumption of finite resources, the use of green polymers is becoming necessary. However, the term “green” describes materials that present green properties (such as biological origin and/or biodegradability) and are produced via sustainable processes conducted under mild conditions and not requiring the use of chemical catalysts, toxic solvents or reagents. Truly green materials must combine these characteristics; consequently, enzymatically synthesized bio-based and/or biodegradable polymers can be characterized as truly green. The present review focuses on the most promising, commercially available aliphatic and alipharomatic polyesters that can be synthesized enzymatically. In particular, the recent developments in the enzymatic polymerization of PLA and PBS and alipharomatic furan-based polyesters (e.g., PBF) are herein analyzed. Based on this analysis, it can be concluded that important steps have been taken toward synthesizing sustainably green polymers. Still, it is necessary to evaluate the applied methods regarding their capability to be used on an industrial scale.
The volatile composition and odor of meat and meat products is based on the precursors present in the raw meat. These are influenced by various pre-slaughter factors (species, breed, sex, age, feed, muscle type). Furthermore, post-mortem conditions (chiller aging, cooking conditions, curing, fermentation, etc.) determine the development of meat volatile organic compounds (VOCs). In this review, the main reactions leading to the development of meat VOCs such as the Maillard reaction; Strecker degradation; lipid oxidation; and thiamine, carbohydrate, and nucleotide degradation are described. The important pre-slaughter factors and post-mortem conditions influencing meat VOCs are discussed. Finally, the pros, cons, and future perspectives of the most commonly used sample preparation techniques (solid-phase microextraction, stir bar sorptive extraction, dynamic headspace extraction) and analytical methods (gas chromatography mass spectrometry and olfactometry, as well as electronic noses) for the analysis of meat VOCs are discussed, and the continued importance of sensorial analysis is pinpointed.
On account of the rigid structure of alginate chains, the oxidation-reductive amination reaction was performed to synthesize the reductive amination of oxidized alginate derivative (RAOA) that was systematically characterized for the development of pharmaceutical formulations. The molecular structure and self-assembly behavior of the resultant RAOA was evaluated by an FT-IR spectrometer, a <sup>1</sup>H NMR spectrometer, X-ray diffraction (XRD), thermal gravimetric analysis (TGA), a fluorescence spectrophotometer, rheology, a transmission electron microscope (TEM) and dynamic light scattering (DLS). In addition, the loading and in vitro release of ibuprofen for the RAOA microcapsules prepared by the high-speed shearing method, and the cytotoxicity of the RAOA microcapsules against the murine macrophage RAW264.7 cell were also studied. The experimental results indicated that the hydrophobic octylamine was successfully grafted onto the alginate backbone through the oxidation-reductive amination reaction, which destroyed the intramolecular hydrogen bond of the raw sodium alginate (SA), thereby enhancing its molecular flexibility to achieve the self-assembly performance of RAOA. Consequently, the synthesized RAOA displayed good amphiphilic properties with a critical aggregation concentration (CAC) of 0.43 g/L in NaCl solution, which was significantly lower than that of SA, and formed regular self-assembled micelles with an average hydrodynamic diameter of 277 nm (PDI = 0.19) and a zeta potential of about −69.8 mV. Meanwhile, the drug-loaded RAOA microcapsules had a relatively high encapsulation efficiency (EE) of 87.6 % and good sustained-release properties in comparison to the drug-loaded SA aggregates, indicating the good affinity of RAOA to hydrophobic ibuprofen. The swelling and degradation of RAOA microcapsules and the diffusion of the loaded drug jointly controlled the release rate of ibuprofen. Moreover, it also displayed low cytotoxicity against the RAW264.7 cell, similar to the SA aggregates. In view of the excellent advantages of RAOA, it is expected to become the ideal candidate for hydrophobic drug delivery in the biomedical field.
In recent decades, demands for novel insecticides against mosquitoes are soaring, yet candidate chemicals with desirable properties are limited. Kathon is a broad-spectrum isothiazolinone microbicide, but other applications remain uncharacterized. First, we treated larvae of <i>Culex quinquefasciatus</i> and <i>Aedes albopictus</i>, two major mosquito vectors of human viral diseases, with Kathon at 15 mg/L (a concentration considered safe in cosmetic and body care products), and at lower concentrations, and found that Kathon treatment resulted in high mortality of larvae. Second, sublethal concentration of Kathon can cause significantly prolonged larval development of <i>C. quinquefasciatus</i>. Third, we explored the effects of two constituents of Kathon, chloromethylisothiazolinone (CMIT) and methylisothiazolinone (MIT), on the survival of larvae, and found that CMIT was the major toxic component. Further, we explored the mechanisms of action of Kathon against insect cells and found that Kathon reduces cell viability and adenosine triphosphate production but promotes the release of lactate dehydrogenase in <i>Drosophila melanogaster</i> S2 cells. Our results indicate that Kathon is highly toxic to mosquito larvae, and we highlight its potential in the development of new larvicides for mosquito control.
Gabriela Brzuska, Gabriela Pastuch-Gawolek, Monika Krawczyk
et al.
Tick-borne encephalitis virus (TBEV) transmitted by ticks is a pathogen of great medical importance. As still no effective antiviral treatment is available, in the present study, a series of uridine glycoconjugates containing amide or/and 1,2,3-triazole moiety in the linker structure was synthesized and evaluated for the antiviral activity against two strains of TBEV: a highly virulent Hypr strain and less virulent Neudoerfl strain, using standardized previously in vitro assays. Our data have shown that four compounds from the series (<b>18–21</b>) possess strong activity against both TBEV strains. The half maximal inhibitory concentration (IC<sub>50</sub>) values of compounds <b>18–21</b> were between 15.1 and 3.7 μM depending on the virus strain, which along with low cytotoxicity resulted in high values of the selectivity index (SI). The obtained results suggest that these compounds may be promising candidates for further development of new therapies against flaviviruses.
Clinton M. Hasenour, Arion J. Kennedy, Tomasz Bednarski
et al.
Fatty liver involves ectopic lipid accumulation and dysregulated hepatic oxidative metabolism, which can progress to a state of elevated inflammation and fibrosis referred to as nonalcoholic steatohepatitis (NASH). The factors that control progression from simple steatosis to NASH are not fully known. Here, we tested the hypothesis that dietary vitamin E (VitE) supplementation would prevent NASH progression and associated metabolic alterations induced by a Western diet (WD). Hyperphagic melanocortin-4 receptor-deficient (MC4R−/−) mice were fed chow, chow+VitE, WD, or WD+VitE starting at 8 or 20 weeks of age. All groups exhibited extensive hepatic steatosis by the end of the study (28 weeks of age). WD feeding exacerbated liver disease severity without inducing proportional changes in liver triglycerides. Eight weeks of WD accelerated liver pyruvate cycling, and 20 weeks of WD extensively upregulated liver glucose and oxidative metabolism assessed by 2H/13C flux analysis. VitE supplementation failed to reduce the histological features of NASH. Rather, WD+VitE increased the abundance and saturation of liver ceramides and accelerated metabolic flux dysregulation compared with 8 weeks of WD alone. In summary, VitE did not limit NASH pathogenesis in genetically obese mice, but instead increased some indicators of metabolic dysfunction.
Three new 30-noroleanane triterpenoid saponins, akebonoic acid 28-O-β-d-glucopyranosyl-(1′′→6′)-β-d-glucopyranosyl ester (1), akebonoic acid 28-O-(6′′-O-caffeoyl)-β-d-glucopyranosyl-(1′′→6′)-β-d-glucopyranosyl ester (Holboelliside A, 2) and 3β,20α,24-trihydroxy-29-norolean-12-en-28-oic acid 3-O-(6′-O-caffeoyl)-β-d-glucopyranoside (Holboelliside B, 3) were isolated from the stems of Holboellia coriacea Diels, together with five known compounds, eupteleasaponin VIII (4), 3α-akebonoic acid (5), quinatic acid (6), 3β-hydroxy-30-norhederagenin (7) and quinatoside A (8). The structures of these compounds were determined on the basis of spectral and chemical evidence. Compounds 1–5 were evaluated for their inhibitory activity against three human tumors HepG2, HCT116 and SGC-7901 cell lines in vitro.
Otávio Augusto Chaves, Ana Paula de O. Amorim, Larissa H. E. Castro
et al.
In the North of Brazil (Pará and Amazonas states) the leaves of the plant Talinum triangulare (popular: cariru) replace spinach as food. From a phytochemical point of view, they are rich in compounds of the group of pheophytins. These substances, related to chlorophyll, have photophysical properties that give them potential application in photodynamic therapy. Human serum albumin (HSA) is one of the main endogenous vehicles for biodistribution of molecules by blood plasma. Association constants and thermodynamic parameters for the interaction of HSA with pheophytin from Talinum triangulare were studied by UV-Vis absorption, fluorescence techniques, and molecular modeling (docking). Fluorescence quenching of the HSA’s internal fluorophore (tryptophan) at temperatures 296 K, 303 K, and 310 K, resulted in values for the association constants of the order of 104 L∙mol−1, indicating a moderate interaction between the compound and the albumin. The negative values of ΔG° indicate a spontaneous process; ΔH° = 15.5 kJ∙mol−1 indicates an endothermic process of association and ΔS° = 0.145 kJ∙mol−1∙K−1 shows that the interaction between HSA and pheophytin occurs mainly by hydrophobic factors. The observed Trp fluorescence quenching is static: there is initial non-fluorescent association, in the ground state, HSA:Pheophytin. Possible solution obtained by a molecular docking study suggests that pheophytin is able to interact with HSA by means of hydrogen bonds with three lysine and one arginine residues, whereas the phytyl group is inserted in a hydrophobic pocket, close to Trp-214.
Background and Aims: Single nucleotide polymorphisms in miRNA binding sites, which are located in mRNA 3' untranslated regions (3'-UTRs), were recently found to influence microRNA-target interactions. Specifically, such polymorphisms can modulatebinding affinity or create or destroy miRNA-binding sites; such variants have also been found to be associated with cancer risk. In this study, we explored the effect of a functional variant at the miR-214 binding site in the methylenetetrahydrofolate reductase gene (rs114673809) on gastric cancer (GC) risk in a hospital-based case-control study in a Chinese Han population. Methods and Results: We genotyped the rs114673809 polymorphism in 345 gastric cancer patients and 376 cancer-free controls using the polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) technique. The functions of rs114673809 were investigated using a luciferase activity assay and validated by immunoblotting. We found that participants carrying the rs114673809 AA genotype or A allele had a significantly increased risk of gastric cancer (OR = 1.667, 95% CI = 1.044-2.660, P = 0.034; OR = 1.261, 95% CI = 1.017-1.563, P = 0.037, respectively) compared to those carrying the GG genotype and G allele. In addition, rs114673809 modified the binding of hsa-miR-214 to MTHFR as well as MTHFR protein levels in gastric cancer patients. Conclusion: Our data suggested that rs114673809, which is located at the miR-214 binding site in the 3'-UTR of MTHFR, may play an important role in the development of gastric cancer in a Chinese Han population.
John B. Bremner, Siritron Samosorn, Brian W. Skelton
et al.
In the course of studies on hybrid antibacterials incorporating 2-aryl-5-nitro-1H-indole moieties as potential bacterial NorA efflux pump inhibitors, the compound 1-[2-(5-nitro-1H-indol-2-yl)phenyl]methylpyridinium chloride (2) was synthesized and structurally characterized. This pyridinium chloride salt crystallized in the monoclinic space group P21/c with the following unit cell dimensions: a 10.274(3) Å, b 13.101(4) Å, c 13.439(4) Å, b 107.702(7)°, V 1723.2(9) Å3, Z (f.u.) = 4; R1 = 0.048, and wR2 = 0.13. Of interest in the single crystal X-ray structure is the (intramolecular) disposition of the pyridinium plane over the indole heterocyclic residue [interplanar dihedral angle 17.91(4)°].
Tieqiang Zhao, Dong Wang, Sergey Y. Cheranov
et al.
To investigate the mechanisms underlying 15(S)-HETE-induced angiogenesis, we have studied the role of the small GTPase, Rac1. We find that 15(S)-HETE activated Rac1 in human retinal microvascular endothelial cells (HRMVEC) in a time-dependent manner. Blockade of Rac1 by adenovirus-mediated expression of its dominant negative mutant suppressed HRMVEC migration as well as tube formation and Matrigel plug angiogenesis. 15(S)-HETE stimulated Src in HRMVEC in a time-dependent manner and blockade of its activation inhibited 15(S)-HETE-induced Rac1 stimulation in HRMVEC and the migration and tube formation of these cells as well as Matrigel plug angiogenesis. 15(S)-HETE stimulated JNK1 in Src-Rac1-dependent manner in HRMVEC and adenovirus-mediated expression of its dominant negative mutant suppressed the migration and tube formation of these cells and Matrigel plug angiogenesis. 15(S)-HETE activated ATF-2 in HRMVEC in Src-Rac1-JNK1-dependent manner and interference with its activation via adenovirus-mediated expression of its dominant negative mutant abrogated migration and tube formation of HRMVEC and Matrigel plug angiogenesis. In addition, 15(S)-HETE-induced MEK1 stimulation was found to be dependent on Src-Rac1 activation. Blockade of MEK1 activation inhibited 15(S)-HETE-induced JNK1 activity and ATF-2 phosphorylation. Together, these findings show that 15(S)-HETE activates ATF-2 via the Src-Rac1-MEK1-JNK1 signaling axis in HRMVEC leading to their angiogenic differentiation.
This paper highlights, for the first time, the changes in the phenolics fraction (anthocyanins, flavonoids and stilbenes) and tocopherols of unpeeled Pistacia vera L. var. bianca with ripening, and the effect of the sun-drying process. The total polyphenol levels in pistachios, measured as mg of Gallic Acid Equivalent (GAE), were: 201 ± 10.1, 349 ± 18.3 and 184.7 ± 6.2 mg GAE/100 g DM in unripe, ripe and dried ripe samples, respectively. Most phenolics in ripe pistachios were found to be anthocyanins. They increased with ripening, while the sun drying process caused a susbtantial loss. Flavonoids found in all pistachio samples were daidzein, genistein, daidzin, quercetin, eriodictyol, luteolin, genistin and naringenin, which decreased both with ripening and drying. Before the drying process both unripe and ripe pistachios showed a higher content of trans-resveratrol than dried ripe samples. γ-Tocopherol was the major vitamin E isomer found in pistachios. The total content (of α- and γ-tocopherols) decreased, both during ripening and during the drying process. These results suggested that unpeeled pistachios can be considered an important source of phenolics, particularly of anthocyanins. Moreover, in order to preserve these healthy characteristics, new and more efficient drying processes should be adopted.
A semi-preparative, analytical high performance liquid chromatographic (HPLC) procedure is described for the isolation of molecular species of GM1 and GD1a gangliosides containing a single long chain base, C18 or C20 sphingosine, C18 or C20 sphinganine, each in its natural erythro or unnatural threo form. The threo forms were obtained from 2,3-dichloro-5,6-dicyanobenzoquinone/NaBH4 -treated gangliosides. The ganglioside molecular species separated by HPLC were analyzed for carbohydrate, fatty acid, and long chain base composition. In particular, long chain bases were submitted to gas-liquid chromatographic-mass spectrometric analyses as their trimethylsilyl (TMS) or N-acetyl-TMS derivatives, and chain length, presence or absence of C4-C5 double bond, and C-3 steric configuration were ascertained. The final preparations of individual molecular species of GM1 and GD1a gangliosides were more than 99% homogeneous in their saccharide moiety, contained a single long chain base (homogeneity higher than 99%), and had a fatty acid composition primarily of stearic acid (92 to 97%). All the individual molecular species of GM1 and GD1a gangliosides were also prepared in radioactive form by selective tritiation at C-3 of the long chain base. Their specific radioactivity ranged from 1.3 to 1.45 Ci/mmol. The availability of these molecular species of gangliosides is expected to facilitate studies aimed at ascertaining the role played by the hydrophobic portion in the functional behavior of gangliosides.