The effects of different starch sources and plasticizers on film blowing of thermoplastic starch: Correlation among process,elongational properties and macromolecular structure

The material compositions and the technological procedures to prepare biodegradable films with the film blowing technology based on thermoplastic starch were studied in this work. The activities were focused on the analysis of the effects of starch source (maize, potato and wheat), supplier (Roquette, Cerestar and Cameo) and the type of plasticizers (glycerol, urea and formamide) and their content on the physical–chemical and mechanical properties. Moreover, in order to develop a film blowing technology, material composition as well as processing condition were optimized. Among 10 varieties of thermoplastic starch prepared, the combination of urea and formamide as plasticizer restrained retrogradation and improved mechanical properties. Extensional rheological properties of the thermoplastic starch films were also investigated: the results showed that the occurrence of strain-hardening behaviour in some of the investigated compositions lead to a positive effect on the film blowing process. In this study we found that the combination of high-amylose (>51%) starch and urea/formamide mixtures as plasticizer produced an homogenous film of a 50 μm thickness and a robust film blowing process due to the good elongational viscosity, high deformability of the melt and strain-hardening behaviour.     

N-1 and C-3 substituted indole Schiff bases as selective COX-2 inhibitors: synthesis and biological evaluation

A group of N-1 and C-3 disubstituted-indole Schiff bases bearing an indole N-1 (R′ = H, CH₂Ph, COPh) substituent in conjunction with a C-3 –CHN–C₆H₄–4-X (X = F, Me, CF₃, Cl) substituent were synthesized and evaluated as inhibitors of cyclooxygenase (COX) isozymes (COX-1/COX-2). Within this group of Schiff bases, compounds 15 (R¹ = CH₂Ph, X = F), 17 (R¹ = CH₂Ph, X = CF₃), 18 (R¹ = COPh, X = F) and 20 (R¹ = COPh, X = CF₃) were identified as effective and selective COX-2 inhibitors (COX-2 IC₅₀’s = 0.32–0.84 μM range; COX-2 selectivity index (SI) = 113 to >312 range). 1-Benzoyl-3-[(4-trifluoromethylphenylimino)methyl]indole (20) emerged as the most potent (COX-1 IC₅₀ >100 μM; COX-2 IC₅₀ = 0.32 μM) and selective (SI >312) COX-2 inhibitor. Furthermore, compound 20 is a selective COX-2 inhibitor in contrast to the reference drug indomethacin that is a potent and selective COX-1 inhibitor (COX-1 IC₅₀ = 0.13 μM; COX-2 IC₅₀ = 6.9 μM, COX-2 SI = 0.02). Molecular modeling studies employing compound 20 showed that the phenyl CF₃ substituent attached to the CN spacer is positioned near the secondary pocket of the COX-2 active site, the CN nitrogen atom is hydrogen bonded (N?NH = 2.85 Å) to the H90 residue, and the indole N-1 benzoyl is positioned in a hydrophobic pocket of the COX-2 active site near W387.     

Structural and diffusion properties of formamide/water mixture interacting with TiO2 surface

The photoreaction and adsorption properties on surfaces, thermal decomposition, chemical transformation, and other properties of the formamide molecule are widely used to understand the origins of the formation of biological molecules (nucleosides, amino acids, DNA, monolayers, etc.) needed for life. The titanium oxide (TiO₂) surface can act both as a template on which the accumulation of adsorbed molecules like formamide occurs through the concentration effect, and as a catalytic material that lowers the activation energy needed for the formation of intermediate products. In this paper, a formamide–water solution interacting with TiO₂ (anatase) surface is simulated using the molecular dynamics method. The structural, diffusion and density properties of formamide–water mixture on TiO₂ are established for a wide temperature range from T = 250 K up to T = 400 K.     

Nitroxyl (HNO) suppresses vascular Nox2 oxidase activity

Nox2 oxidase activity underlies the oxidative stress and vascular dysfunction associated with several vascular-related diseases. We have reported that nitric oxide (NO) decreases reactive oxygen species production by endothelial Nox2. This study tested the hypothesis that nitroxyl (HNO), the redox sibling of NO, also suppresses vascular Nox2 oxidase activity. Specifically, we examined the influence of two well-characterized HNO donors, Angeli’s salt and isopropylamine NONOate (IPA/NO), on Nox2-dependent responses to angiotensin II (reactive oxygen species production and vasoconstriction) in mouse cerebral arteries. Angiotensin II (0.1 μmol/L)-stimulated superoxide (measured by lucigenin-enhanced chemiluminescence) and hydrogen peroxide (Amplex red fluorescence) levels in cerebral arteries (pooled basilar and middle cerebral (MCA)) from wild-type (WT) mice were ~60% lower (P<0.05) in the presence of either Angeli’s salt (1 μmol/L) or IPA/NO (1 μmol/L). Similarly, phorbyl 12,13-dibutyrate (10 μmol/L; Nox2 activator)-stimulated hydrogen peroxide levels were ~40% lower in the presence of IPA/NO (1 μmol/L; P<0.05). The ability of IPA/NO to decrease superoxide levels was reversible and abolished by the HNO scavenger l-cysteine (3 mmol/L; P<0.05), but was unaffected by hydroxocobalamin (100 μmol/L; NO scavenger), ODQ (10 μmol/L; soluble guanylyl cyclase (sGC) inhibitor), or Rp-8-pCPT-cGMPS (10 μmol/L; cyclic guanosine monophosphate (cGMP)-dependent protein kinase inhibitor). Angiotensin II-stimulated superoxide was substantially less in arteries from Nox2-deficient (Nox2^−/y) versus WT mice (P<0.05). In contrast to WT, IPA/NO (1 μmol/L) had no effect on superoxide levels in arteries from Nox2^−/y mice. Finally, angiotensin II (1–1000 μmol/L)-induced constriction of WT MCA was virtually abolished by IPA/NO (1 μmol/L), whereas constrictor responses to either the thromboxane A₂ mimetic U46619 (1–100 nmol/L) or high potassium (122.7 mmol/L) were unaffected. In conclusion, HNO suppresses vascular Nox2 oxidase activity via a sGC–cGMP-independent pathway. Thus, HNO donors might be useful therapeutic agents to limit and/or prevent Nox2-dependent vascular dysfunction.     

An experimental and theoretical study of the electronic spectra of tetraethylammonium [bis(1,3-dithiole-2-thione-4,5-dithiolato)zincate(II)], [NEt4]2[Zn(dmit)2], and tetraethylammonium [bis(1,3-dithiole-2-one-4,5-dithiolato)zincate(II)], [NEt4]2[Zn(dmio)2]

Metal-dmit complexes and related compounds have been the object of intense study in the last decade. Despite such efforts on the study of its structural properties, very few attempts have been made to the spectroscopic study of these metal complexes. Experimental reports of its infrared, Raman and UV–Vis spectra present the main spectroscopic features, however, many details of the electronic structure have still to be fully investigated and inconsistent assignments are found in the literature. This work presents a detailed analysis of the UV–Vis spectra of the zinc-dmit, [Zn(dmit)₂]⁻², and the zinc-dmio complex, [Zn(dmio)₂]⁻². The experimental spectrum was deconvoluted and analysed with several theoretical methodologies including ab initio CI calculations, ab initio TD and zindo semi-empirical methods. The results confirm the multi-configuration nature of several excited states and the calculated results were concordant for several transitions. The results lead to a new assignment of the 457 nm band in the [Zn(dmit)₂]⁻² as π(pS_m) → π*CS band. In the metal-dmio, the sulfur substitution by oxygen results in a larger HOMO–LUMO gap and a change in the nature of the frontier orbitals. As the first transition we found, for the dmit compound, a high-intensity π → π*CS while for the zinc-dmio, a low-intensity π → σ*C–S transition.     

Design,synthesis and biological evaluation of (E)-2-(2-arylhydrazinyl)quinoxalines,a promising and potent new class of anticancer agents

A series of forty-seven quinoxaline derivatives, 2-(XYZC₆H₂CHN–NH)-quinoxalines, 1, have been synthesized and evaluated for their activity against four cancer cell lines: potent cytotoxicities were found (IC₅₀ ranging from 0.316 to 15.749 μM). The structure–activity relationship (SAR) analysis indicated that the number, the positions and the type of substituents attached to the aromatic ring are critical for biological activity. The activities do not depend on the electronic effects of the substituents nor on the lypophilicities of the molecules. A common feature of active compounds is an ortho-hydroxy group in the phenyl ring. A potential role of these ortho-hydroxy derivatives is as N,N,O-tridentate ligands complexing with a vital metal, such as iron, and thereby preventing proliferation of cells. The most active compound was (1: X,Y = 2,3-(OH)₂, Z = H), which displayed a potent cytotoxicity comparable to that of the reference drug doxorubicin.     

Synthesis,spectral and magnetical characterization of monomeric [Cu(2-NO2bz)2(3-pyme)2(H2O)2] and polymeric [Cu{3,5-(NO2)2bz}2(3-pyme)2]n

Two new complexes of composition [Cu(2-NO₂bz)₂(3-pyme)₂(H₂O)₂] (1) and/or [Cu{3,5-(NO₂)₂bz}₂(3-pyme)₂] (2) (3-pyme = 3-pyridylmethanol, ronicol or 3-pyridylcarbinol, 2-NO₂bz = 2-nitrobenzoate and 3,5-(NO₂)₂bz = 3,5-dinitrobenzoate) have been prepared and studied by elemental analysis, electronic, infrared and EPR spectroscopy, magnetic susceptibility measurements and the structure of both complexes has been solved. Complex (1) shows an unusual molecular type of structure consisting of the [Cu(2-NO₂bz)₂(3-pyme)₂(H₂O)₂] molecules held together by hydrogen bonds and van der Waals interactions. Complex (2) exhibits a polymeric chain-like structure [Cu{3,5-(NO₂)₂bz}₂(3-pyme)₂]_n with copper atoms doubly bridged by two 3-pyridylmethanol molecules and the polymeric molecules are held together by van der Waals interactions. Complex (1) exhibits a magnetic moment μ_eff = 1.84 B.M. at 300 K that remains nearly constant within the temperature region (5–300 K). Further cooling results in lowering the magnetic moment to μ_eff = 1.82 B.M. at 1.8 K. The magnetic susceptibility temperature dependence obeys Curie–Weiss law with Curie constant of 0.423 cm³ K mol⁻¹ and with Weiss constant of −0.06 K. The magnetic moment of (2) exhibits a small increase with a decrease in the temperature (μ_eff = 1.80 B.M. at 300 K and μ_eff = 1.85 B.M. at 1.8 K) with Curie constant of 0.409 cm³ K mol⁻¹ and with Weiss constant of +1.1 K, which can indicate a very weak ferromagnetic interaction between the copper atoms within the chain. Applying the molecular field model resulted in obtaining zJ′ values −0.08 cm⁻¹ for complex (1), and −0.07 cm⁻¹ for complex (2), respectively, that could characterize intermolecular and interchain interactions transmitted through π–π stacking.     

Synthesis and in vivo evaluation of [18F]2-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)-dione ([18F]FECUMI-101) as an imaging probe for 5-HT1A receptor agonist in nonhuman primates

The 5-HT_1AR partial agonist PET radiotracer, [¹¹C]CUMI-101, has advantages over an antagonist radiotracer as it binds preferentially to the high affinity state of the receptor and thereby provides more functionally meaningful information. The major drawback of C-11 tracers is the lack of cyclotron facility in many health care centers thereby limiting widespread clinical or research use. We identified the fluoroethyl derivative, 2-(4-(4-(2-(2-fluoroethoxy)phenyl)piperazin-1-yl)butyl)-4-methyl-1,2,4-triazine-3,5(2H,4H)dione (FECUMI-101) (K_i = 0.1 nM; E_max = 77%; EC₅₀ = 0.65 nM) as a partial agonist 5-HT_1AR ligand of the parent ligand CUMI-101. FECUMI-101 is radiolabeled with F-18 by O-fluoroethylation of the corresponding desmethyl analogue (1) with [¹⁸F]fluoroethyltosylate in DMSO in the presence of 1.6 equiv of K₂CO₃ in 45 ± 5% yield (EOS). PET shows [¹⁸F]FECUMI-101 binds specifically to 5-HT_1AR enriched brain regions of baboon. The specificity of [¹⁸F]FECUMI-101 binding to 5-HT_1AR was confirmed by challenge studies with the known 5-HT_1AR ligand WAY100635. These findings indicate that [¹⁸F]FECUMI-101 can be a viable agonist ligand for the in vivo quantification of high affinity 5-HT_1AR with PET.     

N,N-dimethylacetamide/lithium chloride plasticized starch as solid biopolymer electrolytes

In this study, N, N-dimethylacetamide (DMAc) with certain concentration ranges of lithium chloride (LiCl) was used to plasticize starch by melting extrusion. Solid state ionic conductors, DMAc-plasticized starch containing LiCl also had a potential application as solid biopolymer electrolytes. Scanning electron microscope (SEM) showed that many remanent starch granules embed in DMAc-plasticized starch matrix. With increasing LiCl content, the number of remanent starch granules decreased dramatically and homogeneous thermoplastic starch (TPS) could be achieved. Moreover, Fourier Transform infrared (FT-IR) spectroscopy revealed that LiCl could increase the interaction between starch and plasticizers. In addition, the supermolecular structure of starch was destructed by LiCl detected by wide-angle X-ray scattering (WAXS) and thermogravimetric analysis (TGA) respectively. Finally, LiCl not only could increase the water absorption of TPS, but also improved the conductance of TPS. The conductance of TPS with 18 wt% LiCl content could achieve to 10^?0.5 S cm^?1 at 18 wt% water content.     

Synthesis and biological evaluation of substituted 2-phenyl-2H-indazole-7-carboxamides as potent poly(ADP-ribose) polymerase (PARP) inhibitors

A potent series of substituted 2-phenyl-2H-indazole-7-carboxamides were synthesized and evaluated as inhibitors of poly (ADP-ribose) polymerase (PARP). This extensive SAR exploration culminated with the identification of substituted 5-fluoro-2-phenyl-2H-indazole-7-carboxamide analog 48 which displayed excellent PARP enzyme inhibition with IC₅₀ = 4 nM, inhibited proliferation of cancer cell lines deficient in BRCA-1 with CC₅₀ = 42 nM and showed encouraging pharmacokinetic properties in rats compared to the lead 6.     

Purification and characterization of an extremely dimethylsulfoxide tolerant esterase from a salt-tolerant Bacillus species isolated from the marine environment of the Sundarbans

A Bacillus sp. isolated from the Sundarbans region of the Bay of Bengal (NCBI GenBank Accession no. AY723697) which can tolerate 10% (w/v) NaCl, produces esterase optimally in Marine Broth 2216 medium containing 1% (w/v) NaCl. The enzyme was purified 42.7-fold with 6.4% recovery, (specific activity 569.2 U/mg protein) by ammonium sulphate precipitation followed by anion and cation exchange chromatography. The serine type esterolytic enzyme has a molecular weight of 35.0 kDa and is denatured into polypeptides of molecular weights 20 kDa and 15 kDa. The esterase was most active at pH 8.0, the pH of the seawater at the site of collection and is stable in the pH range 6.0–9.0. The optimum temperature of activity of this esterase is 45 °C and the enzyme is very stable after 1 h pre-incubation at 50 °C. Our esterase shows about 100% activity when incubated with 1 M NaCl, the activity drops to about 50% when incubated with 2.5 M sodium chloride and the enzyme is completely inactivated when 4 M NaCl is present during reaction. The esterase is almost inactivated by Ca²⁺, Hg²⁺ and Fe³⁺ ions, reducing agents and detergent. Interestingly, Co²⁺, a known inhibitor of many enzymes, preserved 70% of the activity of this esterase. Specific activity of the esterase increases more than twofold in the presence of water-miscible organic solvents as compared to that in aqueous buffer. When incubated for a period of 10 days in the presence of 30–70% dimethylsufoxide (DMSO), the specific activity increased by approximately two–threefold compared to the enzyme in aqueous buffer throughout the period of study. Specific activity between 1283 and 525 U/mg was maintained by our enzyme when incubated with 50% DMSO for 10 days. The enzyme was most active on p-nitrophenyl acetate, ethyl acetate, alpha isomer of naphthyl acetate but shows relatively lesser activity towards triglycerides of fatty acids. Certain characteristics, such as molecular weight, effects of NaCl, metal ions (Zn²⁺ and Mg²⁺) and reactivity towards para-nitrophenyl and aliphatic esters were strikingly similar to already described marine bacterial derived esterases. Extreme stability in DMSO could make this enzyme a potential immobilized biocatalyst for application in non-aqueous based continuous bioprocesses. Higher specific activity and purification factor, better thermo tolerance and solvent stability would make our enzyme more attractive for biotechnological applications than the marine microbial derived esterases described so far.     

Improved tolerance toward low temperature in banana (Musa AAA Group Cavendish Williams)

To further understand the physiological mechanisms of cold-tolerance in banana plants, the responses of four introducing cultivars (cv.) W811 (via long-term cold adaptation), PB, BJ10 and BJ11 to low-temperature stress (LT) were investigated. LT caused increased malondialdehyde (MDA) content, elevated contents of hydrogen peroxide (H₂O₂) and superoxide radical (O₂⁻), and decreased photochemical efficiency (F_v/F_m) and net photosynthetic rate (P_n) in the leaves of four banana cultivars, but cv. W811 showed better LT tolerance than the other three cultivars. After 72 h of LT, four key antioxidative enzymes in the four cultivars showed different responses. Compared to controls, superoxide dismutase (SOD) activities in the four cultivars showed a significant decrease and W811 had the smallest amount of decrease. Catalase (CAT) activities showed a significant decrease. Peroxidase (POD) activities kept relatively higher activities and showed no significant changes (P > 0.05) in W811, BJ10 and BJ11 whereas that in PB showed a significant increase (P < 0.001). Ascorbate peroxidase (APX) activities in W811 and PB showed no significant changes (P > 0.05). Our results showed that higher cold-tolerance in cv. W811 may correlate with the long-term cold adaptation of the antioxidative enzymes such as SOD, POD and APX that alleviate oxidative stress caused by LT.     

Continuous 2-keto-gluconic acid (2KGA) production from corn starch hydrolysate by Pseudomonas fluorescens AR4

A continuous fermentation process for 2-keto-gluconic acid (2KGA) production from cheap raw material corn starch hydrolysate was developed using the strain Pseudomonas fluorescens AR4. The dilution rate and feeding glucose concentration had a significant effect on the cell concentrations, glucose utilization and 2KGA production performance. The optimal operating factors were obtained as: 0.065 h⁻¹ of dilution rate, 180 g/L of feeding glucose concentration, and 16 h of batch fermentation time as the starting point. Under these conditions, the steady state had the 135.92 g/L of produced 2KGA concentration, 8.83 g/L.h of average volumetric productivity, and 0.9510 g/g of yield. In conclusion, the proposed efficient and stable continuous fermentation process for 2KGA production by the strain P. fluorescens AR4 is potentially competitive for industrial production from corn starch hydrolysate in terms of 2KGA productivity and yield.     

Cloning and overexpression of raw starch digesting α-amylase gene from Bacillus subtilis strain AS01a in Escherichia coli and application of the purified recombinant α-amylase (AmyBS-I) in raw starch digestion and baking industry

Considering the economic and industrial relevance of α-amylases used in food and starch industries, a raw starch digesting α-amylase gene (amyBS-I) from Bacillus subtilis strain AS01a was cloned and expressed in Escherichia coli BL21 cells. The gene also includes its signal peptide sequence (SPS) for facilitating the efficient extracellular expression of recombinant α-amylase (AmyBS-I) in correctly folded (enzymatically active) form. The native AmyBS-I consists of 659 amino acids with a molecular mass and pI of 72,387 Da and 5.8, respectively. The extracellular secretion of AmyBS-I after response surface optimization of culture conditions was found to be 7-fold higher as compared to its production under non-optimized conditions. Purified AmyBS-I demonstrated optimum activity at 70 °C and pH 6.0. It shows K_m and V_max values toward soluble starch as 2.7 mg/ml and 454 U/ml, respectively. Further, it does not require Ca²⁺ ion for its α-amylase activity/thermo-stability, which is an added advantage for its use in the starch industry. The AmyBS-I also hydrolyzed a wide variety of raw starches and produced maltose and glucose as main hydrolyzed products. The bread dough supplemented with AmyBS-I showed better amelioration of the bread quality as compared to the bread supplemented with commercial α-amylase.     

Use of lignocellulosic wastes of pecan (Carya illinoinensis) in the cultivation of Ganoderma lucidum

Background

The wastes of pecan nut (Carya illinoinensis (Wangenh.) K. Koch) production are increasing worldwide and have high concentrations of tannins and phenols.

Zinc protects Ceratophyllum demersum L. (free-floating hydrophyte) against reactive oxygen species induced by cadmium

Evidence for Zn protection against Cd-induced reactive oxygen species in the free-floating hydrophyte Ceratophyllum demersum L. is presented in this paper. Metal treatments of 10 μmol/L Cd, 10 Cd μmol/L supplemented with Zn (10, 50, 100 and 200 μmol/L) and Zn-alone treatments of the same concentrations were used. Using 5,5 dimethyl pyrroline-N-oxide as the spin-probe, electron spin resonance spectra indicated a drastic increase in hydroxyl radicals (OH) in Cd-10 μmol/L treatments, which was closely correlating with the enhanced formation of hydrogen peroxide (H₂O₂) and generation of superoxide radical (O₂^?) triggered by the oxidation of NADPH. The supplementation of adding Zn (10–200 μmol/L) to the Cd-10 μmol/L treatments significantly decreased the production of free radicals especially by eliminating the precursors of OH through inhibition of NADPH oxidation. Cd-enhanced ROS production which substantially increased the oxidative products of proteins measured as carbonyls was effectively inhibited by Zn supplementation.