Relaxation of the folding of globulin around heme of hemoglobin of Homo sapiens by the food-grade additive molecule chlorophyllin

Abstract  

Binding of chlorophyllin (Chln), a food-grade additive molecule with hemoglobin (Hb), has been studied by photophysical and photochemical methods with a view to unravel the biochemical transport pathway of it. The binding affinity constant and binding sites between Chln and Hb are determined and found to be 3.3 × 10⁵ M⁻¹ and 15 (on tryptophan basis), respectively. Fluorimetric quenching experiments entail that Chln is bound in the vicinity of the tryptophan residue of Hb. Circular dichroism studies suggest that Chln induces a change in the α-helical content of Hb. Chlorophyllin is bound in the vicinity of the tryptophan residue of hemoglobin, which has been confirmed from spectrofluorimetric studies, when a quenching in the tryptophan fluorescence occurs because of the chlorophyllin-induced exposure of the tryptophan residue to hydrophillic zone. The cyclic voltammetric studies indicate that the redox reaction of Fe^II of Hb is inhibited shielding of it by the Chln molecule.     

Synthesis and characterization of some bis(cyclopentadienyl)titanium(IV) complexes with internally functionalized oximes(LH): sol–gel transformations of Cp2TiCl2, Cp2TiClL and Cp2TiL2 to nano‐sized anatase titania

Some bis(cyclopentadienyl)titanium(IV) complexes of the type [Cp₂TiCl_2?n{L}_n] {where, n = 1 or 2; L = ONC(R)Ar; R = H or CH₃ and Ar = C₅H₄N‐2, C₄H₃O‐2 or C₄H₃S‐2} have been synthesized by the metathetical reactions of Cp₂TiCl₂ with the sodium salt of internally functionalized oximes in 1:1 and 1:2 stoichiometry in anhydrous THF. All these red to brown colored solid derivatives have been characterized by elemental analyses, FT‐IR and NMR (¹H and ¹³C{¹H}) spectral studies. The FAB mass spectra of some representative derivatives indicate their monomeric nature. Oximato ligands in all the complexes appear to bind the titanium via N and O in a dihapto ( ‐N, O) manner in the solid state. Thermogravimetric curves of [Cp₂TiCl{ONC(CH₃)C₅H₄N‐2}] and [Cp₂Ti{ONC(CH₃)C₅H₄N‐2}₂] suggest the formation of hybrid materials CpTiO(Cl) and Cp₂TiO, respectively, as the final products at 900 °C under nitrogen atmosphere. Sol–gel transformations of Cp₂TiCl₂, [Cp₂TiCl{ONC(CH₃)C₅H₄N‐2}] and [Cp₂Ti{ONC(CH₃)C₅H₄N‐2}₂] yielded titania a–c, respectively, at low sintering temperature (600 °C). The powder XRD patterns, IR as well as Raman spectra of all these oxides indicate the formation of nano‐sized anatase phase. The SEM images of titania a–c indicate agglomers like surface morphologies. The absorption spectra of a–c exhibit an energy band gap in the range of 3.47–3.71 eV. Copyright © 2011 John Wiley & Sons, Ltd.     

Cadmium–halide and mixed cadmium–halide–dicyanamide polymers mediated by ancillary 2-aminoalkyl-pyridine ligands: Synthesis,X-ray single crystal structures and luminescence property

A series of mixed halide–dicyanamide and halide complexes of cadmium(II) mediated by 2-aminoalkyl-pyridine ligands [2-aminomethylpyridine (ampy) and 2-aminoethylpyridine (aepy)] have been synthesized. Five of them, [CdCl(dca)(aepy)]_n (1), [CdBr(dca)(ampy)]_n (2), [CdCl(dca)(ampy)]_n (3) (dca = dicyanamide); [CdI₂(aepy)]_n (4), and [CdI₂(ampy)]_n (5), (dca = dicyanamide) have been characterized by X-ray single crystal structure analysis. The structural determination shows that the compounds are 1D coordination polymers, with the exception of 3 that gives origin to a 2D sheet-like network. The ampy and aepy ligands (also with the occurrence of dca anions in 1–3) reveal to be useful ancillary fragments for the construction of unprecedented Cd–halide polymeric species. The crystal packing shows that the dimensionality of all compounds is enlarged to 2D, and 3D in the case of complex 3, through π–π interactions occurring between the pyridine rings. All the species exhibit interesting luminescence property in solution as well in solid state which is originated from ligand-centered π–π^∗ transitions. The fluorescence band maxima and fluorescence efficiency (in methanol) are found to be dependent not only on the pyridine ligand but also on the type of halide, and the co-ligand. Solid state luminescent study implies that π–π interactions occurring between pyridine rings are also important in controlling the fluorescence intensity. Amongst the synthesized complexes reported, complex 5 exhibits the highest fluorescence efficiency in methanol.     

Microwave-Assisted Synthesis of ZnO–rGO Core–Shell Nanorod Hybrids with Photo- and Electro-Catalytic Activity

The unique two-dimensional structure and surface chemistry of reduced graphene oxide (rGO) along with its high electrical conductivity can be exploited to modify the electrochemical properties of ZnO nanoparticles (NPs). ZnO–rGO nanohybrids can be engineered in a simple new two-step synthesis, which is both fast and energy-efficient. The resulting hybrid materials show excellent electrocatalytic and photocatalytic activity. The structure and composition of the as-prepared bare ZnO nanorods (NRs) and the ZnO–rGO hybrids have been extensively characterised and the optical properties subsequently studied by UV/Vis spectroscopy and photoluminescence (PL) spectroscopy (including decay lifetime measurements). The photocatalytic degradation of Rhodamine B (RhB) dye is enhanced using the ZnO–rGO hybrids as compared to bare ZnO NRs. Furthermore, potentiometry comparing ZnO and ZnO–rGO electrodes reveals a featureless capacitive background for an Ar-saturated solution whereas for an O₂-saturated solution a well-defined redox peak was observed using both electrodes. The change in reduction potential and significant increase in current density demonstrates that the hybrid core–shell NRs possess remarkable electrocatalytic activity for the oxygen reduction reaction (ORR) as compared to NRs of ZnO alone.     

Unlocking the Real Potential of Black Soldier Fly (Hermetia illucens) Larvae Protein Derivatives in Pet Diets

Black soldier fly larvae (BSFL)-derived proteins are gaining popularity as sustainable pet food ingredients. According to the literature, these ingredients have strong antioxidant and antimicrobial activities. Due to the ability of BSFL protein derivatives to donate hydrogen atoms and/or electrons to counterpoise unstable molecules, they could possibly help in the prevention of osteoarthritis. During this study, the antiarthritic potential of BSFL protein derivatives was evaluated using the following assays: (1) proteinase inhibition, (2) erythrocyte membrane stability, (3) reactive oxygen species (ROS) production by activated macrophages, (4) ROS production by monocytes, and (5) cellular toxicity. Additionally, the glucosamine content of these ingredients was also evaluated. Chicken meal is commonly used in pet food formulations and was used as an industrial benchmark. The results obtained during this study demonstrated the strong antiarthritic potential of BSFL protein derivatives. We found that BSFL protein derivatives are not only useful in preventing the development of arthritis but could also help to cure it due to the presence of glucosamine. We also found that chicken meal could contribute to the development of arthritis by increasing ROS production by monocytes.     

Synthesis and Characterization of Andrographolide Derivatives as Regulators of βAPP Processing in Human Cells

Alzheimer’s disease (AD) is a devastating neurodegenerative disorder, one of the main characteristics of which is the abnormal accumulation of amyloid peptide (Aβ) in the brain. Whereas β-secretase supports Aβ formation along the amyloidogenic processing of the β-amyloid precursor protein (βAPP), α-secretase counterbalances this pathway by both preventing Aβ production and triggering the release of the neuroprotective sAPPα metabolite. Therefore, stimulating α-secretase and/or inhibiting β-secretase can be considered a promising anti-AD therapeutic track. In this context, we tested andrographolide, a labdane diterpene derived from the plant Andrographis paniculata, as well as 24 synthesized derivatives, for their ability to induce sAPPα production in cultured SH-SY5Y human neuroblastoma cells. Following several rounds of screening, we identified three hits that were subjected to full characterization. Interestingly, andrographolide (8,17-olefinic) and its close derivative 14α-(5′,7′-dichloro-8′-quinolyloxy)-3,19-acetonylidene (compound 9) behave as moderate α-secretase activators, while 14α-(2′-methyl-5′,7′-dichloro-8′-quinolyloxy)-8,9-olefinic compounds 31 (3,19-acetonylidene) and 37 (3,19-diol), whose two structures are quite similar although distant from that of andrographolide and 9, stand as β-secretase inhibitors. Importantly, these results were confirmed in human HEK293 cells and these compounds do not trigger toxicity in either cell line. Altogether, these findings may represent an encouraging starting point for the future development of andrographolide-based compounds aimed at both activating α-secretase and inhibiting β-secretase that could prove useful in our quest for the therapeutic treatment of AD.     

Polyphenolic Composition,Antioxidant, Antiproliferative and Antidiabetic Activities of Coronopus didymus Leaf Extracts

Coronopus didymus (Brassicaceae) commonly known as lesser swine cress has been reported to be used for its pharmacological activities. This study aimed to evaluate the medicinal potential of C. didymus extracts against cancer, diabetes, infectious bacteria and oxidative stress and the identification of bioactive compounds present in these extracts. The effects of using different solvents for the extraction of C. didymus on the contents of major polyphenols and biological activities were investigated. Plant sample was shade dried, ground to a fine powder, and then soaked in pure acetone, ethanol and methanol. The highest contents of major polyphenols were found in methanol-based extract, i.e., chlorogenic acid, HB acid, kaempferol, ferulic acid, quercetin and benzoic acid with 305.02, 12.42, 11.5, 23.33, 975.7 and 428 mg/g of dry weight, respectively, followed by ethanol- and acetone-based extracts. The methanol-based extract also resulted in the highest antioxidant activities (56.76%), whereas the highest antiproliferative (76.36) and alpha glucosidase inhabitation (96.65) were demonstrated in ethanol-based extracts. No antibacterial property of C. didymus was observed against all the tested strains of bacteria. Further studies should be focused on the identification of specific bioactive compounds responsible for pharmacological activities.     

Syntheses, characterization and solid state thermal studies of N-propyl-1,2-diaminoethane (L) and N-isopropyl-1,2-diaminoethane (L′) complexes of nickel(II) nitrite: X-ray single crystal structure of trans-[NiL2(NO2)2]

Linkage isomers trans-bis(N-propyl-1,2-diaminoethane)dinitronickel(II) (brown, 1), trans-bis(N-isopropyl-1,2-diaminoethane)dinitritonickel(II) (blue-violet, 2a) and trans-bis(N-isopropyl-1,2-diaminoethane)dinitronickel(II) (brown, 2b) have been synthesized from solution and X-ray single crystal structure analysis of complex (1) has been performed. Simultaneous TG-DTA analyses reveal that complex (1) exhibits two successive phase transitions before to undergo decomposition (initial temperature of decomposition, Ti = 215 °C). The first one is reversible (82–98 °C; ΔH = 1.75 kJ mol⁻¹ for heating and 93–77 °C; ΔH = −1.65 kJ mol⁻¹ for cooling) and the second one is irreversible endothermic (135–150 °C kJ mol⁻¹; ΔH = 1.80 kJ mol⁻¹) phase transition. No visual color changes are observed in any of the two transitions. The causes related to the first phase transition remain unexplored. However, on the basis of IR spectral studies the second phase transition is supposed to be due to conformational changes of the diamine chelate rings. On the other hand, complexes (2a) and (2b) undergo decomposition without showing any phase transition [Ti = 185 and 195 °C for (2a) and (2b), respectively].     

Signal amplification based on the local nonlinear Mach–Zehnder interferometer

Using the phase modulation of spatial solitons, a new scheme for all-optical signal amplification has been proposed in this paper. The considered structure is composed of the nonlinear Mach–Zehnder interferometer (NMZI) with the straight control waveguide (CWG), the uniform nonlinear medium (NLM) and the linear output waveguide. The local NMZI functions like a phase shifter. The light-induced index changes in the local nonlinear MZI are responsible for the input beam routing in the uniform nonlinear medium. The coupling of the input beam to the output waveguide depends on its propagation direction in the NLM. It is shown that the signal launched at CWG can deflect the beam launched at the NMZI (input beam) and a modulated (amplified) output could be obtained at the output waveguide. Further, signal pulse may be reshaped by appropriately increasing the NLM length. In addition, amplification factor may be enhanced by increasing the NLM length and injecting an appropriate continuous wave beam along with the signal beam at CWG.