Donkey Milk Fermentation by Lactococcus lactis subsp. cremoris and Lactobacillus rhamnosus Affects the Antiviral and Antibacterial Milk Properties

Background: Milk is considered an important source of bioactive peptides, which can be produced by endogenous or starter bacteria, such as lactic acid bacteria, that are considered effective and safe producers of food-grade bioactive peptides. Among the various types of milk, donkey milk has been gaining more and more attention for its nutraceutical properties. Methods: Lactobacillus rhamnosus 17D10 and Lactococcus lactis subsp. cremoris 40FEL3 were selected for their ability to produce peptides from donkey milk. The endogenous peptides and those obtained after bacterial fermentation were assayed for their antioxidant, antibacterial, and antiviral activities. The peptide mixtures were characterized by means of LC-MS/MS and then analyzed in silico using the Milk Bioactive Peptide DataBase. Results: The peptides produced by the two selected bacteria enhanced the antioxidant activity and reduced E. coli growth. Only the peptides produced by L. rhamnosus 17D10 were able to reduce S. aureus growth. All the peptide mixtures were able to inhibit the replication of HSV-1 by more than 50%. Seventeen peptides were found to have 60% sequence similarity with already known bioactive peptides. Conclusions: A lactic acid bacterium fermentation process is able to enhance the value of donkey milk through bioactivities that are important for human health.     

Purification and radioiodination of 2, 4 di-tertiary- butyl phenol extracted from Lactococcus lactis subsp. lactis CAU: 3138-GM2 and its application on myeloma cells

Journal of Radioanalytical and Nuclear Chemistry - Quantitative calculation based on the joint action of anion exclusion and sorption has not been reported. This article studies the diffusion...     

Activation of reducing agents. Sodium hydride containing complex reducing agents 24. Beneficial effect of Me3SiCl on the reducing properties of NiCRA

Reduction of carbon-carbon double bonds can be achieved with either NiCRA or NiCRASi (nickel containing Complex Reducing Agent activated by Me₃SiCl). Selective reduction of polyunsaturated hydrocarbons or unsaturated ketones are easily performed with both reagents.     

Uncoupler-induced stimulation of photophosphorylation: Effects of carboxylic ionophores and amines at low concentrations on phosphorylation rate,phosphorylation potential and proton motive force in chloroplasts

The rate of steady-state photophosphorylation by spinach chloroplasts is stimulated upon the addition of methylamine and nigericin at concentrations of about 0.5 m M and 10 n M, respectively. Electron transport (H₂O → PS I acceptor) is increased simultaneously, and the ATP/2 e⁻ ratio is not altered by low, stimulating uncoupler concentrations. Stimulation of phosphorylation is observed with thylakoids freshly released from intact chloroplasts by hypotonic treatment, but is abolished by washing the thylakoids in 5 m M MgCl₂. The proton motive force (p.m.f.) in the steady state is lowered upon the addition of low concentrations of methylamine and nigericin; likewise, these uncouplers decrease the maximum attainable phosphorylation potential, [ATP]/{[ADP][Pi]}, from about 4.5 × 10⁴M⁻¹ to (3.0–3.5)× 10⁴M⁻¹. These data suggest that the rate of phosphorylation is under kinetic control, and that an uncoupler-induced removal of a kinetic barrier is responsible for the observed stimulation. The site of control could be the chloroplast coupling factor, and a working model of coupling factor 1 mediated uncoupler-induced stimulation of phosphorylation is proposed.     

Effect of peat humic acids on the kinetics of reduction of anthraquinone dye with sulfur-containing reducing agents

The influence of peat humic acids on the aerobic reduction of Chrome Green Anthraquinone dye with sodium hydroxymethanesulfinate and thiourea dioxide in alkaline solutions was studied.     

Light production in alkaline mixtures of reducing agents and dimethylbiacridylium nitrate.

Abstract— Kinetic studies were made of light production and 0₂ absorption elicited by treatment of dimethylbiacridylium hydroxide [D(OH)₂] with reducing agents in alkaline aqueous solutions. D(OH)2 addition stimulated O₂ uptake which proceeded with zero-order kinetics until nearly all of the O₂ or of the D(OH)₂ was converted to end products. At the termination of the reactions with fructose as reductant the D(OH)₂ was converted to methylacridone and to dimethylbiacridene each compound accounting for approximately one-half the D(OH)₂ consumed. O₂ was reduced to H₂O₂. With hydroxylamine as the reducing agent the emitted light intensity was related to the first power of the D(OH)₂ concentration and the rate of O₂ uptake to the square root of the D(OH)₂. The disappearance of D(OH)₂ in these circumstances was by a first order or pseudo-first order rate. Fructose as a reducing agent by contrast resulted in an O₂ uptake nearly independent of D(OH)₂ concentration over a range from 1 × 10^-5M-1 × 10^-4M, while the light intensity and disappearance of D(OH)₂ followed a one-half order rate. O₂ uptake was by zero order kinetics and the oxidation of fructose proceeded at the same rate as was found with ferricyanide as oxidant. The kinetics, quantum yields and temperature dependence of the fructose reactions were compared with similar reactions employing H₂O₂ as the light eliciting reagent. The results are interpreted as indicating that D(OH)₂ acts as a chain initiator in a manner analogous to better known, radical producing compounds found to accelerate hydrocarbon autooxidations.     

Effects of sodium ions on the electrical and pH gradients across the membrane of Streptococcus lactis cells.

Energized cells of Streptococcus lactis conserve and transduce energy at the plasma membrane in the form of an electrochemical gradient of hydrogen ions (deltap). An increase in energy-consuming processes, such as cation transport, would be expected to result in a change in the steady state deltap. We determined the electrical gradient (deltapsi) from the fluorescence of a membrane potential-sensitive cyanine dye, and the chemical H+ gradient (deltaph) from the distribution of a weak acid. In glycolyzing cells incubated at pH5 the addition of NaCl to 200 mM partially dissipated the deltap by decreasing deltapsi, while the delta pH was constant. The deltap was also determined independently from the accumulation levels of thiomethyl-beta-galactoside. The deltap values decreased in cells fermenting glucose at pH 5 or pH 7 when NaCl was added, while the deltapH values were unaffected; cells fermenting arginine at pH 7 showed similar effects. Thus, these nongrowing cells cannot fully compensate for the energy demand of cation transport.     

Mechanism of antioxidant capacity assays and the CUPRAC (cupric ion reducing antioxidant capacity) assay

We report on the application of a simple and versatile antioxidant capacity assay for dietary polyphenols, vitamin C and vitamin E utilizing the copper(II)-neocuproine (Cu(II)-Nc) reagent as the chromogenic oxidant, which we term the CUPRAC (cupric reducing antioxidant capacity) method. It involves mixing the antioxidant solution (directly or after acid hydrolysis) with solutions of CuCl₂, neocuproine, and ammonium acetate at pH 7, and measuring the absorbance at 450 nm after 30 min. Slowly reacting antioxidants required an incubation at 50 °C for 20 min for color development. The flavonoid glycosides were hydrolyzed to their corresponding aglycones by refluxing in 1.2 M HCl-containing 50% MeOH for fully exhibiting their antioxidant potencies. Certain compounds also needed incubation after acid hydrolysis for color development. The CUPRAC absorbances of mixture constituents were additive, indicating lack of chemical deviations from Beer’s law. The CUPRAC antioxidant capacities of a wide range of polyphenolics are reported in this work and compared to those found by ABTS/persulfate and Folin assays. The trolox-equivalent capacities of the antioxidants were linearly correlated (r = 0.8) to those found by ABTS but not to those of Folin. The highest antioxidant capacities in the CUPRAC method were observed for epicatechin gallate, epigallocatechin gallate, quercetin, fisetin, epigallocatechin, catechin, caffeic acid, epicatechin, gallic acid, rutin, and chlorogenic acid in this order, in accordance with theoretical expectations. The experiences of other CUPRAC users also are summarized. Correspondence: Reşat Apak, Department of Chemistry, Faculty of Engineering, Istanbul University, Avcilar, TR-34320 Istanbul, Turkey     

Protein profiles of the Chinese hamster ovary cells in the resting and proliferating stages.

Identification and characterization of the proteins that regulate the transition from the resting stage (G0) through G1 to S phase of the cell cycle are of central importance to understand the control of cell proliferation and chromosome replication. Unlike in lower organisms, where relatively small numbers of key factors are involved in this process, the factors involved in the same control mechanisms in mammalian systems are much more complex. Furthermore, accumulating lines of evidence now suggest that the nuclear matrix and chromatin organization also play an essential role for the cell cycle control in mammalian cells. To gain a better understanding of the overall dynamics and changes of the protein factors in the context of matrix/chromatin organization, we examined the protein profiles of the Chinese hamster ovary (CHO) cells in different cell cycle compartments. The methods used in this study included subcellular fractionations (cytosol, nuclear extraction, chromatin, and nuclear matrix), two-dimensional polyacrylamide gel electrophoresis (2-D PAGE), silver staining, and immunoblotting. As expected, significant changes of protein profiles were observed when cells entered into proliferating stages from G0. Among approximately 1200 protein spots analyzed by 2-D PAGE, at least 12 showed marked increase or decrease at this transitional period. Further cell-cycle progression from G1 to S phase showed less dramatic changes of overall protein protile. However, the profile of certain proteins showed rather dramatic changes of their subcellular localization during this transitional period. In particular, the levels of proliferating cell nuclear antigen (PCNA) in the nuclear matrix and chromatin dramatically increased in mid-G1 and in the beginning of S phase, respectively, while the overall PCNA level was relatively constant throughout the cell cycle.     

Reaction force constant and projected force constants of vibrational modes along the path of an intramolecular proton transfer reaction

We have explored the relationships between the reaction force F(ξ), the reaction force constant κ(ξ) and the projected force constants of the intramolecular proton transfer HO−NS → ON−SH along the intrinsic reaction coordinate ξ. The structural changes and energetics associated with the reaction are analyzed in terms of the three regions defined by F(ξ): reactant, transition and product. The significance of the similarity between κ(ξ) and the variation of the force constant associated to the reaction coordinate mode, k_ξ(ξ), is discussed in detail.     

Theoretical investigation of the reducing capacity of sodium borohydride and sodium acetoxyborohydride derivatives

The reducing capacity of sodium borohydride and its acetoxy derivatives was studied. Density functional theory using four different functionals were used to investigate the enthalpies, charges and molecular structures of four distinct reactions associated with hydride release. The theoretical results in the gas phase reinforce the experimental observations that the acetoxyborohydride derivative reducing capacities are a consequence of both the inductive electron-withdrawing ability of the acetoxy group and the steric bulk surrounding the BH bond. The electron acceptor effect of the acetoxy group provided a linear relation between the boron GAPT charges and the enthalpy necessary to remove the hydride from sodium borohydride, justifying the smaller or even nonexistent reductor capacity of more substituted borohydrides.     

Effect of electrolytes on the excited-state proton transfer and geminate recombination

Time-resolved emission and steady-state fluorescence techniques are used to study the excited-state intermolecular proton transfer from 8-hydroxypyrene-1,3,6-trisulfonate (HPTS or pyranine) to water in the presence of inert salts, NaCl and MgCl(2). At low salt concentrations, up to about 0.5 M MgCl(2) or about 0.8 M NaCl, the time-resolved emission of both the photoacid and conjugate base can be quantitatively fitted by our diffusion-assisted geminate recombination model. In this concentration range, the proton transfer and geminate recombination rate constants are almost independent of the salt concentrations whereas the proton diffusion constant decreases as the salt concentration increases. At higher salt concentrations, the proton-transfer rate constant decreases while the recombination rate constant increases slightly. For the saturated solution of MgCl(2) (about 5 M at room temperature), the steady-state emission consists of only a single band of the protonated photoacid. Careful examination of the time-resolved emission of HPTS in the presence of a large concentration of MgCl(2) shows that the quality of the fit to the geminate recombination model is rather poor and we fail to find adjustable parameters for a good quality fitting. For this large concentration range of MgCl(2) we were able to get a good fit of the experimental data with a model based on a distribution of proton-transfer rates. The model is consistent with an inhomogeneous water environment next to the excited HPTS molecule in such concentrated solutions.     

Effect of acidification rate,acidification temperature,final pH,and stabilizer content on colloidal stability of whey-based pomegranate beverage

The effect of acidification rate (during 0, 30, and 60 minutes), acidification temperature (25, 50, and 75°C), final pH (3.4, 3.6, and 3.8), and pectin content (0.2, 0.4, and 0.6%) on the stabilization of whey-based pomegranate beverage was studied. Serum separation, particle size distribution, viscosity, zeta potential, pH, and acidity of beverage samples were observed during storage. Results revealed that acidification rate, acidification temperature, and pectin content had a significant effect; however, final pH (of the studied range) had no significant effect on the phase separation. The amount of phase separation decreased and the stability increased with increasing acidification rate, acidification temperature, and stabilizer content. In addition, the results of particle size, zeta potential, and viscosity confirmed the results of phase separation and also the most stable beverage had a pH near 3.8.