Protective Effect of Ferulic Acid against Hydrogen Peroxide Induced Apoptosis in PC12 Cells

Ferulic Acid (FA) is a highly abundant phenolic phytochemical which is present in plant tissues. FA has biological effects on physiological and pathological processes due to its anti-apoptotic and anti-oxidative properties, however, the detailed mechanism(s) of function is poorly understood. We have identified FA as a molecule that inhibits apoptosis induced by hydrogen peroxide (H₂O₂) or actinomycin D (ActD) in rat pheochromocytoma, PC12 cell. We also found that FA reduces H₂O₂-induced reactive oxygen species (ROS) production in PC12 cell, thereby acting as an anti-oxidant. Then, we analyzed FA-mediated signaling responses in rat pheochromocytoma, PC12 cells using antibody arrays for phosphokinase and apoptosis related proteins. This FA signaling pathway in PC12 cells includes inactivation of pro-apoptotic proteins, SMAC/Diablo and Bad. In addition, FA attenuates the cell injury by H₂O₂ through the inhibition of phosphorylation of the extracellular signal-regulated kinase (ERK). Importantly, we find that FA restores expression levels of brain-derived neurotrophic factor (BDNF), a key neuroprotective effector, in H₂O₂-treated PC12 cells. As a possible mechanism, FA increases BDNF by regulating microRNA-10b expression following H₂O₂ stimulation. Taken together, FA has broad biological effects as a neuroprotective modulator to regulate the expression of phosphokinases, apoptosis-related proteins and microRNAs against oxidative stress in PC12 cells.     

Preparation of Antioxidant Protein Hydrolysates from Pleurotus geesteranus and Their Protective Effects on H2O2 Oxidative Damaged PC12 Cells

Pleurotus geesteranus is a promising source of bioactive compounds. However, knowledge of the antioxidant behaviors of P. geesteranus protein hydrolysates (PGPHs) is limited. In this study, PGPHs were prepared with papain, alcalase, flavourzyme, pepsin, and pancreatin, respectively. The antioxidant properties and cytoprotective effects against oxidative stress of PGPHs were investigated using different chemical assays and H₂O₂ damaged PC12 cells, respectively. The results showed that PGPHs exhibited superior antioxidant activity. Especially, hydrolysate generated by alcalase displayed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (91.62%), 2,2-azino-bis (3-ethylbenzothia zoline-6-sulfonic acid) (ABTS) radical scavenging activity (90.53%), ferric reducing antioxidant power, and metal ion-chelating activity (82.16%). Analysis of amino acid composition revealed that this hydrolysate was rich in hydrophobic, negatively charged, and aromatic amino acids, contributing to its superior antioxidant properties. Additionally, alcalase hydrolysate showed cytoprotective effects on H₂O₂-induced oxidative stress in PC12 cells via diminishing intracellular reactive oxygen species (ROS) accumulation by stimulating antioxidant enzyme activities. Taken together, alcalase hydrolysate of P. geesteranus protein can be used as beneficial ingredients with antioxidant properties and protective effects against ROS-mediated oxidative stress.     

Neuroprotective Effect of Phlorotannin Isolated from Ishige okamurae Against H2O2-Induced Oxidative Stress in Murine Hippocampal Neuronal Cells, HT22

The present study is designed to investigate the neuroprotective effect of a kind of phlorotannins, diphlorethohydroxycarmalol (DPHC) isolated from Ishige okamurae against hydrogen peroxide (H₂O₂)-induced oxidative stress in murine hippocampal neuronal cells, HT22. H₂O₂ treatment induced neurotoxicity, whereas DPHC prevented cells from H₂O₂-induced damage then restoring cell viability was significantly increased. DPHC slightly reduced the expression of Bax induced by H₂O₂ but recovered the expression of Bcl-xL as well as caspase-9 and -3 mediated PARP cleavage by H₂O₂. Intracellular reactive oxygen species (ROS) and lipid peroxidation was overproduced as the result of the addition of H₂O₂; however, these ROS generations and lipid peroxidation were effectively inhibited by addition of DPHC in a dose-dependent manner. Moreover, DPHC suppressed the elevation of H₂O₂-induced Ca²⁺ release. These findings indicate that DPHC has neuroprotective effects against H₂O₂-induced damage in neuronal cells, and that an inhibitory effect on ROS production may contribute to the underlying mechanisms.     

Hydrogen Sulfide Donors Activated by Reactive Oxygen Species

Hydrogen sulfide (H₂S) exhibits promising protective effects in many (patho)physiological processes, as evidenced by recent reports using synthetic H₂S donors in different biological models. Herein, we report the design and evaluation of compounds denoted PeroxyTCM, which are the first class of reactive oxygen species (ROS)‐triggered H₂S donors. These donors are engineered to release carbonyl sulfide (COS) upon activation, which is quickly hydrolyzed to H₂S by the ubiquitous enzyme carbonic anhydrase (CA). The donors are stable in aqueous solution and do not release H₂S until triggered by ROS, such as hydrogen peroxide (H₂O₂), superoxide (O₂^?), and peroxynitrite (ONOO^?). We demonstrate ROS‐triggered H₂S donation in live cells and also demonstrate that PeroxyTCM‐1 provides protection against H₂O₂‐induced oxidative damage, suggesting potential future applications of PeroxyTCM and similar scaffolds in H₂S‐related therapies.     

Proton transfer reactions from H3+ ions to N2, O2, and CO molecules

The rate constants for proton transfer from H₃⁺ ions to N₂, O₂, and CO have been measured as function of hydrogen buffer gas partial pressure. The rate constant for proton transfer from H₃⁺ to N₂ shows a very large pressure dependence, increasing from 1.0 × 10^?9 cm³/s at low H₂ partial pressures to 1.7 × 10^?9 cm³/s at high H₂ partial pressures. The rate constants for proton transfer from H₃⁺ to O₂ and CO are constant with partial pressure of H₂; giving values of 6.4 × 10^?10 cm³/s and 1.7 × 10^?9 cm³/s, respectively. The roles of excess vibrational energy in H₃⁺ ions and of equilibrium between forward and back reaction are discussed. Back reaction is observed only for the reaction of H₃⁺ ions with O₂, and an equilibrium constant of K = 2.0 ± 0.4 at 298 K has been determined. From these data the proton affinity of O₂ is deduced to be 0.47 ± 0.11 kcal/mole higher than that of H₂.     

Upper limits for the rate constant for the reaction Br + H2O2 → HBr + HO2

Upper limits for the rate constant for the reaction Br + H₂O₂ → HBr + HO₂ have been measured over the temperature range 298 to 417 K in a discharge flow, system using a mass spectrometer as a detector. Results are K₁< 1.5 × 10^?15 cm³ s^?1 at 298 K and K₁< 3.0 × 10^?15 cm³ s^?1 at 417 K, respectively. The implication to Stratospheric chemistry is discus     

Anthraquinone Redox Relay for Dye‐Sensitized Photo‐electrochemical H2O2 Production

Anthraquinone (AQ) redox mediators are introduced to metal‐free organic dye sensitized photo‐electrochemical cells (DSPECs) for the generation of H₂O₂. Instead of directly reducing O₂ to produce H₂O₂, visible‐light‐driven AQ reduction occurs in the DSPEC and the following autooxidation with O₂ allows H₂O₂ accumulation and AQ regeneration. In an aqueous electrolyte, under 1 sun conditions, a water‐soluble AQ salt is employed with the highest photocurrent of up to 0.4 mA cm^?2 and near‐quantitative faradaic efficiency for producing H₂O₂. In a non‐aqueous electrolyte, under 1 sun illumination, an organic‐soluble AQ is applied and the photocurrent reaches 1.8 mA cm^?2 with faradaic efficiency up to 95 % for H₂O₂ production. This AQ‐relay DSPEC exhibits the highest photocurrent so far in non‐aqueous electrolytes for H₂O₂ production and excellent acid stability in aqueous electrolytes, thus providing a practical and efficient strategy for visible‐light‐driven H₂O₂ production.     

In situ synthesis of red fluorescent gold nanoclusters with enzyme-like activity for oxidative stress amplification in chemodynamic therapy

Chemodynamic therapy（CDT） has attracted tremendous interest in cancer therapy because it is independent of oxygen and photoirradiation.However,the therapeutic efficacy of CDT is restricted by insufficient H₂ O₂ levels in tumor cells.Herein,employing endogenous GSH as a template and cationic polymeric chitosan（CS） as crosslinker and stabilizer exhibiting easy cell uptake,red luminescent gold nanoclusters（denoted CS-GSH@AuNCs） were successfully synthesized in HeLa cells.The i...     

Electronic transitions in Li4CoCl4.10H2O

The electronic spectrum of Li₄CoCl₆.10H₂O was recorded at liquid nitrogen temperature in the 4,000–25,000 cm^?1 spectral region. The simi larity of this spectrum to that of CoCl₂ permitted us to assume O_h syn metry of the [CoCl₆]^4? cluster in our sample. The band assignment was performed in the crystal field approximation using Tanabe and Sugano's energy matrices for Dq = 730 cm^?1, B = 820 cm^?1 and C/B = 4.4.The large number of bands and high intensity of the maxima in the regio 19,000–21,000 cm^?1 is discussed.     

Kinetic studies of the reaction of C2H5 with O2 at 295 K

The reaction between C₂H₅ and O₂ at 295 K has been studied with a flow reactor sampled by a mass spectrometer. With helium as the carrier gas the rate coefficient was found to increase from (1.2 ± 0.3) × 10^?12 to (3.6 ± 0.9) × 10^?12 cm³/s as [He] was increased from 2 × 10¹⁶ to 3.4 × 10¹⁷ cm^?3. The importance of has been determined from a knowledge of the initial C₂H₅ concentration together with a measurement of the C₂H₄ produced in reaction (5). F, the fraction of the C₂H₅ radicals removed by path (5), was found to decrease from 0.15 to 0.06 as [He] increased from 2 × 10¹⁶ to 3.4 × 10¹⁷ cm^?3. The rate coefficient for reaction (5) was found to be independent of [He] and to have a value of (2.1 ± 0.5) × 10^?13 cm³/s. The variation in F reflects the fact that k_1b increases as [He] increases. These observations are taken as evidence for a direct mechanism for C₂H₄ production and a collision-stabilized route for C₂H₅O₂ formation. Calculations indicate that the high-pressure limit for reaction (1b) is ～4.4 × 10^?12 cm³/s and that in the polluted troposphere the branching ratio for reactions (1b) and (5) will be ～l20.     

Effect of plasticizers (EC or PC) on the ionic conductivity and thermal properties of the (PEO)9LiTf: Al2O3 nanocomposite polymer electrolyte system

A new plasticized nanocomposite polymer electrolyte based on poly (ethylene oxide) (PEO)-LiTf dispersed with ceramic filler (Al₂O₃) and plasticized with propylene carbonate (PC), ethylene carbonate (EC), and a mixture of EC and PC (EC+PC) have been studied for their ionic conductivity and thermal properties. The incorporation of plasticizers alone will yield polymer electrolytes with enhanced conductivity but with poor mechanical properties. However, mechanical properties can be improved by incorporating ceramic fillers to the plasticized system. Nanocomposite solid polymer electrolyte films (200–600 μm) were prepared by common solvent-casting method. In present work, we have shown the ionic conductivity can be substantially enhanced by using the combined effect of the plasticizers as well as the inert filler. It was revealed that the incorporating 15 wt.% Al₂O₃ filler in to PEO: LiTf polymer electrolyte significantly enhanced the ionic conductivity [σ _RT (max)?=?7.8?×?10^?6 S cm^?1]. It was interesting to observe that the addition of PC, EC, and mixture of EC and PC to the PEO: LiTf: 15 wt.% Al₂O₃ CPE showed further conductivity enhancement. The conductivity enhancement with EC is higher than PC. However, mixture of plasticizer (EC+PC) showed maximum conductivity enhancement in the temperature range interest, giving the value [σ _RT (max)?=?1.2?×?10^?4 S cm^?1]. It is suggested that the addition of PC, EC, or a mixture of EC and PC leads to a lowering of glass transition temperature and increasing the amorphous phase of PEO and the fraction of PEO-Li⁺ complex, corresponding to conductivity enhancement. Al₂O₃ filler would contribute to conductivity enhancement by transient hydrogen bonding of migrating ionic species with O–OH groups at the filler grain surface. The differential scanning calorimetry thermograms points towards the decrease of T _g , crystallite melting temperature, and melting enthalpy of PEO: LiTf: Al₂O₃ CPE after introducing plasticizers. The reduction of crystallinity and the increase in the amorphous phase content of the electrolyte, caused by the filler, also contributes to the observed conductivity enhancement.     

C2O(X3Σ−): absolute reaction rates measured by laser induced fluoresence

Absolute rate constants are reported for reactions of C₂O($\text{X}\text{?}$³Σ^?) under pseudo-first-order decay conditions. C₂O is generated by laser photodissociation of C₃O₂ at 266 nm, and detected by dye-laser induced fluorescence on the $\text{A}\text{?}$³Π_i-$\text{X}\text{?}$³Σ^? transition. Rate constants of (433 ± 12), (3.30 ± 0.12) and (1.12 ± 0.05) × 10^?13 cm³ molecule^?1 s^?1 are reported for reactions with NO, O₂ and isobutene. The NO value is approximate due to an apparent dark reaction between NO and C₃O₂. Upper limits of 1 × 10^?14 cm³ molecule^?1 s^?1 are reported for reactions with H₂, CO₂, C₃H₂ and C₂H₄. The C₂O + C₃O₂ reaction does not follow pseudo-first-order decay kinetics. Two explanations are proposed to explain this observation. Results are compared with previous relative rate measurements and are discussed in terms of their relevance to combustion chemistry.     

Kinetic study of reactions of C2H5O2 with NO at 298 K and 0.55 – 2 torr

The kinetics of C₂H₅O₂ and C₂H₅O₂ radicals with NO have been studied at 298 K using the discharge flow technique coupled to laser induced fluorescence (LIF) and mass spectrometry analysis. The temporal profiles of C₂H₅O were monitored by LIF. The rate constant for C₂H₅O + NO → Products (2), measured in the presence of helium, has been found to be pressure dependent: k₂ = (1.25±0.04) × 10^?11, (1.66±0.06) × 10^?11, (1.81±0.06) × 10^?11 at P (He) = 0.55, 1 and 2 torr, respectively (units are cm³ molecule^?1 s^?1). The Lindemann-Hinshelwood analysis of these rate constant data and previous high pressure measurements indicates competition between association and disproportionation channels: C₂H₅O + NO + M → C₂H₅ONO + M (2a), C₂H₅O + NO → CH₃CHO + HNO (2b). The following calculated average values were obtained for the low and high pressure limits of k_2a and for k_2b : k = (2.6±1.0) × 10^?28 cm⁶ molecule^?2 s^?1, k = (3.1±0.8) × 10^?11 cm³ molecule^?1 s^?1 and k_2b ca. 8 × 10^?12 cm³ molecule^?1 s^?1. The present value of k, obtained with He as the third body, is significantly lower than the value (2.0±1.0) × 10^?27 cm⁶ molecule^?2 s^?1 recommended in air. The rate constant for the reaction C₂H₅O₂ + NO → C₂H₅O + NO₂ (3) has been measured at 1 torr of He from the simulation of experimental C₂H₅O profiles. The value obtained for k₃ = (8.2±1.6) × 10^?12 cm³ molecule^?1 s^?1 is in good agreement with previous studies using complementary methods. © 1995 John Wiley & Sons, Inc.     

Rate coefficient for the reaction OH + HO2 = H2O + O2 at 1 atmosphere pressure and 308 K

The rate coefficient for the reaction OH + HO₂ =H₂O + O₂ has been determined from measurements of the steady-state absorption of HO₂ at 210 nm, in low-frequency square-wave modulated photolysis of O₃ + H₂O mixtures. The value obtained was (9.9 ± 2.5) × 10^?11 cm³ molecule^?1 s^?1 at 308 K and 1 atm pressure.     

Structure cristalline du tétramétaphosphate de nickel-ammonium heptahydraté: Ni(NH4)2P4O12 · 7H2O

Nickel-ammonium tetrametaphosphate, Ni(NH₄)₂P₄O₁₂ · 7H₂O is triclinic with a = 13.841(3); b = 9.621(5); c = 7.482(2)Å; α = 98.05(4); β = 97.25(4); γ = 103.01(4)°; M = 536.59; V = 947.9ų; Z = 2; D_x = 1.879 g cm^?3; μ = 14.524 cm^?1, and space group $\text{P}\text{1}$. The crystal structure was solved using 1661 independent reflections measured on a single-crystal diffractometer (MoKα). The final R value is 0.056. The two crystallographic independent nickel atoms Ni(1) and Ni(2) are octahedrally coordinated: Ni(1) by four oxygen atoms and two water molecules, Ni(2) by six water molecules. Ni(1), closely connected to two P₄O₁₂ rings, forms a complex anion [Ni(P₄O₁₂)₂(H₂O)₂]^6? which is associated to ammonium polyhedra and [Ni(H₂O)₆]²⁺ octahedra. Another interesting feature of this atomic arrangement is the presence of a large channel (10 × 4) Ų parallel to the $\text{c}$ axis. The internal surface of this channel is covered by six zeolitic water molecules.     

Kinetics of the reaction of CF3O2 with NO

The rate coefficient for the reaction of CF₃O₂ with NO has been measured at 295 K in helium using a flow tube sampled by a mass spectrometer. The value obtained for this rate coefficient was (17.8 ± 3.6) × 10^?12 cm^?3 s^?1 and found to be independent of [He] over the range (6.3 ? 16.8) × 10¹⁶ cm^?3. This value is approximately a factor of 2 higher than earlier measurements of the rate coefficients for CH₃O₂ and C₂H₅O₂ with NO and indicates that further measurements are required for this important class of reactions.     

Aqueous Reactive Oxygen Species Induced by He + O<Subscript>2</Subscript> Plasmas: Chemistry Pathways and Dosage Control Approaches

Plasma–liquid interaction has already been a hotspot in the research field of plasma medicine. Aqueous reactive oxygen species (ROS) generated in this process are widely accepted playing a crucial role in plasma biomedical effects. In this paper, chemistry pathways among various aqueous ROS induced by He + O₂ plasmas are investigated by a numerical model. Simulation results show that these aqueous ROS can be classified into two groups according to their production ways: the group of species including O, ¹O₂ and e directly produced in plasma, and the other group of species including O₂ ^?, H₂O₂, O₃, etc. produced by liquid reactions. A key reaction chain of e → O₂ ^? → HO₂(→ HO₂ ^?) → H₂O₂ is found to be important in the plasma-induced liquid chemistry. Furthermore, impacts of changes in plasma and solution conditions on aqueous ROS concentrations are studied as well. It is found that changes in plasma conditions (O₂ ratio in the discharge gas/power density) can globally influence the concentrations of almost every aqueous ROS, while conditions changes of the treated liquid (pH/dissolved oxygen) only partially influence the concentrations of some specific species including O₂ ^?/HO₂, O₃ ^?/HO₃ and H₂O₂. The revelations of the liquid chemistry pathways and the dependence of ROS dosage on the treatment conditions offer a better understanding on the plasma–liquid interactions, as well as provide optimized dosage control approaches for biomedical applications.     

The temperature dependence of the HO2 + HO2 reaction

The temperature dependence of the rate constant for the reaction HO₂ + HO₂ → H₂O₂ + O₂ (2k₁) has been determined using flash photolysis techniques, over the temperature range 298–510 K, in a nitrogen diluent at a total pressure of 700 Torr. The overall second order state constant is given by k₁ = (4.14 ± 1.15) × 10^?13 exp[(630 ± 115)/T] cm³ molecule^?1 s^?1, where the quoted errors refer to one standard deviation. This result is compared with previous findings and the negative activation energy is shown to be consistent with the observation that the rate constant is pressure dependent at 700 Torr.     

A quantum mechanical approach to the kinetics of the hydrogen abstraction reaction H2O2 + •OH → HO2 + H2O

The kinetics of the hydrogen abstraction from H₂O₂ by ^?OH has been modeled with MP2/6‐31G*//MP2/6‐31G*, MP2‐SAC//MP2/6‐31G*, MP2/6‐31+G**//MP2/6‐31+G**, MP2‐SAC// MP2/6‐31+G**, MP4(SDTQ)/6‐311G**//MP2/6‐31G*, CCSD(T)/6‐31G*//CCSD(T)/6‐31G*, CCSD(T)/6‐31G**//CCSD(T)/6‐31G**, CCSD(T)/6‐311++G**//MP2/6‐31G* in the gas phase. MD simulations have been used to generate initial geometries for the stationary points along the potential energy surface for hydrogen abstraction from H₂O₂. The effective fragment potential (EFP) has been used to optimize the relevant structures in solution. Furthermore, the IEFPCM model has been used for the supermolecules generated via MD calculations. IEFPCM/MP2/6‐31G* and IEFPCM/CCSD(T)/6‐31G* calculations have also been performed for structures without explicit water molecules. Experimentally, the rate constant for hydrogen abstraction by ^?OH drops from 1.75 × 10^?12 cm³ molecule^?1 s^?1 in the gas phase to 4.48 × 10^?14 cm³ molecule^?1 s^?1 in solution. The same trend has been reproduced best with MP4 (SDTQ)/6‐311G**//MP2/6‐31G* in the gas phase (0.415 × 10^?12 cm³ molecule^?1 s^?1) and with EFP (UHF/6‐31G*) in solution (3.23 × 10^?14 cm³ molecule^?1 s^?1). © 2005 Wiley Periodicals, Inc. Int J Chem Kinet 37: 502–514, 2005