• 제목/요약/키워드: hydrogen donor

검색결과 145건 처리시간 0.028초

The Inhibitory Effects of Hydrogen Sulfide on Pacemaker Activity of Interstitial Cells of Cajal from Mouse Small Intestine

  • Parajuli, Shankar Prasad;Choi, Seok;Lee, Jun;Kim, Young-Dae;Park, Chan-Guk;Kim, Man-Yoo;Kim, Hyun-Il;Yeum, Cheol-Ho;Jun, Jae-Yeoul
    • The Korean Journal of Physiology and Pharmacology
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    • 제14권2호
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    • pp.83-89
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    • 2010
  • In this study, we studied whether hydrogen sulfide ($H_2S$) has an effect on the pacemaker activity of interstitial cells of Cajal (ICC), in the small intestine of mice. The actions of $H_2S$ on pacemaker activity were investigated using whole-cell patch-clamp technique, intracellular $Ca^{2+}$ analysis at $30^{\circ}C$ and RT-PCR in cultured mouse intestinal ICC. Exogenously applied sodium hydrogen sulfide (NaHS), a donor of hydrogen sulfide, caused a slight tonic inward current on pacemaker activity in ICC at low concentrations (50 and $100{\mu}m$), but at high concentration ($500{\mu}m$ and 1 mM) it seemed to cause light tonic inward currents and then inhibited pacemaker amplitude and pacemaker frequency, and also an increase in the resting currents in the outward direction. Glibenclamide or other potassium channel blockers (TEA, $BaCl_2$, apamin or 4-aminopydirine) did not have an effect on NaHS-induced action in ICC. The exogenous application of carbonilcyanide p-triflouromethoxyphenylhydrazone (FCCP) and thapsigargin also inhibited the pacemaker activity of ICC as NaHS. Also, we found NaHS inhibited the spontaneous intracellular $Ca^{2+}$ ($[Ca^{2+}]_i$) oscillations in cultured ICC. In doing an RT-PCR experiment, we found that ICC enriched population lacked mRNA for both CSE and CBS, but was prominently detected in unsorted muscle. In conclusion, $H_2S$ inhibited the pacemaker activity of ICC by modulating intracellular $Ca^{2+}$. These results can serve as evidence of the physiological action of $H_2S$ as acting on the ICC in gastrointestinal (GI) motility.

Protection of Primary Cultured Mouse Hepatocytes from Chemical Hypoxia-induced Injury by Hydrogen Sulfide (화학적 허혈에 의해 손상된 마우스 간세포에 대한 hydrogen sulfide의 간세포 보호 효과)

  • Lee, Min Young
    • Journal of Life Science
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    • 제23권11호
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    • pp.1342-1350
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    • 2013
  • We examined the effect of hydrogen sulfide ($H_2S$) in chemical hypoxia-induced injury in mouse hepatocytes. Cell viability was significantly decreased by cobalt chloride ($CoCl_2$), a well-known hypoxia mimetic agent in a time- and dose- dependent manner. Sodium hydrosulfide (NaHS, a donor of $H_2S$) pretreatment before exposure to $CoCl_2$ significantly attenuated the $CoCl_2$-induced decrease of cell viability. $CoCl_2$ treatment resulted in an increase of intracellular ROS generation, which is inhibited by NaHS or N-acetyl-cysteine (NAC, a ROS scavenger), and p38 MAPK phosphorylation, which is also blocked by NaHS or NAC. The $CoCl_2$-induced increase of the Bax/Bcl-2 ratio was attenuated by NaHS, NAC, and SB 203580 (p38 MAPK inhibitor). The $CoCl_2$-induced decrease of cell viability was also attenuated by NaHS, NAC, and SB 203580 pretreatment. Additionally, NaHS inhibited the $CoCl_2$-induced COX-2. Similar to the effect of NaHS, NAC blocked $CoCl_2$-induced COX-2 expression. Furthermore, NS-398 (a selective COX-2 inhibitor) attenuated not only the $CoCl_2$-induced increase of the Bax/Bcl-2 ratio, it also decreased cell viability. Taken together, $H_2S$ protects primary cultured mouse hepatocytes against $CoCl_2$-induced cell injury through inhibition of the ROS-activated p38 MAPK cascade and the COX-2 pathway.

Effect of Nitric Oxide on Paraquat-Tolerance in Lettuce Leaves (상추잎의 Paraquat 내성에 미치는 Nitric oxide의 영향)

  • Lee, Jee-Na;Hong, Jung-Hee
    • Journal of Environmental Science International
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    • 제20권12호
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    • pp.1509-1519
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    • 2011
  • The protective effect of nitric oxide (NO) on the antioxidant system under paraquat(PQ) stress was investigated in leaves of 8-week-old lettuce (Lactuca sativa L.) plants. PQ stress caused a decrease of leaf growth including leaf length, width and weight. Application of NO donor, sodium nitroprusside (SNP), significantly alleviated PQ stress induced growth suppression. SNP permitted the survival of more green leaf tissue preventing chlorophyll content reduction and of higher quantum yield for photosystem II than in non-treated controls under PQ exposure, suggesting that NO has protective effect on chloroplast membrane in lettuce leaves. Flavonoids and anthocyanin were significantly accumulated in the leaves upon PQ exposure. However, the rapid increase of these compounds was alleviated in the SNP treated leaves. PQ treatment resulted in lipid peroxidation and induced accumulation of hydrogen peroxide ($H_2O_2$) in the leaves, while SNP prevented PQ induced increase in malondialdehyde (MDA) and $H_2O_2$. These results demonstrate that SNP serves as an antioxidant agent able to scavenge $H_2O_2$ to protect plant cells from oxidative damage. The activities of two antioxidant enzymes that scavenge reactive oxygen species, superoxide dismutase (SOD) and catalase (CAT) in lettuce leaves in the presence of NO donor under PQ stress were higher than those under PQ stress alone. Application of 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific NO scavenger, to the lettuce leaves arrested SNP mediated protective effect on leaf growth, photosynthetic pigment and antioxidant systems. However, PTIO had little effect on lettuce leaves under PQ stress compared with that of PQ stress alone. The obtained data suggest that the damage caused by PQ stress is in part due to increased generation of active oxygen by maintaining increased antioxidant enzyme activities and SNP protects plants from oxidative stress. From these results it is suggested that NO might act as a signal in activating active oxygen scavenging system that protects plants from oxidative damage induced by PQ stress and thus confer PQ tolerance.

The Study of Donor-Acceptor Chromophores and Diketopyrrolopyrrole(DPP) Analogues (Donor-Acceptor 발색단과 디케토피롤로피롤(DPP) 유도체에 관한 연구)

  • Kim, HunSoo;Kim, SeungHoi;Park, SooYoul
    • Tribology and Lubricants
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    • 제32권5호
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    • pp.141-146
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    • 2016
  • The diketopyrrolopyrrole (DPP) pigment is a bicyclic 8-π-electron system containing two lactam units. Typical DPP derivative pigments have melting points of over 350°C and very low solubility in most solvents, and show absorption in the visible region with a molar extinction coefficient of 33,000 dm2mol−1 and strong photoluminescence with maxima in the range 500–600 nm. X-ray structure analyses of DPP show that the whole molecule is almost in one plane. The phenyl rings are twisted out of the heterocyclic plane and the intermolecular hydrogen bonding between neighboring lactam NH and carbonyl units influences the structure of the DPP pigment in the solid state. In this study, mono-N-alkylation and mono-N-arylation were undertaken for Pigment Red 264 or Pigment Orange 73 with alkyl halide and aryl halide, respectively, in the presence of sodium tert-butoxide as a base catalyst to improve the solubility of DPP pigments and their application as CO2 indicators. The synthetic yield was in the range 11–88%. The indicator dyes are highly soluble in organic solvents and shows pH-dependent absorption (λmax 501 and 572 nm for the protonated and deprotonated forms, respectively) and emission (λmax 524 and 605 nm for the protonated and deprotonated forms, respectively) spectra. The mono-N-alkylated and mono-N-arylated DPP pigment was identified by 1H-NMR (1H-Nuclear Magnetic Resonance Spectrometer), FT-IR (Fourier Transform Infrared Spectroscopy), and MS (Mass Spectrometry). According to the results of color and hue properties obtained by a color matching analyzer, the synthesized DPP pigment material can be used as a CO2 indicator.

Pyrrolo[3,2-b]pyrrole-Based Copolymers as Donor Materials for Organic Photovoltaics

  • Song, Suhee;Ko, Seo-Jin;Shin, Hyunmin;Jin, Youngeup;Kim, Il;Kim, Jin Young;Suh, Hongsuk
    • Bulletin of the Korean Chemical Society
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    • 제34권11호
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    • pp.3399-3404
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    • 2013
  • A new accepter unit, pyrrolo[3,2-b]pyrrole-2,5-dione, was prepared and utilized for the synthesis of the conjugated polymers containing electron donor-acceptor pair for OPVs. Pyrrolo[3,2-b]pyrrole-2,5-dione unit, regioisomer of the known pyrrolo[3,4-c]pyrrole-1,4-dione, is originated from the structure of stable synthetic pigment. The new conjugated polymers with 1,4-diphenylpyrrolo[3,2-b]pyrrole-2,5-dione, thiophene and carbazole were synthesized using Suzuki polymerization to generate P1 and P2. The solid films of P1 and P2 show absorption bands with maximum peaks at about 377, 554 and 374, 542 nm and the absorption onsets at 670 and 674 nm, corresponding to band gaps of 1.85 and 1.84 eV, respectively. To improve the hole mobility of the polymer with 1,4-bis(4-butylphenyl)-pyrrolo[3,2-b]-pyrrole-2,5-dione unit, which was previously reported by us, the butyl group at the 4-positions of the N-substituted phenyl group was substituted with hydrogen and methyl group. The field-effect hole mobility of P2 is $9.6{\times}10^{-5}cm^2/Vs$. The device with $P2:PC_{71}BM$ (1:2) showed $V_{OC}$ value of 0.84 V, $J_{SC}$ value of 5.10 $mA/cm^2$, and FF of 0.33, giving PCE of 1.42%.

Photoelectrochemical Properties of Gallium Nitride (GaN) Photoelectrode Using Cobalt-phosphate (Co-pi) as Oxygen Evolution Catalyst (산소발생용 Cobalt-phosphate (Co-pi) 촉매를 이용한 Gallium Nitride (GaN) 광전극의 광전기화학적 특성)

  • Seong, Chaewon;Bae, Hyojung;Burungale, Vishal Vilas;Ha, Jun-Seok
    • Journal of the Microelectronics and Packaging Society
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    • 제27권2호
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    • pp.33-38
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    • 2020
  • In the photoelectrochemical (PEC) water splitting, GaN is one of the most promising photoanode materials due to high stability in electrolytes and adjustable energy band position. However, the application of GaN is limited because of low efficiency. To improve solar to hydrogen conversion efficiency, we introduce a Cobalt Phosphate (Co-pi) catalyst by photo-electrodeposition. The Co-pi deposition GaN were characterized by SEM, EDS, and XPS, respectively, which illustrated that Co-pi was successfully decorated on the surface of GaN. PEC measurement showed that photocurrent density of GaN was 0.5 mA/㎠ and that of Co-pi deposited GaN was 0.75 mA/㎠. Impedance and Mott-Schottky measurements were performed, and as a result of the measurement, polarization resistance (Rp) and increased donor concentration (ND) values decreased from 50.35 Ω to 34.16 Ω were confirmed. As a result of analyzing the surface components before and after the water decomposition, it was confirmed that the Co-pi catalyst is stable because Co-pi remains even after the water decomposition. Through this, it was confirmed that Co-pi is effective as a catalyst for improving GaN efficiency, and when applied as a catalyst to other photoelectrodes, it is considered that the efficiency of the PEC system can be improved.

Synthesis, Structure and Biological Properties of a Novel Copper (II) Supramolecular Compound Based on 1,2,4-Triazoles Derivatives

  • Qiu, Guang-Mei;Wang, Cui-Juan;Zhang, Ya-Jun;Huang, Shuai;Liu, Xiao-Lei;Zhang, Bing-Jun;Zhou, Xian-Li
    • Bulletin of the Korean Chemical Society
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    • 제33권8호
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    • pp.2603-2608
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    • 2012
  • A novel mononuclear supramolecule of copper(II) has been synthesized with Ippyt ligand (Ippyt=3-(4'-imidazole phenyl)-5-(pyrid-2''-yl)-1,2,4-triazole) (1). Compound 1, namely [$Cu(Ippyt)_2(H_2O)_2$], has been characterized by single-crystal X-ray diffraction, IR spectrum, elemental analysis and thermogravimetric analysis. Structure determination reveals that the elongated-octahedral geometry is formed in the vicinity of the copper (II) atom being coordinated by four nitrogen atoms from two Ippyt ligands occupying the equatorial position and two oxygen atoms from two coordinated water molecules in the axial position, which together form the $N_4O_2$ donor set. Hydrogen bonding interactions between nitrogen and oxygen atoms result in the set up of a supramolecular network architecture. Biological properties including antibacterial activity and superoxide dismutase (SOD) mimetic activity of compound 1 have been investigated by agar diffusion method and the modified Marklund method, respectively. The results indicate that compound 1 exhibits a stronger antibacterial efficiency than the parent ligand and it also has a certain radical-scavenging activity.

Conformational Analysis and Electronic Properties of 2-Cyano-3-(thiophen-2-yl)acrylic Acid in Sensitizers for Dye-sensitized Solar Cells: A Theoretical Study

  • Balanay, Mannix P.;Kim, Se-Mi;Lee, Mi-Jung;Lee, Sang-Hee;Kim, Dong-Hee
    • Bulletin of the Korean Chemical Society
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    • 제30권9호
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    • pp.2077-2082
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    • 2009
  • The conformational and electronic properties of 2-cyano-3-(thiophen-2-yl)acrylic acid (TCA) in analogues used as sensitizers in dye-sensitized solar cells was examined using density functional theory (DFT) and natural bond orbital analysis methods. A relaxed potential energy surface scan was performed on NKX-2677 by rotating the C-C bond between the thiophene and cyanoacrylic acid which yielded activation energy barriers of about 13 kcal/mol for both E and Z configurations. The most stable conformation of all the analogues was E-180 except for NKX-2587 which has an electrostatic repulsion between the oxygen of the coumarin and the nitrogen of the cyanoacrylic acid. The increase in the electron delocalization between the thiophene and cyanoacrylic acid influences the stability for most of the analogues. But for NKX-2600, even though there was a greater deviation from the planarity of TCA, the stability was mainly due to the presence of a weak hydrogen bond between the hydrogen of the methyl group of the amine located in the donor moiety and the nitrogen of the cyanoacrylic acid. The vertical excitation energies of the analogues containing TCA were calculated by time-dependent DFT method. There were slight differences in its vertical excitation energies but the oscillator strengths vary significantly especially in the case of NKX-2600.

The Syntheses of Mn(III) Porphyrin Derivatives and Its Photoreactivity (Mn(III)-porphyrin 유도체의 합성과 그 광반응성)

  • Park, Yong-Tae;Noh, Sang-Gyun;Chung, Jae-Gew
    • Journal of Hydrogen and New Energy
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    • 제2권1호
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    • pp.7-13
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    • 1990
  • We are interested in studying the artificial photolysis of water which mimics the natural plant photosynthesis. In the artificial system there should be a proper photosensitizer, electron donor and electron acceptor. Since Mn-tetramer is known to be the essential part for the oxygten-evolving system in the natural photosynthesis, it is important to know or study the reactivity of Mn-porphyrins. As a model for the Mn-tetramer in the natural photosynthesis, we prepared the lipophilic and hydrophilic Mn-porphyrins. For the lipophilic porphyrin with long hydrocarbon chain, the long hydrocarbon chain was inserted in the porphyrin ring formation step. For the hydrophilic porphyrin, the porphyrin was sulfonated with sulfuric acid. These syntheses of lipophilic and hydrophilic Mn-porphyrins are significant, since the behaviors of these compounds will be different in the microemulsions or vesicles. We also found that the Mn-porphyrins were photoreduced in the microemulsion and water in the presence of amines.

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Viscosity Reduction by Catalytic Aquathermolysis Reaction of Vacuum Residues (접촉식 가수열분해 반응에 의한 감압잔사유의 점도 강하에 대한 연구)

  • Ko, Jin Young;Park, Seung-Kyu
    • Applied Chemistry for Engineering
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    • 제29권4호
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    • pp.468-473
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    • 2018
  • In this study, the reforming reaction of vacuum residues (VR), high viscosity oil residues produced from vacuum distillation process of petroleum oil, was carried out using catalytic aquathermolysis reaction. VR showed a prone to decrease the amount of resins and asphaltenes in the constituents, and to increase saturates and aromatics when reacting with steam at 30 bar and above $300^{\circ}C$ for 24 h. When the amount of steam is not enough at this reaction, the asphaltene content in the products was rather increased after the reaction. As a result of the catalytic aquathermolysis using the metal oxide-zeolite catalyst with the decaline as a hydrogen donor, a 10% decrease in resin and asphaltene as well as a 10% increase in the aromatic hydrocarbon were observed. Consequently, the viscosity of VR decreased by 70% after the reaction. GC-Mass spectroscopy showed that the aquathermolysis of VR resulted in the decomposition of the resins and asphaltens into a low molecular weight material.