• Journal of the Korean Applied Science and Technology
• /
• v.22 no.4
• /
• pp.362-370
• /
• 2005

Copolymers (HSA-98-20, HSA-98-0, HSA-98+20) which are acrylic resin containing 80% solid content were synthesized by the reaction of monomers, including methyl methacrylate, n-butyl acrylate, and 2-hydroxyethyl acrylate with a functional monomer, such as acetoacetoxyethyl methacrylate (AAEM), which may improve in cross-linking density and physical properties of films. The physical properties of prepared acrylic resins, containing AAEM, are as follows : viscosity, $1420{\sim}5760cps$ ; number average molecular weight, $2080{\sim}2300$ ; polydispersity index, $2.07{\sim}2.19$ ; conversions, $88{\sim}93%$, respectively. To prepare acryl resins, four kinds of initiators including ${\alpha},{\alpha}'-azobisisobutyronitirile$ (AIBN), di-tert-butyl peroxide (DTBP), t-amylperoxy-2-ethyl hexanoate (APEH), benzoyl peroxide (BPO) were used. The viscosity of the acrylic resins prepared with these initiators was increased in the order of DTBP>APEH>AIBN>BPO. APEH was proved as a suitable initiator in this study. Shear rates of acrylic resins were constant in respect to viscosity. From these results, it would appear that the resins have Newtonian flow characteristics and good workability.

• BMB Reports
• /
• v.42 no.10
• /
• pp.648-654
• /
• 2009

Overexpression of phospholipid hydroperoxide glutathione peroxidase (PHGPx) genes has been reported to play an important role in protecting host cells from oxidative injury in several model systems. A radish phospholipid hydroperoxide glutathione peroxidase (RsPHGPx) known to have high catalytic activity was applied to mouse 3T3 fibroblasts to determine the protective effects of PHGPx against oxidative injury triggered by hydroperoxides such as hydrogen peroxide ($H_2O_2$), tert-butyl hydroperoxide (t-BHP) and phosphatidylcholine hydroperoxide (PCOOH). We observed that preincubation of cells with RsPHGPx significantly increased cell viability, reduced levels of malondialdehyde (MDA), inhibited generation of reactive oxygen species (ROS), and maintained natural cell shapes after treatment with $H_2O_2$, t-BHP or PCOOH, indicating that the exogenous RsPHGPx can act as an effective hydroperoxide-scavenger and may also protect target cells from oxidative damage. These results suggest the possibility for use of RsPHGPx as a therapeutic protectant.

• Journal of the Korean Applied Science and Technology
• /
• v.38 no.2
• /
• pp.476-487
• /
• 2021

To prepare acrylic resin coatings containing 70% of solids, we used n-butyl methacrylate(BMA), methyl methacrylate(MMA), 2-hydroxyethyl methacrylate(2-HEMA), and acetoacetoxyethyl acrylate(AAEA), caprolactone acrylate(CLA) as raw materials, the glass transition temperature(T_g) of acrylic copolymer was adjusted around 50 ℃. The viscosity and molecular weight of the acrylic resins was increased with increasing OH values. Di-tert-amyl peroxide was found to be the suitable initiator to get high-solids acrylic resins. The optimum reaction conditions found in the study are 5 wt% of initiator, 4 wt% of chain transfer agent, 4 hrs of dropping time, and 140 ℃ of reaction temperature. The structure of the synthesized resins were characterized by FT-IR and ¹H-NMR spectroscopy. Number average molecular weight of 1900~2600 and molecular wight distribution of 1.4~2.1 were obtained. Crosslinked acrylic urethane clear coatings were obtained by curing reaction between the synthesized acrylic resins and hexamethylene diisocyanate trimer(Desmodur N-3300), the equivalent ratio of NCO/OH was 1.2/1.0. The physical properties from the following studies were carried out: viscosity(Zahn cup #2), adhesion, drying time, pot-life, pensil hardness, and 60° specular gloss. Various properties of the acrylic urethane clear coatings were also evaluated on the coating specimens. Adhesion property to a substrate, drying time, pot-life, pencil hardness, and 60° specular gloss of prepared paint showed quite good properties. Futhermore, prepared paint containing 10% of CLA showed quite good properties for adhesion, low viscosity and high hardness.

• Journal of Life Science
• /
• v.31 no.3
• /
• pp.338-345
• /
• 2021

Zizania latifolia has long been used as a tea for both edible and medicinal purposes. However, research into the use of Z. latifolia as a high value-added edible material is lacking. In a previous study, we confirmed that tricin is the major component in Z. latifolia. In this study, we investigated the protective effect of a Z. latifolia extract (ZLE). Toxicity tests of ZLE or tricin on HepG2 cells revealed no toxicity due to ZLE or tricin at all concentrations used. The reduction in cell viability by tert-butyl hydroperoxide (t-BHP) was suppressed by treatment with ZLE or tricin. In addition, ZLE or tricin effectively inhibited the production of reactive oxygen species (generation of hydrogen peroxide, alkoxy free radicals, and peroxyl free radicals by t-BHP) and oxidative damage. ZLE or tricin treatments also increased the protein expression of superoxide dismutase 1 (SOD1), catalase, heme oxygenase-1 (HO-1), and nuclear factor erythroid-related factor 2 (Nrf2), which are known as antioxidant enzymes, suggesting that the protective effect of ZLE is related to activation of tricin. Taken together, the results indicate that Z. latifolia can be developed as a functional food material for improving liver function.

• Elastomers and Composites
• /
• v.49 no.3
• /
• pp.181-190
• /
• 2014

Melt grafting of itaconic acid (IA) onto an ethylene-propylene-diene terpolymer (EPDM) with various organic peroxide initiators was performed. Finding the optimum mixing conditions and concentration of ingredients is critical for effective grafting and optimum properties of grafted materials. This study focused on the effects of mixing conditions (temperature and time), initiator type/concentration and monomer concentration on the grafting degree and efficiency, melt flow index, and gel content of EPDM-g-IA. The initiator, 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101), appeared to meet for the best grafting degree (1.91%). The grafting degree increased markedly by increasing the amounts of monomer IA and initiator T-101. The grafting degree also increased by increasing mixing temperature and time. The optimum monomer and initiator concentrations and reaction temperature and time were found to be about 5wt%/0.05wt% and $160^{\circ}C$/15min, respectively. It was found that the physical properties of EPDM-g-IA were higher than those of the pristine EPDM.

• Elastomers and Composites
• /
• v.48 no.1
• /
• pp.39-45
• /
• 2013

Melt grafting of citraconic acid (CCA) onto an ethylene-propylene-diene terpolymer (EPDM) with various peroxide initiators was performed using a Haake Rheocorder. Finding the optimum running condition and concentration is critical for effective grafting and performance of grafted material. Therefore, this study focused on the effects of mixing (reaction) condition and monomer/initiator dosages on the grafting degree, grafting efficiency and crosslinking degree (gel content), melt flow index and mechanical properties of CCA-g-EPDM. As the grafting degree/crosslinking degrees increased, the tensile strength increased significantly, but elongation at break and melt flow index decreased. The initiator 2,5-dimethyl-2,5-di(tert-butyl peroxy)-hexane (T-101) appeared to meet for the best grafting(2.31%). The grafting degree increased markedly with increasing monomer CCA/initiator T-101 contents. The grafting degree also increased with increasing mixing temperature/time, and then leveled off or decreased/increased a little. The optimum monomer/initiator dosages and reaction temperature/time were found to be about 5/0.05 wt% and $180^{\circ}C$/15min, respectively.

• Herbal Formula Science
• /
• v.31 no.4
• /
• pp.231-243
• /
• 2023

Objectives : Jasminum officinale L. var. grandiflorum is used as a traditional or folk remedy in China to treat arthritis, hepatitis, duodenitis, conjunctivitis, gastritis, and diarrhea. In this study, we aimed to study the hepatocyte protective activity and molecular mechanism of Jasminum officinale L. var. grandiflorum aqueous extract (JGW) using HepG2 hepatocyte cell lines. Methods : HepG2 cells were pretreated with diverse concentrations of JGW, and then the cells were exposed to tert-butyl hydroperoxide (tBHP) for inducing oxidative stress. Hydrogen peroxide (H₂O₂) production, glutathione (GSH) concentration, mitochondrial membrane potential (MMP) and cell viability were measured to investigate hepato-protective effects of JGW. Phosphorylation of AMP-activated protein kinases (AMPK), acetyl coenzyme A carboxylase (ACC) and effects of compound C on cell viability were examined to observe the role of AMPK on JGW-mediated cytoprotection. Results : Pretreatment with JGW (10-300 ㎍/mL) significantly suppressed cytotoxicity induced by tBHP in a concentration dependent manner and reduced the expression of cleaved PARP and cleaved caspase-3 proteins related to apoptosis in HepG2 cells. In addition, pretreatment with JGW significantly prevented the increase in H₂O₂ production, GSH depletion, and lower MMP induced by tBHP. Treatment with JGW (30 minutes of incubation and concentrations of 100 and 300 ㎍/mL) increased the phosphorylation of AMPK and ACC and treatment with compound C, a chemical inhibitor of AMPK, inhibited the cytoprotective effect of JGW. Conclusions : Our results demonstrated that JGW may protect hepatocytes from oxidative stress via activation of AMPK.

• Journal of Acupuncture Research
• /
• v.15 no.2
• /
• pp.135-145
• /
• 1998

Bupleury radix has been used for the treatment of fever, liver disease, inflammation in traditional medicine. The present study was carried out to evaluate the antioxidant effects of Bupleury radix aqua-acupuncture solution (BRAS) in vitro. Oxygen derived free radicals produced in the course of normal aerobic life, such as superoxide anion radical($O_2^-$ ), hydroxyl radicaI( OH), hydrogen peroxide($H_2O_2$) and singlet oxygen($^1O_2$) can attack polyunsaturated fatty acid in cell membranes, enzymes, other cell compounds, and give rise to lipid peroxidation, DNA damage, lipofuscin accumulation, structure alteration of cell membrane and cell death. In this study, antioxidant effects of BRAS on lipid peroxidation were determined according to the method of TBA. BRAS inhibited markedly peroxidation of linoleic acid during the autoxidation, and also inhibited lipid peroxidation induced by hydroxyl radical derived from $H_2O_2-Fe^{2+}$ in rat liver homogenate. And BRAS showed 30% scavenging effect on DPPH radical, also exhibited a 30% inhibitory effect on superoxide generation from xanthine-xanthine oxidase system. In addition, BRAS protected the cell death induced by tert-butyl hydroperoxide(t-BHP) and significantly increased cell viability in the normal rat liver cell(Ac2F).

• Polymer(Korea)
• /
• v.31 no.4
• /
• pp.343-348
• /
• 2007

In this study, terpolymer of vinylidene fluoride (VDF), trifluoroethylene (TrFE), and chlorotrifluoroethylene (CTFE) were prepared by suspension polymerization using di-tertiary-butyl peroxide (DTBP) as an initiator. The structural characteristics including microstructure and chain conformation of the polymers have been carefully elucidated as a function of the chemical composition using NMR, FT-IR. The intensity of absorption bands of the $\beta$-phase gradually decreases and the $\gamma$-phase increases with the increment of CTFE mol%. The analysis results of DSC shows that the Curie phase transition temperature ($T_c$) of the terpolymer gradually shifts to ambient temperature and trace becomes smaller and broader with the increment of CTFE mol%. Also, activation energies of the samples were calculated by Freeman-Carroll method.

• The Journal of Internal Korean Medicine
• /
• v.23 no.1
• /
• pp.57-64
• /
• 2002

Objective : This study was designed to investigate the anti-oxidative effects of Oldenlandiae Diffusae Herba Water extract (ODHW) on lipid peroxidation by free radicals oxidative hepatic injury. Methods : In order to evaluate anti-oxidative activities of ODHW in the liver cell, cultured normal rat liver cells(Ac2F) were incubated with or without ODHW. After 16 hours to 18 hours of experiment, cells were placed in DMEM medium without serum, and then incubated with 1mM tert-butyl hydro-peroxide(t-BHP) for two hours. Viable cells were detected by MTT assay. The levels of LPO induced by hydroxyl radical derived from H2O2-Fe2+ system in rat liver homogenate were determined by means of TBA. Inhibitory effect of ODHW on superoxide generation was measured by xanthine-xanthine oxidase system. Results : In the linoleic acid autoxidation system, ODHW exhibited antioxidant activity, which inhibited 85% of linoleic acid peroxidation. These effects were similar to those of dl-a-tocopherol. ODHW showed scavenging effects on DPPH radical, inhibited superoxide generation in xanthine-xanthine oxidase system, and also inhibited lipid peroxidation of rat liver tissue with hydroxyl radical derived from $H_2O_2-Fe^{2+}$ system. In addition, ODHW protected the cell death induced by t-BHP and it significantly increased cell viability in a normal rat liver cell(Ac2F)