• Proceedings of the Plant Resources Society of Korea Conference
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• 2023.04a
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• pp.54-54
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• 2023

Nypa fruticans Wurmb (N. fruticans) is a plant that belongs to Araceae and N. fruticans is mainly found in tropical mangrove systems. The parts (leaves, stems, and roots) of N. fruticans are traditionally used for asthma, sore throat, and liver disease. N. fruticans contains flavonoids and polyphenols, which are substances that have inhibitory effects on cancer and oxidant. In previous studies, some pharmaceutical effects of N. fruticans on melanogenesis and inflammation have been reported. The present study is conducted to investigate the effect of the ethyl acetate fraction of N. fruticans (ENF) on oxidative DNA damage and UVB-induced DNA damage. DNA damage response (DDR) pathway is important in research on cancer, apoptosis, and so on. DDR pathways are considered a crucial factor affecting the alleviation of cellular damage. ENF could reduce oxidative DNA damage derived from reactive oxygen species by the Fenton reaction. Also, ENF reduced the intensity of intracellular ROS in the live cell image by DCFDA assay. UVB is known to cause skin and cellular damage, then finally contribute to causing the formation of tumors. As for the strategies of reducing DNA damage by UVB, inhibition of p53, H2AX, and Chk2 can be important indexes to protect the human body from DNA damage. As a result of confirming the protective effect of ENF for UVB damage, MMPs significantly decreased, and the expression of apoptosis-related factors tended to decrease. In conclusion, ENF can provide protective effects against double-stranded DNA break (DSB) caused by oxidative DNA damage and UVB-induced DNA damage. These results are considered to be closely related to the protective effect against radicals based on catechin, epicatechin, and isoquercitrin contained in ENF. Based on these results, it is thought that additional mechanism studies for inhibiting cell damage are needed.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.1
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• pp.18-26
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• 2000

Boiler high-temperature pipelines such as main steam pipe, header and steam drum in fossil power plants are degraded by creep damage due to severe operating conditions such as high temperature and high pressure for an extended period time. Conventional measurement techniques(replica method, electric resistance method, and hardness test method) for measuring creep damage have such disadvantages as complex preparation and measurement procedures, too many control parameters. And also these techniques have low practicality and applied only to component surfaces with good accessibility. In this paper, artificial creep degradation test and ultrasonic measurement for their creep degraded specimens(Cr-Mo alloy steels) were carried out for the purpose of evaluation for creep damage. Absolute measuring method of quantitative ultrasonic measurement for material degradation was established, and long term creep degradation tests using life prediction formula were carried out. As a result of ultrasonic tests for crept specimens. we conformed that both the sound velocity decreased and attenuation coefficient linearly increased in proportion to the Increase of creep life fraction($\Phi$c).

• Preventive Nutrition and Food Science
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• v.15 no.4
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• pp.255-261
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• 2010

Ischemic stroke, a major cause of death and disability worldwide, is caused by occlusion of cerebral arteries that, coupled with or without reperfusion, results in prolonged ischemia (hypoxia and hypoglycemia) and, ultimately, brain damage. In this study, we examined whether methanol extract of the whole plant of Cassia mimosoides var. nomame Makino that grows naturally in Korea, as well as Japan and China, and some of its fractions obtained by partitioning with organic solvents could protect human hepatocellular carcinoma cells (HepG2) under hypoxic condition by inhibiting apoptosis. We also investigated if these extracts could attenuate brain damage in a rat model of 2 hr of ischemia, generated by middle cerebral artery occlusion, and 22 hr of reperfusion. The whole extract ($100{\mu}g$/mL) maintained the cell number at more than half of that initially plated, even after 24 hr of cell culture under hypoxic condition (3% $O_2$). In the absence of the whole extract, almost all of the cells were dead by this time point. This improvement of cell viability came from a delay of apoptosis, which was confirmed by observing the timing of the formation of a DNA ladder when assessed by gel electrophoresis. Of fractions soluble in hexane, ethyl acetate (EA), butanol and water, EA extracts were selected for the animal experiments, as they improved cell viability at the lowest concentration ($10{\mu}g$/mL). The whole extract (200 mg/kg) and EA extract (10 and 20 mg/kg) significantly reduced infarct size, a measure of brain damage, by 34.7, 33.8 and 45.2.0%, respectively, when assessed by 2,3,5-triphenyl tetrazolium chloride staining. The results suggest that intake of Cassia mimosoides var. nomame Makino might be beneficial for preventing ischemic stroke through inhibition of brain cell apoptosis.

• The Korea Journal of Herbology
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• v.30 no.2
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• pp.31-36
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• 2015

Objectives : In this study, we demonstrated the antioxidant activities and the inhibitory effect on oxidative DNA damage of ethyl acetate fractions extracted from Sophorae Flos and Sophorae fructus. Methods : Sophorae Flos and Sophorae fructus were extracted with methanol(MeOH) and divided to Petroleum ether, Ethyl acetate(EtOAC) and Water fraction. The antioxidant activities were conducted by the 1,1-diphenyl-2-picryl hydrazyl(DPPH) radical, 2, 2'-Azine-bis(3-ethylbenzothiazoline-6 sulfonic acid) diammonium salt(ABTS) radical scavenging assay, $Fe^{2+}$ chelating assay and Reducing power assay. The inhibitory effect of DNA damage were characterized on ${\varphi}$ X-174 RF I plasmid DNA cleavage assay. In addition, we analyzed the Total phenol contents and the Vitamin C contents of Sophorae Flos and Sophorae fructus. Results : The results of DPPH were 92.71% and 94.72%, ABTS were 87.16% and 62.44%, and $Fe^{2+}$ chelating were 95.81% and 85.11% at $200{\mu}g/m{\ell}$ of Sophorae Flos and Sophorae fructus respectively. The Sophorae Flos showed stronger effect than Sophorae fructus in Reducing Power assay. Total phenol content was 111.77 mg/g and 122.54 mg/g, and Vitamin C content was 2.59 mg/g and 3.03 mg/g. Also both Sophorae Flos and Sophorae fructus have inhibitory antioxidant effect on ${\varphi}$ X-174 RF I plasmid DNA cleavage assay. Conclusions : Over all, this study suggests that Sophorae Flos and Sophorae fructus can be used as not only effective antioxidant but also natural medicine.

• Korean Journal of Plant Resources
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• v.31 no.3
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• pp.228-236
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• 2018

In this study, we evaluated the antioxidant activity and protective effects against oxidative DNA damage of the ethyl acetate fraction from the callus of Abeliophyllum distichum Nakai (ECA). Callus of A. distichum was induced on MS medium containing NAA (1 mg/L) and 2,4-D (1 mg/L), and a sufficient amount was obtained for the extraction by subculture. Acteoside was analyzed and quantified (0.39 mg/g callus) from ECA using the high-performance liquid chromatography-photodiode array detector method. ECA showed very high antioxidative activity as revealed by DPPH and ABTS scavenging assays. The $IC_{50}$ values were 12.4 and $6.8{\mu}g/ml$, respectively. ECA showed protective effects against oxidative DNA damage evaluated by using ${\Psi}X-174$ RF I plasmid DNA. It also inhibited DNA damage by suppressing the oxidative stress-induced protein and mRNA levels of ${\gamma}$-H2AX and p53 in NIH/3T3 cells. In conclusion, ECA protects against oxidative DNA damage through its powerful antioxidant activity.

• Journal of the Korea Concrete Institute
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• v.27 no.4
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• pp.411-418
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• 2015

This paper investigates the effects of fiber volume fraction and panel thickness on face damage characteristics of steel fiber-reinforced concrete (SFRC) under high-velocity globular projectile impact. The target specimens were prepared with $200{\times}200mm$ prismatic panels with thickness of 30 or 50 mm. All panels were subjected to the impact of a steel projectile with a diameter of 20 mm and velocity of 350 m/s. Specifically, this paper explores the correlation between mechanical properties and face damage characteristics of SFRC panels with different fiber volume fraction and panel thickness. The mechanical properties of SFRC considered in this study included compressive strength, modulus of rupture, and toughness. Test results indicated that the addition of steel fiber significantly improve the impact resistance of conventional concrete panel. The front face damage of SFRC panels decreased with increasing the compressive toughness and rear face damage decreased as the modulus of rupture and flexural toughness increased. To evaluate the damage response of SFRC panels under high-velocity impact, finite element analysis conducted using ABAQUS/Explicit commercial program. The predicted face damage of SFRC panels based on simulation shows well agreement with the experimental result in similar failure mode.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1090-1097
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• 2017

Rhus verniciflua Stokes (RVS), an herbal medicine found in East Asia, was extracted and further fractionated to investigate its antioxidant capacity and neuroprotective effects. The RVS ethyl acetate (EtOAc) fraction had the highest level of total phenolics and antioxidant capacity among all solvent fractions tested. Pretreatment of PC-12 cells with the EtOAc fraction effectively attenuated $H_2O_2$-induced oxidative damage. Furthermore, the EtOAc fraction significantly attenuated caspase-3 activity, resulting in inhibition of $H_2O_2$-induced apoptosis. We identified and quantified fustin, sulfuretin, and butein in the EtOAc fraction using accurate mass quadrupole time-of-flight mass spectrometry and reversed-phase high-performance liquid chromatography. The intracellular antioxidant capacity and superoxide dismutase (SOD) activity were significantly increased in PC-12 cells treated with the EtOAc fraction and with individual flavonoids. When cells were pretreated with the EtOAc fraction or individual flavonoids and then co-incubated with diethyldithiocarbamic acid (an inhibitor of SOD activity), cell viability against $H_2O_2$-induced oxidative stress was attenuated. These results suggest that the RVS EtOAc fraction and its flavonoid constituents protect PC-12 cells against $H_2O_2$-induced neurotoxicity through their antioxidant properties.

• Journal of Physiology & Pathology in Korean Medicine
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• v.28 no.4
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• pp.379-383
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• 2014

The purpose of this study is to investigate the effects of silkworm extracts (SWE) on reactive oxygen species formation in mice (C57BL/6). Mice were administrated intraperitoneally with SWE (20 mg/kg/day) for 14 days. All animals were sacrificed 24 hours after the last SWE treatment and then extracted the blood and brain tissue in mouse. The researcher measured several parameters related to reactive oxygen species formation, malondialdehyde (MDA) and hydrogen peroxide ($H_2O_2$) contents in serum, whole brain, cerebral cortex and cerebellum. The results showed that MDA content of pre-SWE treatment was decreased significantly in serum, mitochondrial and cytosolic fraction of whole brain and cerebellum (P<0.01). The $H_2O_2$ content of pre-SWE treatment was decreased significantly in mitochondrial fraction of whole brain, cerebral cortex and cerebellum (P<0.01). These results suggest that SWE plays an important role for inhibition of oxidative damage of cells as well as antioxidant effect, aging delay and cells protected from irradiation.

• Tribology and Lubricants
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• v.21 no.2
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• pp.63-70
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• 2005

This study presents the thermal cracking on a commercial vehicle ventilated brake disk. Distributions of temperature and thermal stress of the disk were analysed, using FEM analysis, under the several driving conditions with actual vehicle specifications. The results from the fatigue tests on the disk material were compared with those from FEM analysis. In case of deceleration of 0.6 g with initial vehicle speed of 97, 140, and 160 km/h, the maximum compressive stress at the disk surface of disk due to braking was 224, 318, and 362 MPa, respectively. It was estimated that each damage fraction of 0.00005, 0.00050, 0.00136 per full stop was imposed on the brake disk in case of deceleration of 0.6 g with initial vehicle speed of 97, 140, and 160 km/h, respectively.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2002.10a
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• pp.139-142
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• 2002

This study presents a mathematical model predicting the stress-strain behavior of fiber reinforced (FMMCs) and fiber/particle reinforced metal matrix composites (F/P MMCs). MMCs were fabricated by squeeze casting method using Al2O3 short fiber and particle as reinforcement, and A356 aluminum alloy as matrix. The fiber/particle ratios of F/P MMCs were 2:1, 1:1, 1:2 with the total reinforcement volume fraction of 20 vol.%, and the FMMCs were reinforced with 10 vol,%, 15 vol. %, 20 vol. % of fibers. Tensile tests were conducted and compared with predictions which were derived using laminate analogy theory and multi-failure model of reinforcements. Results show that the tensile strength of FMMCs with 10 vol.% of fiber was well matched with prediction, and as the fiber volume increases, predictions become larger than experimental results. The difference between the prediction and experiment is considered to be a result of matrix allowance of fiber damage in tensile loading. As the fiber volume fraction in FMMCs increases, the fiber damage increases and so that the tensile strength is reduced. The strength of F/P MMCs approaches more closely to the prediction than FMMCs reinforced with 20 vol.% of fibers because F/P MMCs contains small quantity of fibers and thus has a positive effect in fiber strengthening.