• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.487-492
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• 2010

For developing a two-stroke free-piston hydrogen engine with high efficiency and low emission, determination of the scavenging type is one of the most important factor. In this research, backfire characteristics for loop scavenging were analyzed with the number of piston crevice volume and piston expansion speed. Rapid Compression Expansion Machine, RCEM was used for combustion research of the free piston $H_2$ engine in the experiment. As the results, it was shown that although backfire occurring in a loop scavenging type can be partially controled by a complete exhaust of burned gas, possibility of backfire basically exist due to the structure which piston crevice volumes contact with fresh mixture in a scavenging port. However, a loop scavenging may be considered as combustion chamber of a free piston $H_2$ engine from the point of view that backfire does not occur nearby lean equivalence ratio obtained high thermal efficiency. It was also analyzed that an advances of backfire occurrence timing with increase of the fuel-air equivalence ratio were due to promotion of flame propagation into piston crevice volumes by decrease of the quenching distance.

• Korean Journal of Organic Agriculture
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• v.26 no.3
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• pp.477-488
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• 2018

This study examined the total phenolic and flavonoid compounds, and the antioxi dant activity of major cultivars of Prunus mume in Korea. The total phenolic content ranged from 64.13 to $93.43mg{\cdot}100g^{-1}$, with the content in 'Osuku' being higher than that in the other cultivars; a difference in the content among cultivars was observed. The total flavonoid content was $6.16{\sim}18.57mg{\cdot}100g^{-1}$, showing a significant difference, with the highest content being noted in 'Gojirou'. The DPPH radical scavenging activity was measured and was relatively high for Nanko, Kamakami, Natsuka, Dana, and Osuku cultivars. When ABTS radical scavenging activity was measured, all the cultivars showed a scavenging activity over 80%, with the scavenging activity of 'Osuku' being the highest. With respect to nitrite scavenging ability, all cultivars exhibited a high scavenging activity of over 50%, with the highest activity observed for 'Nanko' (76.03%), 'Gojirou' (70.56%), and 'Yourou' (70.32%). Based on the study results, it is considered that Prunus mume can be a useful resource because of various substances with functional physiological activities.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.10
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• pp.1601-1605
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• 2004

To develop the functional food, methanol extracts of dried plantain (Plantago asiatica L.) was fractionated in hexane, chloroform, ethyl acetate, butanol and aqueous fraction. DPPH radical scavenging effect, reducing power, nitrite scavenging effect and antimicrobial activities of these fractions were investigated. Ethyl acetate fraction among these fractions showed the highest effect of all experiments. Ethyl acetate fraction showed about 60% scavenging effect on the DPPH radicals at 400 $\mu$g/5 mL. Nitrite scavenging effect of ethyl acetate and butanol fraction was more than 70~80% at concentration above of 500 $\mu$g. Among various solvent fractions from methanol extracts of plantain, ethyl acetate fraction showed the highest inhibitory effect on the microorganism such as Staphylococcus aureus, Bacillus cereus and Vibrio parahaemolyticus at 5 mg/disc.

• Journal of Microbiology and Biotechnology
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• v.25 no.6
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• pp.820-827
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• 2015

The present study was performed to investigate the various radical scavenging activities of fermented Undaria pinnatifida by the mycelia fermentation method. U. pinnatifida was fermented with Cordyceps militaris (C. militaris ) mycelia using solid culture and compared with unfermentated U. pinnatifida and C. militaris mycelia for antioxidant activities. The various radical scavenging activities of extracts from U. pinnatifida fermented with C. militaris mycelia (FUCM) were evaluated by electron spin resonance. The antioxidant activities of the FUCM extracts were assayed for ferric reducing antioxidant power, 2,2'-azinobis-(3-ethybenzothiazoline-6-sulfonic acid) radical scavenging activity, and oxygen radical absorption capacity. The free radical scavenging activity of FUCM extracts was higher than that of C. militaris mycelia or U. pinnatifida alone. FUCM extracts were significantly (p < 0.05) increased up to 35 times, 10 times, and 16 times that of U. pinnatifida extracts on DPPH, alkyl, and hydroxyl radical scavenging activities, respectively. These results indicate that FUCM extracts have different chemical ingredients from U. pinnatifida and could provide beneficial antioxidant activity.

• Toxicological Research
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• v.26 no.4
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• pp.321-327
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• 2010

The ability of 80% ethanol extracts from five medicinal plants, Aralia continentalis, Paeonia suffruticosa, Magnolia denudata, Anemarrhena asphodeloides, and Schizonepeta tenuifolia, to neutralize hydroxyl radical, peroxyl radical and peroxynitrite was examined using the total oxyradical scavenging capacity (TOSC) assay. Peroxyl radical was generated from thermal homolysis of 2,2'-azobis(2-methylpropionamidine) dihydrochloride (ABAP); hydroxyl radical by an iron-ascorbate Fenton reaction; peroxynitrite by spontaneous decomposition of 3-morpholinosydnonimine N-ethylcarbamide (SIN-1). The oxidants generated react with $\alpha$-keto-$\gamma$-methiolbutyric acid (KMBA) to yield ethylene, and the TOSC of the substances tested is quantified from their ability to inhibit ethylene formation. Extracts from P. suffruticosa, M. denudata, and S. tenuifolia were determined to be potent peroxyl radical scavenging agents with a specific TOSC (sTOSC) being at least six-fold greater than that of glutathione (GSH). These three plants also showed sTOSCs toward peroxynitrite markedly greater than sTOSC of GSH, however, only P. suffruticosa revealed a significant hydroxyl radical scavenging capacity. Seven major active constituents isolated from P. suffruticosa, quercetin, (+)-catechin, methyl gallate, gallic acid, benzoic acid, benzoyl paeoniflorin and paeoniflorin, were determined for their antioxidant potential toward peroxynitrite, peroxyl and hydroxyl radicals. Quercetin, (+)-catechin, methyl gallate, and gallic acid exhibited sTOSCs 40~85 times greater than sTOSC of GSH. These four components also showed a peroxynitrite scavenging capacity higher than at least 10-fold of GSH. For antioxidant activity against hydroxyl radical, methyl gallate was greatest followed by gallic acid and quercetin. Further studies need to be conducted to substantiate the significance of scavenging a specific oxidant in the prevention of cellular injury and disease states caused by the reactive free radical species.

• Journal of Marine Bioscience and Biotechnology
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• v.9 no.2
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• pp.43-48
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• 2017

Temperature is a major factor that affects the physiochemical properties of compounds. This study focus on the determination of thermostability and the effect of temperature on antioxidant activities of Ecklonia cava (E. cava) ethanoic extract. The ethanoic extracts of E. cava were evaluated at $30^{\circ}C$, $60^{\circ}C$ and $90^{\circ}C$ for 0 to 7 days. The antioxidant activities were determined by DPPH, hydroxyl radical and hydrogen peroxide scavenging activities. The intracellular reactive oxygen species (ROS) scavenging activity was investigated using DCFH-DA assay. Results revealed that the ethanoic extract of E. cava incubated at different temperatures for 0 to 7 days, showed stable scavenging activities on DPPH, hydroxyl radical and hydrogen peroxide. The ROS scavenging activities of ethanoic extract and ascorbic acid were also investigated. The extract showed a stable ROS scavenging activity from 0 to 7 day at $90^{\circ}C$. However, the scavenging activity of ascorbic acid at $90^{\circ}C$ decreased starting from day 3. These results indicated that the antioxidant effects of this food grade ethanoic extract of E. cava could remain stable during the employed temperatures of food processing.

• Preventive Nutrition and Food Science
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• v.22 no.2
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• pp.107-117
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• 2017

The purpose of this study was to evaluate the antioxidant and anticholinesterase activities of yellow and white bitter yams from South Western Nigeria using methanolic extraction and simulated gastrointestinal digestion models. The phenolic compounds in the bitter yam varieties were evaluated by high performance liquid chromatography with a diode array detector (HPLC-DAD). The total phenolic content of the bitter yams was measured by the Folin-Ciocalteu method, reductive potential by assessing the ability of the bitter yam to reduce $FeCl_3$ solution, and the antioxidant activities were determined by the 2,2-diphenyl-1-picrylhydrazyl radical ($DPPH^{\cdot}$) scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation ($ABTS^{{\cdot}+}$) scavenging activity, nitric oxide radical ($NO^{\cdot}$) scavenging ability, hydroxyl radical scavenging ability, and ability to inhibit $Fe^{2+}$-induced lipid oxidation. The HPLC-DAD analysis revealed the presence of some phenolic compounds in the studied bitter yam varieties, with varying degree of quantitative changes after cooking. The antioxidant indices (total phenolic content, total flavonoid content, reducing power, $DPPH^{\cdot}$ scavenging activity, $ABTS^{{\cdot}+}$ scavenging activity, and $NO^{\cdot}$ scavenging activity) were higher in the simulated gastrointestinal digestion model compared to the methanolic extract, with the in vitro digested cooked white bitter yam ranking higher. Similarly, the in vitro digested yams had a higher inhibitory action against lipid oxidation compared to the methanolic extracts, with the cooked white bitter yam ranking high. The methanolic extracts and in vitro enzyme digests showed no acetylcholinesterase inhibitory abilities, while methanolic extracts and the in vitro enzyme digest displayed some level of butyrylcholinesterase inhibitory activities. Therefore the studied bitter yams could be considered as possible health supplements.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.453-458
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• 1988

This research was carried out to investigate the effects of Maillard reaction products and nondialyzable melanoidins on the nitrite-scavenging. Nitrite-scavenging reactions were done at the different pH conditions(pH 1.2, 4.2 and 6.0). Maillard reaction products and nondialyzable melanoidins, produced from the glucose-amino acids(lys., gly., arg., his.)model systems, had a great of nitrite-scavenging effects. Nitrite-scavenging effects of Maillard reaction products and nondialyzable melanoidins were also pH dependent, being higher at pH 1.2 and lower at pH 6.0. By the treatment of Maillard reaction products and nondialyzable melanoidins with sodium borohydride, nitrite-scavenging effects were remarkably decreased at pH 1.2.

• Natural Product Sciences
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• v.9 no.2
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• pp.73-79
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• 2003

To discover the sources with antioxidative activity in traditional medicines, 100 extracts of Korean medicinal plants were screened for their scavenging effect on peroxynitrite $(ONOO^{-})$ and total reactive oxygen species (ROS). The potency of total ROS scavenging activity was shown in the extracts of 25 plants, and 4 of their species, Macleaya cordata R. Br., Salvia plebeia R. Br., Cassia tora L. and Angelica gigas Nakai, had a greater effect with $IC_{50}$ values of $1.7{\pm}0.36$, $4.3{\pm}1.08$, $4.9{\pm}0.17$ and $5.8{\pm}1.01\;{\mu}g/ml$, respectively, than that of trolox, positive control $(7.61{\pm}0.12\;{\mu}g/ml)$. Another 35 extracts exhibited inhibitory effect of below 50 percent at $100\;{\mu}g/ml$ of sample concentrations on total ROS, while the rest observed total ROS generators rather than scavengers. The peroxynitrite scavenging activities were observed in the greater part of the plants tested. Five of them, Schisandra chinensis Baill, Campsis grandiflora (Thunb.) K. Schum., Cedrela sinensis A. Juss., Pleuropterus multiflorus Turcz. and Veronica linariaefolia Pall represented scavenging activities on peroxynitrite twice as strong with $IC_{50}$ Values of $0.48{\pm}0.10$, $0.59{\pm}0.15$, $0.60{\pm}0.10$, $0.64{\pm}0.10$ and $0.91{\pm}0.23\;{\mu}g/ml$, respectively, as that of penicillamine $(1.72{\pm}0.05\;{\mu}g/ml)$, positive control. Consequently, 25 species of the entire plants tested, exhibited scavenging activities on total ROS and $ONOO^{-}$, Salvia plebeia R. Br., Macleaya cordata R. Br., Cassia tora L. and Angelica gigas Nakai exerted potent scavenging activities on both radicals.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.6
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• pp.1615-1621
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• 2005

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are widely implicated in the aging process and age-related diseases. The present study was carried out to investigate scavenging activities of Junglans sinensis extract and its subfraction using fluorescent probes, DCF-DA, DAF-2 and DHR 123. Jungians sinensis was washed and crushed. The crushed Junglans sinensis was extracted 3times, each time with 3 volumes of methyl alcohol at $60^{\circ}C$ for 24 h. The extract was filtered and evaporated under a reduced pressure using a rotary evaporator to yield 16 g. Scavenging activities of $ONOO^-$ was measured by Kooy' method and ROS was measured by DCFDA assay. Junglans sinensis had the marked scavenging activites of $ONOO^-$, NO and $O_2^-$. Junglans sinensis scavenged $ONOO^-$ through electron donation and dose-dependently inhibited the nitration of bovine serum albumin by $ONOO^-$. Junglans sinensis also had ROS scavenging activity. Especially, ethylacetate fraction of Junglans sinensis showed the most effective scavenging activities for ROS and RNS. These results suggest that Junglans sinensis might be developed as an effective ROS and RNS scavenger Therefore, Junglans sinensis might be used as a preventive agent for the aging and relevant to aging of illness.