• 연구논문집
• /
• 통권28호
• /
• pp.49-58
• /
• 1998

포핏밸브형 2행정 기관의 소기 시스템 형상 변화에 따른 소기유동 및 소기효율의 개선 효과를 해석하기 위해, 각 흡기포트 형상별 소기 유동 가시화와 소기효율 정량화 연구를 수행하고자 한다. 소기시스템의 형상은 기계연구원에서 독자 개발한 RSSV(Rotatable Shrouded Scavenging Valve)의 슈라우드 각도를 변화시켰으며, 소기 효율 정량화를 위해 정상상태하에서 등유와 착색된 물을 사용한 single-cycle method. 동적모사장치(dynamic simulatior)에서 $CO_2$와 $O_2$가스를 사용한 가스추출법(gas sampling method)을 적용하였으며 실제 기관에서의 소기 효율을 측정하기 위해 압력 선도를 해석하였다. 위 실험들의 결과로부터 $90^circ$슈라우드 밸브가 가장 높은 효율을 가지는 것으로 판명되었으며, 특히 이들 실험방법들은 2행정 엔진 개발에 있어 시간과 비용을 절감하는데 아주 유용한 기법임을 알 수 있었다.

• 산업식품공학
• /
• 제15권1호
• /
• pp.6-14
• /
• 2011

The polysaccharides from fruit body of Auricularia auricula and Tremella fuciformis were extracted using hot water, and partially purified through ethanol precipitation and dialysis. Free radical scavenging activities of the crude and purified polysaccharides were examined and compared each other. Free radical scavenging activities of the partially purified polysaccharides were higher than those of crude polysaccharides. DPPH free radical, ABTS radical and SOD-like activities of partially purified polysaccharide at 1 mg/mL of concentration from A. auricula were 61.7, 9.6 and 38.9%, respectively, while those of T. fuciformis were 9.6, 5.7 and 15.3%, respectively. Results of site and non-site specific hydroxyl radical scavenging activities indicated that the partially purified polysaccharide fractions from A. auricula and T. fuciformis exhibited the hydroxyl radical scavenging effect by hydrogen donating ability and iron ion chelating ability. Also, reducing powers of A. auricula and T. fuciformis were 77.1 and 14.7% of BHT (0.1%) as standard, respectively. It was suggested that antioxidant activities of A. auricula were about 1.4~6.4 times higher than those of T. fuciformis due to different levels of polyphenol content.

• 한국식품영양학회지
• /
• 제24권4호
• /
• pp.713-719
• /
• 2011

The antioxidant activities of the ethanol extract of Arctium lappa were assessed by measuring the 1,1-diphenyl-2-picrylhydrazyl( DPPH) radical scavenging effect, inhibition of $Fe^{2+}$-induced lipid peroxidation, inhibition of malondialdehyde(MDA)-bovine serum albumin(BSA) conjugation reaction and antimutagenic capacities using the Ames test. The DPPH radical scavenging activity and inhibition of $Fe^{2+}$-induced lipid peroxidation of the $Arctium$ $lappa$ ethanol extract significantly increased in a dose-dependent manner. In the radical scavenging assay using DPPH, the $IC_{50}$ of the Arctium lappa extract was 296 ${\mu}g$/assay(1.29 mg of dry sample). In addition, the $IC_{50}$ in the inhibition of $Fe^{2+}$-induced lipid peroxidation was 1,759 ${\mu}g$/assay(7.65 mg of dry sample). This extract also significantly inhibited the MDA-BSA conjugation reaction with an $IC_{50}$ of 57.58 mg/assay(250 mg of dry sample). However, no inhibitory effects against the direct and indirect mutagenicities in $Salmonella$ Typhimurium TA98 and TA100 were observed. Based on these results, the ethanol extract of $Arctium$ $lappa$ was shown to display considerable antioxidative activities.

• Food Science and Biotechnology
• /
• 제18권4호
• /
• pp.849-854
• /
• 2009

Water extracts of injinssuk (Artemisia iwayomogi Kitamura) (WE) were obtained from the dried and ground leaves and stems of injinssuk. The WE was further fractionated into crude polysaccharide (C-PS) and nonpolysaccharide fractions (N-PS). The protective activities against the tert-butyl hydro peroxide induced mutangenecity on Escherichia coli PQ37 and reactive oxygen species scavenging activity of the WE, C-PS, and N-PS were studied. The WE obtained from leaves showed a significantly higher inhibitory effect on the mutagenicity than WE from stem. The WE obtained from the leaves having higher crude polysaccharide content but lower content of total carbohydrates had significantly higher antimutagenicity than that from the leaves with lower crude polysaccharide but higher total carbohydrate contents. Further study showed that C-PS fraction showed markedly stronger antimutagenic effect than N-PS. C-PS was also more effective than N-PS for hydroxyl radical scavenging activity, but was similar to N-PS in superoxide radical scavenging activity.

• KSBB Journal
• /
• 제31권4호
• /
• pp.200-207
• /
• 2016

In the present study, antioxidant activity of crude extract and its solvent-partitioned subfractions (n-hexane, 85% aqueous methanol, n-butanol, and water) obtained from Atriplex gmelinii was investigated using several different antioxidant assays. The tested samples possessed different antioxidant and radical-scavenging activities in different assays. n-butanol fraction showed the most potent radical-scavenging activity on reducing power while 85% aqueous methanol fraction exhibited the highest radical-scavenging activity on DPPH radicals and intracellular reactive oxygen species (ROS). On the otherhand, n-BuOH and 85% aqueous methanol revealed the similar inhibitory effect on peroxynitrite-scavenging and genomic DNA oxidation. These results suggest that the Atriplex gmelinii can be used as the valuable source for developing a natural antioxidant.

• KSBB Journal
• /
• 제19권1호
• /
• pp.67-71
• /
• 2004

본 연구에서는 염생식물의 하나인 해당화의 항산화효과를 탐색하기 위해 해당화의 dichloromethane과 methanol의 조추출물을 합하여 n-hexane, 15% aq. MeOH, n-BuOH, $H_2O$로써 순차적으로 용매 분획하여 DPPH 라디칼, peroxynitrite의 소거 활성과 지질 과산화 저해 활성을 측정하였다. 그 결과 각각의 실험에서 해당화의 유의적인 항산화 효과가 확인되었으며, 특히, 4개의 분획물들 중 n-BuOH 획분이 가장 뛰어난 항산화 효과가 있는 것으로 나타났다. 따라서 해당화의 항산화 효과는 비교적 극성이 큰 2차 대사산물에 의한 것임을 추측할 수 있으며, 해당화의 많은 생물학적인 활성들 중 peroxynitrite 소거 효과와 마우스 간 균질물을 이용한 지질 과산화물 생성 억제 활성에 관한 보고는 이것이 처음이다.

• Food Science and Biotechnology
• /
• 제14권5호
• /
• pp.614-620
• /
• 2005

The antioxidative effect of Ecklonia cava, a brown marine alga, was investigated on radical scavenging, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), and hydroxyl and alkyl radicals, using an electron spin resonance (ESR) technique, and on the inhibition of $H_2O_2$-induced DNA damage using comet assay. E. cava was enzymatically hydrolyzed with five food industrial proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase and Protamex) to prepare water-soluble extracts. All the proteolytic hydrolysates exhibited strong dose-dependent radical scavenging activities (above 80%) at a concentration of $2.5\;{\mu}g/mL$. Kojizyme extract (obtained by proteolytic hydrolysation of E. cava with Kojizyme) showed the highest hydroxyl radical scavenging activity of around 98%. In addition, the $H_2O_2$-induced DNA damage was determined using a comet assay, which was quantified by measuring the tail length. Reduction of DNA damage increased with increasing concentrations of Kojizyme extract from E. cava. These results indicated that E. cava has a potential as a valuable natural antioxidative source.

• 한국약용작물학회지
• /
• 제17권1호
• /
• pp.15-20
• /
• 2009

This study was carried out in order to determine the biological activities such as antioxidant activities in nine cultivars of Momordica charantia L. (Korea, China, Japan and Philippine native cultivars). Their antioxidant activities were measured using DPPH free radical scavenging, ABTS cation radical scavenging, and Nitrite scavenging ability. The highest total polyphenol content (16.82 ${\mu}g/m{\ell}$) measured in the native Korea cultivar, and this value was 4.0 ${\mu}g/m{\ell}$ higher than that of the 'Verde Beuhas' cultivar (12.82 ${\mu}g/m{\ell}$). The 'Peacock' cultivar had the highest total flavonoid amount which was 4.38 ${\mu}g/m{\ell}$. The free radical scavenging activity using DPPH method was the highest in the native China cultivar ($RC_{50}$ = 102.6 ${\mu}g/m{\ell}$). ABTS cation radical scavenging activity according to cultivars was significantly higher in 'Peacock'. Nitrite scavenging ability showed the most remarkable effect at the pH 1.2, exhibited to 81.5${\sim}$86.9% by addition of ethanol extract 1${\mu}g/m{\ell}$ from Momordica charantia L. These results suggest that Momordica charantia L. had the potent biological activities, and that their activities exhibited differently depending on cultivars.

• 한국자원식물학회지
• /
• 제29권3호
• /
• pp.289-296
• /
• 2016

This study was executed to evaluate the immune activity, nitrite scavenging activity and ABTS radical scavenging activity against extracts of various concentration of ethanol solvent from Codonopsis lanceolata cultured at 6 local regions. The immune responses from both human T and B cell line was significantly enhanced in the cell growth compared to control while the cell growth was influenced at a certain period of culture. The results revealed that the cell growth of both human T and B cell was altered in a time dependent manner. The nitrite scavenging activity of ethanol extracts from various solvent concentration of C. lanceolata were affected by pH. At a pH of 1.2, the nitrite scavenging effect of all of the extracts tested observed higher than that of the other two pH ranges. There was no distinct detection of nitrite scavenging effects of the pH range 6.0. The ABTS radical scavenging activity was progressively increased in a dose-dependent manner, and the activity was the highest in 100% ethanol extract. The result from this investigation suggests that the extract of Codonopsis lanceolata could be an addition to basic medicine for immune modulation and natural food additives.

• 동의생리병리학회지
• /
• 제17권6호
• /
• pp.1524-1527
• /
• 2003

In this study, we demonstrated the antioxidant effect of the Caesalpinia sappan L. extract through the scavenging effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and the protective effect on protein damage and PC12 cells against cupric ion/hydrogen peroxide. Its IC/sub 50/ value of the scavenging effect against DPPH radical was 7.7 ㎍. Protection of its extract against oxidative bovine serum albumin (BSA)damage induced by hydrogen peroxide was more effective than that of vitamin C. The protective effect on PC12 cells by hydrogen peroxide was shown to be more potent in is extract than in vitamin C. DNA fragmentation analysis also supports this result.