• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.3
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• pp.369-377
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• 2013

In order to increase the utilization of sweet potato leaves and stalks as much as roots, it is necessary to study their beneficial potential. In this study, the antioxidant, antiallergic and anti-inflammatory effects of sweet potato leaves and stalks were evaluated by measuring total polyphenol and flavonoid contents, DPPH radical scavenging effects, the reducing power and inhibition effects on xanthine oxidase (XO), 5-lipoxygenase (LOX), and cyclo-oxygenase (COX)-2 activities. Blanched sweet potato leaves (SL), raw whole purple stalks (ST) and peeled stalks (PST) were freeze-dried and extracted with 95% ethanol. Total polyphenol content was highest in SL (11.03 mg/g), followed by ST (0.87 mg/g), and PST (0.37 mg/g). Total flavonoid content was highest for SL (9.01 mg/g), followed by ST (0.50 mg/g) and PST (0.25 mg/g). The $IC_{50}$ for DPPH radical scavenging effects was highest for SL ($43.6{\mu}g/mL$), followed by ST ($308.4{\mu}g/mL$) and PST ($1,631.3{\mu}g/mL$). The reducing power was highest for SL ($59.72{\mu}g$ ascorbic acid eq./mL), followed by ST ($12.56{\mu}g$ ascorbic acid eq./mL) and PST ($2.18{\mu}g$ ascorbic acid eq./mL) with $1,000{\mu}g/mL$ of ethanol extract. The inhibition rate on XO activity was highest for SL (13.06%), followed by ST (5.05%) and PST (0.0%) at $250{\mu}g/mL$ extract treatment. The inhibition rate on COX-2 activity was highest for SL (55.34%), followed by ST (2.18%) and PST (0.0%) at $250{\mu}g/mL$ extract treatment. The inhibition rate on 5-LOX activity was highest for SL (91.16%), followed by ST (33.38%) and PST (14.93%) at $50{\mu}g/mL$ treatment. Taken together, sweet potato leaves showed high antioxidative, anti-allergic and anti-inflammatory activities, especially with very strong inhibition effects on 5-LOX activity. These beneficial effects of sweet potato leaves might be mainly caused by the high content of polyphenols and flavonoids.

• Toxicological Research
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• v.35 no.1
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• pp.83-91
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• 2019

Nanoparticles (NPs) have been recognized as both useful tools and potentially toxic materials in various industrial and medicinal fields. Previously, we found that zinc oxide (ZnO) NPs that are neurotoxic to human dopaminergic neuroblastoma SH-SY5Y cells are mediated by lipoxygenase (LOX), not cyclooxygenase-2 (COX-2). Here, we examined whether human bone marrow-derived mesenchymal stem cells (MSCs), which are different from neuroblastoma cells, might exhibit COX-2- and/or LOX-dependent cytotoxicity of ZnO NPs. Additionally, changes in annexin V expression, caspase-3/7 activity, and mitochondrial membrane potential (MMP) induced by ZnO NPs and ZnO were compared at 12 hr and 24 hr after exposure using flow cytometry. Cytotoxicity was measured based on lactate dehydrogenase activity and confirmed by trypan blue staining. Rescue studies were executed using zinc or iron chelators. ZnO NPs and ZnO showed similar dose-dependent and significant cytotoxic effects at concentrations ${\geq}15{\mu}g/mL$, in accordance with annexin V expression, caspase-3/7 activity, and MMP results. Human MSCs exhibited both COX-2 and LOX-mediated cytotoxicity after exposure to ZnO NPs, which was different from human neuroblastoma cells. Zinc and iron chelators significantly attenuated ZnO NPs-induced toxicity. Conclusively, these results suggest that ZnO NPs exhibit both COX-2- and LOX-mediated apoptosis by the participation of mitochondrial dysfunction in human MSC cultures.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.122-126
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• 2006

Two types of pressurization system and low weight feeding piping system are developed. With sub-system tests, ullage pressure control performance was verified for 1 step and 2 step pressurization system and the feeding performance of feeding piping system was also verified. The weight of the feeding piping system is low enough for the application of launch vehicle. In addition, LOX conditioning system is developed for avoiding geysering and LOX temperature rise. Integrated performance was verified through integrated on-board feeding system performance tests.

• Aerospace Engineering and Technology
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• v.8 no.1
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• pp.26-31
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• 2009

Three Lox pumps and one fuel pump are manufactured for turbopump real-propellent tests and water tests of the pumps are performed in order to estimate the performance characteristics of the pumps. According to the test results, the test region(flow ratio, cavitation number) of the pumps at the water tests cover the operating region at the real-propellent tests and also all the pumps satisfy the design requirement. The head of the Lox pumps shows a 2% difference among them due to the internal geometry, but the efficiency and overall cavitation performance are almost same. It is found that the fuel pump has a similar head and efficiency compared with the previous model of the same internal geometry, while it has a little inferior cavitation performance.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.6
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• pp.91-100
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• 2016

Efficiency characteristics of centrifugal turbopumps for a liquid rocket engine were investigated. Predicting the performance of pumps for a turbopump assembly test, the variation on pump efficiency by working fluids was analyzed from pump component tests. Water and liquid nitrogen (LN2) were used for the component test, kerosene (Jet A-1) and liquid oxygen (LOX) were adapted for the turbopump assembly (TPU) test as working fluids. Overall performance of the pumps was investigated covering design/off-design operating points and the pump efficiency on the environment of real media (LOX/kerosene) could be modified from the pump component tests.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.1
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• pp.9-16
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• 2020

A performance evaluation of the 200 N-class GCH₄/LOx small rocket engine was performed through ground hot-firing test. As a result, the combustion pressure and thrust raised with the increase of the oxidizer supply pressure, and thus the specific impulse, characteristic velocity, and their efficiency increased. The characteristic velocity was measured at about 90% performance efficiency. The change of chamber aspect ratio did not affect the performance of the rocket engine in the test condition specified. In addition, uncertainty evaluation was conducted to ensure the reliability of the test results.

• Journal of Life Science
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• v.28 no.11
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• pp.1277-1284
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• 2018

In this study, a repeated yeast integrative plasmid (R-YIp) harboring Cre/loxP system was constructed to integrate various gene expression cassettes into the yeast chromosome. The R-YIp system contains a reusable selective marker (CgTRP1), loxP sequence, and target sequence for integration. Therefore, many gene expression cassettes can be integrated into the same position of the same yeast chromosome. In the present study, several model enzymes involving xylan/xylose metabolism were examined, including endoxylanase (XYLP), ${\beta}$-xylosidase (XYLB), xylose reductase (GRE3) and xylitol dehydrogenase (XYL2). Efficient expression of these genes was obtained using two promoters (GAL10p and ADH1p) and various plasmids (pGMF-GENE and pAMF-GENE plasmids) were constructed. The XYLP, XYLB, GRE3, and XYL2 genes were efficiently expressed under the control of the GAL10 promoter. Subsequently, R-YIps containing the GAL10p-GENE-GAL7t cassette were constructed, resulting in pRS-XylP, pRS-XylB, pRS-Gre3, and pRS-Xyl2 plasmids. These plasmids were sequentially integrated into chromosome VII of a Saccharomyces cerevisiae strain by repeated gene integration and selective marker rescue. These genes were integrated by the R-YIp system and were stably expressed in the yeast transformants to produce active recombinant enzymes. Therefore, we expect that the R-YIp system will be able to overcome current limitations of the host cells and allow selective marker selection for the integration of various genes into the yeast chromosome.

• Archives of Pharmacal Research
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• v.25 no.6
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• pp.747-758
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• 2002

The skin displays a highly active metabolism of polyunsaturated fatty acids (PUFA). Dietary deficiency of linoleic acid (LA), an 18-carbon (n-6) PUFA, results in characteristic scaly skin disorder and excessive epidermal water loss. Although arachidonic acid (AA), a 20-carbon (n6) PUFA, is metabolized via cyclooxygenase pathway into predominantly prostaglandin $E_2(PGE_2)$ and $PGF_{2{\alpha}}$, the metabolism of AA via the 15-lipoxygenase (15-LOX) pathway, which is very active in skin epidermis and catalyzes the transformation of M into predominantly 15S-hydroxyeicosatetraenoic acid (15S-HETE). Additionally, the 15-LOX also metabolizes the 18-carbon LA into 13S-hydroxyoctadecadienoic acid (13S-HODE), respectively. Interestingly, 15-LOX catalyzes the transformation of $dihomo-{\gamma}-linolenic$ acid (DGLA), derived from dietary gamma-linolenic acid, to 15S-hydroxyeicosatrienoic acid (15S-HETrE). These monohydroxy fatty acids are incorporated into the membrane inositol phospholipids which undergo hydrolytic cleavage to yield substituted-diacylglycerols such as 13S-HODE-DAG from 13S-HODE and 15S-HETrE-DAG from 15S-HETrE. These substituted-monohydroxy fatty acids seemingly exert anti-inflammatory/antiproliferative effects via the modulation of selective protein kinase C as well as on the upstream/down-stream nuclear MAP-kinase/AP-1/apoptotic signaling events.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.2
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• pp.1-9
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• 2004

The flow in the LOX manifold of liquid rocket (KSR-III) has been analyzed using a CAE technique with an objective of modeling injector orifices in order to reduce the computational cost for the flow analysis without much losing the accuracy of capturing the flow physics. The numerical result shows that the flow just above the injector orifices is not uniformly distributed in terms of pressure and mass flow rate in case pre-distributors are not equipped inside the manifold. This non-uniformity of mass flux is attributed to the presence of large-scale flow patterns. Several boundary conditions which were designed to effectively replace the presence of injector orifices have been tested and it was found that a simple modeling can be possible by mimicking the actual shape of the orifices.

• BMB Reports
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• v.51 no.6
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• pp.302-307
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• 2018

Pinosylvin is known to have anti-inflammatory activity in endothelial cells. In this study, we found that pinosylvin had a pro-apoptotic activity in lipopolysaccharide (LPS)-preconditioned leukocytes. This finding suggests that pinosylvin has an effect on the resolution of inflammation. To understand the detailed mechanism, we examined if pinosylvin enhances cyclooxygenase (COX) or lipoxygenase (LOX) activity in THP-1 and U937 cells. LOX activity was found to be markedly increased by pinosylvin, whereas COX activity was not altered. Furthermore, we found that pinosylvin enhanced both levels of ALOX 15 mRNA and protein, implying that LOX activity, elevated by pinosylvin, is attributed to upregulation of ALOX 15 expression. From this cell signaling study, pinosylvin appeared to promote phosphorylations of ERK and JNK. ERK or JNK inhibitors were found to attenuate ALOX 15 expression and LPS-induced apoptosis promoted by pinosylvin. In conclusion, pinosylvin enhances the apoptosis of LPS-preconditioned leukocytes by up-regulating ALOX 15 expression through ERK and JNK. These findings suggest that pinosylvin may induce the resolution of inflammation.