• Korean Journal of Pharmacognosy
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• v.30 no.4
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• pp.397-403
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• 1999

Tyrosinase plays an important role in the process of melanin polymer biosynthesis. Therefore, the enzyme inhibitors have been of great concern as cosmetics to have skin-whitening effects on the local hyperpigmentation. During the search for new inhibitory compounds on melanin polymer biosynthesis from natural sources, MeOH extracts of 589 higher plants were tested for the inhibitory effect on tyrosinase activity by the muschroom tyrosinase assay in vitro. Among plants tested, the leaves of Cercis chinensis exhibited potent inhibitory effect on mushroom tyrosinase activity. Subsequently seven active compounds were isolated from the ethyl acetate soluble part of acetone extract of the leaves of C. chinensis by the activity guided fractionation monitoring the inhibitory effect on tyrosinase activity. Their chemical structures were identified as $kaempferol-3-0-{\alpha}-L-rhamnoside$, quercitrin, $myricetin-3-0-{\alpha}-L-rhamnoside$, myricetin-3-0-(2'-O-galloyl)- ${\alpha}$ -L-rhamopyranoside (desmanthin), (-)-epicatechin-3-0-gallate, (-)-epigallocatechin-3-0-gallate, and methyl gallate on the basis of the speculation of spectral data and chemical reaction. Among the flavonol rhamnosides, myricetin-3-0-(2'-O-galloyl)- -L-rhamnoside(desmanthin) showed most potent inhibitory effect on tyrosinase activity and the structure of B-ring in flavonol moiety was related to the activity. (-)-Epigallocatechin-3-O-gallate having pyrogallol group in flavan-3-ol moiety exhibited more potent inhibitory effect than (-)-epicatechin-3-0-gallate having catechol group in flavan-3-ol moiety on mushroom tyrosinase activity.

• Natural Product Sciences
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• v.26 no.3
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• pp.191-199
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• 2020

Fucoidan, a natural component of brown seaweed, has various biological activities such as anti-cancer activity, anti-oxidant, and anti-inflammatory against various cancer cells. However, the fucoidan has been implicated in melanoma cells via apoptosis signaling pathway. Therefore, we investigated apoptosis with fucoidan in A2058 human melanoma cells with dose- and time-dependent manners. In our results, A2058 cells viability decreased at relatively short-time and low-concentration through fucoidan. This effects of fucoidan on A2058 cells appeared to be mediated by the induction of apoptosis, as manifested by morphological changes through DNA-binding dye Hoechst 33342 staining. When a dose of 80 ㎍/mL fucoidan was treated, the cells were observed: crescent or ring-like structure, chromatin condensation, and nuclear fragmentation. With the increase at 100 ㎍/mL fucoidan, the cell membrane is intact throughout the total process, including membrane blebbing and loss of membrane integrity as well as increase of sub-G1 DNA. Furthermore, to understand the exact mechanism of fucoidan-treated in A2058 cells, western blotting was performed to detect apoptosis-related protein expression. In this study, Bcl-2 family proteins can be regulated by fucoidan, suggesting that fucoidan-induced apoptosis is modulated by intrinsic pathway. Therefore, expression of Bcl-2 and Bax may result in altered permeability, activating caspase-3 and caspase-9. And the cleaved form of poly ADP-ribose polymerase was detected in fucoidan-treated A2058 cells. These results suggest that A2058 cells are highly sensitive to growth inhibition by fucoidan via apoptosis, as evidenced by activation of extracellular signal-regulated kinases/p38/Bcl-2 family signaling, as well as alteration in caspase-9 and caspase-3.

• Applied Biological Chemistry
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• v.37 no.4
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• pp.287-294
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• 1994

New 3-phenyl-1-(2-furyl)propenones, 1 and 3-phenyl-1-(2-furyl)-3-thiophenyl-propanone, 2 derivatives were synthesized, and their fungicidal activities in vitro against Botrytis cineria (BC), Valsa ceratosperma (VC), Scelerotium cepivorum (SC) and Phytophthora capsici (PC) were investigated using a generalized structure-activity relationship (SAR). The activity of 1 was superior to those of 2, and nonsubstituent, 1a and chloro group substituent, 1d of E (Syn) conformer were the most effective $(EC_{50}=10{\sim}12\;ppm)$ compound to BC. Antifungal activities were able to predict to depend essentially on the ${\beta}$ carbon and their positive charge from the results that the good correlation $(r^2=0.90)$ was observed between hydrolysis rate constant (logk) of 1 and the electronic parameter $({\sigma})$ of X-substituent on the ${\beta}-phenyl$ ring.

• Applied Biological Chemistry
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• v.37 no.6
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• pp.516-521
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• 1994

New seventeen imazapyr derivatives, 2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)-3-(N-methyl-N-X(sub.)-phenylaminooxoacetyl)pyridine, 6 were synthesized and their pre-emergence herbicidal activity$(pI_{50})$ in vivo against Corn (Zea mays L.) and Pigweed (Amaranthus viridis L.) were studied by the pot test under paddly conditions. Quantitative structure activity relationships (QSARs) were analyzed using the physicochemical parameters of substituent(X) on the phenyl ring of 3-(N-methyl-N-X(sub.)-phenylaminooxoacetyl) group and regression analysis. The herbicidal activities were related to the steric effect of X-substituent. The effect was rationalized by paraholic function of MR and $L_1$, where the optimal values were MR=5.56 (Zea mays L.) and $L_1=3.34\;{{\AA}}$ (Amaranthus viridis L.). Among them, 2,5-difluoro substituted compound, 6i showed good herbicidal activity against Pigweed with excellent tolerance to Corn.

• Applied Biological Chemistry
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• v.48 no.3
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• pp.252-257
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• 2005

Three-dimensional quantitative structure-activity relationships (3D-QSARs) for the herbicidal activities against pre-emergence barnyard grass (Echinochloa crus-galli) by new 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpropion amide derivatives were studied quantitatively using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methodologies. The best CoMFA model (AI-2) and CoMSIA model (AII-4) were derived from an atom based fit alignment and a combination of CoMFA fields. The herbicidal activities from CoMFA and CoMSIA contour maps showed that the activity will be able to be increased according to the substituents variation on the N-phenyl ring.

• Journal of the Korea Furniture Society
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• v.28 no.1
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• pp.88-93
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• 2017

A study was carried out to observe the 1% aqueous safranine solution flow speed in longitudinal and radial directions of softwood Larix kaempferi (Lamb.)Carriere, diffuse-porous wood Betula davurica Pall.. and ring-porouswood Castanea crenata S.etZ. In radial direction, ray cells and in longitudinal direction, tracheids, vessel and wood fiber were considered for the measurement of liquid penetration speed at less than 12% moisture contents (MC). The length, lumen diameter, pit diameter, end wall pit diameter and the numbers of end wall pits determined for the flow rate. The liquid flow in the those cells was captured via video and the capillary flow rate in the ones were measured. Vessel in hardwood species and tracheids in softwood was found to facilitate prime role in longitudinal penetration. Anatomical features like the length and diameter, end-wall pit numbers of ray parenchyma were found also responsible fluid flow differences. On the other hand, vessel and fiber structure affected the longitudinal flow of liquids. Therefore, the average liquid penetration depth in longitudinal tracheids of Larix kaempferi was found the highest among all cells considered in Betula davurica and Castanea crenata, In radial direction, ray parenchyma of Larix kaempferi was found the highest depth and the one of Betula davurica was the lowest. The solution was penetrated lowest depth in the wood fiber of Castanea crenata. The large vessel of Castanea crenata was found the lowest depth among the vessels. The solutin was penetrated to the wood fiber of Betula davurica higher than the one of Castanea crenata.

• Journal of Food Hygiene and Safety
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• v.30 no.1
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• pp.115-119
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• 2015

${\beta}$-cyclodextrin has an ability to protect compounds from oxidative reaction by collecting them within its ring-like structure. So, In harsh condition ($40^{\circ}C$), marker compound, quercetin, was dramatically reduced in Hovenia dulcis fruit extract containing dextrin at 4 and 8 week compared to 0 week, but not that containing ${\beta}$-cyclodextrin. To evaluate the effects of dextrin and ${\beta}$-cyclodextrin on protective effect of H.dulcis fruit extract against alcohol-induced liver damage, The mice were orally injected alcohol, H. dulcis fruit extract/dextrin (HD) and H. dulcis fruit extract/${\beta}$-cyclodextrin (HCD), respectively, for 7 days. The mice orally administrated with alcohol significantly enhanced the serum concentration of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and the activity of lactate dehydrogenase (LDH) in serum compared to the control group. HD and HCD significantly decreased the levels of serum ALT and AST and serum LDH activities compared to alcohol group. And also alcohol group significantly increased the level of total cholesterol compared to the control group, but HD and HCD significantly reduced it compared to the alcohol group. However, the levels of TG in blood were not significantly changed in all groups. The activities of alcohol dehydrogenase (ADH) were significantly increased in HD and HCD group although those of aldehyde dehydrogenase showed an increasing tendency. This data suggested that HD and HCD were able to induce alcohol degradation in the liver tissues. All together, the results showed that HCD demonstrated their ability to protect liver from alcohol-induced damage on equal terms with HD.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.2
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• pp.373-380
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• 2020

A valve product can be over-designed or too heavy. Finite element analysis was performed using ANSYS for two and three-dimensional ball valve models, and the ball weight was reduced by optimization within the allowable design criteria. The ball is structurally safe according to the computed stress values, which are within the material's admissible stress. The weight was reduced by about 22%, and the structural safety factor was 1.25. The structural safety of the seat insert and ring, which are used to prevent leakage, was confirmed through finite element analysis. It is shown that the two-dimensional analysis can result in similar values to the three-dimensional analysis for the axisymmetric structure. The redesign of the valve is not included in the results since such changes require a whole new design process, including all valve components.

• Journal of Microbiology and Biotechnology
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• v.13 no.4
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• pp.529-536
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• 2003

The growth-inhibitory activity of Cassia tora seed-derived materials against seven intestinal bacteria was examined in vitro, and compared with that of anthraquinone, anthraflavine, anthrarufin, and 1-hydroxyanthraquinone. The active constituent of C. tore seeds was characterized as quinizarin, using various spectroscopic analyses. The growth responses varied depending on the compound, dose, and bacterial strain tested. At 1 mg/disk, quinizarin exhibited a strong inhibition of Clostridium perfringens and moderate inhibition of Staphylococcus aureus without any adverse effects on the growth of Bifidobacterium adolescentis, B. bifidum, B. longum, and Lactobacillus casei. Furthermore, the isolate at 0.1 mg/disk showed moderate and no activity against C. perfringens and S. aureus. The structure-activity relationship revealed that anthrarufin, anthraflavine, and quinizarin moderately inhibited the growth of S. aureus. However. anthraquinone and 1-hydroxyanthraquinone did not inhibit the human intestinal bacteria tested. As for the morphological effect of 1 mg/disk quinizarin, most strains of C. perfringens were damaged and disappeared, indicating that the strong activity of quinizarin was morphologically exhibited against C. perfringens. The inhibitory effect on aflatoxin $B_1$ biotransformation by anthraquinones revealed that anthrarufin ($IC_50,\;11.49\mu\textrm{M}$) anthraflavine ($IC_50,\;26.94\mu\textrm{M}$), and quinizarin ($IC_50,\;4.12\mu\textrm{M}$), were potent inhibitors of aflatoxin ${B_1}-8,9-epoxide$ formation. However, anthraquinone and 1-hydroxyanthraquinone did not inhibit the mouse liver microsomal sample to convert aflatoxin $B_1$ to aflatoxin ${B_1}-8,9-epoxide$. These results indicate that the two hydroxyl groups on A ring of anthraquinones may be essential for inhibiting the formation of aflatoxin ${B_1}-8,9-epoxide$. Accordingly, as naturally occurring inhibitory agents, the C. tora seed-derived materials described could be useful as a preventive agent against diseases caused by harmful intestinal bacteria, such as clostridia, and as an inhibitory agent for the mouse liver microsomal conversion of aflatoxin $B_1$ to aflatoxin ${B_1}-8,9-epoxide$.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.7
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• pp.592-600
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• 2007

Nowadays, researches for replacing material systems for cryotanks by composites have been being performed for the purpose of lightweight launch vehicle. In this paper, a type 3 propellant tank, which is composed of the composite developed for cryogenic use and an aluminum liner, was fabricated and tested considering actual operating environment, that is, cryogenic temperature and pressure. For this aim, liquid nitrogen (LN2) was injected into the fabricated tank and in turn, gaseous nitrogen (GN2) was used for pressurization. During this test procedure, strains and temperatures on the tank surface were measured. The delamination between hoop layer and helical one, was detected during the experiment. Several attempts were followed to investigate the cause analytically and experimentally. Thermo-elastic analysis in consideration of the progressive failure was done to evaluate the failure index. Experimental approach through a LN2 immersion test of composite/aluminum ring specimens suitable for simulating the Type 3 tank structure.