• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.10
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• pp.1498-1502
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• 2005

This study evaluated the isolation and identification of biologically active compounds from the ethyl acetate fraction of grape seed extract (Campbell early). Ethyl acetate fraction was further purified with sephadex LP-20 column chromatography. Each biologically active compound for free radical scavenging effect and lipid peroxidation inhibition was isolated and identified with ${1}^H$ and${12}^C$-NMR. Major compounds were identified as (+)-catechin and (-)-epicatechin respectively. The amounts of (+)-catechin and (-)-epicatechin in grape seed were 45.7$\%$ and 35.1$\%$, respectively. The purified (+)-catechin and (-)-epicatechin showed more strong free radical scavenging effects ($RC_{50}$= 11.1 $\mu$g/mL and 10.4 $\mu$g/mL) than ethyl acetate fraction ($RC_{50}$= 15.4 $\mu$g/mL). However, ethyl acetate fraction showed much stronger lipid oxidative inhibition effect than the purified (+)-catechin and (-)-epicatechin.

• Journal of Life Science
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• v.21 no.11
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• pp.1579-1585
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• 2011

Natural anti-diabetic semipurified ethyl acetate fraction was isolated from the submerged-liquid culture of Agaricus blaze Murill (AB) in a medium containing soybean flakes. Hot-water extract of AB (HEAB) was prepared by extraction at $121^{\circ}C$ for 60 min, followed by filtering through a filter presser filled with diatomate. The ${\beta}$-glucan-free HEAB, which was a supernatant fraction from HEAB by precipitation in an 80% ethanol solution, was fractionated into hexane, chloroform, ethyl acetate, and butanol fractions. The inhibition of the ${\alpha}$-glucosidase activity by fractions was 59.0, 17.0, 61.6, and 37.9%, respectively, suggesting that ethyl acetate fraction was the most active. A subfraction having a strong ${\alpha}$-glucosidase inhibitory activity (80.4%) was isolated from the ethyl acetate fraction. This subfraction contained isoflavones (genistin and daidzin) and their conjugates with sugars as potent inhibiters of ${\alpha}$-glucosidase activity. These results suggest that the ethyl acetate fraction or HEAB containing isoflavones and their sugars conjugates could be useful sources for controlling blood sugar levels in humans.

• Korean journal of food and cookery science
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• v.16 no.6
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• pp.644-651
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• 2000

This study was carried out to evaluate the effects of fractions of methanol(MeOH) extracts of Lycopus lucidic Turcz on hyperglycemia and energy metabolites in streptozotocin(STZ) diabetic rats. Diabetes mellitus was induced in male Sprague-Dawley rats weighing 200-220 g by an injection of STZ dissolved in a citrate buffer into the tail vein at a dose of 45 mg/kg of body weight, and the rats were divided into 7 groups, that is, one normal group and 6 diabetic groups: STZ-control, hexane, chloroform(CHCl$\sub$3/). ethylacetate(EtOAc), butanol(BuOH) and H$\sub$2/O fraction-fed groups. All groups were fed an AIN-93 diet and the fractions of Lycopus lucidic Turcz were administered orally with 2 % Tween 80 for 14 days after the STZ injection. Body weight, diet intake and organ weights were monitored. The plasma levels of blood glucose, insulin and protein were determined. The plasma concentrations of cholesterol, HDL-cholesterol, triglycerides and free fatty acid were assayed. The plasma activities of aspartate aminotransferase (AST) and alanine aminotransferase(ALT) were also measured. Body weight losses were observed by feeding the fractions of Lycopus lucidic Turcz in STZ experimental groups, and the kidney weight was increased. The extent of blood glucose decrement was significantly greater in the hexane and BuOH fraction-fed groups than STZ-control group. The plasma protein level was significantly lower in the H$\sub$2/O fraction-fed group. The plasma cholesterol level was decreased in BuOH and H$\sub$2/O fraction-fed groups compared with the STZ-control group. The levels of free fatty acids in the CHC1$\sub$3/ and H$\sub$2/O fraction-fed groups were significantly decreased(p<0.05). ALT activitiy of BuOH fraction-fed group was lower than control but it was not significantly different. These results suggest that the fractions of Lycopus lucidic Turcz are capable of lowering blood glucose and fat metabolites concentrations when administered to STZ-treated rats, and AST/ALT activity and insulin levels show the possibility of therapeutic use to diabetes mellitus.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.135-135
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• 1999

It is well known that Raman spectroscopy is powerful tool in analysis of sp3/sp3 bonding fraction in diamond-like carbon(DLC) films. Raman spectra of DLC film is composed of D-peak centered at 1350cm-1 and G-peak centered at 1530cm-1. The sp3/sp3 fraction is qualitatively acquired by deconvolution method. However, in case of DLC film, it is generally observed that G-peak position shifts toward low wavenumber as th sp3 fraction increases. However, opposite results were frequently observed in ta-C films. ta-C film has much higher residual compressive stress due to its high sp3 fraction compared to the DLC films deposited by CVD method. Effect of residual stress on G-peak position is most recommendable parameter in Raman analysis of ta-C, due to its smallest fitting error among many parameters acquired by peak deconvolution of symmetric spectra. In current study, the effect of residual stress on Raman spectra was quantitatively evaluated by free-hang method. ta-C films of different residual stress were deposited on Si-wafer by modifying DC-bias voltage during deposition. The variation of the G-peak position along the etching depth were observed in the free-hangs of 20~30${\mu}{\textrm}{m}$ etching depth. Mathematical result based on Airy stress function, was compared with experimental results. The more reliable analysis excluding stress-induced shift was possible by elimination of the Raman shift due to residual compressiove stress.

• Applied Biological Chemistry
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• v.45 no.3
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• pp.162-167
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• 2002

Free, soluble esterified and insoluble bounded phenolic acids were separated from Eungi chestnut endoderm. The composition and contents of phenolic acid were analyzed by gas chromatography, and their antioxidant activity was examined by DPPH assay, 2-deoxyribose oxidation, and ferric thiocyanate method. Gallic, ellagic, salicylic, and gentisic acids in free phenolic acid fraction, gallic, ellagic, and protocatechuic acids in soluble esterified fraction, sianpic and gentisic acids were the major phenolic acids in insoluble bounded fraction. Marked differences were observed in the phenolic acid composition and contents among the fractions. Free phenolic acid fraction showed the strongest antioxidant activity. Results revealed chestnut endoderm could be a potential antioxidant source containing gallic and ellagic acids.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.41 no.2
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• pp.181-187
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• 2015

In this study, the methanol fraction and aglycone fraction were made from Gynura procumbens (G. procumbens) extracts and their antioxidative effects were investigated. The free radical scavenging activity (1,1-diphenyl-2-picrylhydrazyl, DPPH), total antioxidant capacity by luminol-dependent chemiluminescence assay, and the protective effects against reactive oxygen species (ROS) in erythrocytes were measured to evaluate the antioxidative activities of the extracts. Free radical scavenging activities ($FSC_{50}$) of the methanol fraction and aglycone fraction were 90.25 and $81.38{\mu}g/mL$, respectively. Total antioxidant capacities ($OSC_{50}$) of the methanol fraction and aglycone fraction were 16.96 and $12.30{\mu}g/mL$, respectively. The free radical scavenging activity and total antioxidant capacity of the aglycone fraction were greater than those of methanol fraction. The cellular protective effect on the $^1O_2$-induced cellular damage of human erythrocytes was confirmed by ${\tau}_{50}$ value. The ${\tau}_{50}$ value of the methanol fraction and aglycone fraction were 36.7 min and 76.1 min, respectively in $5{\mu}g/mL$, and the aglycone fraction showed about 2 times higher cellular protecive effect than (+)-${\alpha}$-tocopherol (35.4 min). These results indicate that the aglycone fraction of G. procumbens extracts has application possibility as antioxidant ingredient of cosmetic.

• Food Science and Preservation
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• v.2 no.1
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• pp.173-183
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• 1995

This paper was carried out to investigate changes in chromatograms of polysacctatides and soluble pectins on Sephadex G-50 and non-cellulosic neutral sugars of polysaccharides isolated from cell wall of persimmon fruits treated with polygalacturonase and $\beta$-galactosidase in vitro. The chromatogram pattern of soluble pectins extracted from cell wall treated with $\beta$-galactosidase on Sephacryl S-500 column were similar to those of untreatment, but contents of soluble pectins treated with $\beta$-galactosidase were different from those of untreatment. The patterns of chromatograms In soluble pectins extracted from cell wall treated with polygalacturonase were more complex and lower molecular polymer than those of other cell wall-degrading enzyme treatments. Non-cellulosic neutral sugar of polysaccharides in fraction I of soluble material treated with polygalacturonase was rhamnose, those in fraction II were similar to those in fraction III and contents of arabinose, xylose and glucose were higher than contents of other non-cellulosic neutral sugars. Non-cellulosic neutral sugars of polysaccharides in fraction I in soluble material by $\beta$-galactosidase treatment were rhamnose, arabinose, galactose and mannose. Content of glucose of polysaccharides in fraction II was higher than that in fraction I . Non-cellulosic neutral sugars treated with mixed enzyme were rhamnose, fucose, arabinose, xylose, mannose, galactose and glucose. Compositions of non-cellulosic neutral sugars of polysaccharides in fraction I were similar to those in fraction II and III.

• Steel and Composite Structures
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• v.26 no.3
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• pp.273-287
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• 2018

Buckling and free vibration analysis of sandwich micro plate (SMP) integrated with piezoelectric layers embedded in orthotropic Pasternak are investigated in this paper. The refined Zigzag theory (RZT) is taken into consideration to model the SMP. Four different types of functionally graded (FG) distribution through the thickness of the SMP core layer which is reinforced with single-wall carbon nanotubes (SWCNTs) are considered. The modified couple stress theory (MCST) is employed to capture the effects of small scale effects. The sandwich structure is exposed to a two dimensional magnetic field and also, piezoelectric layers are subjected to external applied voltages. In order to obtain governing equation, energy method as well as Hamilton's principle is applied. Based on an analytical solution the critical buckling loads and natural frequency are obtained. The effects of volume fraction of carbon nanotubes (CNTs), different distributions of CNTs, foundation stiffness parameters, magnetic and electric fields, small scale parameter and the thickness of piezoelectric layers on the both critical buckling loads and natural frequency of the SMP are examined. The obtained results demonstrate that the effects of volume fraction of CNTs play an important role in analyzing buckling and free vibration behavior of the SMP. Furthermore, the effects of magnetic and electric fields are remarkable on the mechanical responses of the system and cannot be neglected.

• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.231-241
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• 2019

In this paper, a new higher order shear deformation model is developed for static and free vibration analysis of functionally graded beams with considering porosities that may possibly occur inside the functionally graded materials (FGMs) during their fabrication. Different patterns of porosity distributions (including even and uneven distribution patterns, and the logarithmic-uneven pattern) are considered. In addition, the effect of different micromechanical models on the bending and free vibration response of these beams is studied. Various micromechanical models are used to evaluate the mechanical characteristics of the FG beams whose properties vary continuously across the thickness according to a simple power law. Based on the present higher-order shear deformation model, the equations of motion are derived from Hamilton's principle. Navier type solution method was used to obtain displacement, stresses and frequencies, and the numerical results are compared with those available in the literature. A comprehensive parametric study is carried out to assess the effects of volume fraction index, porosity fraction index, micromechanical models, mode numbers, and geometry on the bending and natural frequencies of imperfect FG beams.

• Structural Engineering and Mechanics
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• v.85 no.4
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• pp.445-459
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• 2023

The current investigation is the first endeavor to apply the full layerwise finite element method (FEM) in free vibration analysis of functionally graded (FG) composite plates reinforced with graphene nanoplatelets (GPLs) in thermal environment. Unlike the equivalent single-layer (ESL) theories, the layerwise FEM focuses on all three-dimensional (3D) effects. The GPLs weight fraction is presumed invariable in each layer but varies through the plate thickness in a layerwise model. The modified Halpin-Tsai model is employed to acquire the effective Young's modulus. The rule of mixtures is applied to specify the effective Poisson's ratio and mass density. First, the current method is validated by comparing the numerical results with those stated in the available works. Next, a thorough numerical study is performed to examine the influence of various factors involving the pattern of distribution, weight fraction, geometry, and size of GPLs, together with the thickness-to-span ratio, thermal environment, and boundary conditions of the plate, on its free vibration behaviors. Numerical results demonstrate that employing a small percentage of GPL as reinforcement considerably grows the natural frequencies of the pure epoxy. Also, distributing more square-shaped GPLs, involving a smaller amount of graphene layers, and vicinity to the upper and lower surfaces make it the most efficient method to enhance the free vibration behaviors of the plate.