• Journal of the Society of Cosmetic Scientists of Korea
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• v.38 no.4
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• pp.263-270
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• 2012

Ascorbic acid (Vitamin C) becomes unstable in the aqueous phase by oxygen, light and alkali, etc. The properties are limited in application to cosmetics. The most important factor that determines the destabilization of ascorbic acid in the aqueous phase was tried to understand considering its molecular deformation and degradation. In this study, we changed the polyols and emulsification technique for the stability of ascorbic acid. Then we observed the color and concentration change of ascorbic acid at room temperature and high temperature ($42^{\circ}C$) for 6 weeks and identified the stability using HPLC regularly. As a result, we found that glycerin was the most appropriate polyol for stability of the ascorbic acid. Also the technique of nonaqueous emulsification stabilized ascorbic acid than P/S emulsification. Also, P/S emulsification, glycerin was more stable than propylene glycol. By the results we suggest that ascorbic acid could be stabilized by nonaqueous emulsification method and this data could be applied to stabilization methods for cosmetic products.

• Biomedical Science Letters
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• v.3 no.2
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• pp.151-160
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• 1997

This study was planned to evaluate the urinary ascorbic acid as a new biological marker for the intoxication of cadmium, which could possibly be driven by its increased utilization and environmental pollution. In order to meet this goal, we have peformed measurement of urinary ascorbic acid concentration, histopathological examination of the kidney, and biochemical test for the liver function using cadmium-intoxicated rats by oral administration. The average concentrations of urinary ascorbic acid in the $CdCl_2$-treated rats were 214.0 mg/dl for 100 ppm group and 254.3 mg/dl for 200 ppm group during experimental period of 50 days. These levels are 24 and 28 times higher than one in the control group (9.0 mg/dl), respectively. Ultrastructural study showed the eosinophilic hyaline cast and focal effacement, fusion in the renal tubules, as well as loss of foot processes on the glomerular epithelial cells. These results suggested that cadmium may be responsible for renal glomerular injury. The blood levels of AST, ALT and LDH in the treated groups (199 IU/I, 88 IU/I, 1190 U/I for the 100 ppm group and 270 IU/I, 226 IU/I, 760 U/I for the 200 ppm group) were higher than ones in the control group(143 IU/I, 50 IU/I, 334 U/I). These results indicated the cadmium induced the damage of liver function. In conclusion, the administration of cadmium showed a remarkable increase of urinary ascorbic acid with renal and hepatic damage. Therefore, it is expected that measurement of urinary ascorbic acid would be an powerful method as a noninvasive biomarker for cadmium intoxication.

• Journal of Applied Biological Chemistry
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• v.59 no.4
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• pp.361-364
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• 2016

We developed a spectrophotometric assay method for polyethoxylated ascorbic acidusing 3-ethyl ascorbic acid as standard material. The analytical method was validated by linearity, accuracy, precision, and stability. The coefficient of variation of the precision of the assay was less than 3.4 %. The linearity of the calibration curves in the desired concentration range is good ($r^2$>0.998). 3-Ethyl ascorbic acid and polyethoxylated ascorbic acid were stable in stock solution at room temperature for up to at least 6 h. The developed assay could be used for the content analysis of polyethoxylated ascorbic acid in samples.

• Journal of the Korean Home Economics Association
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• v.29 no.4
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• pp.37-43
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• 1991

Oxidative stability of crude wheat germ oil (WGO) was determined by the active oxygen method(Rancimat, hrs at 98$^{\circ}C$). The induction time of crude WGO was 7.6hrs as compared to 23.7hrs of crude soybean oil. However, the induction time of WGO could be extended by 2-3 times with 300ppm of mixed tocopherols and 200ppm of organic acids. The antioxidant effect of organic acids increased in the order of L-ascorbic acid > tartaric acid > citric acid > malic acid. Especially, the induction time of WGO could be extended by ca. 38hrs with 500ppm of L-ascorbic acid. This antioxiative effect of 500ppm L-ascorbic acid with mixed tocopherol(100, 200, 300 or 500ppm). It seems that the synergistic effect of L-ascorbic acid was due to the high content of tocopherols(0.4%) in WGO.

• Carbon letters
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• v.24
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• pp.1-9
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• 2017

We studied the basic properties and fabrication of reduced graphene oxide (rGO) prepared using eco-friendly reduction agents in the graphene solution process. Hydrazine is generally used to reduce graphene oxide (GO), which results in polluting emissions as well as fixed nitrogen functional groups on different defects in the graphene sheets. To replace hydrazine, we developed eco-friendly reduction agents with similar or better reducing properties, and selected of them for further analysis. In this study, GO layers were produced from graphite flakes using a modified Hummer's method, and rGO layers were reduced using hydrazine hydrate, L-ascorbic acid, and gluconic acid. We measured the particle sizes and the dispersion stabilities in the rGO dispersed solvents for the three agents and analyzed the structural, electrical, and optical properties of the rGO films. The results showed that the degree of reduction was in the order L-ascorbic acid ${\geq}$ hydrazine > glucose. GO reduced using L-ascorbic acid had a sheet resistance of $121k{\Omega}/sq$, while that reduced using gluconic acid showed worse electrical properties than the other two reduction agents. Therefore, L-ascorbic acid is the most suitable eco-friendly reduction agent that can be substituted for hydrazine.

• Textile Coloration and Finishing
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• v.19 no.2
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• pp.1-6
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• 2007

In order to improve the light fastness of a natural colorant berberine, several natural antioxidants such as gallic acid, L-ascorbic acid, and ${\alpha}-tocopherol$ were applied by aftertreatment method. Even though the increase in light fastness of berberine colorant was not substantial, L-ascorbic acid was the most effective. It was considered that this improvement of the light fastness was due to high antioxidation action of L-ascorbic acid to colorant, which led very highly excited species of the colorant formed by photo-energy to return to the original stable state without being decomposed.

• Journal of Nutrition and Health
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• v.29 no.9
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• pp.1042-1048
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• 1996

In order to investigate heating rate of commercial milk products in korean market, lactulose content and availability of calcium and ascorbic acid were measured. The pH range for raw and commercial milk was 6.5-6.75, and protein content was 2.5-3.13%. The acid degree value (。SH)showed between 5.3 and 7.1. There were no differences in pH, protein and acid degree among 3 types of milk. The portion ionic Ca content in UHT-milk(32.4%) and pasteurized milk (27%) increased significantly in comparison with raw milk (4.6%). Pasteurization led to loss of 20% ascorbic acid, and losses of UHT-treatment are approximately twice as high. Significant differences of lactulose content between UHT milk and pasteurized milk were observed. Some of UHT milk products showed very high value of lactulose content like sterilized milk. It is well known that the stress caused by indirect UHT treatment is slightly higher compared with the direct process. The results in this experiment suggested that most of UHT milk in korean market may be treated by indirect UHT method. In oder to keep the adventages of milk component, the heating methods of milk have to be reconsidered.

• Korean Journal of Food Science and Technology
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• v.36 no.3
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• pp.461-464
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• 2004

Antioxidant artivity of Maesil (Prunus mume) was evaluated based on peroxide value (POV), thiobarbiturie acid reactive substances (TBARS value), and electron-donating ability using 1,1-diphenyl-2-pycryl hydrazil (DPPH) method. POVs for soybean oil with 0.02% antioxtdants were 276.93, 223.32, 217.38, 238.40, and 226.55 meq/kg in control, ascorbic acid, dibutyl hydroxytoluene (BHT), extract of dehydrated Maesil flesh (EDMF), and extract of dehydrated Maesil juice (EDMJ), respectively, Antioxidant activities for TBA values were 29.94. 45.35 13.81, and 25.00% In ascorbic acid, BHT, EDMF, and EDMJ, respectively. Electron-donating abilities by DPPH were 96.69, 77.82, 34.84, and 43.50% in ascorbic acid, BHT, EDMF, and EDMJ, respectively, EDAs by DPPH with 0.02% EDMF and EDMJ were 53.21 and 59.19%, respectively.

• Journal of Chest Surgery
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• v.34 no.7
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• pp.515-523
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• 2001

Background: More than 70% of morbidity and mortality of diabetes mellitus is due to macrovascular complications. These complications may be associated with defect of endothelium-dependent vascular relaxation. There have been suggestions that this defect might be due to direct toxicities of oxygen-free radical. So in this study ascorbic acid was used as a dietary supplement in streptozotocin induced diabetic rats to correct this defect. Material and Method: Sixty male Sprague-Dawley rats were used in this study. They were divided into control and experimental groups. Streptozotocin was injected to the 33 rats of experimental group and then divided into two the other receiving subgroups; one receiving ascorbic acid supplement(1 g/l in drinking water); and nosupplements. At 6, 9 and 12 weeks, abdominal aortic rings were obtained to make tissue preparations for evaluation of vascular smooth muscle contractility. Result: While control group showed good response to acetylcholine induced relaxation, diabetic group showed decreased relaxation regardless of ascorbic acid supplement at the experiments 6 weeks after streptozotocin treatment. This abnormal endothelium-dependent vascular relaxation was markedly reversed at 9 and 12 weeks into the diabetic group with ascorbic acid supplement. There were no differences in sodium nitroprusside induced relaxation responses between control and experimental groups; also, norepinephrine induced contractile responses did not show any remarkable effects. Conclusion: These results strongly suggest that the endothelial cells have defects in diabetic rats. Dietary supplement of ascorbic acid can reverse the defects of diabetic endothelial cells through its antioxidant effects and it may further protect against vascular disease in diabetic patients.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.1
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• pp.27-30
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• 1983

This study was carried out to measure the extracted L-ascorbic acid (AsA) amounts of Korean green tea under the different extracting conditions and the measurement followed the method of 2,4-dinitrophey lhydrazine (DNP) which were reformed by Tamula. The results are summarized as follows : 1. The better he quality of green tea was, the higher the rete of AsA extraction was and the green tea having a good quality was well extracted even in low temperature. 2. The rate of AsA extraction of green tea became higher in proportion to the temperature and in the case of $80^{\circ}C$ the extracted amounts reached to 85% in the first three minutes. 3. In relation between the boiling time of test water and the extracted AsA amounts, the extracted AsA amounts was increased in proportion to the boiling time of test water.