• 한국축산식품학회지
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• 제30권4호
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• pp.674-684
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• 2010

The effects of ascorbic acid (AA) alone or in combination with sodium acetate/calcium lactate (AA+SACL) and chitosan (AA+CH) on the physicochemical properties and microbial growth of beef and pork patties stored at $5^{\circ}C$ were investigated. The patties were case-ready packed in an air-containing polypropylene (PP) tray and sealed with polyethylene terephthlate (PETP)/casted polypropylene (CPP) top film. Treatments with AA, AA+SACL and AA+CH were effective in inhibiting total aerobic bacteria from day 4 compared to the control. In general, thiobarbituric acid, volatile basic nitrogen, and hue values in treated samples were lower than the control over the storage, whereas Hunter ${\alpha}^*$ (redness) values and sensory scores for surface color and off-odor were higher. Regarding quality and shelf-life extension, ground beef and pork patties treated with AA+SACL produced the most desirable results among all treatments during storage.

• Bulletin of the Korean Chemical Society
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• 제12권1호
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• pp.61-67
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• 1991

Conformational free energy calculations using an empirical potential function and the hydration shell model (a program CONBIO) were carried out on the neutral L-ascorbic acid (AA) in the unhydrated and hydrated states. The conformational energy was minimized from starting conformations which included possible conformations of six torsion angles in the molecule. The conformational entropy of each low energy conformation in both states was computed using a harmonic approximation. From the analysis of conformational free energies for AA in both states, intramolecular hydrogen bonds (HBs) are proved to be an essential factor in stabilizing the overall conformations, and cause the conformations in both states to be quite different from those in crystal. In the case of hydrated AA, there is a competition between HBs and hydration, and the hydration around the two hydroxyl groups attached to the acyclic side chain forces the molecule to form less stable HBs. The hydration affects strongly the conformational energy surfaces of AA. Several feasible conformations obtained in this work indicate that there exists an ensemble of several conformations in aqueous solution. The calculated probable conformations for the rotation about the C5-C6 bond of the acyclic side chain are trans and gauche +, which are in good agreement with results of NMR experiment.

• Bulletin of the Korean Chemical Society
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• 제26권9호
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• pp.1403-1409
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• 2005

A sensitive and selective electrochemical method was developed for the amperometric determination of ascorbic acid (AA) at a glassy carbon electrode (GCE) modified with single-wall carbon nanotubesdihexadecyl hydrogen phosphate (SWNT-DHP) composite film. The SWNT-DHP composite film modified GCE was characterized with SEM. The SWNT-DHP composite film modified GCE exhibited excellent electrocatalytic behaviors toward the oxidation of AA. Compared with the bare GCE, the oxidation current of AA increased greatly and the oxidation peak potential of AA shifted negatively to about -0.018 V (vs. SCE) at the SWNT-DHP composite film modified GCE. The experimental parameters, which influence the oxidation current of AA, were optimized. Under the optimal conditions, the amperometric measurements were performed at a applied potential of -0.015 V and a linear response of AA was obtained in the range from 4 ${\times}$ $10^{-7}$ to 1 ${\times}$ $10^{-4}$ mol $L^{-1}$ and with a limit of detect (LOD) of 1.5 ${\times}$ $10^{-7}$ mol $L^{-1}$. The interferences study showed that the SWNT-DHP composite film modified GCE exhibited good sensitivity and excellent selectivity in the presence of high concentration uric acid and dopamine. The proposed procedure was successfully applied to detect AA in human urine samples with satisfactory results.

• International Journal of Oral Biology
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• 제45권4호
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• pp.169-178
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• 2020

L-ascorbic acid (L-AA; vitamin C) induces apoptosis in cancer cells. This study aimed to elucidate the molecular mechanisms of L-AA-induced apoptosis in human laryngeal epidermoid carcinoma Hep-2 cells. L-AA suppressed the viability of Hep-2 cells and induced apoptosis, as shown by the cleavage and condensation of nuclear chromatin and increased number of Annexin V-positive cells. L-AA decreased Bcl-2 protein expression but upregulated Bax protein levels. In addition, cytochrome c release from the mitochondria into the cytosol and activation of caspase-9, -8, and -3 were enhanced by L-AA treatment. Furthermore, apoptosis-inducing factor (AIF) and endonuclease G (EndoG) were translocated into the nucleus during apoptosis of L-AA-treated Hep-2 cells. L-AA effectively inhibited the constitutive nuclear factor-κB (NF-κB) activation and attenuated the nuclear expression of the p65 subunit of NF-κB. Interestingly, L-AA treatment of Hep-2 cells markedly activated Akt and mitogen-activated protein kinase (MAPK; extracellular signal-regulated kinase 1/2, p38, and c-Jun N-terminal kinase [JNK]) and and LY294002 (Akt inhibitor), SB203580 (p38 inhibitor) or SP600125 (a JNK inhibitor) decreased the levels of Annexin V-positive cells. These results suggested that L-AA induces the apoptosis of Hep-2 cells via the nuclear translocation of AIF and EndoG by modulating the Bcl-2 family and MAPK/Akt signaling pathways.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2363-2368
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• 2007

A glassy carbon electrode (GCE) modified with phytic acid (PA) and single-walled carbon nanotubes (SWNTs) were investigated by voltammetric methods in buffer solution. The PA-SWNTs/GCE-modified electrode demonstrated substantial enhancements in electrochemical sensitivity and selectivity towards dopamine (DA) in the presence of L-ascorbic acid (AA). The PA-SWNTs films promoted the electron transfer reaction of DA, while the PA film, acting as a negatively charged linker, combined with the positively charged DA to induced DA accumulation in the film at pH under 7.4. However, the PA film restrained the electrochemical response of the negatively charged AA due to the electrostatic repulsion. The anodic peak potentials of DA and AA could be separated by electrochemical techniques, and the interferences from AA were effectively eliminated in the DA determination. Linear calibration plots were obtained in the DA concentration range of 0.1-10 μM and the detection limit of the DA oxidation current was determined to be 0.06 μM at a signal-to-noise ratio of 3. The results indicated that the modified electrode is used to determine DA without interference from AA.

• 한국식품조리과학회지
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• 제25권3호
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• pp.297-305
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• 2009

This study aimed to determine the physicochemical, microbiological, and sensory qualityies of steamed chicken samples by prepared with combined additions of oregano-allspice and Ascorbic acid (OA/AA), and processed by a sous-vide cook - chill system. The hurdle effect of the OA/AA addition was examined in terms of microbial stability improvements and their effects on sensory were also evaluated. First, the microbial risk was lowered and chicken quality was good with the addition of the OA/AA hurdle as compared to the control. Second, over various days of storage, the microbial quality of the OA/AA samples was relatively high. In standard plate counts, the control group presented a bacteria level of 2.75 LogCFU/g at 10 days of storage, but the OA/AA groups were had counts of 2.38, 1.89 and 1.81 LogCFU/g, respectively. And at 15 days of storage, the control group had a level of 3.65 LogCFU/g whereas the OA/AA groups had counts of 3.55, 3.54, and 3.24 LogCFU/g, respectively. Lastly, the sensory scores of the OA/AA groups were higher than those of the control group. Accordingly, overall microbial and sensory characteristics were better in the OA/AA hurdle groupsf than in the control group. Thus, the combined addition of Oregano-allspice and Ascorbic acid may be and alternative means for extending shelf - life.

• Journal of Microbiology and Biotechnology
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• 제16권1호
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• pp.64-67
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• 2006

To enhance the stability of ascorbic acid, the glycosylation of ascorbic acid was studied using the transfructosylation activity of levan fructotransferase. When levan was used as glycosyl donor, a novel fructoside (ascorbic acid 2-ffuctoside) was formed by the transfructosylation activity of the levan fructotransferase. The production of ascorbic acid 2-fructoside was highly affected by the concentration of the fructosyl acceptor (ascorbic acid). When $35\%$ of ascorbic acid and $2\%$ of levan were incubated with LFTase of 0.5 unit/glevan at $37^{\circ}C$ for 85 h, a maximum 52 g/l of AA-2F was produced.

• 산업식품공학
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• 제15권1호
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• pp.75-79
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• 2011

산화방지제인 아스코르빈산(AA), 에리쏘르빈산(isoAA), 아스코르빌파르미테이트(AP), 아스코르빌스테아레이트(AS)에 대한 '식품 중 식품첨가물 분석법'을 검증하고 미비점을 개선하였다. 고속액체크로마토그래피 자외선검출기법을 이용하여 검출한계(LOD), 정량한계(LOQ), 상관계수($R^2$) 등을 측정하였고 돼지기름(lard), 사이다를 이용한 모델식품에서의 회수율과 재현성을 측정하였다. AA와 isoAA의 검출한계는 각각 0.46, 0.48 ${\mu}g/mL$이었으며, 회수율은 각각 86.35-94.78, 84.76-95.02%를 나타내었고 상관계수는 모두 0.999이상을 보였다. AP와 AS의 현 분석법은 메탄올을 용매로 사용하지만 메탄올 용매에서 AP와 AS는 불안정하였다. 냉장온도에서 에탄올을 용매로 사용 시 다른 용매에 비해 유의적으로 높은 안정성을 나타내어 기존 용매의 불안정성을 개선할 수 있었다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제50권4호
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• pp.206-215
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• 2024

Objectives: The current in vitro study aimed to assess the effects of ascorbic acid augmented albumin platelet-rich fibrin (AA Alb-PRF) on the wound healing activity of human gingival fibroblasts (HGFs) purported to be a regenerative biomaterial in surgical procedures. Materials and Methods: All assays were performed on three HGF groups, group I: complete media; group II: Alb-PRF, and group III: AA Alb-PRF. Alb-PRF was prepared following the protocol by Fujioka-Kobayashi et al. (2021). For preparation of AA Alb-PRF, 2,500 ㎍ AA was added to the blood pre-centrifugation. All groups were subjected to 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay to estimate cell viability and proliferation, scratch assay for migration (0, 4, 12, and 24 hours) and transwell migration assay for chemotactic migration assessment (24 hours). Outcome variables were optical density (OD) for MTT assay, percentage of wound closure in scratch assay, and number of migrated cells in transwell migration assay. One-way ANOVA for MTT and transwell migration assays and two-way ANOVA for scratch assay with Bonferroni correction were performed with significance set at P<0.05. Results: Cell viability and proliferation (OD: 0.684±0.003 and proliferation: 28%) and wound closure (49.92%±1.62% at 4 hours and 61.39%±0.88% at 12 hours) were significantly higher in group III, while group II demonstrated the maximum number of HGFs migrating across the transwell membrane (9.25±2.49) with P<0.05. Conclusion: HGFs demonstrated a significant increase in viability and proliferation along with rapid wound closure in the presence AA Alb-PRF compared to Alb-PRF alone, indicating additional beneficial effects of AA. Thus, AA Alb-PRF potentiates the wound healing activity of HGFs and could be employed in oral, maxillofacial, and periodontal surgeries as a regenerative biomaterial.

• Journal of Microbiology and Biotechnology
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• 제11권2호
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• pp.242-250
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• 2001

A Gram-positive bacterium (strain JB-13) that was isolated from soil as a producer of cyclodextrin glucanotransferase (CGTase) [EC 2.4.1.19] was identified as Panibacillus sp. JB-13. This CGTase could catalyze the transglucosylation reaction from soluble starch to L-ascorbic acid (AA). A main product formed by this enzyme with ${\alpha}-glucosidase$ was identified as $2-O-{\alpha}-D-glucopyranosyl{\;}_{L}-ascorbic$ acid (AA-2G) by the HPLC profile and the elemental analysis. CGTase was purified to homogeneity using ammonium sulfate fractionation, ion-exchange chromatography on DEAE-Seohadex A-50, and gel chromatography on Sephacryl S-200HR. The molecular weight was determined to be 66,000 by both gel chromatography and SDS-PAGE. The isoelectric point of the purified enzyme was 5.3. The optimum pH and temperature was PH 7.0 and $45^{\circ}C$ respectively. The enzyme was stable in the range of pH 6-9 and at temperatures of $75{\circ}C$ or less in the presence of 15 mM ${CaCl_2}.\;{Hg^2+},\;{Mn^+2},{Ag^+},\;and\;{Cu^2+}$ all strongly inhibited the enzyme's activity.