• Journal of Korean society of Dental Hygiene
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• v.6 no.4
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• pp.481-493
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• 2006

The purpose of the review article was to summarize and discuss the available information concerning the effect of bleaching on human teeth and reduced treatment on negative influence. Tooth bleaching effect was differ from extent of concentration and application period of a tooth bleaching agent, certainly full knowledge prior treatment about adverse effect possible appearance and follow clinical treatment for the least reduce. It remains unclear in how far those observation may result in significant adverse effect under clinical conditions. Nevertheless, further investigation are necessary to elucidate these aspect more precisely. The findings of the study were as follows : 1. It is recommended to delay placement of restorations after termination of bleaching therapy for at least 1-3 weeks. 2. Reduced negative influence that is clinical feasibility of catalase in protecting bleached surface against Oxygen radical. 3. The residual peroxide in tooth after bleaching seems to be removed by gradual diffusion and it may be possible to eliminate the adverse effect on tooth by using water displacement solution, ethylalcohol and aceton including it for effective removal of free radical oxygen.

• Journal of Forest and Environmental Science
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• v.13 no.1
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• pp.153-165
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• 1997

Hydroxyl radicals were detected and their qualitative yields were estimated by using chemiluminescence method and $\gamma$-irradiation technique in oxygen or chlorine dioxide radicals bleaching conditions. The correlation of hydroxyl radical formation and lignin model(Apocynol) or carbohydrate model($\alpha$-D-glucopyranose and methyl-$\beta$-D-glucopyranoside) degradation was studied in the presence of metal ion or without metal ion. The results showed that the presence of metal ions efficiently affected the formation of hydroxyl radicals in oxygen bleaching process, in the order of $Cu^{2+}$ > $Mn^{2+}$ > $Mg^{2+}$ > $Fe^{2+}$, and these metal gave also rise to the degradation of carbohydrate. But it was found that the addition of $100{\mu}m\;Mg^{2+}$ gave an efficient protection against carbohydrate degradation and suppressed the hydroxyl radical formation under oxygen bleaching conditions. And the presence of $Cu^{2+}$ had a detrimental effect on the stability of carbohydrates, whereas the addition of $3{\mu}m\;Mn^{2+}$ surprisingly had a small protective effect on methyl--$\beta$-D-glucopyranoside. In the $ClO_2$ radical bleaching conditions the hydroxyl radical expected to generate from water or substrates was not detected in the presence of metals.

• Restorative Dentistry and Endodontics
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• v.26 no.5
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• pp.399-408
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• 2001

Tooth bleaching has been prevailing recently for its ability to recover the color and shape of natural teeth without reduction of tooth material. However, it has been reported that bleaching procedure adversely affects the adhesive bond strength of composite resin to tooth. At the same time the bond strength was reported to be regained by application of some chemical agents. The purpose of this in vitro study was to investigate the effect of the removal of residual peroxide on the composite- enamel adhesion and also evaluated fracture mode between resin and enamel after bleaching. Sixty extracted human anterior and premolars teeth were divided into 5 groups and bleached by combined technique using of office bleaching with 35 % hydrogen peroxide and matrix bleaching with 10% carbamide peroxide for 4 weeks. After bleaching, the labial surfaces of each tooth were treated with catalase, 70% ethyl alcohol, distilled water and filled with composite resin. Shear bond strength was tested and the fractured surfaces were also examined with SEM. Analysis revealed significantly higher bond strength values. (p＜0.05) for catalase-treated specimens, but water-treated specimens showed reduction of bond strength, alcohol- treated specimens had medium value between the two groups(p＜0.05). The fracture mode was shown that the catalase group and the alcohol group had cohesive failure but the water sprayed group had adhesive failure. It was concluded that the peroxide residues in tooth after bleaching seems to be removed by gradual diffusion and the free radical oxygen from peroxide prevents polymerization by combining catalyst in the resin monomer. Therefore it may be possible to eliminate the adverse effect on the adhesion of composite resin to enamel after bleaching by using water displacement solution or dentin bonding agent including it for effective removal of residual peroxide.

• KSBB Journal
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• v.16 no.2
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• pp.179-182
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• 2001

The use of 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)(ABTS) as a radical mediator enhanced the bleaching efficiency of kraft pulp by horseradish peroxidase(HRP) and $H_2O_2$. High concentrations of up to 20 mM $H_2O_2$. were used. The bleaching of the kraft pulp increased as the amount of HRP and ABTS concentration were inceased up to 0.3 mg/90 mL and 2 mM, respectively. The bleaching of the kraft pulp was closely related with the HRPs activity and its adsorption onto the pulp. The activity of HRP and bleaching of kraft pulp were maximum at pH 7 and were reduced either in a acidic or alkaline solutions. The adsorption of HRP onto pulp was low in solutions of pH 6-8 and high in an acidic(pH5) and an alkaline solutions(pH 9). The adsorption of the enzyme was greater for alkali-lignin than for crystalline cellulose, the two major components of pulp.

• KSBB Journal
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• v.10 no.2
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• pp.183-190
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• 1995

The effects of enzymatic pretreatments on the bleaching of kraft pulp were studied. The kappa number of pulp samples which represents the lignin content of pulp decreased by 25.2% by the pretreatments with xylanase(EC 3.2.1.8, Pulpzyme HB) while it decreased by 13.7% without enzyme pretreatments after the extraction of the pretreated pulp samples in 1N NaOH. To enhance the effects of enzymatic pretreatment on the bleaching of kraft pulp, phenols were used as radical carriers with the simultaneous use of peroxidase(EC 1.11.1.7, Novozyme 502), $H_2O_2$, and xylanase. Guaiacol (1mM) was most effective by decreasing the kappa number by 29.6% when a low initial concentration of $H_2O_2$ (0.1mM) was used. The use of either a higher initial concentration of $H_2O_2$ or phenols lacking electron donating substituents such as phenol and p-chloyophenol, however, decreased the efficiency of enzymatic pretreatment indicating that the production rate and the stability of phenolic radicals are important parameters.

• Journal of the Korean Society of Food Culture
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• v.20 no.1
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• pp.77-85
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• 2005

이 연구에서는 미국산 R. rhabarbarum L.과 중국산 R. palmatum L.의 줄기 추출물과 그리고 한국산 R. undulatum L.의 뿌리 추출물이 천연항산화제로서의 사용 가능성을 평가하였다. 대황의 페놀화합물을 추출하기 위해서 물, 에탄올, 메탄올이 사용되었다. 에탄올이 대황(Rhubarb)에서 페놀화합물을 추출하는데 가장 효과적인 용매였으며 50% 에탄올은 R. rhabarbarum L. 줄기에, 70% 에탄올은 R. palmatum L.의 줄기에, 80% 에탄올은 R. undulatum L.의 뿌리에서 페놀을 추출하는데 각각 가장 효과적인 용매농도였다. 또한 추출물리 항산화능을 알기 위해 ${\beta}-carotene$ bleaching inhibition activity와 DPPH radical scavenging activity를 측정하였으며 합성항산화제인 BHT와 비교하여 측정하였다. ${\beta}-Carotene$ bleaching inhibition activity 실험에서 추출물의 농도가 증가하면 대황추출물의 항산화능이 역시 증가하였다. 추출물의 농도가 5mg/ml와 10mg/ml 일때 R. undulatum L. 뿌리추출물과 BHT의 항산화능은 유의적 차이는 없었다$(p{\leq}0.05)$. 그러나 DPPH radical scavenging activity에서 R undulatum L. 뿌리추출물이 0.4 mg/mL 농도 이상에서는 BHT 보다 높은 항산화능을 나타내었다. 결과적으로 대황(R. undulatum L.)의 80% 에탄올 추출물이 천연항산화제로의 사용이 가능하였다. 그러나 합성항산화제인 BHT의 식품에 사용농도를 비교하여 볼 때 대황 추출물의 항산화능이 BHT와 동일하기 위해서는 보다 높은 농도를 필요로 하였다.

• Journal of the Korean Applied Science and Technology
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• v.32 no.2
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• pp.312-319
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• 2015

In this study, n-butanol and ethyl acetate extracts were prepared from raw yam (Dioscorea batatas DECNE.). Their antioxidative potencies were investigated employing various in vitro methods, such as ferrous ion chelating, ${\beta}$-carotene bleaching assay, lipid peroxidation inhibition and nitric oxide (NO) radical scavenging and nitrite scavenging activity. The n-butanol fraction was assayed to possess stronger antioxidant activity by ${\beta}$-carotene bleaching assay, lipid peroxidation inhibition and NO radical scavenging activity. However, ethyl acetate extract was more effective in chelating ferrous ion and scavenging nitrite. Based on the results obtained, yam is a potential active ingredient that could be applied in antioxidation as well as bio-health functional food to take a good part in prevention of human diseases and aging.

• Advances in Traditional Medicine
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• v.7 no.2
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• pp.162-170
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• 2007

Woodfordia fruticosa Kurz. (Lythraceae), commonly known as Dhayero, is used in the treatment of various ailments in Nepal. In this study, the antioxidant capacity of crude extract and different polarity fractions of Woodfordia fruticosa flowers were assayed for their scavenging abilities against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and nitric oxide radicals, competitive ${\beta}$-carotene bleaching, reducing power, metal chelating ability and total phenolic content. Crude extract and polar fractions showed stronger antioxidant capacity and contained very high level of total phenolics. They exhibited strong DPPH radical scavenging, nitric oxide scavenging and reducing power, medium ${\beta}$-carotene bleaching and poor metal chelating capacity. Positive correlation obtained between total phenolic content and antioxidant capacity assays, indicated the contribution of phenolics toards antioxidant capacity.

• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.342-351
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• 2016

The bioactive compound and antioxidant property of Korean yam (Dioscorea batatas DECNE.) were studied using in vitro methods. Yam available in Korea was analyzed for lycopene, chlorophyll a, b, tannin, phytic acid and total saponin contents. 70% Methanol, 70% ethanol and chloroform-methanol mixture (CM, 2:1, v/v) were used to extract yam. Then the antioxidant activity evaluated through ferrous ion chelating activity, ${\beta}$-carotene bleaching method, lipid peroxidation inhibition and nitric oxide (NO) radical scavenging activity. 70% Methanol extract showed the highest ferrous ion chelating activity and NO radical scavenging activity. And CM extract was the most effective in inhibition of linoleic acid peroxidation evaluated by ${\beta}$-carotene bleaching assay and lipid peroxidation inhibition assay. Based on the results obtained, yam is a potential active ingredient that could be applied in antioxidation as well as bio-health functional food to take a good part in prevention of human diseases and aging.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.1
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• pp.13-18
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• 2006

The antioxidant activity of the extract of Erigeron annuus was assessed by means of two different in vitro tests: bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test) and the scavenging of authentic peroxynitrite in company with peroxynitrite generation from 3-morpholinosydnonimine (SIN-1). In both tests, the 85% aq. MeOH and n-BuOH soluble fractions of the crude extract showed a significant scavenging effect on peroxynitrite and DPPH radical in comparison to L-ascorbic acid. And bioassay-guided fractionation of the n-BuOH soluble fraction led to the isolation of three compounds: Apigenin (1), quercetin-3-O-glucoside (2), and caffeic acid (3). The structures of the isolated compounds were elucidated on the basis of their spectroscopic data and their antioxidant activities were measured by determining their capacity to scavenge peroxynitrite and the DPPH radical.