• Journal of Microbiology and Biotechnology
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• v.21 no.2
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• pp.147-153
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• 2011

Bacillus species have been involved in metal association as biosorbents, but there is not a clear understanding of this chelating property. In order to evaluate this metal chelating capacity, cultures and spores from Grampositive bacteria of species either able or unable to produce surface layer proteins (S-layers) were analyzed for their capacity of copper biosorption. Only those endowed of S-layers, like Bacillus sphaericus and B. thuringiensis, showed a significant biosorption capacity. This capacity (nearly 50%) was retained after heating of cultures, thus supporting that structural elements of the envelopes are responsible for such activity. Purified S-layers from two Bacillus sphaericus strains had the ability to biosorb copper. Copper biosorption parameters were determined for strain B. sphaericus 2362, and after analyses by means of the Langmuir model, the affinity and capacity were shown to be comparable to other bacterial biosorbents. A competitive effect of $Ca^{2+}$ and $Zn^{2+}$, but not of $Cd^{2+}$, was also observed, thus indicating that other cations may be biosorbed by this protein. Spores that have been shown to be proficient for copper biosorption were further analyzed for the presence of S-layer content. The retention of S-layers by these spores was clearly observed, and after extensive treatment to eliminate the S-layers, the biosorption capacity of these spores was significantly reduced. For the first time, a direct correlation between S-layer protein content and metal biosorption capacity is shown. This capacity is linked to the retention of S-layer proteins attached to Bacillus spores and cells.

• Journal of Ecology and Environment
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• v.30 no.3
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• pp.271-276
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• 2007

A simple and efficient protocol was developed for culturing Cu-tolerant and Cu-accumulating plants via pre-adaptation to Cu during plant tissue culture. We induced multiple shoots from begonia (Begonia evansiana Andr.) leaf explants on MS medium supplemented with naphtaieneacetic acid and benzyladenine. After 3 months, small plantlets were transferred to MS medium supplemented with $100{\mu}M\;CuCl_2$ for pre-adaptation to Cu and cultured for 5 months. Then, these plantlets were individually planted in pots containing artificial soil. An additional 500 mg of Cu dissolved in 1/4 strength MS solution was applied to each pot during irrigation over the course of 2 months. We planted pre-adapted and control begonias in soil from the II-Kwang Mine, an abandoned Cu mine in Pusan, Korea, to examine their ability to tolerate and accumulate Cu for phytore-mediation. Pre-adapted begonias accumulated $1,200{\mu}g$ Cu/g dry root tissue over the course of 45 days. On the other hand, non-Cu-adapted controls accumulated only $85{\mu}g$ Cu/g dry root tissue. To enhance Cu extraction, chelating agents, ethylenediamine tetraacetic acid (EDTA)-dipotassiun and pyridine-2,6-dicarboxylic acid (PDA), were applied. While the chelating agents did not enhance accumulation of Cu in the roots of control begonias, EDTA application increased the level of Cu in the roots of pre-adapted begonias twofold (to $2,500{\mu}g$ Cu/g dry root tissue). Because pre-adapted begonias accumulated a large amount of Cu, mainly in their roots, they could be used for phytostabilization of Cu-contaminated soils. In addition, as a flowering plant, begonias can be used to create aesthetically pleasing remediation sites.

• Restorative Dentistry and Endodontics
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• v.40 no.3
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• pp.195-201
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• 2015

Objectives: The use of chitosan nanoparticles (CNPs) in endodontics is of interest due to their antibiofilm properties. This study was to investigate the ability of bioactive CNPs to remove the smear layer and inhibit bacterial recolonization on dentin. Materials and Methods: One hundred bovine dentin sections were divided into five groups (n = 20 per group) according to the treatment. The irrigating solutions used were 2.5% sodium hypochlorite (NaOCl) for 20 min, 17% ethylenediaminetetraacetic acid (EDTA) for 3 min and 1.29 mg/mL CNPs for 3 min. The samples were irrigated with either distilled water (control), NaOCl, NaOCl-EDTA, NaOCl-EDTA-CNPs or NaOCl-CNPs. After the treatment, half of the samples (n = 50) were used to assess the chelating effect of the solutions using portable scanning electronic microscopy, while the other half (n = 50) were infected intra-orally to examine the post-treatment bacterial biofilm forming capacity. The biovolume and cellular viability of the biofilms were analysed under confocal laser scanning microscopy. The Kappa test was performed for examiner calibration, and the non-parametric Kruskal-Wallis and Dunn tests (p < 0.05) were used for comparisons among the groups. Results: The smear layer was significantly reduced in all of the groups except the control and NaOCl groups (p < 0.05). The CNPs-treated samples were able to resist biofilm formation significantly better than other treatment groups (p < 0.05). Conclusions: CNPs could be used as a final irrigant during root canal treatment with the dual benefit of removing the smear layer and inhibiting bacterial recolonization on root dentin.

• Bulletin of the Korean Chemical Society
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• v.29 no.1
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• pp.43-46
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• 2008

The aim of present study was to examine the inhibitory effects of hydroxamic acid derivatives on the melanogenesis. We found that hydroxamic acid moiety was important for anti-melanogenic activity. Compounds 1a and 1b strongly inhibited melanin synthesis via deactivation of tyrosinase. Hydroxamic acid has metal ion chelating ability which is similar to that kojic acid, however, anti-tyrosinase mechanism of compounds 1a and 1b was different from that of kojic acid. They showed noncompetitive inhibition kinetics

• Natural Product Sciences
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• v.13 no.1
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• pp.40-45
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• 2007

The methanol extract of Coscinium fenestratum, commonly own as tree turmeric, which is widely used in the indigenous system of medicine was studied for its in vitro scavenging activity in different methods viz DPPH scavenging, nitric oxide scavenging, iron chelation activity, superoxide scavenging, ABTS radical scavenging and lipid peroxidation. The results were analyzed statistically by regression method. Its antioxidant activity was estimated by $IC_{50}$ value and the values are $57.1\;{\mu}g/ml$ for DPPH radical scavenging, $36.5\;{\mu}g/ml$ for iron chelating activity, $51.7\;{\mu}g/ml$ for nitric oxide scavenging, $53.63\;{\mu}g/ml$ for ABTS scavenging, $44.2\;{\mu}g/ml$ for superoxide scavenging, and $40\;{\mu}g/ml$ for lipid peroxidation. In all the methods, the extract showed its ability to scavenge free radicals in a concentration dependent manner. The results indicate that C. fenestratum has potent antiofidant activity.

• Korean Journal of Poultry Science
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• v.27 no.3
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• pp.209-213
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• 2000

Phosvitin, an iron chelating protein in egg yolk, was measured for its ability to inhibit lipid oxidation in egg oil model system. Phosvitin(75$\mu$M) could inhibit both iron(50∼150$\mu$M) and copper(5∼15$\mu$M) catalyzed oxidation of egg oil, and much more effective in the presence of iron than copper. The antioxidant activity of phosvitin in egg oil decreased with increasing temperature up to 121$\^{C}$. But phosvitin was relatively heat stable maintaining 79 and 73% of its antioxidant activity after being heated for 6 min at 100$\^{C}$ and 2 min at 121$\^{C}$, respectively.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1532-1536
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• 2009

The objective of this study was to evaluate the antioxidant effects and acetylcholinesterase (AChE) inhibition activity of mulberry fruit extracts prepared by hot water (MFH) and 80% ethanol (MFE). Total polyphenolic contents of MFH and MFE were $195{\pm}3.4\;mg$ gallic acid equivalents/g MFH and $185{\pm}2.8\;mg$ gallic acid equivalents/g MFE. MFH and MFE significantly quenched 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydrogen peroxide dose-dependently, and showed high chelating ability and reducing power in non-cellular systems. MFH and MFE also inhibited the formation of intracellular reactive oxygen species and lipid peroxidation, and elevated intracellular glutathione (GSH) levels in RAW264.7 cells. In addition, MFH and MFE also dose-dependently suppressed AChE activity.

• Nutrition Research and Practice
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• v.2 no.4
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• pp.247-251
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• 2008

This study investigated the antioxidant activity of methanol (MeOH) and water extracts from roots of Cirsium japonicum in vitro, MeOH extract showed a stronger tree radical scavenging activity than water extract. However, both of extracts showed a concentration dependent hydroxyl radical scavenging activity, reducing power and metal chelating ability, MeOH extract had greater phenolic and flavonoid contents than water extract. The antidiabetic activity of these two extracts was evaluated by the a-glucosidase inhibition assay, The water extract showed a considerable a-glucosidase inhibitory activity. To our knowledge, this may be the first time to report the antioxidant and antidiabetic activities in Cirsium japonicum roots.

• Korean Journal of Plant Resources
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• v.24 no.1
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• pp.23-29
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• 2011

In order to screen the functional constituents from nature resource, we studied the bioactivities of methanol extract of the Liriodendron tulipifera branch(MLT). The total phenolic and flavonoid contents, DPPH radical scavenging capacity, reducing power, $Fe^{2+}$ chelating ability, inhibition of lipid peroxidation and cell toxicity of MLT were investigated in this study. We found that the total phenolic and flavonoid content of MLT is 75.34 mg gallic acid/g and 20.15 mg quercetin/g respectively. MLT exhibited the antioxidant activity on DPPH radical with a $EC_{50}$ value of $289.68\;{\mu}g$/mL, the absorbance is 0.388 at $100\;{\mu}g$/mL in reducing power assay, MLT prevented 38.56% lipid peroxidation at $200\;{\mu}g$/mL. Furthermore, MLT exhibits the potent anti-proliferative activity which inhibited 56.94%, 35.73% growth of HT-29 and Hela cell at $200\;{\mu}g$/mL respectively. It showed that the antioxidant activities of MLT were correlated with its total phenolic and flavonoid contents. However further study need to be exploring in the future.

• Food Science of Animal Resources
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• v.33 no.2
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• pp.268-275
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• 2013

This study was performed to investigate the antioxidant activity of cherry added into meat products. Water and methanol were used to extract the antioxidant compounds from cherry. Total phenolic compounds of the methanol and water extract of cherry were 2.17 g/100 g and 2.77 g/100 g, respectively. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of methanol extract showed similar activities to those with ascorbic acid at all concentrations (from 0.1% to 2.0%). Especially, water extract of cherry showed similar activity to those of ascorbic acid (AA), and methanol extract, when 2% of cherry extract was added. The reducing power of cherry was not comparable to those with AA, however no differences in reducing power were observed between the water and methanol extract. The iron chelating ability of cherry was observed in the range of 17.8-94.0% at both water and methanol extracts. An increased iron chelating ability was observed with increased concentration up to 2%. Iron chelating ability for water extract of cherry tended to be lower than those with methanol extract. After pork patties were manufactured with methanol extract of cherry at 0.5 and 1.0%, physicochemical properties, lipid oxidation and microbial changes of patties were measured. The addition of methanol extract of cherry reduced pH, brightness, redness, yellowness and thiobarbituric acid reactive substance (TBARS). During 14 d of storage, pH, TBARS and microbial counts were increased, while redness and yellowness values were decreased. Since the addition of methanol extract of cherry lowered TBARS during storage, it could be used as a natural antioxidant in meat products.