• Mycobiology
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• v.31 no.4
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• pp.248-250
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• 2003

Kojic acid was investigated for its antifungal activity against the human pathogenic fungi including Candida albicans, Cryptococcus neoformans and Trichophyton rubrum. For C. albicans, C. neoformans and T. rubrum, the MIC(minimum inhibitory concentration) of kojic acid was 640, 80 and 160 ${\mu}g/ml$, respectively. In C. neoformans, melanin-producing yeast, kojic acid-treated nonmelanized cell was more susceptible to magainin than melanized cell, suggesting melanin give a protective function against microbial peptide.

• Journal of Applied Biological Chemistry
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• v.51 no.3
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• pp.111-116
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• 2008

Aralia elata seeds were successively extracted with water, methanol, ethanol, acetone and chloroform. The crude extracts were investigated for antioxidant and antidiabetic activities. The antioxidant properties of various extracts were evaluated by antioxidant tests, such as DPPH free radical-scavenging activity, hydroxyl radical-scavenging assay, metal-chelating activity, lipid peroxidation inhibition activity and reducing power assay. The 70% methanol extract exhibited the highest activity in the in vitro models of DPPH free radical-scavenging activity, metal-chelating activity, and reducing power assay. Acetone extract showed good effects on lipid peroxidation inhibition and hydroxyl radical-scavenging assay at a low concentration. In addition, the $\alpha$-glucosidase inhibition assay showed that 70% methanol extract had the highest activity. These results indicate the high possibility of using A. elata seeds for medical application due to their efficient antioxidant properties.

• Biomedical Science Letters
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• v.16 no.4
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• pp.271-277
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• 2010

This study was conducted to investigate the biological activities of Areca catechu L. The antioxidative, fibrinolytic, thrombin inhibitory, and ${\alpha}$-glucosidase inhibitory activities of Areca catechu L extracted with hexane, $CHCl_3$, ethyl acetate, butanol, and water were measured. The water fraction showed the highest extraction yield at 3.65% (w/w). The butanol, $CHCl_3$, water, and ethyl acetate fractions showed strong antioxidative activities at 81.6%, 87.1%, 88.0%, and 89.5%, respectively. The fibrinolytic activity was strong only in the ethyl acetate fraction at 0.84 plasmin units/ml. The 100-fold dilution of the water fraction had the strongest thrombin inhibitory activity at 59.2%. The 100-fold dilution of butanol fraction displayed the strongest ${\alpha}$-glucosidase inhibitory activity at 88.6%. In conclusion, the extracts of Areca catechu L hold promise for use in the development of biofunctional foods to prevent cardiovascular diseases.

• Journal of Applied Biological Chemistry
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• v.51 no.4
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• pp.160-164
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• 2008

Potential antioxidant activities of methanol and water extracts of Cirsium japonicum var. ussuriense (CJ) leaves were examined. The reducing power and hydroxyl raical-scavenging activity assays showed that the methanol extract had a significantly higher activity than the water extract. In addition, the methanol extract showed a concentration-dependent reducing power, ranging from 0.228 to 1.072($0.1{\sim}0.5\;mg/mL$), as well as a high DPPH free radical-scavenging activity($EC_{50}=40.25\;{\mu}/mL$). The total phenolic(as tannic acid) and flavonoid(as quercetin) contents of the extract were 62.41 mg/g and 13.48 mg/g, respectively. The cytotoxic activity indicated that the methanol extract has an inhibition activity in the stomach carcinoma cell (35.40%), suggesting that the methanol extract of CJ leaves could be used as a potential source of pharmaceutical material.

• Food Science and Biotechnology
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• v.16 no.2
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• pp.177-182
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• 2007

The beneficial effects of fruits, vegetables, and beverages on human health have been attributed to their antioxidant activities. Therefore, antioxidant activity of food products is recognized as one of the important parameters in determining their functional values. Until now, antioxidant activity has been measured by various chemical and biological methods; however, many factors confound the reliability and reproducibility of measurements of antioxidant activity of food. In vitro methods may provide a useful indication of antioxidant activity but their results may not translate to the human biological system, while in vivo tests are difficult to carry out due to the intricate processes of uptake, cellular transportation, and metabolism of individual antioxidant components. Therefore, as long as these limitations exist, our best option is to measure the antioxidant activity in food directly. This review briefly summarizes currently available methods for the measurement of antioxidant activity in food and examines their respective validity.

• Journal of Microbiology and Biotechnology
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• v.16 no.3
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• pp.491-495
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• 2006

Methanol extracts of fruits of 67 plants were screened for in vivo antifungal activity against Magnaporthe grisea, Corticium sasaki, Botrytis cinerea, Phytophthora infestans, Puccinia recondita, and Blumeria graminis f. sp. hordei. Among them, 13 plant extracts ($3,000\;{\mu}g/ml$) showed more than 90% disease-control efficacy against at least one of six plant diseases. Specifically, the extracts of Aleurites fordii, Angelica dahurica, Camellia japonica, Chamaecyparis pisifera, Pittosporum tobira, and Styrax japonica controlled more than 90% of the development of rice blast at $1,000{\mu}g/ml$. Extracts of both S. japonica and A. dahurica fruits at $333{\mu}g/ml$ concentration displayed strong antifungal activity against M. grisea on rice seedlings.

• Journal of Microbiology and Biotechnology
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• v.17 no.10
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• pp.1585-1590
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• 2007

Although a number of melanogenesis inhibitors have recently been reported and used as cosmetic additives, none is completely satisfactory, leaving a need for novel skin-depigmenting agents. Thus, to develop a novel skin depigmenting agent from natural sources, the inhibition of melanogenesis by Chinese plants was evaluated. A methanolic extract of Nigella glandulifera Freyn was found to inhibit the melanin synthesis of murine B16F10 melanoma cells by 43.7% and exhibited a low cytotoxicity (8.1%) at a concentration of $100\;{\mu}g/ml$. Thus, to identify the melanogenesis-inhibiting mechanism, the inhibitory activity towards tyrosinase, the key enzyme of melanogenesis, was further evaluated, and the results showed inhibitory effects on the activity of intracellular tyrosinase yet not on mushroom tyrosinase. Finally, to isolate the compounds with a hypopigmenting capability, activity-guided isolation was performed, and Dioctyl phthalate identified as inhibiting melanogenesis.

• BMB Reports
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• v.34 no.2
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• pp.109-113
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• 2001

The Serratia marcescens metalloprotease inhibitor (SmaPI) is a proteinase inhibitor toward Serratia marcescens metalloprotease (SMP). The three-dimensional structure of SmaPI was calculated by computer modeling using the structure complex between SMP and the Erwinia chrysanthemi inhibitor as a template. Based on this model structure, the substitution of the amino acid residues, Ala4, Leu-5, Pro-6, and Thr-7, were located at the hinge region of the N-terminal segment by site-directed mutagenesis. Although the A4R and T7A mutant SmaPIs showed a nearly full inhibitory activity, the inhibitory activity of SmaPI decreased significantly when the Leu-5 was converted to Ala, Gly, Ile, or Val. Surprisingly, the L5I and L5V mutant SmaPIs showed less inhibitory activities than the L5A mutant. From these results, we suggested that the orientations and positions of respective aliphatic groups in the side-chain of position 5 mainly affected the inhibitory activity of SmaPI. The overall side-chain hydrophobicity was only slightly affected. The side-chain of the Leu-5 residue contributed approximately 0.79 kcal/mol out of 8.44 kcal/mol to the binding of SmaPI with SMP The inhibitory activities of P6A and F6G were also severely decreased. The Pro-6 may have a critical role in maintaining the strict conformation of the N-terminal portion that may be important in the inhibitory activity of SmaPI. In conclusion, Leu-5 and Pro-6 have crucial roles in the inhibitory function of SmaPI toward SMP.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.193-199
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• 2017

This study was aimed to evaluate the antimicrobial activity of Penicillium purpurogenum ED76 on several clinically important microorganisms. The endophytic fungus P. purpurogenum ED76 was previously isolated from Swietenia macrophylla leaf. The antimicrobial efficacy of P. purpurogenum ED76 dichloromethane extract was determined via disc diffusion and broth microdilution assay. A kill curve study was conducted and the morphology of extract treated bacterial cells were viewed under scanning electron microscope. The dichloromethane extract showed significant inhibitory activity on 4 test bacteria and 2 test yeasts. The minimal inhibitory concentration of the extract ranged from 125 to $1,000{\mu}g/ml$, which indicates the different susceptibility levels of the test microorganisms to the fungal extract. The kill curve study has revealed a concentration-dependent inhibition for all test microorganisms. With the increase of the extract concentration, the microbial growth was significantly reduced. The scanning electron micrograph of dichloromethane extract-treated Staphylococcus aureus cells showed the total damage of the cells. The cell wall invagination of the bacterial cells also indicates the loss of cellular materials and metabolic activity. The gas chromatography mass spectrometry analysis of the extract also showed that the major compound was stigmasterol, which constitutes 45.30% of the total area. The dichloromethane extract of P. purpurogenum ED76 exhibited significant inhibitory activity on several clinically important bacteria and yeasts. The study proposed a possible mode of action that the extract cause significant damage to the morphology of S. aureus cells.

• Molecules and Cells
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• v.26 no.6
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• pp.611-615
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• 2008

DNA methylation is an epigenetic mechanism for gene silencing. In Arabidopsis, MET1 is the primary DNA methyltransferase that maintains CG DNA methylation. Plants having an overall reduction of MET1 activity, caused by a met1 mutation or a constitutively expressed MET1 antisense gene, display genome hypomethylation, inappropriate gene and transposon transcription, and developmental abnormalities. However, the effect of a transient reduction in MET1 activity caused by inhibiting MET1 expression in a restricted set of cells is not known. For this reason, we generated transgenic plants with a MET1 antisense gene fused to the DEMETER (DME) promoter (DME:MET1 a/s). Here we show that DME is expressed in leaf primordia, lateral root primoridia, in the region distal to the primary root apical meristem, which are regions that include proliferating cells. Endogenous MET1 expression was normal in organs where the DME:MET1 a/s was not expressed. Although DME promoter is active only in a small set of cells, these plants displayed global developmental abnormalities. Moreover, centromeric repeats were hypomethylated. The developmental defects were accumulated by the generations. Thus, not maintaining CG methylation in a small population of proliferating cells flanking the meristems causes global developmental and epigenetic abnormalities that cannot be rescued by restoring MET1 activity. These results suggest that during plant development there is little or no short-term molecular memory for reestablishing certain patterns of CG methylation that are maintained by MET1. Thus, continuous MET1 activity in dividing cells is essential for proper patterns of CG DNA methylation and development.