• Korean Journal of Organic Agriculture
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• v.28 no.1
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• pp.95-108
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• 2020

To develop an environment-friendly fungicide for controlling tomato wilt diseases, antifungal active substance was isolated Rheum australe D. Don roots against Fusarium oxysporum f. sp. lycopersici, a pathogen of tomato wilt, in this study. Methanol extract obtained from Rheum australe roots was successively fractionated with hexane, chloroform, ethyl acetate, butanol and water. The ethyl acetate fraction, which showed the highest antifungal activity, was separated by column chromatography, and 60 subfractions were obtained. The 60 subfractions were anlayzed for antifungal activities by bioassay. The active compound was identified as 5-[(E)-2- (3-hydroxy-4-methoxyphenyl)ethenyl]benzene-1,3-diol (rhapontigenin) by NMR and GC-MS analysis. As a result of testing antifungal activity of rhapontigenin against Fusarium oxysporum, EC₅₀ of rhapontigenin was showed strong antifungal activity at 7.48 mg/L. Therefore, this study showed that the Rheum australe roots extract can be a potential candidate which is a environment-friendly fungicide against Fusarium oxysporum.

• Natural Product Sciences
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• v.14 no.1
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• pp.62-67
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• 2008

The leaf extract of Ligularia stenocephala showed the highest anti-platelet aggregating activity in large numbers of edible and herbal plants. The active fraction fractionationed from L. stenocephala extract by using preparative HPLC inhibited the platelet aggregation up to above 80% and its blood coagulating time (PT and APTT) also showed similar effect to aspirin (0.2 ${\mu}g/mL$), known as an anti-thrombus compound. Two antithrombus active compounds were purified and identified as 3,5-dicaffeoylquinic acid and 3,4-dicaffeoylquinic acid, respectively, on the basis of NMR and FAB-MS spectroscopic data. Two active compounds has not only antiplatelet aggregating activity, but also has anticoagulating activity.

• Journal of Ginseng Research
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• v.31 no.2
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• pp.69-73
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• 2007

Since chemical structures of ginsenoside as active ingredient of Panax ginseng are known, accumulating evidence have shown that ginsenoside is one of bio-active ligands through the diverse physiological and pharmacological evaluations. Chemical structures of ginsenoside could be divided into three parts depending on diol or triol ginsenoside: Steroid- or cholesterol-like backbone structure, carbohydrate portions, which are attached at the carbon-3, -6 or -20, and aliphatic side chain coupled to the backbone structure at the carbon-20. Ginsenosides also exist as stereoisomer at the carbon-20. Bioactive ligands usually exhibit the their structure-function relationships. In ginsenosides, there is little known about the relationship of chemical structure and biological activity. Recent reports have shown that ginsenoside $Rg_3$, one of active ginsenosides, exhibits its differential physiological or pharmacological actions depending on its chemical structure. This review will show how ginsenoside $Rg_3$, as a model compound, is functionally coupled to voltage-gated ion channel or ligand-gated ion channel regulations in related with its chemical structure.

• Bulletin of the Korean Chemical Society
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• v.28 no.5
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• pp.772-776
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• 2007

In order to study the role of residue in the active site of glutathione S-transferase (GST), Arg13 residue in human GST P1-1 was replaced with alanine, lysine and leucine by site-directed mutagenesis to obtain mutants R13A, R13K and R13L. These three mutant enzymes were expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized GSH. Mutation of Arg13 into Ala caused a substantial reduction of the specific activity by 10-fold. Km GSH, Km DCNB and Km EPNP values of R13A were approximately 2-3 fold larger than those of the wild type. Mutation of Arg13 into Ala also significantly affected I50 values of S-methyl-GSH that compete with GSH and ethacrynic acid, an electrophilic substrate-like compound. These results appeared that the substitution of Arg13 with Ala resulted in significant structural change of the active site. Mutation of Arg13 into Leu reduced the catalytic activity by approximately 2-fold, whereas substitution by Lys scarcely affected the activity, indicating the significance of a positively charged residue at position 13. Therefore, arginine 13 participates in catalytic activity as mainly involved in the construction of the proper electrostatic field and conformation of the active site in human GST P1-1.

• Journal of Welding and Joining
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• v.30 no.3
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• pp.38-43
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• 2012

In this study, active metal brazing methods for $ZrO_2$ and Ti alloy were discussed. To get a successful metal-ceramic bonding, various factors (melting temperature, corrosion, sag resistance, thermal expansion coefficient etc. of base materilas and filler metal) should be considered. Moreover, in order to clarify bonding between the metal and ceramic, the mechanism of the interfacial structure of the joints should be identified. The driving force for the formation of metal and ceramic interfaces is the reduction of the free energy which occurs when their contact becomes complete. Interfacial bonding depends on the material combinations and the bonding processes. This study describes the bonding between ceramic and metal in an active metal brazing.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.35 no.3
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• pp.203-208
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• 2009

Doenjang (Korean fermented soybean paste) is a unique fermented food in Korea. It has been traditionally manufactured from soybeans, by Jang Yang process. We focused on the newly formed compound in highly aged Doenjang and its biological activity. One new o-dihydroxyisoflavone, 7,3',4'-trihydroxyisoflavone and two known o-dihydroxyisoflavone derivatives were isolated from 5-year-old Doenjang and evaluated as potent antioxidant and whitening effect by comparing with other known isoflavone. 7,8,4'-Trihydroxyisoflavone (compound 1), 7,3',4'-trihydroxyisoflavone (compound 2) and 6,7,4'-trihydroxyisoflavone (compound 3) inhibited DPPH (diphenyl-1-picrylhydrazyl) formation by 50 % at a concentration of $21.5{\pm}0.2$, $28.7{\pm}0.4$ and $32.6{\pm}0.6$ ($IC_{50}$) respectively, whereas daidzein showed weak DPPH radical scavenging activity. In superoxide scavenging effect were measured in one assay. Compound 1 ($IC_{50}=18.10{\pm}0.2{\mu}M$) and 2 ($IC_{50}=10.54{\pm}0.4{\mu}M$) show significant inhibitory activity and greater effect than L-ascorbic acid. But compound 3 and daidzein showed lower inhibition activity. Also, o-dihydroxyisoflavone derivatives evaluated as potent inhibitors on tyrosinase activity and melanin formation in melan-a cells. Compound 1 ($IC_{50}=11.21{\pm}0.2{\mu}M$), compound 2 ($IC_{50}=5.23{\pm}0.6{\mu}M$) exhibited significant inhibitory effect on tyrosinase activity. Furthermore, those compounds are significantly suppressed the cellular melanin formation by 50 % at a concentration of $12.23{\pm}0.7{\mu}M$ (1) and $7.83{\pm}0.7{\mu}M$ (2). This result suggests that 7,3',4'-trihydroxyisoflavone from highly aged Doenjang could be used as an active ingredient for cosmetics.

• Journal of Physiology & Pathology in Korean Medicine
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• v.21 no.1
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• pp.70-75
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• 2007

In the present study, we has been isolated the anti-cariogenic component, stigmasterol, from Aralia continentalis (A. continentalis) and identified by MS, $^1$H-NMR and $^{13}$C-NMR and also investigated the anti-cariogenic properties of stigmasterol. The methanol extract of ,A. continentalis showed concentration-dependent inhibitory activity against the growth and acid production of S. mutans. The MeOH extract was suspended in H$_2$O and sequentially partitioned with n-hexane, CHCl$_3$, EtOAc, and n-BuOH. The CHCl$_3$ fraction showed remarkable antibacterial activity against S. mutans. The anti-cariogenic compound, stigmasterol, has been isolated successively through the screening system and various chromatography methods. Anti-cariogenic properties of stigmasterol were also investigated. From this active chloroform subfraction, isolation and identification finally gave (24E)-stigmasta-5,22-dien-3${\beta}$-ol (stigmasterol) {[a]$_D\;^{25}$ -48.33$^{\circ}C$(C 0.28, CHCl$_3$)} by spectroscopic methods (MS, $^1$H-NMR and $^{13}$C-NMR) as an active principle. The compound, stigmasterol, showed significant growth, acid production, adhesion and water-insoluble glucan synthesis inhibitory effect against S. mutans. These results suggest that stigmasterol from ,A. continentalis may inhibit cariogenic properties of S. mutans and these properties may provide some scientific rationales that the local inhabitants used the extracts for treatment of dental diseases.

• Applied Biological Chemistry
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• v.42 no.4
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• pp.271-276
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• 1999

Several Streptomyces strains were tested for potent antifungal agents active against phytopathogenic fungi. Among the tested, S. hygroscopicus MJM1004 showed a potent antifungal activity when assayed using Candida albicans as indicator organism. With the strain of MJM1004, fermentation medium for the production of an antifungal agent was developed with varying carbon sources, nitrogen sources, and mineral elements, which resulted in the highest productivity in the medium containing 2% soybean meal, 1% glucose, 2% starch, 0.3% $CaCO_3$, 0.05% $MgSO_4{\cdot}7H_2O$, 0.05% $K_2HPO_4$. The active compound showed a broad spectrum of antifungal activity against several plant pathogenic fungi. The antifungal compound was purified and showed the physicochemical characteristics similar to azalomycin F complex in NMR and MS analysis.

• YAKHAK HOEJI
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• v.50 no.2
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• pp.136-143
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• 2006

Roots of Scutellaria baicalensis have been used for fever remedy; diuresis, antiphlogistic. For the investigation of the active component from aerial parts of Scutellaria baicalensis, MeOH extracts from aerial parts of Scutellaria baicalensis were suspended with $H_2O$, and partitioned by $CHCl_3$. In order to investigate the efficacy of antioxidative activity the activity guided fraction and isolation of physiologically active substance were peformed. Its $H_2O,\;30\%,\;60\%$ MeOH and MeOH fractions were examined on antioxidative activity using DPPH method and TBARS assay; It was revealed that $30\%\;and\;60\%$ MeOH fractions have significant anti-oxidative activity. its fractions testing type I allergy, compound 48/80 induced systemic anaphylaxis was applied. As a result, compared with reference (cromolygate), these fraction significantly inhibited systemic anaphylaxis by $71\%\;and\;57\%$, respectively. From $30\%,\;60\%$ MeOH fraction, five compounds were isolated and elucidated apigenin 6-C-${\alpha}$-L-arabinopyranosyl-8-C-${\beta}$-D-glucopyranoside (isoschaftside, I), scutellarein 7-O-${\beta}$-D-glucuronopyranoside (scutellarin, II), apigenin 7-O- ${\beta}$-D-glucuronopyranoside (III), isoscutellarein 8-O-${\beta}$-D-glucuronopyranoside (IV), kaempferol 3-O-${\beta}$-D-glucopyranoside (V) through their physicochemical data and spectroscopic methods. We measured radical scavenging activity with DPPH method and anti-lipid peroxidative efficacy on human LDL with TBARS assay. [$I] showed antioxidant activities in order. Type I allergy compound 48/80 induced systemic anaphylaxis was applied. $[V inhibited systemic anaphylaxis in order.

• The Korea Journal of Herbology
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• v.21 no.2
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• pp.1-7
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• 2006

Objectives : The purpose of this study is to isolate tyrosinase inhibitory material from Pinellia ternata and characterize its own structure and activity. Methods : Pinellia ternata (600g) was extracted with 95% methanol (1L) at $37^{\circ}C$ for 4 days, with shaking at 250rpm. The extract was further solvent-fractionated with n-hexane, chloroform, ethylacetate and water. The active fraction was subjected to JAI recycling prep-HPLC JAIGEL GS-320 column. The structure was identified for the active peak with NMR and GC. Results : Tyrosinase was potently inhibited by 95% methanol extracts from Pinellia ternata. The $IC_{50}$ value of the extracts was estimated to be 0.05mg/ml. The extracts was divided into four solvent-fractions, and the most potent tyrosinase inhibition was found in ethylacetate layer. $IC_{50}$ value of ethylacetate fraction was 0.001mg/ml. This fraction was further purified with JAI Recycling Preparative HPLC (Model: LC 9104). The isolated compound showing inhibitory activity was characterized on its chemical structure by NMR and the compound was identified as 3,4-dihydroxybenzaldehyde. $IC_{50}$ was found to be 7.74 ${\mu}M$ which is much lower than that of kojic acid $(66.5{\mu}M)$. Conclusions : The data suggest that 3,4-dihydroxybenzaldehyde isolated and identified from Pinellia ternata is very strong inhibitor to melanin biosynthesis.