• Title/Summary/Keyword: Elimination reactions

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Recent Studies on the Chemical Constituents of Korean Ginseng (Panax ginseng C. A. Meyer) (고려인삼의 화학성분에 관한 고찰)

  • 박종대
    • Journal of Ginseng Research
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    • v.20 no.4
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    • pp.389-415
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    • 1996
  • Panax ginseng C.A. Meyer(Araliaceae) has been traditionally used as an expensive and precious medicine in oriental countries for more than 5, 000 years. Ginseng saponin isolated from the root of Panax ginseng have been regarded as the main effective components responsible for the pharmacological and biological activities. Such as antiaging effects. antidiabetic effects anticancer effects. Protection against physical and chemical stress. Analgesic and antipyretic effects. Effects on the central nervous system, tranquilizing action and others. Thirty kinds of ginsenosides have been so far isolated from ginseng saponin and their chemical structures have been elucidated since 1960's. Among which protopanaxadiol type is 19 kinds. protopanaxatriol type. 10 kinds and oleanane type, one. Since ginsenosides are generally labile under acidic conditions ordinary acid hydrolysis is always accompanied by many side reactions, such as epimerization. hydroxylation and cyclization of side chain of the sapogenins Especially. it is well known that C-20 glycosyl linkage of ginsenoside was hydrolysed on heating with acetic acid to give an equilibrated mixture of 20(S) and 20(R) epimers. And also, the chemical transformations of the secondary metabolites have appeared during the steaming process to prepare red ginseng. Indicating demalonylation of malonyl ginsenosides, elimination of glycosyl residue at C-20 and isomerization of hydroxyl configuration at C-20. But these studies have not provided a comprehensive picture in explaning how these ginsenosides showed val'iotas pharmacological activities of ginseng. Though some of them have been involved in the mechanism of pharmacological actions. Recently, non-saponin components have received a great deal of attention for their antioxidant, anticancer antidiabetic, immunomodulating. anticomplementary activities and so on. To meet the demand for such wide applications, studies on the non-saponin components play an important role in providing a good evidence of pharmacological and biol ogical activities. Among the non-saponin constituents of Korean ginseng, polyacetylenes, phenols. Sesquiterpenes, alkaloids. polysaccharides oligosaccharides, oligopeptides and aminoglycosides together with ginsenosides of terrestrial part are mainly described.

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A LAMP-SNP Assay Detecting C580Y Mutation in Pfkelch13 Gene from Clinically Dried Blood Spot Samples

  • Khammanee, Thunchanok;Sawangjaroen, Nongyao;Buncherd, Hansuk;Tun, Aung Win;Thanapongpichat, Supinya
    • Parasites, Hosts and Diseases
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    • v.59 no.1
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    • pp.15-22
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    • 2021
  • Artemisinin resistance (ART) has been confirmed in Greater Mekong Sub-region countries. Currently, C580Y mutation on Pfkelch13 gene is known as the molecular marker for the detection of ART. Rapid and accurate detection of ART in field study is essential to guide malaria containment and elimination interventions. A simple method for collection of malaria-infected blood is to spot the blood on filter paper and is fast and easy for transportation and storage in the field study. This study aims to evaluate LAMP-SNP assay for C580Y mutation detection by introducing an extra mismatched nucleotide at the 3' end of the FIP primer. The LAMP-SNP assay was performed in a water bath held at a temperature of 56℃ for 45 min. LAMP-SNP products were interpreted by both gel-electrophoresis and HNB-visualized changes in color. The method was then tested with 120 P. falciparum DNA from dried blood spot samples. In comparing the LAMP-SNP assay results with those from DNA sequencing of the clinical samples, the 2 results fully agreed to detect C580Y. The sensitivity and specificity of the LAMP-SNP assay showed 100%. There were no cross-reactions with other Plasmodium species and other Pfkelch13 mutations. The LAMP-SNP assay performed in this study was rapid, reliable, and useful in detecting artemisinin resistance in the field study.

Methanol-involved heterogeneous transformation of ginsenoside Rb1 to rare ginsenosides using heteropolyacids embedded in mesoporous silica with HPLC-MS investigation

  • Mengya Zhao;Yusheng Xiao;Yanyan Chang;Lu Tian;Yujiang Zhou;Shuying Liu;Huanxi Zhao;Yang Xiu
    • Journal of Ginseng Research
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    • v.48 no.4
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    • pp.366-372
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    • 2024
  • Background: The biological activity and pharmacological effects of rare ginsenosides have been proven to be superior to those of the major ginsenosides, but they are rarely found in ginseng. Methods: Ginsenoside Rb1 was chemically transformed with the involvement of methanol molecules by a synthesized heterogeneous catalyst 12-HPW@MeSi, which was obtained by the immobilization of 12-phosphotungstic acid on a mesoporous silica framework. High-performance liquid chromatography coupled with mass spectrometry was used to identify the transformation products. Results: A total of 18 transformation products were obtained and identified. Methanol was found to be involved in the formation of 8 products formed by the addition of methanol molecules to the C-24 (25), C-20 (21) or C-20 (22) double bonds of the aglycone. The transformation pathways of ginsenoside Rb1 involved deglycosylation, addition, elimination, cycloaddition, and epimerization reactions. These pathways could be elucidated in terms of the stability of the generated carbenium ion. In addition, 12-HPW@MeSi was able to maintain a 60.5% conversion rate of Rb1 after 5 cycles. Conclusion: Tandem and high-resolution mass spectrometry analysis allowed rapid and accurate identification of the transformation products through the characteristic fragment ions and neutral loss. Rare ginsenosides with methoxyl groups grafted at the C-25 and C-20 positions were obtained for the first time by chemical transformation using the composite catalyst 12-HPW@MeSi, which also enabled cyclic heterogeneous transformation and facile centrifugal separation of ginsenosides. This work provides an efficient and recyclable strategy for the preparation of rare ginsenosides with the involvement of organic molecules.

Exploring the molecular characteristics, detoxification functions, and immune responses of two glutathione S-transferases in redlip mullet (Liza haematochelia)

  • Jeongeun Kim;Welivitiye Kankanamge Malithi Omeka;Qiang Wan;Jehee Lee
    • Fisheries and Aquatic Sciences
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    • v.27 no.5
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    • pp.314-328
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    • 2024
  • The mechanism for the elimination of xenobiotics undergoes three different phases of reactions in organisms. Among these, glutathione S-transferases (GSTs) are classified as phase II detoxification enzymes, catalyzing the conjugation of electrophilic substrates to glutathione or reduced hydroperoxides. This study aimed to investigate the molecular characteristics, detoxification functions, and immune responses of GST omega (LhGSTO1) and kappa (LhGSTK1) in redlip mullet. The open reading frames of LhGSTO1 (720 bp) and LhGSTK1 (687 bp) encoded proteins of 239 and 228 amino acids, respectively. Sequence analysis revealed that LhGSTO1 and LhGSTK1 possessed GSH-binding sites in their N-terminal domains. Substrate-binding sites in the C-terminal domain were exclusively identified in LhGSTO1. In the tissue-specific transcription profile analysis, both LhGSTO1 and LhGSTK1 were ubiquitously expressed in all tissues of healthy mullets. Temporal expression analysis of LhGSTO1 and LhGSTK1 in the blood showed that their expression was significantly modulated by polyinosinic:polycytidylic (poly I:C), lipopolysaccharide (LPS), and Lactococcus garvieae. Different chemical and cellular assays were performed to assess the detoxification and cellular protective abilities of the two proteins. A substrate specificity test using the recombinant proteins revealed that both proteins possessed specific activity toward 1-chloro-2,4-dinitrobenzene (CDNB). In the disk diffusion assay, the smallest clearance zones were observed for LhGSTO1 and LGSTK1 against CdCl2. In the cell protection assay, both LhGSTO1 and LhGSTK1 showed significant Cd detoxification ability compared to the control. Collectively, these results demonstrate that GST omega and kappa are involved in host defense against immune stimulants and xenobiotics in redlip mullet.

Removal Characteristics of Heavy Metals in Acid Mine Drainage (AMD) Using Porous Starfish Ceramics (II) - Treatment of AMD in a Column Reactor System (불가사리 소재 다공성 세라믹을 이용한 산성광산배수 내 중금속의 제거특성(II) - 컬럼연속 실험을 통한 산성광산배수의 처리특성)

  • Lee, Yonghwan;Yim, Soobin
    • Journal of the Korean GEO-environmental Society
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    • v.15 no.12
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    • pp.25-34
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    • 2014
  • The objective of this study was to investigate the removal characteristics and the elimination mechanism of heavy metals in Acid Mine Drainage (AMD) using spherical-type porous Zeolite-StarFish ceramics (porous ZSF ceramics) packed in a continuous column reactor system. The average removal efficiencies of heavy metals in AMD were Al 98.7, As 98.7, Cd 96.0, Cu 89.1, Fe 99.5, Mn 94.4, Pb 96.3 and Zn 80.8 % during 110 days of operation time. The average removal capacity of porous ZSF ceramics for heavy metals were measured to be Al 21.76, As 1.52, Cd 1.27, Cu 3.41, Fe 44.83, Mn 3.48, Pb 2.36 and Zn $3.76mg/kg{\cdot}day$. The analysis results of mechanism using SEM, EDS and XRD exhibited that the porous ZSF ceramics could act as a multi-functional ceramics for the removal of heavy metals in AMD through the reactions of precipitation, adsorption and ion-exchange. The experimental results of column reactor system displayed that the porous ZSF ceramics would be a consistently efficient agent for the removal of heavy metals in AMD for a long term.

Reactions of Iridium(Ⅰ) Complexes with Acrylonitrile and Polymerization of Acrylonitrile with Iridium(Ⅰ)-Acrylonitrile Complex (이리듐(Ⅰ) 착물과 아크릴로니트릴의 반응 및 이리듐(Ⅰ)-아크릴로니트릴 착물에 의한 아크릴로니트릴의 중합반응)

  • Sang Ha Kim;Chong Sik Chin
    • Journal of the Korean Chemical Society
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    • v.27 no.5
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    • pp.340-344
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    • 1983
  • It has been found that both of the iridium (Ⅰ) complexes, Ir$(ClO_4$)(AN)(CO)$(Ph_3P)_2$(AN = $CH_2$CHCN, $Ph_3P = (C_6H_5)_3$P) and [Ir(AN)(CO)$(Ph_3P)_2]ClO_4$, react with $Cl^-$ to give IrCl(AN)(CO)$(Ph_3P)_2$, and [Ir(AN)(CO)$(Ph_3P)_2]ClO_4$ dissociates AN to yield Ir$(ClO_4)(CO)(Ph_3P)_2$ in the absence of excess AN added, and Ir$(ClO_4)(CO)(Ph_3P)_2$ reacts with $Cl^-$ to produce IrCl(CO)$(Ph_3P)_2$. It is suggested that the catalytic polymerization of AN with Ir$(ClO_4)(AN)(CO)(Ph_3P)_2$ proceeds through the formation of [(CO)(Ph_3P)_2$Ir(-CH=CHCN)(H)($CH_2$=CHCN)]Cl$O_4$ followed by the formation of iridium(alkyl)(alkenyl) type complex which undergoes a reductive elimination to produce the polymer of acrylonitrile.

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Structure and Reactivity of Alkylchloroformates. MO Theoretical Interpretations on Halide Exchange Reaction (염화 포름산 알킬의 구조와 반응성. 할로겐화 이온 교환반응에 대한 분자궤도론적 고찰)

  • Lee, Bon Su;Lee, Ik Choon
    • Journal of the Korean Chemical Society
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    • v.18 no.4
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    • pp.223-238
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    • 1974
  • CNDO/2 MO theoretical studies and kinetic studies of halide exchange reactions for alkylchloroformates have been carried out in order to investigate structure-reactivity relationship of alkylchloroformates. From the result of energetics, it was concluded that the most stable configuration of alkylchloroformate is that in which alkyl group and chlorine are trans to each other, and that the hindered rotation about the bond between the carbonyl carbon and alkoxy-oxygen bond is attributed to the ${\pi}-$electron delocalization. It has been found that the large charge separation is due to -M effect of carbonyl and alkoxy oxygens and-I effect of chlorine. The order of rates in solvents studied was $(CH_3)_2 > CO > CH_3CN{\gg}MeOH.$$I^->Br^->Cl^-$ in protic solvent, and of Cl^->Br^- >I^-$ in dipolar aprotic solvents. Alkyl group contribution has the decreasing order of $CH_3-> C_2H-{\gg}i-C_3H_7-.$ The solvent effect has been interpreted on the basis of initial and final state contribution. A transition state model has been suggested, and it has been proposed that the most favorable mechanism is the addition-elimination. From the results of activation parameters and electronic properties, an energy profile has been proposed. Structural factors determining reactivities of alkylchloroformates have been shown to be charge, energy level of ${\alpha}^*LUMO$ to C-Cl bond and ${\alpha}^{\ast} $antibonding strength with respect to C-Cl bond in this MO. Charge and polarizability of nucleophile, and the interaction of these effects with solvent structures are also found to be important.

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A Follow-Up Study of Cow's Milk-Sensitive Enteropathy: Clinical Outcome (우유 과민성 장병증(cow's milk-sensitive enteropathy)의 장기 추적관찰)

  • Song, Ae-Ryong;Choi, Eun-Jin;Han, Chang-Ho;Chung, Hai-Lee;Kwon, Young-Dae;Hwang, Jin-Bok
    • Pediatric Gastroenterology, Hepatology & Nutrition
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    • v.4 no.1
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    • pp.47-53
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    • 2001
  • Purpose: Following up the cases of cow's milk-sensitive enteropathy (CMSE), We observed the development of clinical tolerance with cow's milk and other foods. We investigated the clinical outcome of CMSE. Methods: We reviewed the clinical records of patients who had been admitted and diagnosed as CMSE by responses to cow's milk challenge and elimination test and the findings of small intestinal biopsy at Department of Pediatrics, Taegu Catholic University Hospital from March 1992 to March 1997. All of them were being fed with protein hydrolysate before 6 months old, and tried cow's milk and other foods challenge test at following each two month. Twenty-one cases of them returned to be followed. The age at admission was $30.7{\pm}8.8$ (18~47) days old and at survey was $43.4{\pm}23.7$ (16~84) months old. Results: 1) Although the body weight at birth of the patients was 25~75 percentile, all on admission was below 3 percentile. The body weight on interview was 25~75 percentile. 2) The development of clinical tolerance in cow's milk was observed at 16~24 months of age and the tolerance rate was 61% at 12 months of age, 90% at 16 months of age. The development of clinical tolerance in other foods was observed at 10~24 months of age and the tolerance rate was 33% at 12 months of age, 80% at 18 months of age. 3) Adverse reactions after challenge test with cow's milk were observed at 19 cases, manifestated as vomiting (31%), diarrhea (31%), irritability or lethargy (21%), skin rash (10%), and abdominal distention (5%). 4) Comparing serum IgE and milk RAST positive group on admission (5 cases) and negative group on admission (16 cases), there was no significant difference at the age of tolerance in cow's milk (p>0.05), the age of tolerance in other foods (p>0.05), allergy history in family, and the incidence of other allergic diseases. 5) The history of family allergy was observed in 3 cases (14%) in 21 patients and 3 cases (14%) showed rhinitis, urticaria or asthma through a follow-up interview. Conclusion: The development of clinical tolerance in cow's and other foods was sharply increased at 12 months of age and most of all tolerated within 24 months of age. CMSE is a temporary disorder of infancy.

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