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Ki Hun Park - One of the best experts on this subject based on the ideXlab platform.
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effectiveness of Prenyl group on flavonoids from epimedium koreanum nakai on bacterial neuraminidase inhibition
Molecules, 2019Co-Authors: Hong Min Choi, Jeong Yoon Kim, Yeong Jun Ban, Janar Jenis, Aizhamal Baiseitova, Ki Hun ParkAbstract:In this study, the inhibitory potential of bacterial neuraminidase (NA) was observed on the leaves of Epimedium koreanum Nakai, which is a popular ingredient in traditional herbal medicine. This study attempted to isolate the relevant, responsible metabolites and elucidate their inhibition mechanism. The methanol extraction process yielded eight flavonoids (1–8), of which compounds 7 and 8 were new compounds named koreanoside F and koreanoside G, respectively. All the compounds (1–8) showed a significant inhibition to bacterial NA with IC50 values of 0.17–106.3 µM. In particular, the Prenyl group on the flavonoids played a critical role in bacterial NA inhibition. Epimedokoreanin B (compound 1, IC50 = 0.17 µM) with two Prenyl Groups on C8 and C5′ of luteolin was 500 times more effective than luteolin (IC50 = 85.6 µM). A similar trend was observed on compound 2 (IC50 = 0.68 µM) versus dihydrokaempferol (IC50 = 500.4 µM) and compound 3 (IC50 = 12.6 µM) versus apigenin (IC50 = 107.5 µM). Kinetic parameters (Km, Vmax, and Kik/Kiv) evaluated that all the compounds apart from compound 5 showed noncompetitive inhibition. Compound 5 was proven to be a mixed type inhibitor. In an enzyme binding affinity experiment using fluorescence, affinity constants (KSV) were tightly related to inhibitory activities.
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Effectiveness of Prenyl Group on Flavonoids from Epimedium koreanum Nakai on Bacterial Neuraminidase Inhibition
MDPI AG, 2019Co-Authors: Hong Min Choi, Jeong Yoon Kim, Yeong Jun Ban, Janar Jenis, Aizhamal Baiseitova, Ki Hun ParkAbstract:In this study, the inhibitory potential of bacterial neuraminidase (NA) was observed on the leaves of Epimedium koreanum Nakai, which is a popular ingredient in traditional herbal medicine. This study attempted to isolate the relevant, responsible metabolites and elucidate their inhibition mechanism. The methanol extraction process yielded eight flavonoids (1–8), of which compounds 7 and 8 were new compounds named koreanoside F and koreanoside G, respectively. All the compounds (1–8) showed a significant inhibition to bacterial NA with IC50 values of 0.17–106.3 µM. In particular, the Prenyl group on the flavonoids played a critical role in bacterial NA inhibition. Epimedokoreanin B (compound 1, IC50 = 0.17 µM) with two Prenyl Groups on C8 and C5′ of luteolin was 500 times more effective than luteolin (IC50 = 85.6 µM). A similar trend was observed on compound 2 (IC50 = 0.68 µM) versus dihydrokaempferol (IC50 = 500.4 µM) and compound 3 (IC50 = 12.6 µM) versus apigenin (IC50 = 107.5 µM). Kinetic parameters (Km, Vmax, and Kik/Kiv) evaluated that all the compounds apart from compound 5 showed noncompetitive inhibition. Compound 5 was proven to be a mixed type inhibitor. In an enzyme binding affinity experiment using fluorescence, affinity constants (KSV) were tightly related to inhibitory activities
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Prenylated Flavonoids from Epimedium koreanum Nakai and their Human Neutrophil Elastase Inhibitory Effects
ACG Publications, 2017Co-Authors: Soo Min Lee, Yeong Jun Ban, Yeong Hun Song, Zia Uddin, Ki Hun ParkAbstract:Human neutrophil elastase (HNE) has been linked to immune system functions, including inflammation, as well as the development of skin wrinkles, suggesting that HNE inhibitors have many practical applications. In this study, the methanol extract of Epimedium koreanum Nakai contained potent HNE inhibitory flavonoids (1–4) with IC 50 values of 6.06–125.80 μM. Prenyl Groups within these flavonoids were critical for the inhibitory effects. For example, epimedokoreanin B (1) (IC 50 = 6.06 μM) showed 6-fold higher efficacy than that of its parent luteolin (IC 50 = 36.01 μM). A similar trend was observed for compound 2 (IC 50 = 6.28 μM) and its parent, apigenin (IC 50 = 37.94 μM). Lineweaver–Burk plots showed that the compounds exhibit mixed-type inhibition. In a detailed kinetic study, compound 1 was assigned to mixed type I and exhibited the greatest binding to the free enzyme (K I = 11.7 μM, K IS = 40.9 μM)
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anticholinesterase potential of flavonols from paper mulberry broussonetia papyrifera and their kinetic studies
Food Chemistry, 2012Co-Authors: Marcus J Curtislong, Sunin Jung, Il Yun Jeong, Kyu Young Kang, Ki Hun ParkAbstract:Abstract It is necessary to develop food additives to help treat chronic disorders like neurodegenerative diseases from medicinal plants. Ethanol extracts of paper mulberry were found to display significant inhibition against cholinesterases, enzymes that are strongly linked with Alzheimer’s disease (AD). The active components were identified as Prenylated flavonols ( 2 – 4 ) that inhibited two related human cholinesterases in a dose-dependent manner, with IC 50 ’s ranging between 0.8 and 3.1 μM and between 0.5 and 24.7 μM against human acetylcholinesterase (hAChE) and butylcholinesterase (BChE), respectively. Prenyl Groups within these flavonols were found to play a critical role for inhibition because the parent compound 1 , quercetin, was inactive (IC 50 > 500 μM) towards the target enzymes. Flavonols ( 2 – 4 ) showed mixed inhibition kinetics as well as slow and time-dependent reversible inhibition toward hAChE. The affinity between protein and inhibitors was investigated using fluorescence quenching. The affinity constants ( K SA ) of inhibitors increased in proportion to their inhibitory potencies.
Miguel C. Seabra - One of the best experts on this subject based on the ideXlab platform.
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A novel statin-mediated Prenylation block-and-release assay provides insight into the membrane targeting mechanisms of small GTPases
Biochemical and Biophysical Research Communications, 2010Co-Authors: Ian Nouvel, Ka Fai Leung, Miguel C. SeabraAbstract:Ras super-family small GTPases regulate diverse cellular processes such as vesicular transport and signal transduction. Critical to these activities is the ability of these proteins to target to specific intracellular membranes. To allow association with membranes Ras-related GTPases are post-translationally modified by covalent attachment of Prenyl Groups to conserved cysteine residues at or near their C-terminus. Here we used the HMG-CoA (3-hydroxy-3-methylglutaryl-coenzyme A) reductase (HMGCR) inhibitor mevastatin to develop a ‘Prenylation block-and-release’ assay that allows membrane targeting of Prenylated proteins to be visualized in living cells. Using this assay we investigated the cytosol to membrane targeting of several small GTPases to compartments of the secretory and endocytic pathways. We found that all Rabs tested were targeted directly to the membrane on which they reside at steady-state and not via an intermediate location as reported for Ras and Rho proteins. However, we observed that the kinetics of cytosol to membrane targeting differed for each Rab tested. Comparison of the mevastatin sensitivity and kinetics of membrane targeting of Rab23, Rab23 Prenylation motif mutants and H-Ras revealed that these parameters are strongly dependent upon the Prenyl transferase with Rab geranylgeranyl transferase substrates exhibiting higher sensitivity and requiring greater time to recover from mevastatin inhibition than farnesyl transferase substrates. We propose that this assay is a useful tool to investigate the kinetics, biological functions and the mechanisms of membrane targeting of Prenylated proteins.
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Are Prenyl Groups on proteins sticky fingers or greasy handles
Biochemical Journal, 2003Co-Authors: Anthony I. Magee, Miguel C. SeabraAbstract:This Commentary discusses the work of Dietrich et al. in this issue of the Biochemical Journal, which sheds new light on the biological roles of protein-bound Prenyl Groups by providing evidence that the alpha-subunit of the heterotrimeric G-protein transducin has a binding site for the geranylgeranyl group of the gamma-subunit.
M Dos H Santos - One of the best experts on this subject based on the ideXlab platform.
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leishmanicidal activity of benzophenones and extracts from garcinia brasiliensis mart fruits
Phytomedicine, 2010Co-Authors: Ivan De Oliveira Pereira, Marcos Jose Marques, Ana Laura Raymundo Pavan, B S Codonho, Clara Lucia Barbieri, Luiz Alberto Beijo, Antonio C Doriguetto, E C Dmartin, M Dos H SantosAbstract:Infections by protozoans of the genus Leishmania are the major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials, which exert renal and cardiac toxicity. Thus, there is a strong need for safer and more effective treatments against leishmaniasis. The present study was designated to evaluate, by a bioguided assay, the leishmanicidal activity of extracts (hexane, ethyl-acetate and ethanolic) and molecules both obtained by means of extraction from pericarps of Garcinia brasiliensis fruits. The hexane extract presented the best activity on the extracellular (promastigotes) and intracellular (amastigotes) forms of Leishmania (L.) amazonensis, when compared to the other extracts. Based on these findings, this extract was fractionated by silica gel column chromatography, affording nine fractions then resulting in three purified Prenylated benzophenones - 7-epi-clusianone (1), garciniaphenone (2) and guttiferone-a (3). They showed significant activity on Leishmania (L.) amazonensis, and little toxicity for mammalian cells. Structure-activity relationships were evaluated showing that the IC(50) value displayed is dependent of Prenyl Groups and phenolic hydroxyls number, and inversely proportional to the hydrophobicity. Our results are promising, showing that these compounds are biologically active on Leishmania (L.) amazonensis.
Hong Min Choi - One of the best experts on this subject based on the ideXlab platform.
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effectiveness of Prenyl group on flavonoids from epimedium koreanum nakai on bacterial neuraminidase inhibition
Molecules, 2019Co-Authors: Hong Min Choi, Jeong Yoon Kim, Yeong Jun Ban, Janar Jenis, Aizhamal Baiseitova, Ki Hun ParkAbstract:In this study, the inhibitory potential of bacterial neuraminidase (NA) was observed on the leaves of Epimedium koreanum Nakai, which is a popular ingredient in traditional herbal medicine. This study attempted to isolate the relevant, responsible metabolites and elucidate their inhibition mechanism. The methanol extraction process yielded eight flavonoids (1–8), of which compounds 7 and 8 were new compounds named koreanoside F and koreanoside G, respectively. All the compounds (1–8) showed a significant inhibition to bacterial NA with IC50 values of 0.17–106.3 µM. In particular, the Prenyl group on the flavonoids played a critical role in bacterial NA inhibition. Epimedokoreanin B (compound 1, IC50 = 0.17 µM) with two Prenyl Groups on C8 and C5′ of luteolin was 500 times more effective than luteolin (IC50 = 85.6 µM). A similar trend was observed on compound 2 (IC50 = 0.68 µM) versus dihydrokaempferol (IC50 = 500.4 µM) and compound 3 (IC50 = 12.6 µM) versus apigenin (IC50 = 107.5 µM). Kinetic parameters (Km, Vmax, and Kik/Kiv) evaluated that all the compounds apart from compound 5 showed noncompetitive inhibition. Compound 5 was proven to be a mixed type inhibitor. In an enzyme binding affinity experiment using fluorescence, affinity constants (KSV) were tightly related to inhibitory activities.
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Effectiveness of Prenyl Group on Flavonoids from Epimedium koreanum Nakai on Bacterial Neuraminidase Inhibition
MDPI AG, 2019Co-Authors: Hong Min Choi, Jeong Yoon Kim, Yeong Jun Ban, Janar Jenis, Aizhamal Baiseitova, Ki Hun ParkAbstract:In this study, the inhibitory potential of bacterial neuraminidase (NA) was observed on the leaves of Epimedium koreanum Nakai, which is a popular ingredient in traditional herbal medicine. This study attempted to isolate the relevant, responsible metabolites and elucidate their inhibition mechanism. The methanol extraction process yielded eight flavonoids (1–8), of which compounds 7 and 8 were new compounds named koreanoside F and koreanoside G, respectively. All the compounds (1–8) showed a significant inhibition to bacterial NA with IC50 values of 0.17–106.3 µM. In particular, the Prenyl group on the flavonoids played a critical role in bacterial NA inhibition. Epimedokoreanin B (compound 1, IC50 = 0.17 µM) with two Prenyl Groups on C8 and C5′ of luteolin was 500 times more effective than luteolin (IC50 = 85.6 µM). A similar trend was observed on compound 2 (IC50 = 0.68 µM) versus dihydrokaempferol (IC50 = 500.4 µM) and compound 3 (IC50 = 12.6 µM) versus apigenin (IC50 = 107.5 µM). Kinetic parameters (Km, Vmax, and Kik/Kiv) evaluated that all the compounds apart from compound 5 showed noncompetitive inhibition. Compound 5 was proven to be a mixed type inhibitor. In an enzyme binding affinity experiment using fluorescence, affinity constants (KSV) were tightly related to inhibitory activities
Mrinal K. Bera - One of the best experts on this subject based on the ideXlab platform.
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Towards an enantiospecific total synthesis of garsubellin A and related phloroglucin natural products: the α-pinene approach
Tetrahedron Letters, 2004Co-Authors: Goverdhan Mehta, Mrinal K. BeraAbstract:The first enantiospecific approach to garsubellin A and related phloroglucin natural product nemorosone, of contemporary interest from (−)alpha -pinene, has been delineated. Through a series of stereospecific operations, the requisite stereochemistry of the Prenyl Groups has been secured. Kende cyclization has been employed as the key step to construct the functionalized bicyclo[3.3.1]nonane core.