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Cytospyrone and Cytospomarin: Two New Polyketides Isolated from Mangrove Endophytic Fungus, Cytospora sp. Molecules 2020; 25:molecules25184224. [PMID: 32942587 PMCID: PMC7570828 DOI: 10.3390/molecules25184224] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 09/04/2020] [Accepted: 09/10/2020] [Indexed: 11/16/2022] Open
Abstract
Two new polyketides, cytospyrone (1), cytospomarin (2), together with three known metabolites dimethoxyphtalide (3), integracin A (4) and integracin B (5), were isolated from the culture of Cytospora sp. from the Chinese mangrove Ceriops tagal. Their structures were elucidated by extensive spectroscopic analyses and time dependent density functional theory (TDDFT), calculation of electronic circular dichroism (ECD) and optical rotation (OR) data. Compound 2 displayed weak inhibitory activity against Escherichia coli GIM1.201 (minimum inhibitory concentration (MIC) value of 0.35 mM). Compounds 4 and 5 displayed significant cytotoxicity against human cancer cell line HepG2 (IC50 values of 5.98 ± 0.12 µM and 9.97 ± 0.06 µM, respectively), more potent than the positive control 5-fluorouracil (IC50 value of 43.50 ± 3.69 µM).
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2
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Oliveira MCLD, Paulo AJ, Lima CDA, de Lima Filho JL, Souza-Motta CM, Vidal EE, Nascimento TP, Marques DDAV, Porto ALF. Lovastatin producing by wild strain of Aspergillus terreus isolated from Brazil. Prep Biochem Biotechnol 2020; 51:164-172. [PMID: 32795118 DOI: 10.1080/10826068.2020.1805624] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Lovastatin is a drug in the statin class which acts as a natural inhibitor of 3-hydroxy-3-methylglutaryl, a coenzyme reductase reported as being a potential therapeutic agent for several diseases: Alzheimer's, multiple sclerosis, osteoporosis and due to its anti-cancer properties. Aspergillus terreus is known for producing a cholesterol reducing drug. This study sets out to evaluate the production of lovastatin by Brazilian wild strains of A. terreus isolated from a biological sample and natural sources. Carbon and nitrogen sources and the best physicochemical conditions using factorial design were also evaluated. The 37 fungal were grown to produce lovastatin by submerged fermentation. A. terreus URM5579 strain was the best lovastatin producer with a level of 13.96 mg/L. Soluble starch and soybean flour were found to be the most suitable substrates for producing lovastatin (41.23 mg/L) and biomass (6.1 mg/mL). The most favorable production conditions were found in run 16 with 60 g/L soluble starch, 15 g/L soybean flour, pH 7.5, 200 rpm and maintaining the solution at 32 °C for 7 days, which led to producing 100.86 mg/L of lovastatin and 17.68 mg/mL of biomass. Using natural strains and economically viable substrates helps to optimize the production of lovastatin and promote its use.
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Affiliation(s)
- Marcella Cardoso Lemos de Oliveira
- Department of Morphology and Animal Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Brazil
- Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Recife, Brazil
| | - Anderson José Paulo
- Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Recife, Brazil
| | | | - José Luiz de Lima Filho
- Laboratory of Immunopathology Keizo Asami (LIKA), Federal University of Pernambuco (UFPE), Recife, Brazil
| | | | - Esteban Espinosa Vidal
- Central Analytical, Northeastern Center of Strategic Technologies (CETENE), Recife, Brazil
| | - Thiago Pajeú Nascimento
- Department of Morphology and Animal Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Brazil
| | - Daniela de Araújo Viana Marques
- Laboratory of Biotechnology Applied to Infectious and Parasitic Diseases, Biological Science Institute, University of Pernambuco-ICB/UPE, Recife, Brazil
| | - Ana Lucia Figueiredo Porto
- Department of Morphology and Animal Physiology, Federal Rural University of Pernambuco (UFRPE), Recife, Brazil
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3
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Guo F, Zhang S, Yan X, Dan Y, Wang J, Zhao Y, Yu Z. Bioassay-guided isolation of antioxidant and α-glucosidase inhibitory constituents from stem of Vigna angularis. Bioorg Chem 2019; 87:312-320. [DOI: 10.1016/j.bioorg.2019.03.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 02/27/2019] [Accepted: 03/15/2019] [Indexed: 10/27/2022]
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Monakhova YB, Fareed J, Yao Y, Diehl BW. Improving reliability of chemometric models for authentication of species origin of heparin by switching from 1D to 2D NMR experiments. J Pharm Biomed Anal 2018; 153:168-174. [DOI: 10.1016/j.jpba.2018.02.041] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 02/20/2018] [Accepted: 02/20/2018] [Indexed: 01/19/2023]
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Monakhova YB, Diehl BWK, Do TX, Schulze M, Witzleben S. Novel method for the determination of average molecular weight of natural polymers based on 2D DOSY NMR and chemometrics: Example of heparin. J Pharm Biomed Anal 2017; 149:128-132. [PMID: 29112901 DOI: 10.1016/j.jpba.2017.11.016] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 09/26/2017] [Accepted: 11/01/2017] [Indexed: 11/26/2022]
Abstract
Apart from the characterization of impurities, the full characterization of heparin and low molecular weight heparin (LMWH) also requires the determination of average molecular weight, which is closely related to the pharmaceutical properties of anticoagulant drugs. To determine average molecular weight of these animal-derived polymer products, partial least squares regression (PLS) was utilized for modelling of diffused-ordered spectroscopy NMR data (DOSY) of a representative set of heparin (n=32) and LMWH (n=30) samples. The same sets of samples were measured by gel permeation chromatography (GPC) to obtain reference data. The application of PLS to the data led to calibration models with root mean square error of prediction of 498Da and 179Da for heparin and LMWH, respectively. The average coefficients of variation (CVs) did not exceed 2.1% excluding sample preparation (by successive measuring one solution, n=5) and 2.5% including sample preparation (by preparing and analyzing separate samples, n=5). An advantage of the method is that the sample after standard 1D NMR characterization can be used for the molecular weight determination without further manipulation. The accuracy of multivariate models is better than the previous results for other matrices employing internal standards. Therefore, DOSY experiment is recommended to be employed for the calculation of molecular weight of heparin products as a complementary measurement to standard 1D NMR quality control. The method can be easily transferred to other matrices as well.
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Affiliation(s)
- Yulia B Monakhova
- Spectral Service AG, Emil-Hoffmann-Straße 33, 50996 Köln, Germany; Institute of Chemistry, Saratov State University, Astrakhanskaya Street 83, 410012 Saratov, Russia.
| | - Bernd W K Diehl
- Spectral Service AG, Emil-Hoffmann-Straße 33, 50996 Köln, Germany
| | - Tung X Do
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Von-Liebig-Straße 20, 53359 Rheinbach, Germany
| | - Margit Schulze
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Von-Liebig-Straße 20, 53359 Rheinbach, Germany
| | - Steffen Witzleben
- Department of Natural Sciences, University of Applied Sciences Bonn-Rhein-Sieg, Von-Liebig-Straße 20, 53359 Rheinbach, Germany
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6
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Pagès G, Gilard V, Martino R, Malet-Martino M. Pulsed-field gradient nuclear magnetic resonance measurements (PFG NMR) for diffusion ordered spectroscopy (DOSY) mapping. Analyst 2017; 142:3771-3796. [DOI: 10.1039/c7an01031a] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The advent of Diffusion Ordered SpectroscopY (DOSY) NMR has enabled diffusion coefficients to be routinely measured and used to characterize chemical systems in solution. Indeed, DOSY NMR allows the separation of the chemical entities present in multicomponent systems and provides information on their intermolecular interactions as well as on their size and shape.
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Affiliation(s)
- G. Pagès
- INRA
- AgroResonance – UR370 Qualité des Produits Animaux
- Saint Genès Champanelle
- France
| | - V. Gilard
- Groupe de RMN Biomédicale
- Laboratoire de Synthèse et Physicochimie de Molécules d'Intérêt Biologique
- UMR CNRS 5068
- Université de Toulouse
- 31062 Toulouse cedex 9
| | - R. Martino
- Groupe de RMN Biomédicale
- Laboratoire de Synthèse et Physicochimie de Molécules d'Intérêt Biologique
- UMR CNRS 5068
- Université de Toulouse
- 31062 Toulouse cedex 9
| | - M. Malet-Martino
- Groupe de RMN Biomédicale
- Laboratoire de Synthèse et Physicochimie de Molécules d'Intérêt Biologique
- UMR CNRS 5068
- Université de Toulouse
- 31062 Toulouse cedex 9
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7
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Structural studies of pravastatin and simvastatin and their complexes with SDS micelles by NMR spectroscopy. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2015.10.059] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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8
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Bizukojc M, Ledakowicz S. Bioprocess Engineering Aspects of the Cultivation of a Lovastatin Producer Aspergillus terreus. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2015; 149:133-70. [PMID: 25633258 DOI: 10.1007/10_2014_302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The aim of this work is to review bioprocess engineering aspects of lovastatin (antihypercholesterolemia drug) production by Aspergillus terreus in the submerged culture in the bioreactors of various scale presented in the scientific literature since the nineties of the twentieth century. The key factor influencing the cultivation of any filamentous species is fungal morphology and that is why this aspect was treated as the starting point for further considerations. Fungal morphology is known to have an impact on the following issues connected with the cultivation of A. terreus reviewed in this article. These are broth viscosity in conjunction with non-Newtonian behaviour of the cultivation broths, and multistage oxygen transfer processes: from gas phase (air) to liquid phase (broth) and diffusion in the fungal agglomerates. The latest achievements concerning the controlling A. terreus morphology during lovastatin biosynthesis with the use of morphological engineering techniques were also reviewed. Last but not least, some attention was paid to the type of a bioreactor, its operational mode and kinetic modelling of lovastatin production by A. terreus.
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Affiliation(s)
- Marcin Bizukojc
- Faculty of Process and Environmental Engineering, Department of Bioprocess Engineering, Lodz University of Technology, ul. Wolczanska 213, 90-924, Lodz, Poland,
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Dikshit R, Tallapragada P. Bio-synthesis and screening of nutrients for lovastatin by Monascus sp. under solid-state fermentation. Journal of Food Science and Technology 2015; 52:6679-86. [PMID: 26396416 DOI: 10.1007/s13197-014-1678-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 11/25/2014] [Accepted: 12/08/2014] [Indexed: 12/14/2022]
Abstract
In this study Monascus strains were screened for lovastatin production. These strains namely Monascus purpureus, Monascus sanguineus and their co-culture were able to produce lovastatin in solid state fermentation. Sensitivity of lovastatin was tested on Saccharomycess cerevaceae and Candida sp. where the former exhibited large zone of inhibition as compared to the latter. Presence of lovastatin was confirmed by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Quantification of lovastatin was done with UV spectrometer at 238 nm. Further, Plackett-Burman methodology was applied for screening of nutrients for lovastatin production. Different substrates were screened and amongst them, wheat bran was found to be the best substrate for lovastatin synthesis. Seven nutrients were screened according to the Plackett-Burman design for lovastatin yield. MgSO4.7H2O showed the positive impact on lovastatin yield whereas lactose showed the maximum negative effect with M. purpureus. For M. sanguineus, CaCl2.2H2O displayed the dominant negative effect and soybean the significant positive. With co-culture, the effect of lactose was positive whereas that of malt extract was negative and dominant. The maximum lovastatin yield for M. sanguineus, M. purpureus and co-culture was estimated to be 0.402, 0.27 and 0.26 mg/g respectively.
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Affiliation(s)
- Rashmi Dikshit
- Department of Microbiology, Centre for PG Studies, Jain University, 18/3, 9th Main road, 3rd Block, Jayanagar, Bangalore, 560,011 Karnataka, India
| | - Padmavathi Tallapragada
- Department of Microbiology, Centre for PG Studies, Jain University, 18/3, 9th Main road, 3rd Block, Jayanagar, Bangalore, 560,011 Karnataka, India
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Galiullina LF, Rakhmatullin IZ, Klochkova EA, Aganov AV, Klochkov VV. Structure of pravastatin and its complex with sodium dodecyl sulfate micelles studied by NMR spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2015; 53:110-114. [PMID: 25264019 DOI: 10.1002/mrc.4146] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 08/13/2014] [Accepted: 08/20/2014] [Indexed: 06/03/2023]
Abstract
The aim of this work was to study the mechanisms of interaction between pravastatin and cell membranes using model membranes (sodium dodecyl sulfate micelles) by nuclear magnetic resonance spectroscopy methods. On the basis of the nuclear magnetic resonance experiments, it was established that pravastatin can form intermolecular complexes with sodium dodecyl sulfate micelles by the interaction of its hydrophilic groups with the polar surface of the micelle. Conformational features of pravastatin molecule were also studied.
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Affiliation(s)
- L F Galiullina
- Institute of Physics, Kazan Federal University, 420008, Kazan, Russia
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Almeida C, Kehraus S, Prudêncio M, König GM. Marilones A-C, phthalides from the sponge-derived fungus Stachylidium sp. Beilstein J Org Chem 2011; 7:1636-42. [PMID: 22238541 PMCID: PMC3252867 DOI: 10.3762/bjoc.7.192] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 09/02/2011] [Indexed: 12/17/2022] Open
Abstract
The marine-derived fungus Stachylidium sp. was isolated from the sponge Callyspongia sp. cf. C. flammea. Culture on a biomalt medium supplemented with sea salt led to the isolation of three new phthalide derivatives, i.e., marilones A-C (1-3), and the known compound silvaticol (4). The skeleton of marilones A and B is most unusual, and its biosynthesis is suggested to require unique biochemical reactions considering fungal secondary metabolism. Marilone A (1) was found to have antiplasmodial activity against Plasmodium berghei liver stages with an IC(50) of 12.1 µM. Marilone B (2) showed selective antagonistic activity towards the serotonin receptor 5-HT(2B) with a K(i) value of 7.7 µM.
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Affiliation(s)
- Celso Almeida
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, D-53115 Bonn, Germany
| | - Stefan Kehraus
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, D-53115 Bonn, Germany
| | - Miguel Prudêncio
- Instituto de Medicina Molecular, Malaria Unit, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Gabriele M König
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, D-53115 Bonn, Germany
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Seenivasan A, Subhagar S, Aravindan R, Viruthagiri T. Microbial production and biomedical applications of lovastatin. Indian J Pharm Sci 2011; 70:701-9. [PMID: 21369428 PMCID: PMC3040861 DOI: 10.4103/0250-474x.49087] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 06/13/2008] [Accepted: 11/10/2008] [Indexed: 11/21/2022] Open
Abstract
Lovastatin is a potent hypercholesterolemic drug used for lowering blood cholesterol. Lovastatin acts by competitively inhibiting the enzyme, 3-hydroxy-3-methylglutaryl coenzyme A reductase involved in the biosynthesis of cholesterol. Commercially lovastatin is produced by a variety of filamentous fungi including Penicillium species, Monascus ruber and Aspergillus terreus as a secondary metabolite. Production of lovastatin by fermentation decreases the production cost compared to costs of chemical synthesis. In recent years, lovastatin has also been reported as a potential therapeutic agent for the treatment of various types of tumors and also play a tremendous role in the regulation of the inflammatory and immune response, coagulation process, bone turnover, neovascularization, vascular tone, and arterial pressure. This review deals with the structure, biosynthesis, various modes of fermentation and applications of lovastatin.
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Affiliation(s)
- A Seenivasan
- Biochemical Engineering Laboratory, Department of Chemical Engineering, Annamalai University, Annamalai Nagar-608 002, India
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Bizukojc M, Pecyna M. Lovastatin and (+)-geodin formation by Aspergillus terreus ATCC 20542 in a batch culture with the simultaneous use of lactose and glycerol as carbon sources. Eng Life Sci 2011. [DOI: 10.1002/elsc.201000179] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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14
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Pecyna M, Bizukojc M. Lovastatin biosynthesis by Aspergillus terreus with the simultaneous use of lactose and glycerol in a discontinuous fed-batch culture. J Biotechnol 2011; 151:77-86. [DOI: 10.1016/j.jbiotec.2010.10.079] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2010] [Revised: 10/27/2010] [Accepted: 10/29/2010] [Indexed: 12/19/2022]
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Novoa-Carballal R, Fernandez-Megia E, Jimenez C, Riguera R. NMR methods for unravelling the spectra of complex mixtures. Nat Prod Rep 2010; 28:78-98. [PMID: 20936238 DOI: 10.1039/c005320c] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The main methods for the simplification of the NMR of complex mixtures by selective attenuation/suppression of the signals of certain components are presented. The application of relaxation, diffusion and PSR filters and other techniques to biological samples, pharmaceuticals, foods, living organisms and natural products are illustrated with examples.
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Affiliation(s)
- Ramon Novoa-Carballal
- Department of Organic Chemistry and Centre for Research in Biological Chemistry and Molecular Materials, University of Santiago de Compostela, Santiago de Compostela, Spain
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Statistical optimization of anticholesterolemic drug lovastatin production by the red mold Monascus purpureus. FOOD AND BIOPRODUCTS PROCESSING 2010. [DOI: 10.1016/j.fbp.2010.01.006] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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17
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Khera S, Grillo M, Schnier P, Hollis S. Application of diffusion-edited NMR spectroscopy for the structural characterization of drug metabolites in mixtures. J Pharm Biomed Anal 2010; 51:164-9. [DOI: 10.1016/j.jpba.2009.07.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 07/06/2009] [Accepted: 07/07/2009] [Indexed: 11/16/2022]
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18
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Quinoline alkaloids in honey: Further analytical (HPLC-DAD-ESI-MS, multidimensional diffusion-ordered NMR spectroscopy), theoretical and chemometric studies. J Pharm Biomed Anal 2009; 50:432-9. [DOI: 10.1016/j.jpba.2009.05.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2009] [Accepted: 05/25/2009] [Indexed: 11/18/2022]
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Mueller D, Stahl U, Meyer V. Application of hammerhead ribozymes in filamentous fungi. J Microbiol Methods 2006; 65:585-95. [PMID: 16298445 DOI: 10.1016/j.mimet.2005.10.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 10/11/2005] [Accepted: 10/11/2005] [Indexed: 11/25/2022]
Abstract
Metabolic engineering in filamentous fungi is a emerging field of research as many fungi produce high value primary and secondary metabolites. Ribozyme technology can be used as a tool for metabolic engineering to influence metabolic pathways and to knock down the expression of specific genes of interest. Hammerhead ribozymes can target virtually any mRNA sequence of choice and prevent gene expression on the post-transcriptional level. They are thus a versatile tool for timed and spatial elimination of unwanted gene products. As current research has only investigated the application of ribozymes in bacteria, yeast and mammalian cells, we decided to carry out a study on whether this technology can also function with filamentous fungi. We employed a sensitive, quantitative reporter-based model system as a proof of concept, using the Escherichia coli beta-glucuronidase transcript (uidA) as the target mRNA and Aspergillus giganteus as the host. This system was used to validate the in vivo activities of seven different hammerhead ribozymes, which were selected by in silico analysis of the uidA mRNA. All ribozymes tested were able to reduce the reporter activity up to a maximum of 100%, demonstrating that ribozyme technology is indeed a useful tool in fungal metabolic engineering.
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Affiliation(s)
- Dirk Mueller
- Technische Universität Berlin, Institut für Biotechnologie, Fachgebiet Mikrobiologie und Genetik, Germany
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Bradley SA, Paschal J, Kulanthaivel P. DOSY of sample-limited mixtures: comparison of cold, nano and conventional probes. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2005; 43:31-35. [PMID: 15505820 DOI: 10.1002/mrc.1504] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The DOSY analysis of dilute mixtures can be a challenge because a high signal-to-noise ratio is required for the best DOSY results. The sensitivity increase gained from new probe technologies (e.g. cold and nano probes) could enable one to acquire good DOSY spectra on sample amounts too low for conventional probes. In this article, we investigated the performance of cold and nano probes for qualitative DOSY analysis of concentrated and sample-limited mixtures, and compared the results with those of the conventional probe. We first measured the fluid flow for each probe. All three probes exhibited only relatively small levels of flow; consequently, a double-stimulated echo pulse sequence was not employed in the subsequent DOSY experiments. This decision was based on three facts: (1) flow-induced phase distortions were not observed, (2) our intentions are only to perform qualitative mixture analysis, and (3) discarding 50% of the already limited signal cannot be afforded. Although the cold and nano probes produced DOSY results for the concentrated mixture that were inferior to the conventional probe, the increase in the signal-to-noise ratio observed with these probes proved to be advantageous for the dilute three-component mixture. Furthermore, the cold probe showed slightly superior performance over the nano probe; thus, we conclude that among the probes examined the cold probe is best suited for qualitative DOSY analysis of sample-limited mixtures.
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Affiliation(s)
- Scott A Bradley
- Discovery Drug Disposition, Lilly Research Laboratories, Indianapolis, IN 46285, USA.
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Bapat PM, Wangikar PP. Optimization of rifamycin B fermentation in shake flasks via a machine-learning-based approach. Biotechnol Bioeng 2004; 86:201-8. [PMID: 15052640 DOI: 10.1002/bit.20056] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Rifamycin B is an important polyketide antibiotic used in the treatment of tuberculosis and leprosy. We present results on medium optimization for Rifamycin B production via a barbital insensitive mutant strain of Amycolatopsis mediterranei S699. Machine-learning approaches such as Genetic algorithm (GA), Neighborhood analysis (NA) and Decision Tree technique (DT) were explored for optimizing the medium composition. Genetic algorithm was applied as a global search algorithm while NA was used for a guided local search and to develop medium predictors. The fermentation medium for Rifamycin B consisted of nine components. A large number of distinct medium compositions are possible by variation of concentration of each component. This presents a large combinatorial search space. Optimization was achieved within five generations via GA as well as NA. These five generations consisted of 178 shake-flask experiments, which is a small fraction of the search space. We detected multiple optima in the form of 11 distinct medium combinations. These medium combinations provided over 600% improvement in Rifamycin B productivity. Genetic algorithm performed better in optimizing fermentation medium as compared to NA. The Decision Tree technique revealed the media-media interactions qualitatively in the form of sets of rules for medium composition that give high as well as low productivity.
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Affiliation(s)
- Prashant M Bapat
- Department of Chemical Engineering, Indian Institute of Technology, Bombay, Powai, Mumbai 400 076, India
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