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Wheatley DE, Fontenelle CQ, Kuppala R, Szpera R, Briggs EL, Vendeville JB, Wells NJ, Light ME, Linclau B. Synthesis and Structural Characteristics of all Mono- and Difluorinated 4,6-Dideoxy-d- xylo-hexopyranoses. J Org Chem 2021; 86:7725-7756. [PMID: 34029099 DOI: 10.1021/acs.joc.1c00796] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein-carbohydrate interactions are implicated in many biochemical/biological processes that are fundamental to life and to human health. Fluorinated carbohydrate analogues play an important role in the study of these interactions and find application as probes in chemical biology and as drugs/diagnostics in medicine. The availability and/or efficient synthesis of a wide variety of fluorinated carbohydrates is thus of great interest. Here, we report a detailed study on the synthesis of monosaccharides in which the hydroxy groups at their 4- and 6-positions are replaced by all possible mono- and difluorinated motifs. Minimization of protecting group use was a key aim. It was found that introducing electronegative substituents, either as protecting groups or as deoxygenation intermediates, was generally beneficial for increasing deoxyfluorination yields. A detailed structural study of this set of analogues demonstrated that dideoxygenation/fluorination at the 4,6-positions caused very little distortion both in the solid state and in aqueous solution. Unexpected trends in α/β anomeric ratios were identified. Increasing fluorine content always increased the α/β ratio, with very little difference between regio- or stereoisomers, except when 4,6-difluorinated.
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Affiliation(s)
- David E Wheatley
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Clement Q Fontenelle
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Ramakrishna Kuppala
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Robert Szpera
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Edward L Briggs
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | | | - Neil J Wells
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Mark E Light
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
| | - Bruno Linclau
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K
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Vickman AE, Pohl NLB. Probing deoxysugar conformational preference: A comprehensive computational study investigating the effects of deoxygenation. Carbohydr Res 2018; 475:17-26. [PMID: 30771703 DOI: 10.1016/j.carres.2018.12.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 11/26/2018] [Accepted: 12/06/2018] [Indexed: 10/27/2022]
Abstract
Deoxysugars are intrinsic components in a number of antibiotics, antimicrobials, and therapeutic agents that often dictate receptor binding, improve efficacy, and provide a diverse toolbox in modifying glycoconjugate function due to an extensive number of unique isomers and inherent conformational flexibility. Hence, this work provides a comprehensive examination of the conformational effects associated with deoxygenation of the pyranose ring. Both the location and degree of deoxygenation were evaluated by interrogating the energetic landscape for a number of mono- and dideoxyhexopyranose derivatives using DFT methods (M05-2X/cc-pVTZ(-f)). Both anomeric forms and in some cases, the alternate chair form, have been investigated in the gas phase. As was documented in a preceding study, variation of the C-6 oxidation state has been shown to affect the anomeric preference of select glucose stereoisomers. Similar results were also observed for several deoxysugar isomers in this work, wherein the alternate anomer was favored upon reduction to the 6-deoxyhexose derivative or oxidation to the hexonic acid. Additionally, comparison of relative Gibbs free energies revealed C-3 deoxygenation imparts greater instability compared to C-2 or C-4 deoxygenation, as indicated by an increase in free energy for 3-deoxysugars. A polarizable continuum solvation model was also applied to empirically validate theoretical results for several deoxysugars, wherein good agreement with both carbon (σ = 1.6 ppm) and proton (σ = 0.20 ppm) NMR shifts was observed for the majority of isomers. Solvated and gas phase anomeric ratios were also calculated and compared favorably to reported literature values, although some discrepancies are noted.
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Affiliation(s)
- Alison E Vickman
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA
| | - Nicola L B Pohl
- Department of Chemistry, Indiana University, Bloomington, IN, 47405, USA.
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Stulberg ER, Lozano GL, Morin JB, Park H, Baraban EG, Mlot C, Heffelfinger C, Phillips GM, Rush JS, Phillips AJ, Broderick NA, Thomas MG, Stabb EV, Handelsman J. Genomic and Secondary Metabolite Analyses of Streptomyces sp. 2AW Provide Insight into the Evolution of the Cycloheximide Pathway. Front Microbiol 2016; 7:573. [PMID: 27199910 PMCID: PMC4853412 DOI: 10.3389/fmicb.2016.00573] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 04/07/2016] [Indexed: 11/13/2022] Open
Abstract
The dearth of new antibiotics in the face of widespread antimicrobial resistance makes developing innovative strategies for discovering new antibiotics critical for the future management of infectious disease. Understanding the genetics and evolution of antibiotic producers will help guide the discovery and bioengineering of novel antibiotics. We discovered an isolate in Alaskan boreal forest soil that had broad antimicrobial activity. We elucidated the corresponding antimicrobial natural products and sequenced the genome of this isolate, designated Streptomyces sp. 2AW. This strain illustrates the chemical virtuosity typical of the Streptomyces genus, producing cycloheximide as well as two other biosynthetically unrelated antibiotics, neutramycin, and hygromycin A. Combining bioinformatic and chemical analyses, we identified the gene clusters responsible for antibiotic production. Interestingly, 2AW appears dissimilar from other cycloheximide producers in that the gene encoding the polyketide synthase resides on a separate part of the chromosome from the genes responsible for tailoring cycloheximide-specific modifications. This gene arrangement and our phylogenetic analyses of the gene products suggest that 2AW holds an evolutionarily ancestral lineage of the cycloheximide pathway. Our analyses support the hypothesis that the 2AW glutaramide gene cluster is basal to the lineage wherein cycloheximide production diverged from other glutarimide antibiotics. This study illustrates the power of combining modern biochemical and genomic analyses to gain insight into the evolution of antibiotic-producing microorganisms.
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Affiliation(s)
- Elizabeth R Stulberg
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, CT, USA
| | - Gabriel L Lozano
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, CT, USA
| | - Jesse B Morin
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, CT, USA
| | - Hyunjun Park
- Department of Bacteriology, University of Wisconsin-Madison Madison, WI, USA
| | - Ezra G Baraban
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, CT, USA
| | - Christine Mlot
- Department of Bacteriology, University of Wisconsin-Madison Madison, WI, USA
| | | | | | - Jason S Rush
- Department of Chemistry, Yale University New Haven, CT, USA
| | | | - Nichole A Broderick
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, CT, USA
| | - Michael G Thomas
- Department of Bacteriology, University of Wisconsin-Madison Madison, WI, USA
| | - Eric V Stabb
- Department of Microbiology, University of Georgia Athens, GA, USA
| | - Jo Handelsman
- Department of Molecular, Cellular and Developmental Biology, Yale University New Haven, CT, USA
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Elshahawi SI, Shaaban KA, Kharel MK, Thorson JS. A comprehensive review of glycosylated bacterial natural products. Chem Soc Rev 2015; 44:7591-697. [PMID: 25735878 PMCID: PMC4560691 DOI: 10.1039/c4cs00426d] [Citation(s) in RCA: 299] [Impact Index Per Article: 33.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A systematic analysis of all naturally-occurring glycosylated bacterial secondary metabolites reported in the scientific literature up through early 2013 is presented. This comprehensive analysis of 15 940 bacterial natural products revealed 3426 glycosides containing 344 distinct appended carbohydrates and highlights a range of unique opportunities for future biosynthetic study and glycodiversification efforts.
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Affiliation(s)
- Sherif I Elshahawi
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Khaled A Shaaban
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
| | - Madan K Kharel
- School of Pharmacy, University of Maryland Eastern Shore, Princess Anne, Maryland, USA
| | - Jon S Thorson
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY, USA. and Center for Pharmaceutical Research and Innovation, College of Pharmacy, University of Kentucky, Lexington, KY, USA
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