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Abstract
Natural products are constructed by organisms in impressive ways through various highly selective enzyme-catalyzed chemical reactions. Over the past century, there has been considerable interest in understanding and emulating the underlying biosynthetic logic for the target molecule. The successful implementation of a biomimetic strategy usually has some uniquely valuable benefits over other abiotic routes in total synthesis by (1) corroborating the chemical feasibility of a given biogenetic hypothesis and further unraveling some insightful implications for future biosynthetic studies and (2) providing remarkably more concise access to not only the original synthetic target but also diversified biogenetically related congeners, which may result in either the structural reassignment of previously disclosed natural products or the anticipation of undiscovered natural products. However, for the devised essential biomimetic transformation, fine-tuning the optimization of the substrates and the reaction conditions can sometimes be painstakingly challenging. Turning to nature for inspiration can provide additional impetus for methodological innovations.Previously used as oral veterinary drugs, lankacidins have potential as next-generation antibiotics to tackle the problems caused by multidrug-resistant bacteria with novel modes of action (MoAs). The hypersensitive and densely functionalized lactonic core within this family of macrocyclic polyketides poses a formidable challenge for chemical total synthesis and derivatization. In this account, we summarized the evolution of a unified biomimetic approach toward 10 lankacidin antibiotics and their linear biosynthetic intermediates in the longest linear 7-12 steps from readily available starting materials. Our endeavor commenced with an intermolecular bioinspired amido sulfone-based Mannich reaction approach to assemble 2 advanced fragments under mild biphasic organocatalytic conditions. It successfully gave rise to stereodivergent access to 4 C2/C18-isomeric lankacyclinols but failed to efficiently deliver lactone-containing congeners through Stille macrocyclization. Facilitated by the thermolysis chemistry of N,O-acetal to generate the requisite N-acyl-1-azahexatriene species, we realized the projected Mannich macrocyclization and eight macrocyclic lankacidins can be produced by orchestrated desilylative manipulations. In this process, we were able to perform structural reassignments of isolankacidinol (7 to 50) and isolankacyclinol (104 to 83) and, for the first time, elucidate the natural occurrence of 2,18-bis-epi-lankacyclinol (84). Moreover, the inability of the current biomimetic route to cofurnish the reported structure of 2,18-seco-lankacidinol A (15) triggered a proposed structural revision that is rooted in reconsidered biogenesis and was confirmed by a divergent synthesis that enabled us to identify the correct isomer (116). Finally, the modular, diversity-oriented design also provided streamlined entries to acyclic 2,18-seco-lankacidinol B (120) and the biosynthetic intermediate LC-KA05 (17) together with its C7-O-deacetylated congeners in all C4/C5-stereochemical variations (18, 127-129), culminating in a need for structural revision to the six-membered lactonic segment in LC-KA05-2. The selection and execution of biomimetic strategies in lankacidin total synthesis give rise to all the previously mentioned advantages at the current stage. The modular-based, late-stage diversified complex construction offers an exceptionally high level of synthetic flexibility for future synthetic forays toward newly isolated or chemically modified congeners within the lankacidin family.
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Affiliation(s)
- Kuan Zheng
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, PR China
| | - Ran Hong
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, PR China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, PR China
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Cai L, Seiple IB, Li Q. Modular Chemical Synthesis of Streptogramin and Lankacidin Antibiotics. Acc Chem Res 2021; 54:1891-1908. [PMID: 33792282 DOI: 10.1021/acs.accounts.0c00894] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Continued, rapid development of antimicrobial resistance has become worldwide health crisis and a burden on the global economy. Decisive and comprehensive action is required to slow down the spread of antibiotic resistance, including increased investment in antibiotic discovery, sustainable policies that provide returns on investment for newly launched antibiotics, and public education to reduce the overusage of antibiotics, especially in livestock and agriculture. Without significant changes in the current antibiotic pipeline, we are in danger of entering a post-antibiotic era.In this Account, we summarize our recent efforts to develop next-generation streptogramin and lankacidin antibiotics that overcome bacterial resistance by means of modular chemical synthesis. First, we describe our highly modular, scalable route to four natural group A streptogramins antibiotics in 6-8 steps from seven simple chemical building blocks. We next describe the application of this route to the synthesis of a novel library of streptogramin antibiotics informed by in vitro and in vivo biological evaluation and high-resolution cryo-electron microscopy. One lead compound showed excellent inhibitory activity in vitro and in vivo against a longstanding streptogramin-resistance mechanism, virginiamycin acetyltransferase. Our results demonstrate that the combination of rational design and modular chemical synthesis can revitalize classes of antibiotics that are limited by naturally arising resistance mechanisms.Second, we recount our modular approaches toward lankacidin antibiotics. Lankacidins are a group of polyketide natural products with activity against several strains of Gram-positive bacteria but have not been deployed as therapeutics due to their chemical instability. We describe a route to several diastereomers of 2,18-seco-lankacidinol B in a linear sequence of ≤8 steps from simple building blocks, resulting in a revision of the C4 stereochemistry. We next detail our modular synthesis of several diastereoisomers of iso-lankacidinol that resulted in the structural reassignment of this natural product. These structural revisions raise interesting questions about the biosynthetic origin of lankacidins, all of which possessed uniform stereochemistry prior to these findings. Finally, we summarize the ability of several iso- and seco-lankacidins to inhibit the growth of bacteria and to inhibit translation in vitro, providing important insights into structure-function relationships for the class.
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Affiliation(s)
- Lingchao Cai
- Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing Forestry University, Nanjing 210037, Jiangsu China
| | - Ian B. Seiple
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California, San Francisco, San Francisco, California 94158, United States
| | - Qi Li
- Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
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Zheng K, Shen D, Zhang B, Hong R. Landscape of Lankacidin Biomimetic Synthesis: Structural Revisions and Biogenetic Implications. J Org Chem 2020; 85:13818-13836. [PMID: 32985194 DOI: 10.1021/acs.joc.0c01930] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In this report, a unified biomimetic approach to all known macrocyclic lankacidins is presented. By taking advantage of the thermolysis of N,O-acetal to generate the requisite N-acyl-1-azahexatriene species, we eventually realized the biomimetic Mannich macrocyclization, from which all of the macrocyclic lankacidins can be conquered by orchestrated desilylation. The reassignments of the reported structures of isolankacidinol (7 to 10) and the discovery of a recently isolated "lankacyclinol" found to be in fact 2,18-bis-epi-lankacyclinol (72) unraveled the previously underappreciated chemical diversity exhibited by the enzymatic macrocyclization. In addition, the facile elimination/decarboxylation/protonation process for the depletion of C1 under basic conditions resembling a physiological environment may implicate more undiscovered natural products with variable C2/C18 stereochemistries (i.e., 62, 73, and 75). The notable aspect provided by a biomimetic strategy is significantly reducing the step count compared with the two previous entries to macrocyclic lankacidins.
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Affiliation(s)
- Kuan Zheng
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Defeng Shen
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Bingbing Zhang
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.,University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Ran Hong
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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Cai L, Yao Y, Yeon SK, Seiple IB. Modular Approaches to Lankacidin Antibiotics. J Am Chem Soc 2020; 142:15116-15126. [PMID: 32786797 DOI: 10.1021/jacs.0c06648] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Lankacidins are a class of polyketide natural products isolated from Streptomyces spp. that show promising antimicrobial activity. Owing to their complex molecular architectures and chemical instability, structural assignment and derivatization of lankacidins are challenging tasks. Herein we describe three fully synthetic approaches to lankacidins that enable access to new structural variability within the class. We use these routes to systematically generate stereochemical derivatives of both cyclic and acyclic lankacidins. Additionally, we access a new series of lankacidins bearing a methyl group at the C4 position, a modification intended to increase chemical stability. In the course of this work, we discovered that the reported structures for two natural products of the lankacidin class were incorrect, and we determine the correct structures of 2,18-seco-lankacidinol B and iso-lankacidinol. We also evaluate the ability of several iso- and seco-lankacidins to inhibit the growth of bacteria and to inhibit translation in vitro. This work grants insight into the rich chemical complexity of this class of antibiotics and provides an avenue for further structural derivatization.
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Affiliation(s)
- Lingchao Cai
- Jiangsu Provincial Key Lab for the Chemistry and Utilization of Agro-Forest Biomass, Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jinagsu Key Lab of Biomass-Based Green Fuels and Chemicals, Nanjing Forestry University, Nanjing, 210037 Jiangsu, China.,Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
| | - Yanmin Yao
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
| | - Seul Ki Yeon
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
| | - Ian B Seiple
- Department of Pharmaceutical Chemistry and Cardiovascular Research Institute, University of California at San Francisco, San Francisco, California 94158, United States
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Zheng K, Hong R. Postulated Biogenesis-Guided Total Synthesis and Structural Revision of 2,18-seco-Lankacidinol A. Org Lett 2020; 22:3785-3788. [DOI: 10.1021/acs.orglett.0c00993] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Kuan Zheng
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Ran Hong
- CAS Key Laboratory of Synthetic Chemistry of Natural Substances, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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Zheng K, Shen D, Hong R. Biomimetic Synthesis of Lankacidin Antibiotics. J Am Chem Soc 2017; 139:12939-12942. [DOI: 10.1021/jacs.7b08500] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Kuan Zheng
- Key
Laboratory of Synthetic Chemistry of Natural Substances, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Defeng Shen
- Key
Laboratory of Synthetic Chemistry of Natural Substances, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
- University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing 100049, China
| | - Ran Hong
- Key
Laboratory of Synthetic Chemistry of Natural Substances, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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Synthesis of macrocyclic precursors of lankacidins using Stille reactions of 4-(2-iodo-alkenyl)azetidinones and related compounds for ring closure. Tetrahedron 2010. [DOI: 10.1016/j.tet.2010.04.129] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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The structure of ribosome-lankacidin complex reveals ribosomal sites for synergistic antibiotics. Proc Natl Acad Sci U S A 2010; 107:1983-8. [PMID: 20080686 PMCID: PMC2804743 DOI: 10.1073/pnas.0914100107] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Crystallographic analysis revealed that the 17-member polyketide antibiotic lankacidin produced by Streptomyces rochei binds at the peptidyl transferase center of the eubacterial large ribosomal subunit. Biochemical and functional studies verified this finding and showed interference with peptide bond formation. Chemical probing indicated that the macrolide lankamycin, a second antibiotic produced by the same species, binds at a neighboring site, at the ribosome exit tunnel. These two antibiotics can bind to the ribosome simultaneously and display synergy in inhibiting bacterial growth. The binding site of lankacidin and lankamycin partially overlap with the binding site of another pair of synergistic antibiotics, the streptogramins. Thus, at least two pairs of structurally dissimilar compounds have been selected in the course of evolution to act synergistically by targeting neighboring sites in the ribosome. These results underscore the importance of the corresponding ribosomal sites for development of clinically relevant synergistic antibiotics and demonstrate the utility of structural analysis for providing new directions for drug discovery.
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Towards EPC-syntheses of the structural class of cochleamycins and macquarimicins. Part 1: EPC-synthesis of the hydrindene subunit of the cochleamycins. Tetrahedron 2007. [DOI: 10.1016/j.tet.2007.05.092] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Brain CT, Chen A, Nelson A, Tanikkul N, Thomas EJ. An approach to the total synthesis of lankacidins: synthesis of the requisite building blocks. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(00)02260-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Chen A, Nelson A, Tanikkul N, Thomas EJ. An approach to the total synthesis of lankacidins: synthesis of advanced macrocyclic precursors. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(00)02261-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Williams DR, Cortez GS, Bogen SL, Rojas CM. Total Synthesis of Lankacyclinol Generous financial support for this research was provided by the National Institutes of Health (Award no.: GM41560). Additionally, a National Institutes of Health Minority Predoctoral Fellowship (Award no.: GM18547) to G.S.C. is gratefully acknowledged. We also wish to thank Dr. Tsuneaki Hida and Dr. Yoshio Kozai, Takeda Chemical Ltd. (Japan), for providing us with an authentic sample of lankacyclinol as well as copies of the original (1)H NMR spectrum. Angew Chem Int Ed Engl 2000; 39:4612-4615. [PMID: 11169688 DOI: 10.1002/1521-3773(20001215)39:24<4612::aid-anie4612>3.0.co;2-c] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- David R. Williams
- Department of Chemistry Indiana University 800 East Kirkwood Avenue, Bloomington, IN 47405 (USA)
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Thomas EJ, Williams AC. Development of a synthesis of lankacidins: stereoselective synthesis of the δ-lactone fragment. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/p19950000351] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hayashi T, Suenaga I, Narukawa N, Yamazaki T. In vitro and in vivo activities of sedecamycin against Treponema hyodysenteriae. Antimicrob Agents Chemother 1988; 32:458-61. [PMID: 3377458 PMCID: PMC172201 DOI: 10.1128/aac.32.4.458] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Sedecamycin (lankacidin A), one of the lankacidin-group antibiotics, showed potent activity against Treponema hyodysenteriae. The MICs of sedecamycin against 79 field isolates of T. hyodysenteriae ranged from 0.78 to 12.5 micrograms/ml, the MIC for 90% of the strains tested (MIC90) being 3.13 micrograms/ml. The protective and therapeutic effects of sedecamycin were compared with those of carbadox, tiamulin, and lincomycin against experimental infection with T. hyodysenteriae in mice. The protective effect of sedecamycin was similar to that of carbadox, two times more potent than that of tiamulin, and three times greater than that of lincomycin. In the therapeutic test, sedecamycin showed activity similar to that of carbadox and was two times more active than both tiamulin and lincomycin. At doses of 10 mg or more of sedecamycin per kg, the recurrence of shedding of T. hyodysenteriae into the feces of mice was not detected for at least 8 weeks postmedication.
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Affiliation(s)
- T Hayashi
- Animal Health Products Division, Takeda Chemical Industries, Ltd., Osaka, Japan
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McFarland JW, Pirie DK, Retsema JA, English AR. Side chain modifications in lankacidin group antibiotics. Antimicrob Agents Chemother 1984; 25:226-33. [PMID: 6370129 PMCID: PMC185479 DOI: 10.1128/aac.25.2.226] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Novel N-acyl analogs of lankacidin may be prepared from 3-isocyanatolankone diformate [7,13-bis(formyloxy)-2-isocyanato-1,4,10,19-tetramethyl-16- oxabicyclo[13.2.2.]nonadeca-3,5,9,11-tetraen-17,18-dione]. Of seven such analogs evaluated in vitro only homolankacidin diformate showed significant activity. However, in a cell-free system two of the inactive analogs inhibited polypeptide synthesis as well as did lankacidin itself or erythromycin. Antibacterial activity, therefore, is a function of the ability of a congener to penetrate the bacterial cell membrane in addition to its intrinsic activity. Similarly, lankacidinol is as potent as lankacidin or erythromycin as an inhibitor of bacterial polypeptide synthesis in a cell-free system. This intrinsic activity is expressed as potent antibacterial activity against growing gram-positive cultures in O(2')-acyl derivatives with the proper lipophilicity.
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Sebek OK, Perlman D. Microbial transformations of antibiotics. ADVANCES IN APPLIED MICROBIOLOGY 1971; 14:123-50. [PMID: 4334327 DOI: 10.1016/s0065-2164(08)70542-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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