1
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Ernst L, Lyu H, Liu P, Paetz C, Sayed HMB, Meents T, Ma H, Beerhues L, El-Awaad I, Liu B. Regiodivergent biosynthesis of bridged bicyclononanes. Nat Commun 2024; 15:4525. [PMID: 38806518 PMCID: PMC11133429 DOI: 10.1038/s41467-024-48879-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 05/15/2024] [Indexed: 05/30/2024] Open
Abstract
Medicinal compounds from plants include bicyclo[3.3.1]nonane derivatives, the majority of which are polycyclic polyprenylated acylphloroglucinols (PPAPs). Prototype molecules are hyperforin, the antidepressant constituent of St. John's wort, and garcinol, a potential anticancer compound. Their complex structures have inspired innovative chemical syntheses, however, their biosynthesis in plants is still enigmatic. PPAPs are divided into two subclasses, named type A and B. Here we identify both types in Hypericum sampsonii plants and isolate two enzymes that regiodivergently convert a common precursor to pivotal type A and B products. Molecular modelling and substrate docking studies reveal inverted substrate binding modes in the two active site cavities. We identify amino acids that stabilize these alternative binding scenarios and use reciprocal mutagenesis to interconvert the enzymatic activities. Our studies elucidate the unique biochemistry that yields type A and B bicyclo[3.3.1]nonane cores in plants, thereby providing key building blocks for biotechnological efforts to sustainably produce these complex compounds for preclinical development.
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Affiliation(s)
- Lukas Ernst
- Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Braunschweig, Germany.
| | - Hui Lyu
- Max Planck Institute for Chemical Ecology, NMR/Biosynthesis Group, Jena, Germany
| | - Pi Liu
- Chinese Academy of Sciences, Tianjin Institute of Industrial Biotechnology, Biodesign Center, Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin, China
| | - Christian Paetz
- Max Planck Institute for Chemical Ecology, NMR/Biosynthesis Group, Jena, Germany
| | - Hesham M B Sayed
- Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Braunschweig, Germany
- Assiut University, Faculty of Pharmacy, Department of Pharmacognosy, Assiut, Egypt
| | - Tomke Meents
- Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Braunschweig, Germany
| | - Hongwu Ma
- Chinese Academy of Sciences, Tianjin Institute of Industrial Biotechnology, Biodesign Center, Key Laboratory of Engineering Biology for Low-carbon Manufacturing, Tianjin, China
| | - Ludger Beerhues
- Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Braunschweig, Germany
- Technische Universität Braunschweig, Center of Pharmaceutical Engineering, Braunschweig, Germany
| | - Islam El-Awaad
- Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Braunschweig, Germany.
- Assiut University, Faculty of Pharmacy, Department of Pharmacognosy, Assiut, Egypt.
- Technische Universität Braunschweig, Center of Pharmaceutical Engineering, Braunschweig, Germany.
| | - Benye Liu
- Technische Universität Braunschweig, Institute of Pharmaceutical Biology, Braunschweig, Germany.
- Technische Universität Braunschweig, Center of Pharmaceutical Engineering, Braunschweig, Germany.
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2
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Zhang Z, Qian X, Gu Y, Gui J. Controllable skeletal reorganizations in natural product synthesis. Nat Prod Rep 2024; 41:251-272. [PMID: 38291905 DOI: 10.1039/d3np00066d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2024]
Abstract
Covering: 2016 to 2023The synthetic chemistry community is always in pursuit of efficient routes to natural products. Among the many available general strategies, skeletal reorganization, which involves the formation, cleavage, and migration of C-C and C-heteroatom bonds, stands out as a particularly useful approach for the efficient assembly of molecular skeletons. In addition, it allows for late-stage modification of natural products for quick access to other family members or unnatural derivatives. This review summarizes efficient syntheses of steroid, terpenoid, and alkaloid natural products that have been achieved by means of this strategy in the past eight years. Our goal is to illustrate the strategy's potency and reveal the spectacular human ingenuity demonstrated in its use and development.
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Affiliation(s)
- Zeliang Zhang
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
| | - Xiao Qian
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
| | - Yucheng Gu
- Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire RG42 6EY, UK
| | - Jinghan Gui
- State Key Laboratory of Chemical Biology, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China.
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3
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Sanchez A, Gurajapu A, Guo W, Kong WY, Laconsay CJ, Settineri NS, Tantillo DJ, Maimone TJ. A Shapeshifting Roadmap for Polycyclic Skeletal Evolution. J Am Chem Soc 2023. [PMID: 37279177 DOI: 10.1021/jacs.3c03960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Polycyclic ring systems are ubiquitous three-dimensional (3D) structural motifs central to the function of many biologically active small molecules and organic materials. Indeed, subtle changes to the overall molecular shape and connectivity of atoms in a polycyclic framework (i.e., isomerism) can drastically alter its function and properties. Unfortunately, direct evaluation of these structure-function relationships typically requires the development of distinct synthetic strategies toward a specific isomer. Dynamic, "shapeshifting" carbon cages present a promising approach for sampling isomeric chemical space but are often difficult to control and are largely limited to thermodynamic mixtures of positional isomers about a single core scaffold. Here, we describe the development of a new shapeshifting C9-chemotype and a chemical blueprint for its evolution into structurally and energetically diverse isomeric ring systems. By leveraging the unique molecular topology of π-orbitals interacting through-space (homoconjugation), a common skeletal ancestor evolved into a complex network of valence isomers. This unusual system represents an exceedingly rare small molecule capable of undergoing controllable and continuous isomerization processes through the iterative use of just two chemical steps (light and organic base). Computational and photophysical studies of the isomer network provide fundamental insight into the reactivity, mechanism, and role of homoconjugative interactions. Importantly, these insights may inform the rational design and synthesis of new dynamic, shapeshifting systems. We anticipate this process could be a powerful tool for the synthesis of structurally diverse, isomeric polycycles central to many bioactive small molecules and functional organic materials.
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Affiliation(s)
- Andre Sanchez
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Anjali Gurajapu
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Wentao Guo
- Department of Chemistry, University of California-Davis, 1 Shields Ave, Davis, California 95616, United States
| | - Wang-Yeuk Kong
- Department of Chemistry, University of California-Davis, 1 Shields Ave, Davis, California 95616, United States
| | - Croix J Laconsay
- Department of Chemistry, University of California-Davis, 1 Shields Ave, Davis, California 95616, United States
| | - Nicholas S Settineri
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Dean J Tantillo
- Department of Chemistry, University of California-Davis, 1 Shields Ave, Davis, California 95616, United States
| | - Thomas J Maimone
- Department of Chemistry, University of California-Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
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4
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Luo Y, Grossman RB, Nie XB, Yang XW. Total synthesis and structural reassignment of garcinielliptone FC, a polycyclic polyprenylated acylphloroglucinol with diverse bioactivity. Chem Commun (Camb) 2023; 59:6215-6218. [PMID: 37129081 DOI: 10.1039/d3cc01268a] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Garcinielliptone FC (GFC) was assigned to be a type A polycyclic polyprenylated acylphloroglucinol (PPAP) and was found to exhibit diverse biological activities. Now we revise the structure of GFC to xanthochymol, a type B PPAP, via NMR and total synthesis methods. The total syntheses of (±)-xanthochymol and (±)-cycloxanthochymol were accomplished in 12 and 13 steps, respectively.
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Affiliation(s)
- Yang Luo
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, People's Republic of China.
| | - Robert B Grossman
- Department of Chemistry, University of Kentucky, Lexington, Kentucky 40506-0055, USA
| | - Xiao-Bin Nie
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, People's Republic of China.
| | - Xing-Wei Yang
- School of Pharmaceutical Sciences (Shenzhen), Sun Yat-sen University, Shenzhen 518107, People's Republic of China.
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5
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Bitchagno GTM, Nchiozem-Ngnitedem VA, Melchert D, Fobofou SA. Demystifying racemic natural products in the homochiral world. Nat Rev Chem 2022; 6:806-822. [PMID: 37118098 PMCID: PMC9562063 DOI: 10.1038/s41570-022-00431-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2022] [Indexed: 12/03/2022]
Abstract
Natural products possess structural complexity, diversity and chirality with attractive functions and biological activities that have significantly impacted drug discovery initiatives. Chiral natural products are abundant in nature but rarely occur as racemates. The occurrence of natural products as racemates is very intriguing from a biosynthetic point of view; as enzymes are chiral molecules, enzymatic reactions generating natural products should be stereospecific and lead to single-enantiomer products. Despite several reports in the literature describing racemic mixtures of stereoisomers isolated from natural sources, there has not been a comprehensive review of these intriguing racemic natural products. The discovery of many more natural racemates and their potential enzymatic sources in recent years allows us to describe the distribution and chemical diversity of this ‘class of natural products’ to enrich discussions on biosynthesis. In this Review, we describe the chemical classes, occurrence and distribution of pairs of enantiomers in nature and provide insights about recent advances in analytical methods used for their characterization. Special emphasis is on the biosynthesis, including plausible enzymatic and non-enzymatic formation of natural racemates, and their pharmacological significance. ![]()
Racemic natural products display a wealth of bioactivities and chemical diversity. Their derivation from intriguing racemization processes, through enzymatic or non-enzymatic pathways, are discussed here, as well as their pharmacological properties and the analytical techniques developed for their identification, resolution and characterization.
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6
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LIU S, YU B, DAI J, CHEN R. Targeting the biological activity and biosynthesis of hyperforin: a mini-review. Chin J Nat Med 2022; 20:721-728. [DOI: 10.1016/s1875-5364(22)60189-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Indexed: 11/03/2022]
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7
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Phang YL, Liu S, Zheng C, Xu H. Recent advances in the synthesis of natural products containing the phloroglucinol motif. Nat Prod Rep 2022; 39:1766-1802. [PMID: 35762867 DOI: 10.1039/d1np00077b] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Covering: June 2009 to 2021Natural products containing a phloroglucinol motif include simple and oligomeric phloroglucinols, polycyclic polyprenylated acylphloroglucinols, phloroglucinol-terpenes, xanthones, flavonoids, and coumarins. These compounds represent a major class of secondary metabolites which exhibit a wide range of biological activities such as antimicrobial, anti-inflammatory, antioxidant and hypoglycaemic properties. A number of these compounds have been authorized for therapeutic use or are currently being studied in clinical trials. Their structural diversity and utility in both traditional and conventional medicine have made them popular synthetic targets over the years. In this review, we compile and summarise the recent synthetic approaches to the natural products bearing a phloroglucinol motif. Focus has been given on ingenious strategies to functionalize the phloroglucinol moiety at multiple positions. The isolation and bioactivities of the compounds are also provided.
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Affiliation(s)
- Yee Lin Phang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China. .,Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai 201203, China
| | - Song Liu
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China. .,Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai 201203, China
| | - Changwu Zheng
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China. .,Engineering Research Center of Shanghai Colleges for TCM New Drug Discovery, Shanghai 201203, China
| | - Hongxi Xu
- Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, 201203, China.
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8
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Leisering S, Ponath S, Shakeri K, Mavroskoufis A, Kleoff M, Voßnacker P, Steinhauer S, Weber M, Christmann M. Synthesis of 3- epi-Hypatulin B Featuring a Late-Stage Photo-Oxidation in Flow. Org Lett 2022; 24:4305-4309. [PMID: 35536108 DOI: 10.1021/acs.orglett.2c00689] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
A synthesis of 3-epi-hypatulin B, a highly oxygenated and densely functionalized bicyclic scaffold, is reported. The carbon skeleton was prepared by functionalization of a cyclopentanone and an intramolecular Mukaiyama aldol reaction. Highlights include a late-stage photo-oxidation of a methoxyallene to provide an ester group. The problems encountered in the batch process were solved by translation into a flow protocol. Our synthesis highlights the value of flow chemistry to enable challenging late-stage transformations in natural product synthesis.
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Affiliation(s)
- Stefan Leisering
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Sebastian Ponath
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Kamar Shakeri
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Alexandros Mavroskoufis
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Merlin Kleoff
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Patrick Voßnacker
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Simon Steinhauer
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Manuela Weber
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - Mathias Christmann
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
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9
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Sanchez A, Maimone TJ. Taming Shapeshifting Anions: Total Synthesis of Ocellatusone C. J Am Chem Soc 2022; 144:7594-7599. [PMID: 35420799 DOI: 10.1021/jacs.2c02627] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Guided by a synthetic design aimed at late-stage diversification, we report the preparation of unusual shapeshifting anions and their subsequent application to the total synthesis of the polyketide natural product ocellatusone C. Site-selective core functionalization of a readily accessible bicyclo[3.3.1]nonane architecture sets the stage for shape-selective side chain installation via a nonfluxional π-allyl Pd-complex derived from a barbaralyl-type anion. Several interesting chemical findings, including substituent-dependent bridged bicycloisomerism and the isolation of a stabilized, 3° carbon-bound Pd-ketone enolate complex, are reported.
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Affiliation(s)
- Andre Sanchez
- Department of Chemistry, University of California─Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Thomas J Maimone
- Department of Chemistry, University of California─Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
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10
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Ji Y, Hong B, Franzoni I, Wang M, Guan W, Jia H, Li H. Enantioselective Total Synthesis of Hyperforin and Pyrohyperforin. Angew Chem Int Ed Engl 2022; 61:e202116136. [DOI: 10.1002/anie.202116136] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Indexed: 12/18/2022]
Affiliation(s)
- Yunpeng Ji
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Benke Hong
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Ivan Franzoni
- NuChem Sciences Inc. 2350 rue Cohen Suite 201 Saint-Laurent Quebec H4R 2N6 Canada
| | - Mengyang Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Weiqiang Guan
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Hongli Jia
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Houhua Li
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
- State Key Laboratory of Medicinal Chemical Biology Nankai University 38 Tongyan Rd Tianjin 300350 China
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11
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Ji Y, Hong B, Franzoni I, Wang M, Guan W, Jia H, Li H. Enantioselective Total Synthesis of Hyperforin and Pyrohyperforin. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202116136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Yunpeng Ji
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Benke Hong
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Ivan Franzoni
- NuChem Sciences Inc. 2350 rue Cohen Suite 201 Saint-Laurent Quebec H4R 2N6 Canada
| | - Mengyang Wang
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Weiqiang Guan
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Hongli Jia
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
| | - Houhua Li
- State Key Laboratory of Natural and Biomimetic Drugs, Chemical Biology Center School of Pharmaceutical Sciences Peking University Xue Yuan Road No. 38 Beijing 100191 China
- State Key Laboratory of Medicinal Chemical Biology Nankai University 38 Tongyan Rd Tianjin 300350 China
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12
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Huang JC, Sheng L, Zong JF, Zhou YB, Li J, Hou AJ. Enantiomeric pairs of meroterpenoids with 11/5/6 spiro-heterocyclic systems from Hypericum kouytchense. Org Chem Front 2022. [DOI: 10.1039/d2qo01485h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Undescribed enantiomeric pairs of acylphloroglucinol related meroterpenoids with 11/5/6 spiro-heterocyclic systems were isolated from Hypericum kouytchense.
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Affiliation(s)
- Jin-Chang Huang
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China
- School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Li Sheng
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Jian-Fa Zong
- School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Yu-Bo Zhou
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Jia Li
- National Center for Drug Screening, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Ai-Jun Hou
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai 200240, China
- School of Pharmacy, Fudan University, Shanghai 201203, China
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13
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Jang D, Choi M, Chen J, Lee C. Enantioselective Total Synthesis of (+)-Garsubellin A. Angew Chem Int Ed Engl 2021; 60:22735-22739. [PMID: 34398517 PMCID: PMC8519110 DOI: 10.1002/anie.202109193] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 08/05/2021] [Indexed: 01/03/2023]
Abstract
Garsubellin A is a meroterpene capable of enhancing the enzyme choline acetyltransferase whose decreased level is believed to play a central role in the symptoms of Alzheimer's disease. Due to the potentially useful biological activity together with the novel bridged and fused cyclic molecular architecture, garsubellin A has garnered substantial synthetic interest, but its absolute stereostructure has been undetermined. We report here the first enantioselective total synthesis of (+)‐garsubellin A. Our synthesis relies on stereoselective fashioning of a cyclohexanone framework and double conjugate addition of 1,2‐ethanedithiol that promotes aldol cyclization to build the bicyclic [3.3.1] skeleton. The twelve‐step, protecting group‐free synthetic route has enabled the syntheses of both the natural (−)‐garsubellin A and its unnatural (+)‐antipode for biological evaluations.
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Affiliation(s)
- Dongseok Jang
- Department of ChemistrySeoul National UniversitySeoul08826Republic of Korea
| | - Minchul Choi
- Department of ChemistrySeoul National UniversitySeoul08826Republic of Korea
| | - Jinglong Chen
- Department of ChemistryPrinceton UniversityPrincetonNew Jersey08540USA
- Current address: College of Materials Science and EngineeringFuzhou UniversityFuzhou350108China
| | - Chulbom Lee
- Department of ChemistrySeoul National UniversitySeoul08826Republic of Korea
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14
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Jang D, Choi M, Chen J, Lee C. Enantioselective Total Synthesis of (+)‐Garsubellin A. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109193] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Dongseok Jang
- Department of Chemistry Seoul National University Seoul 08826 Republic of Korea
| | - Minchul Choi
- Department of Chemistry Seoul National University Seoul 08826 Republic of Korea
| | - Jinglong Chen
- Department of Chemistry Princeton University Princeton New Jersey 08540 USA
- Current address: College of Materials Science and Engineering Fuzhou University Fuzhou 350108 China
| | - Chulbom Lee
- Department of Chemistry Seoul National University Seoul 08826 Republic of Korea
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15
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Tong B, Belcher BP, Nomura DK, Maimone TJ. Chemical investigations into the biosynthesis of the gymnastatin and dankastatin alkaloids. Chem Sci 2021; 12:8884-8891. [PMID: 34257889 PMCID: PMC8246081 DOI: 10.1039/d1sc02613e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 05/31/2021] [Indexed: 12/25/2022] Open
Abstract
Electrophilic natural products have provided fertile ground for understanding how nature inhibits protein function using covalent bond formation. The fungal strain Gymnascella dankaliensis has provided an especially interesting collection of halogenated cytotoxic agents derived from tyrosine which feature an array of reactive functional groups. Herein we explore chemical and potentially biosynthetic relationships between architecturally complex gymnastatin and dankastatin members, finding conditions that favor formation of a given scaffold from a common intermediate. Additionally, we find that multiple natural products can also be formed from aranorosin, a non-halogenated natural product also produced by Gymnascella sp. fungi, using simple chloride salts thus offering an alternative hypothesis for the origins of these compounds in nature. Finally, growth inhibitory activity of multiple members against human triple negative breast cancer cells is reported. Total synthesis sheds light on biosynthetic relationships among the chlorinated gymnastatin and dankastatin alkaloids.![]()
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Affiliation(s)
- Bingqi Tong
- Department of Chemistry, University of California-Berkeley Berkeley CA 94720 USA .,Novartis-Berkeley Center for Proteomics and Chemistry Technologies, University of California-Berkeley Berkeley CA 94720 USA
| | - Bridget P Belcher
- Department of Chemistry, University of California-Berkeley Berkeley CA 94720 USA .,Novartis-Berkeley Center for Proteomics and Chemistry Technologies, University of California-Berkeley Berkeley CA 94720 USA
| | - Daniel K Nomura
- Department of Chemistry, University of California-Berkeley Berkeley CA 94720 USA .,Novartis-Berkeley Center for Proteomics and Chemistry Technologies, University of California-Berkeley Berkeley CA 94720 USA.,Departments of Nutritional Science and Toxicology, Cell and Molecular Biology, The Innovative Genomics Institute, University of California-Berkeley Berkeley CA 94720 USA
| | - Thomas J Maimone
- Department of Chemistry, University of California-Berkeley Berkeley CA 94720 USA .,Novartis-Berkeley Center for Proteomics and Chemistry Technologies, University of California-Berkeley Berkeley CA 94720 USA
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16
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Foglia F, Lyonnard S, Sakai VG, Berrod Q, Zanotti JM, Gebel G, Clancy AJ, McMillan PF. Progress in neutron techniques: towards improved polymer electrolyte membranes for energy devices. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:264005. [PMID: 33906172 DOI: 10.1088/1361-648x/abfc10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 04/27/2021] [Indexed: 06/12/2023]
Abstract
Design and implementation of advanced membrane formulations for selective transport of ions and molecular species are critical for creating the next generations of fuel cells and separation devices. It is necessary to understand the detailed transport mechanisms over time- and length-scales relevant to the device operation, both in laboratory models and in working systems under realistic operational conditions. Neutron scattering techniques including quasi-elastic neutron scattering, reflectivity and imaging are implemented at beamline stations at reactor and spallation source facilities worldwide. With the advent of new and improved instrument design, detector methodology, source characteristics and data analysis protocols, these neutron scattering techniques are emerging as a primary tool for research to design, evaluate and implement advanced membrane technologies for fuel cell and separation devices. Here we describe these techniques and their development and implementation at the ILL reactor source (Institut Laue-Langevin, Grenoble, France) and ISIS Neutron and Muon Spallation source (Harwell Science and Technology Campus, UK) as examples. We also mention similar developments under way at other facilities worldwide, and describe approaches such as combining optical with neutron Raman scattering and x-ray absorption with neutron imaging and tomography, and carrying out such experiments in specialised fuel cells designed to mimic as closely possible actualoperandoconditions. These experiments and research projects will play a key role in enabling and testing new membrane formulations for efficient and sustainable energy production/conversion and separations technologies.
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Affiliation(s)
- Fabrizia Foglia
- Department of Chemistry, Christopher Ingold Laboratory, University College London, 20 Gordon St., London WC1H 0AJ, United Kingdom
| | - Sandrine Lyonnard
- University Grenoble Alpes, CNRS, CEA, IRIG-SyMMES, 38000 Grenoble, France
| | - Victoria García Sakai
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Chilton OX11 0QX, United Kingdom
| | - Quentin Berrod
- University Grenoble Alpes, CNRS, CEA, IRIG-SyMMES, 38000 Grenoble, France
| | - Jean-Marc Zanotti
- Laboratoire Léon Brillouin (CEA-CNRS), Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France
| | - Gérard Gebel
- University Grenoble Alpes, CEA LITEN, 38000 Grenoble, France
| | - Adam J Clancy
- Department of Chemistry, Christopher Ingold Laboratory, University College London, 20 Gordon St., London WC1H 0AJ, United Kingdom
| | - Paul F McMillan
- Department of Chemistry, Christopher Ingold Laboratory, University College London, 20 Gordon St., London WC1H 0AJ, United Kingdom
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17
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Wang X, Phang Y, Feng J, Liu S, Zhang H, Fu W, Zhou H, Xu G, Xu H, Zheng C. Stereodivergent Strategy in Structural Determination: Asymmetric Total Synthesis of Garcinol, Cambogin, and Related Analogues. Org Lett 2021; 23:4203-4208. [PMID: 34029109 DOI: 10.1021/acs.orglett.1c01139] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The asymmetric total synthesis of five biologically significant polycyclic polyprenylated acylphloroglucinols (PPAPs), including garcinol and cambogin, was achieved through a highly diastereoselective and stereodivergent strategy. Along the way, an efficient cascade Dieckmann cyclization was employed to construct the bicyclo[3.3.1]nonane core in one step. The synthesis provided a general approach toward the chiral endo-type B PPAPs and their C-30 diastereomers in a single sequence, which resolved the challenges of the absolute configuration determination/structural revision of PPAPs bearing exocyclic stereocenters.
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Affiliation(s)
- Xueying Wang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Yeelin Phang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Jiling Feng
- Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Song Liu
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Hong Zhang
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Wenwei Fu
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Hua Zhou
- Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Gang Xu
- State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
| | - Hongxi Xu
- Shuguang Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Changwu Zheng
- School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.,Key Laboratory of Synthetic Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China
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18
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Shen X, Thach DQ, Ting CP, Maimone TJ. Annulative Methods in the Synthesis of Complex Meroterpene Natural Products. Acc Chem Res 2021; 54:583-594. [PMID: 33448794 DOI: 10.1021/acs.accounts.0c00781] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
From the venerable Robinson annulation to the irreplaceable Diels-Alder cycloaddition, annulation reactions have fueled the progression of the field of natural product synthesis throughout the past century. In broader terms, the ability to form a cyclic molecule directly from two or more simpler fragments has transformed virtually every aspect of the chemical sciences from the synthesis of organic materials to bioconjugation chemistry and drug discovery. In this Account, we describe the evolution of our meroterpene synthetic program over the past five years, enabled largely by the development of a tailored anionic annulation process for the synthesis of hydroxylated 1,3-cyclohexanediones from lithium enolates and the reactive β-lactone-containing feedstock chemical diketene.First, we provide details on short total syntheses of the prototypical polycyclic polyprenylated acylphloroglucinol (PPAP) natural products hyperforin and garsubellin A, which possess complex bicyclo[3.3.1]nonane architectures. Notably, these molecules have served as compelling synthetic targets for several decades and induce a number of biological effects of relevance to neuroscience and medicine. By merging our diketene annulation process with a hypervalent iodine-mediated oxidative ring expansion, bicyclo[3.3.1]nonane architectures can be easily prepared from simple 5,6-fused bicyclic diketones in only two chemical operations. Leveraging these two key chemical reactions in combination with various other stereoselective transformations allowed for these biologically active targets to be prepared in racemic form in only 10 steps.Next, we extend this strategy to the synthesis of complex fungal-derived meroterpenes generated biosynthetically from the coupling of 3,5-dimethylorsellinic acid (DMOA) and farnesyl pyrophosphate. A Ti(III)-mediated radical cyclization of a terminal epoxide was used to rapidly prepare a 6,6,5-fused tricyclic ketone which served as an input for our annulation/rearrangement process, ultimately enabling a total synthesis of protoaustinoid A, an important biosynthetic intermediate in DMOA-derived meroterpene synthesis, and its oxidation product berkeleyone A. Through a radical-based, abiotic rearrangement process, the bicyclo[3.3.1]nonane cores of these natural products could again be isomerized, resulting in the 6,5-fused ring systems of the andrastin family and ultimately delivering a total synthesis of andrastin D and preterrenoid. Notably, these isomerization transformations proved challenging when employing classic, acid-induced conditions for carbocation generation, thus highlighting the power of radical biomimicry in total synthesis. Finally, further oxidation and rearrangement allowed for access to terrenoid and the lactone-containing metabolite terretonin L.Overall, the merger of annulative diketene methodology with an oxidative rearrangement transformation has proven to be a broadly applicable strategy to synthesize bicyclo[3.3.1]nonane-containing natural products, a class of small molecules with over 1000 known members.
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Affiliation(s)
- Xingyu Shen
- Department of Chemistry, University of California−Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Danny Q. Thach
- Department of Chemistry, University of California−Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
| | - Chi P. Ting
- Department of Chemistry, University of California−Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
- Department of Chemistry, Edison-Lecks Laboratory, Brandeis University, 415 South Street, Waltham, Massachusetts 02453, United States
| | - Thomas J. Maimone
- Department of Chemistry, University of California−Berkeley, 826 Latimer Hall, Berkeley, California 94720, United States
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19
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Boyce JH, Reisman BJ, Bachmann BO, Porco JA. Synthesis and Multiplexed Activity Profiling of Synthetic Acylphloroglucinol Scaffolds. Angew Chem Int Ed Engl 2021; 60:1263-1272. [PMID: 32965753 PMCID: PMC7855714 DOI: 10.1002/anie.202010338] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Indexed: 12/20/2022]
Abstract
Reported here are novel formic-acid-mediated rearrangements of dearomatized acylphloroglucinols to access a structurally diverse group of synthetic acylphloroglucinol scaffolds (SASs). Density-functional theory (DFT) optimized orbital and stereochemical analyses shed light on the mechanism of these rearrangements. Products were evaluated by multiplexed activity profiling (MAP), an unbiased platform which assays multiple biological readouts simultaneously at single-cell resolution for markers of cell signaling, and can aid in distinguishing genuine activity from assay interference. MAP identified a number of SASs that suppressed pS6 (Ser235/236), a marker for activation of the mTOR and ERK signaling pathways. These results illustrate how biomimetic synthesis and multiplexed activity profiling can reveal the pharmacological potential of novel chemotypes by diversity-oriented synthesis.
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Affiliation(s)
- Jonathan H Boyce
- Department of Chemistry and Center for Molecular Discovery (BU-CMD), Boston University, 590 Commonwealth Avenue, Boston, MA, 02215, USA
- Current Address: Department of Pharmaceutical Chemistry, University of California, San Francisco, 555 Mission Bay Blvd S., San Francisco, CA, 94158, USA
| | - Benjamin J Reisman
- Vanderbilt University, Chemistry Department, 7330 Stevenson Center, Nashville, TN, 37235, USA
| | - Brian O Bachmann
- Vanderbilt University, Chemistry Department, 7330 Stevenson Center, Nashville, TN, 37235, USA
| | - John A Porco
- Department of Chemistry and Center for Molecular Discovery (BU-CMD), Boston University, 590 Commonwealth Avenue, Boston, MA, 02215, USA
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20
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Wang L, Wang X, Zhang G, Fu W, Zhang H, Zhou H, Xu H, Zheng C. Strategies towards endo-type B polycyclic polyprenylated acylphloroglucinols: total synthesis of regio-hyperibone L and (+)- epi-clusianone. Org Chem Front 2021. [DOI: 10.1039/d1qo00282a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The first and general method for the total synthesis of regio-hyperibone L and (+)-epi-clusianone via domino Dieckmann cyclization was developed.
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Affiliation(s)
- Liping Wang
- School of Pharmacy
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Xueying Wang
- School of Pharmacy
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Guocai Zhang
- School of Pharmacy
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Wenwei Fu
- School of Pharmacy
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Hong Zhang
- School of Pharmacy
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Hua Zhou
- Shuguang Hospital
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Hongxi Xu
- Shuguang Hospital
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
| | - Changwu Zheng
- School of Pharmacy
- Shanghai University of Traditional Chinese Medicine
- Shanghai 201203
- China
- Key Laboratory of Synthetic Chemistry of Natural Substances
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21
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Boyce JH, Reisman BJ, Bachmann BO, Porco JA. Synthesis and Multiplexed Activity Profiling of Synthetic Acylphloroglucinol Scaffolds. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202010338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jonathan H. Boyce
- Department of Chemistry and Center for Molecular Discovery (BU-CMD) Boston University 590 Commonwealth Avenue Boston MA 02215 USA
- Current Address: Department of Pharmaceutical Chemistry University of California, San Francisco 555 Mission Bay Blvd S. San Francisco CA 94158 USA
| | - Benjamin J. Reisman
- Vanderbilt University Chemistry Department 7330 Stevenson Center Nashville TN 37235 USA
| | - Brian O. Bachmann
- Vanderbilt University Chemistry Department 7330 Stevenson Center Nashville TN 37235 USA
| | - John A. Porco
- Department of Chemistry and Center for Molecular Discovery (BU-CMD) Boston University 590 Commonwealth Avenue Boston MA 02215 USA
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22
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Fukuyama Y, Kubo M, Harada K. The search for, and chemistry and mechanism of, neurotrophic natural products. J Nat Med 2020; 74:648-671. [PMID: 32643028 PMCID: PMC7456418 DOI: 10.1007/s11418-020-01431-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2020] [Accepted: 06/28/2020] [Indexed: 12/13/2022]
Abstract
Abstract Neurotrophic factors, now termed neurotrophins, which belong to a class of polypeptidyl agents, have been shown to potentially be beneficial for the treatment of neurodegenerative diseases such as Alzheimer’s disease, because endogenous neurotrophic factors (NGF, BDNF, NT3, NT4) have been recognized to play critical roles in the promotion of neurogenesis, differentiation, and neuroprotection throughout the development of the central nervous system. However, high-molecular weight proteins are unable to cross the blood–brain barrier and are easily decomposed by peptidase under physiological conditions. To address this issue, small molecules that can mimic the functions of neurotrophic factors would be promising alternatives for the treatment of neurodegenerative disease. We have continued to search for natural products having typical neurotrophic properties, which can cause neurogenesis, enhance neurite outgrowth, and protect neuronal death using three cellular systems (PC12, rat cortical neurons, and MEB5 cells). In this review, we summarize the neurotrophic activities and synthesis of dimeric isocuparane-type sesquiterpenes from the liverwort, Mastigophora diclados, the mechanism of neurotrophic neolignans, magnolol, honokiol and their sesquiterpene derivatives, and introduce unique neurotrophin-mimic natural products, including seco-prezizaane-type sesquiterpenes from the Illicium species, vibsane-type diterpenes from Viburnum awabuki, and miscellaneous natural products with neurotrophic effects discovered by us. Graphic abstract ![]()
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Affiliation(s)
- Yoshiyasu Fukuyama
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, 770-8514, Japan.
| | - Miwa Kubo
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, 770-8514, Japan
| | - Kenichi Harada
- Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Tokushima, 770-8514, Japan
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23
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Harmange Magnani CS, Thach DQ, Haelsig KT, Maimone TJ. Syntheses of Complex Terpenes from Simple Polyprenyl Precursors. Acc Chem Res 2020; 53:949-961. [PMID: 32202757 DOI: 10.1021/acs.accounts.0c00055] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
From structure elucidation and biogenesis to synthetic methodology and total synthesis, terpene natural products have profoundly influenced the development of organic chemistry. Moreover, their myriad functional attributes range from fragrance to pharmaceuticals and have had great societal impact. Ruzicka's formulation of the "biogenetic isoprene rule," a Nobel Prize winning discovery now over 80 years old, allowed for identification of higher order terpene (aka "isoprenoid") structures from simple five-carbon isoprene fragments. Notably, the isoprene rule still holds pedagogical value to students of organic chemistry today. Our laboratory has completed syntheses of over two dozen terpene and meroterpene structures to date, and the isoprene rule has served as a key pattern recognition tool for our synthetic planning purposes. At the strategic level, great opportunity exists in finding unique and synthetically simplifying ways to connect the formal C5 isoprene fragments embedded in terpenes. Biomimetic cationic polyene cyclizations represent the earliest incarnation of this idea, which has facilitated expedient routes to certain terpene polycycle classes. Nonetheless, a large swath of terpene chemical space remains inaccessible using this approach.In this Account, we describe strategic insight into our endeavors in terpene synthesis published over the last five years. We show how biosynthetic understanding, combined with a desire to utilize abundant and inexpensive [C5]n building blocks, has led to efficient, abiotic syntheses of multiple complex terpenes with disparate ring systems. Informed by nature, but unconstrained by its processes, our synthetic assembly exploits chemical reactivity across diverse reaction types-including radical, anionic, pericyclic, and metal-mediated transformations.First, we detail an eight-step synthesis of the cembrane diterpene chatancin from dihydrofarnesal using a bioinspired-but not -mimetic-cycloaddition. Next, we describe the assembly of the antimalarial cardamom peroxide using a polyoxygenation cascade to fuse multiple units of molecular oxygen onto a dimeric skeleton. This three-to-four-step synthesis arises from (-)-myrtenal, an inexpensive pinene oxidation product. We then show how a radical cyclization cascade can forge the hallmark cyclooctane ring system of the complex sesterterpene 6-epi-ophiobolin N from two simple polyprenyl precursors, (-)-linalool and farnesol. To access the related, more complex metabolite 6-epi-ophiobolin A, we exploited the plasticity of our synthetic route and found that use of geraniol (C10) rather than farnesol (C15) gave us the flexibility needed to address the additional oxidation found in this congener. Following this work, we describe two strategies to access several guaianolide sesquiterpenes. Retrosynthetic disconnection to monoterpenes, carvone or (-)-linalool, coupled with a powerful allylation strategy allowed us to address guaianolides with disparate stereochemical motifs. Finally, we examine a semisynthetic approach to the illicium sesquiterpenes from the abundant 15-carbon feedstock terpene (+)-cedrol using an abiotic ring shift and multiple C-H oxidation reactions inspired by a postulated biosynthesis of this natural product class.
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Affiliation(s)
| | - Danny Q. Thach
- Department of Chemistry, University of California—Berkeley, Berkeley, California 94720, United States
| | - Karl T. Haelsig
- Department of Chemistry, University of California—Berkeley, Berkeley, California 94720, United States
| | - Thomas J. Maimone
- Department of Chemistry, University of California—Berkeley, Berkeley, California 94720, United States
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