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Yan M, Ding X, Zhao L, Lü X, He HY, Fan S, Yang Z. Mechanistic Insights into the Nonenzymatic Biosynthesis of Artemisinin and Related Natural Products: A Quantum Chemical Study. J Chem Inf Model 2025; 65:4090-4106. [PMID: 40223241 DOI: 10.1021/acs.jcim.5c00034] [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: 04/15/2025]
Abstract
Artemisinin (Qinghaosu) is an important antimalaria natural medicine containing a unique endoperoxide bridge in its sesquiterpene structure. The last phase of artemisinin biosynthesis involves conversion of dihydroartemisinic acid (DHAA) to artemisinin, and the detailed mechanism remains unclear. Based on previous experimental studies, this work investigated the possible mechanism of nonenzymatic conversion of DHAA to artemisinin and identified the most chemically plausible reaction pathway using quantum chemical computations. The rate-determining step in this pathway is acid-catalyzed oxidation of the enol by triplet O2, with an overall free energy barrier of 22.5 kcal/mol. This pathway also gives byproducts dihydroarteannuin B and dihydro-epi-arteannuin B. In addition, the nonenzymatic formation mechanism of 21 natural products from Artemisia annua was discussed in this work. These results provide fundamental knowledge of the biosynthetic processes of artemisinin and related natural products, as well as important references for semisynthesis and structural modification studies of artemisinin.
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Affiliation(s)
- Maocai Yan
- School of Pharmacy, Jining Medical University, Rizhao 276800, Shandong, China
| | - Xinfa Ding
- School of Pharmacy, Jining Medical University, Rizhao 276800, Shandong, China
| | - Likun Zhao
- School of Pharmacy, Jining Medical University, Rizhao 276800, Shandong, China
| | - Xudong Lü
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing100050, China
| | - Hai-Yan He
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing100050, China
| | - Shuai Fan
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing100050, China
| | - Zhaoyong Yang
- Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing100050, China
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2
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Nakano M, Hiasa K, Sato-Shimizu S, Sato H. Seven-Membered Ring Formation in Triterpene Biosynthesis: A Key Cyclopropane Rearrangement in Ilelic Acid Biosynthesis. J Org Chem 2025; 90:2907-2914. [PMID: 39960431 DOI: 10.1021/acs.joc.4c02541] [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: 03/01/2025]
Abstract
Triterpenes represent a crucial class of natural compounds with diverse biological activities and structural complexity. Among the various skeletal modifications in triterpene biosynthesis, the formation of seven-membered rings through ring expansion reactions significantly contributes to their structural diversity and, consequently, their functional versatility. This study elucidates the detailed reaction mechanism of a key seven-membered ring formation via cyclopropane rearrangement in the biosynthesis of ilelic acid. Using density functional theory (DFT) calculations, we thoroughly investigated the biosynthetic pathway of ilelic acid, focusing on the critical ring expansion step. Our computational analysis reveals that the seven-membered ring formation proceeds through a cationic mechanism rather than a radical-mediated process. Notably, we found that the inherent instability of the secondary carbocation intermediate drives a concerted reaction pathway, avoiding the formation of high-energy intermediates. This mechanistic understanding not only sheds light on the biosynthesis of ilelic acid but also offers broader implications for comprehending similar transformations in other triterpene biosynthetic pathways. Our findings contribute to the fundamental understanding of triterpene skeletal diversity and pave the way for potential biomimetic approaches in the synthesis of complex seven-membered ring-containing terpenes. Furthermore, this work underscores the power of computational methods in unraveling intricate biosynthetic mechanisms.
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Affiliation(s)
- Moe Nakano
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
| | - Kazuma Hiasa
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
| | - Satoko Sato-Shimizu
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
| | - Hajime Sato
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
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Watanabe Y, Hashishin T, Sato H, Matsuyama T, Nakajima M, Haruta JI, Uchiyama M. DFT Study on Retigerane-Type Sesterterpenoid Biosynthesis: Initial Conformation of GFPP Regulates Biosynthetic Pathway, Ring-Construction Order and Stereochemistry. JACS AU 2024; 4:3484-3491. [PMID: 39328767 PMCID: PMC11423320 DOI: 10.1021/jacsau.4c00313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 06/29/2024] [Accepted: 07/01/2024] [Indexed: 09/28/2024]
Abstract
Retigerane-type sesterterpenoids, which feature a unique 5/6/5/5/5 fused pentacyclic structure with an angular-type triquinane moiety, are biosynthesized via successive carbocation-mediated reactions triggered by terpene cyclases. However, the precise biosynthetic pathways/mechanisms, wherein steric inversion of the carbon skeleton occurs at least once, remain elusive. Two plausible reaction pathways have been proposed, which differ in the order of ring cyclization: A → B/C → D/E-ring(s) (Route 1) and A → E → B → C/D-ring(s) (Route 2). Since the reaction intermediates of these complicated domino-type reaction sequences are experimentally inaccessible, we employed comprehensive density functional theory (DFT) calculations to evaluate these routes. The results indicate that retigeranin biosynthesis proceeds via Route 2 involving a multistep carbocation cascade, in which the order of ring cyclization (A → E → B → C/D) is the key to constructing the angular 5/5/5 triquinane structure with the correct stereochemistry at C3. The result also suggests that slight differences in the initial conformation have a significant effect on the order of cyclization and steric inversion. The computed pathway/mechanism also provides a rational basis for the formation of various related terpenes/terpenoids.
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Affiliation(s)
- Yuichiro Watanabe
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Graduate
School of Pharmaceutical Sciences, Osaka
University, Suita-shi, Osaka 565-0871, Japan
| | - Takahiro Hashishin
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Hajime Sato
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Interdisciplinary
Graduate School of Medicine and Engineering, University of Yamanashi, Kofu, Yamanashi 400-8510, Japan
| | - Taro Matsuyama
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Masaya Nakajima
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Jun-ichi Haruta
- Graduate
School of Pharmaceutical Sciences, Osaka
University, Suita-shi, Osaka 565-0871, Japan
| | - Masanobu Uchiyama
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Research
Initiative for Supra-Materials (RISM), Shinshu
University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
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Abstract
Covering: January to the end of December 2022This review covers the literature published in 2022 for marine natural products (MNPs), with 645 citations (633 for the period January to December 2022) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1417 in 384 papers for 2022), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of NP structure class diversity in relation to biota source and biome is discussed.
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Affiliation(s)
- Anthony R Carroll
- School of Environment and Science, Griffith University, Gold Coast, Australia.
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Australia
| | - Brent R Copp
- School of Chemical Sciences, University of Auckland, Auckland, New Zealand
| | - Tanja Grkovic
- Natural Products Branch, Developmental Therapeutics Program, Division of Cancer Treatment and Diagnosis, and Molecular Targets Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Robert A Keyzers
- Centre for Biodiscovery, and School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand
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Sato H. Theoretical Study of Natural Product Biosynthesis Using Computational Chemistry. Chem Pharm Bull (Tokyo) 2024; 72:524-528. [PMID: 38825452 DOI: 10.1248/cpb.c24-00082] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
The biosynthetic pathways of natural products are complicated, and it is difficult to fully elucidate their details using experimental chemistry alone. In recent years, efforts have been made to elucidate the biosynthetic reaction mechanisms by combining computational and experimental methods. In this review, we will discuss the biosynthetic studies using computational chemistry for various terpene compounds such as cyclooctatin, sesterfisherol, quiannulatene, trichobrasilenol, asperterpenol, preasperterpenoid, spiroviolene, and mangicol.
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Affiliation(s)
- Hajime Sato
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi
- PRESTO, Japan Science and Technology Agency
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Gu B, Goldfuss B, Schnakenburg G, Dickschat JS. Subrutilane-A Hexacyclic Sesterterpene from Streptomyces subrutilus. Angew Chem Int Ed Engl 2023; 62:e202313789. [PMID: 37846897 DOI: 10.1002/anie.202313789] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 10/16/2023] [Accepted: 10/17/2023] [Indexed: 10/18/2023]
Abstract
Mining of a terpene synthase from Streptomyces subrutilus resulted in the identification of the hexacyclic sesterterpene subrutilane, besides eight pentacyclic side products. Subrutilane represents the first case of a saturated sesterterpene hydrocarbon. Its structure, including the absolute configuration, was unambiguously determined through X-ray crystallographic analysis and stereoselective deuteration. The cyclisation mechanism to subrutilane and its side products was investigated in all detail by isotopic labelling experiments and DFT calculations. The subrutilane synthase (SrS) also converted (2Z)-GFPP into one major product. Additional compounds were obtained from the substrate analogues (7R)-6,7-dihydro-GFPP and (2Z,7R)-6,7-dihydro-GFPP with blocked reactivity at the C6-C7 bond. Interestingly, the early steps of the cyclisation cascade with (2Z)-GFPP and the saturated substrate analogues were analogous to those of GFPP, but then deviations from the natural cyclisation mode occur.
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Affiliation(s)
- Binbin Gu
- Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Bernd Goldfuss
- Department for Chemistry, University of Cologne, Greinstraße 4, 50939, Cologne, Germany
| | - Gregor Schnakenburg
- Institute for Inorganic Chemistry, University of Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
| | - Jeroen S Dickschat
- Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Straße 1, 53121, Bonn, Germany
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Matsuyama T, Togashi K, Nakano M, Sato H, Uchiyama M. Revision of the Peniroquesine Biosynthetic Pathway by Retro-Biosynthetic Theoretical Analysis: Ring Strain Controls the Unique Carbocation Rearrangement Cascade. JACS AU 2023; 3:1596-1603. [PMID: 37388688 PMCID: PMC10301677 DOI: 10.1021/jacsau.3c00039] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 04/22/2023] [Accepted: 04/24/2023] [Indexed: 07/01/2023]
Abstract
Peniroquesine, a sesterterpenoid featuring a unique 5/6/5/6/5 fused pentacyclic ring system, has been known for a long time, but its biosynthetic pathway/mechanism remains elusive. Based on isotopic labeling experiments, a plausible biosynthetic pathway to peniroquesines A-C and their derivatives was recently proposed, in which the characteristic peniroquesine-type 5/6/5/6/5 pentacyclic skeleton is synthesized from geranyl-farnesyl pyrophosphate (GFPP) via a complex concerted A/B/C-ring formation, repeated reverse-Wagner-Meerwein alkyl shifts, three successive secondary (2°) carbocation intermediates, and a highly distorted trans-fused bicyclo[4.2.1]nonane intermediate. However, our density functional theory calculations do not support this mechanism. By applying a retro-biosynthetic theoretical analysis strategy, we were able to find a preferred pathway for peniroquesine biosynthesis, involving a multistep carbocation cascade including triple skeletal rearrangements, trans-cis isomerization, and 1,3-H shift. This pathway/mechanism is in good agreement with all of the reported isotope-labeling results.
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Affiliation(s)
- Taro Matsuyama
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Ko Togashi
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Moe Nakano
- Interdisciplinary
Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
| | - Hajime Sato
- Interdisciplinary
Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
| | - Masanobu Uchiyama
- Graduate
School of Pharmaceutical Sciences, The University
of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Research
Initiative for Supra-Materials (RISM), Shinshu
University, 3-15-1 Tokida, Ueda, Nagano 386-8567, Japan
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8
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Larmore SP, Champagne PA. Cyclopropylcarbinyl-to-Homoallyl Carbocation Equilibria Influence the Stereospecificity in the Nucleophilic Substitution of Cyclopropylcarbinols. J Org Chem 2023. [PMID: 37141426 DOI: 10.1021/acs.joc.3c00257] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The synthesis of quaternary homoallylic halides and trichloroacetates from cyclopropylcarbinols, as reported by Marek (J. Am. Chem. Soc. 2020, 142, 5543-5548), is one of the few reported examples of stereospecific nucleophilic substitution involving chiral bridged carbocations. However, for the phenyl-substituted substrates, poor specificity is observed and mixtures of diastereomers are obtained. To understand the nature of the intermediates involved and explain the loss of specificity for certain substrates, we have performed a computational investigation of the reaction mechanism using ωB97X-D optimizations and DLPNO-CCSD(T) energy refinements. Our results indicate that cyclopropylcarbinyl cations are stable intermediates in this reaction, while bicyclobutonium structures are high-energy transition structures that are not involved. Instead, multiple rearrangement pathways of cyclopropylcarbinyl cations were located, including ring openings to homoallylic cations. The activation barriers required to reach such structures are correlated to the nature of the substituents; while direct nucleophilic attack on the chiral cyclopropylcarbinyl cations is kinetically favored for most systems, the rearrangements become competitive with nucleophilic attack for the phenyl-substituted systems, leading to a loss of specificity through rearranged carbocation intermediates. As such, stereospecific reactions of chiral cyclopropylcarbinyl cations depend on the energies required to access their corresponding homoallylic structures, from which selectivity is not guaranteed.
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Affiliation(s)
- Sean P Larmore
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
| | - Pier Alexandre Champagne
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, New Jersey 07102, United States
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9
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Sato H, Nakano M. Concertedness and Activation Energy Control by Distal Methyl Group during Ring Contraction/Expansion in Scalarane-Type Sesterterpenoid Biosynthesis. Chemistry 2023; 29:e202203076. [PMID: 36411271 DOI: 10.1002/chem.202203076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Revised: 11/17/2022] [Accepted: 11/21/2022] [Indexed: 11/23/2022]
Abstract
Salmahyritisol A, similan A, and hippospongide A, which are scalarane-type sesterterpenoids, feature 6/6/5/7/5 pentacyclic skeletons. Although their biosyntheses have been previously proposed to involve a unique skeletal rearrangement reaction, the detailed reaction mechanism remains unclear as none of the corresponding biosynthetic enzymes for this reaction have been reported. Herein, this skeletal rearrangement reaction was investigated using computational techniques, which revealed the following four key features: (i) the distal 24-Me substituent controls both the concertedness and activation energy of this transformation, (ii) enzymes are not responsible for the observed regioselectivity of C12-C20 bond formation, (iii) stereoselectivity is enzyme-regulated, and (iv) protonation is a key step in this skeletal rearrangement process. These new findings provide insight into the C-ring-contraction and D-ring-expansion mechanisms in scalarane-type sesterterpenoid biosyntheses.
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Affiliation(s)
- Hajime Sato
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Moe Nakano
- Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, 4-4-37 Takeda, Kofu, Yamanashi 400-8510, Japan
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Abstract
Herein, we report the enantioselective total synthesis of dysiherbols A, C, and D, a unique group of 6/6/5/6/6 pentacyclic quinone/hydroquinone sesquiterpenes, featuring a photo-induced quinone-alkene [2 + 2] cycloaddition and a tandem [1,2]-anionic rearrangement/cyclopropane fragmentation as key elements. Based on our total synthesis, the originally proposed structures of dysiherbols C and D have been revised. Detailed computational studies were carried out to gain deep insight into the unprecedented [1,2]-anionic rearrangement, which revealed that the transformation, albeit a symmetry-forbidden process, proceeded through a concerted manner owing to the release of high ring-strain energy and the evolution of local aromaticity in the transition state. Taking all, the present work offers a mechanistically interesting and synthetically useful approach to accessing dysiherbols and related congeners.
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Affiliation(s)
- Shengkun Hu
- Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Yefeng Tang
- School of Pharmaceutical Sciences, MOE Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology, Tsinghua University, Beijing 100084, China
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