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Ferenczi E, Keglevich P, Tayeb BA, Minorics R, Papp D, Schlosser G, Zupkó I, Hazai L, Csámpai A. Synthesis and Antiproliferative Effect of New Alkyne-Tethered Vindoline Hybrids Containing Pharmacophoric Fragments. Int J Mol Sci 2024; 25:7428. [PMID: 39000534 PMCID: PMC11242353 DOI: 10.3390/ijms25137428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2024] [Revised: 06/26/2024] [Accepted: 07/04/2024] [Indexed: 07/16/2024] Open
Abstract
In the frame of our diversity-oriented research on multitarget small molecule anticancer agents, utilizing convergent synthetic sequences terminated by Sonogashira coupling reactions, a preliminary selection of representative alkyne-tethered vindoline hybrids was synthesized. The novel hybrids with additional pharmacophoric fragments of well-documented anticancer agents, including FDA-approved tyrosine-kinase inhibitors (imatinib and erlotinib) or ferrocene or chalcone units, were evaluated for their antiproliferative activity on malignant cell lines MDA-MB-231 (triple negative breast cancer), A2780 (ovarian cancer), HeLa (human cervical cancer), and SH-SY5Y (neuroblastoma) as well as on human embryonal lung fibroblast cell line MRC-5, which served as a reference non-malignant cell line for the assessment of the therapeutic window of the tested hybrids. The biological assays identified a trimethoxyphenyl-containing chalcone-vindoline hybrid (36) as a promising lead compound exhibiting submicromolar activity on A2780 cells with a marked therapeutic window.
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Affiliation(s)
- Etelka Ferenczi
- Department of Organic Chemistry, Eötvös Loránd University (ELTE), Pázmány P. sétány 1/A, H-1117 Budapest, Hungary;
- Hevesy György PhD School of Chemistry, Pázmány P. sétány 1/A, H-1117 Budapest, Hungary;
| | - Péter Keglevich
- Department of Organic Chemistry and Technology, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary; (P.K.); (L.H.)
| | - Bizhar Ahmed Tayeb
- Institute of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.A.T.); (R.M.); (I.Z.)
| | - Renáta Minorics
- Institute of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.A.T.); (R.M.); (I.Z.)
| | - Dávid Papp
- Hevesy György PhD School of Chemistry, Pázmány P. sétány 1/A, H-1117 Budapest, Hungary;
- MTA-ELTE Lendület Ion Mobility Mass Spectrometry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary;
| | - Gitta Schlosser
- MTA-ELTE Lendület Ion Mobility Mass Spectrometry Research Group, Institute of Chemistry, ELTE Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary;
| | - István Zupkó
- Institute of Pharmacodynamics and Biopharmacy, University of Szeged, Eötvös u. 6, H-6720 Szeged, Hungary; (B.A.T.); (R.M.); (I.Z.)
| | - László Hazai
- Department of Organic Chemistry and Technology, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary; (P.K.); (L.H.)
| | - Antal Csámpai
- Department of Organic Chemistry, Eötvös Loránd University (ELTE), Pázmány P. sétány 1/A, H-1117 Budapest, Hungary;
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2
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Asia, Sammer Y, Vendier L, Massiot G. Structure and Synthesis of Vindolicine and Derivatives. Chem Biodivers 2024; 21:e202301928. [PMID: 38409504 DOI: 10.1002/cbdv.202301928] [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] [Received: 12/06/2023] [Accepted: 01/15/2024] [Indexed: 02/28/2024]
Abstract
This article describes the reaction of vindoline with formaldehyde and trimethyl orthoformate to prepare vindolicine, tris-vindolicinyl methane and higher molecular weight homologues. The synthesis of 10-formyl vindoline as an intermediate allowed further exploration of its chemistry, in particular the reaction with acetone which yielded a symmetrical dimer, which was further reacted with vindoline to give molecules containing three and four vindoline units. These molecules were characterized by NMR and for some of them (vindolicine, 10-formyl vindoline, 10-(1'-(but-1'-en-3'-one))-vindoline) by X-ray crystallography. Depending on the substitution and on the absence of axes of symmetry, the NMR spectra displayed non-equivalent spin systems for the vindoline moieties. The dimer formed from the double condensation of 10-formyl vindoline with acetone showed cytotoxic activity in the micromolar range.
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Affiliation(s)
- Asia
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Sindh, Pakistan
| | - Yousuf Sammer
- H. E. J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, 75270, Sindh, Pakistan
| | - Laure Vendier
- UPR CNRS 8241, Laboratoire de Chimie de Coordination, 205 Route de Narbonne, 31077, Toulouse Cedex 04, France
| | - Georges Massiot
- Institut de Chimie Moléculaire de Reims, UMR CNRS 7312, Université Reims-Champagne-Ardenne, UFR Sciences, BP 1039, CEDEX 2, 51687, Reims, France
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3
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Dai Y, Qian M, Li Y. Structural Modification Endows Small-Molecular SN38 Derivatives with Multifaceted Functions. Molecules 2023; 28:4931. [PMID: 37446591 DOI: 10.3390/molecules28134931] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/21/2023] [Accepted: 06/21/2023] [Indexed: 07/15/2023] Open
Abstract
As a camptothecin derivative, 7-ethyl-10-hydroxycamptothecin (SN38) combats cancer by inhibiting topoisomerase I. SN38 is one of the most active compounds among camptothecin derivatives. In addition, SN38 is also a theranostic reagent due to its intrinsic fluorescence. However, the poor water solubility, high systemic toxicity and limited action against drug resistance and metastasis of tumor cells of SN38 indicates that there is great space for the structural modification of SN38. From the perspective of chemical modification, this paper summarizes the progress of SN38 in improving solubility, increasing activity, reducing toxicity and possessing multifunction and analyzes the strategies of structure modification to provide a reference for drug development based on SN38.
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Affiliation(s)
- Yi Dai
- College of Pharmaceutical Science, Anhui Xinhua University, Hefei 230088, China
- Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Meng Qian
- College of Pharmaceutical Science, Anhui Xinhua University, Hefei 230088, China
| | - Yan Li
- College of Pharmaceutical Science, Anhui Xinhua University, Hefei 230088, China
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4
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Synthesis and In Vitro Anticancer Evaluation of Flavone-1,2,3-Triazole Hybrids. MOLECULES (BASEL, SWITZERLAND) 2023; 28:molecules28020626. [PMID: 36677683 PMCID: PMC9860848 DOI: 10.3390/molecules28020626] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/04/2023] [Accepted: 01/04/2023] [Indexed: 01/11/2023]
Abstract
Hybrid compounds of flavones, namely chrysin and kaempferol, and substituted 1,2,3-triazole derivatives, were synthesized by click reaction of the intermediate O-propargyl derivatives. 4-Fluoro- and 4-nitrobenzyl-1,2,3-triazole-containing hybrid molecules were prepared. The mono- and bis-coupled hybrids were investigated on 60 cell lines of 9 common cancer types (NCI60) in vitro as antitumor agents. Some of them proved to have a significant antiproliferative effect.
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Matadamas‐Martínez F, Yépez‐Mulia L, Pérez‐Koldenkova V, Cortés‐Benítez F, Leyte‐Lugo M, Palacios‐Espinosa JF, Rodríguez‐Villar K, Soria‐Arteche O, Pérez‐Villanueva J. Synthesis and Antitumor Activity of 2,3‐Diphenyl‐2
H
‐indazole Derivatives as Potent Antitubulin Agents. ChemistrySelect 2022. [DOI: 10.1002/slct.202202056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Félix Matadamas‐Martínez
- Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
| | - Lilián Yépez‐Mulia
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias Unidad Médica de Alta Especialidad-Hospital de Pediatría Centro Médico Nacional Siglo XXI Instituto Mexicano del Seguro Social Mexico City 06720 Mexico
| | - Vadim Pérez‐Koldenkova
- Laboratorio Nacional de Microscopia Avanzada del Centro Médico Nacional Siglo XXI Centro Médico Nacional Siglo XXI Instituto Mexicano del Seguro Social Mexico City 06720 Mexico
| | - Francisco Cortés‐Benítez
- Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
| | - Martha Leyte‐Lugo
- Catedrático CONACYT Comisionado a Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
| | - Juan Francisco Palacios‐Espinosa
- Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
| | - Karen Rodríguez‐Villar
- Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
| | - Olivia Soria‐Arteche
- Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
| | - Jaime Pérez‐Villanueva
- Departamento de Sistemas Biológicos División de Ciencias Biológicas y de la Salud Universidad Autónoma Metropolitana-Xochimilco (UAM−X) Mexico City 04960 Mexico
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6
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Mayer S, Nagy N, Keglevich P, Szigetvári Á, Dékány M, Szántay Junior C, Hazai L. Synthesis of Novel Vindoline-Chrysin Hybrids. Chem Biodivers 2021; 19:e202100725. [PMID: 34874114 DOI: 10.1002/cbdv.202100725] [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: 09/06/2021] [Accepted: 11/15/2021] [Indexed: 11/05/2022]
Abstract
Vinca alkaloids are well-known microtubule targeting agents, which are used against some types of cancer. Vindoline is one of the monomeric Vinca alkaloids which does not have anti-tumor effect, although its derivatives have serious impact on the field of these indole alkaloids. Chrysin is a secondary plant metabolite, which has broad-spectrum biological activity, among others anticancer activity. Chrysin had shown synergic effect with several antiproliferative compounds (e. g., doxorubicin, cisplatin and ciglitazone), therefore, we attempted the synthesis of a novel vindoline-chrysin hybrid molecule. However, in the first case a diphenylamine structure was isolated. The mechanism of the unexpected reaction was studied, and then the originally targeted hybrid was synthesized by a reverse route coupling. A further hybrid was produced using a different site of the molecule. The antitumor activities were determined against 60 human tumor cell lines (NCI60), where the aimed hybrid showed low micromolar GI50 values on most of the cell lines.
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Affiliation(s)
- Szabolcs Mayer
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111, Budapest, Gellért tér 4., Hungary
| | - Nóra Nagy
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111, Budapest, Gellért tér 4., Hungary
| | - Péter Keglevich
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111, Budapest, Gellért tér 4., Hungary
| | - Áron Szigetvári
- Spectroscopic Research Department, Gedeon Richter Plc., H-1475, Budapest 10, P.O. Box 27, Hungary
| | - Miklós Dékány
- Spectroscopic Research Department, Gedeon Richter Plc., H-1475, Budapest 10, P.O. Box 27, Hungary
| | - Csaba Szántay Junior
- Spectroscopic Research Department, Gedeon Richter Plc., H-1475, Budapest 10, P.O. Box 27, Hungary
| | - László Hazai
- Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111, Budapest, Gellért tér 4., Hungary
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Addition of Vindoline to p-Benzoquinone: Regiochemistry, Stereochemistry and Symmetry Considerations. Molecules 2021; 26:molecules26216395. [PMID: 34770804 PMCID: PMC8587549 DOI: 10.3390/molecules26216395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/18/2021] [Accepted: 10/20/2021] [Indexed: 11/17/2022] Open
Abstract
Vindoline and catharanthine are the major alkaloids of Catharanthus roseus and are extracted in large quantities to prepare the pharmaceutically important Vinca type alkaloids vincaleukoblastine, vincristine and navelbine. The higher yield of vindoline relative to catharanthine makes it an attractive substrate for developing new chemistry and adding value to the plant. In this context, we have reacted vindoline with a selection of electrophiles among which benzoquinone. Conditions were developed to optimize the synthesis of a mono-adduct, of five bis-adducts, and of tri-adducts and tetra-adducts, several of these adducts being mixtures of conformational isomers. Copper(II) was added to the reactions to promote reoxidation of the intermediate hydroquinones and simplify the reaction products. The structures were solved by spectroscopic means and by symmetry considerations. Among the bis-isomers, the 2,3-diadduct consists of three unseparable species, two major ones with an axis of symmetry, thus giving a single set of signals and existing as two different species with indistinguishable NMR spectra. The third and minor isomer has no symmetry and therefore exhibits nonequivalence in the signals of the two vindoline moieties. These isomers are designated as syn (minor) and anti (major) and there exists a high energy barrier between them making their interconversion difficult. DFT calculations on simplified model compounds demonstrate that the syn-anti interconversion is not possible at room temperature on the NMR chemical shift time scale. These molecules are not rigid and calculations showed a back-and-forth conrotatory motion of the two vindolines. This “windshield wiper” effect is responsible for the observation of exchange correlations in the NOESY spectra. The same phenomenon is observed with the higher molecular weight adducts, which are also mixtures of rotational isomers. The same lack of rotations between syn and anti isomers is responsible for the formation of four tri-adducts and of seven tetra-adducts. On a biological standpoint, the mono adduct displayed anti-inflammatory properties at the 5 μM level while the di-adducts and tri-adducts showed moderate cytotoxicity against Au565, and HeLa cancer cell lines.
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8
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Zhang RH, Guo HY, Deng H, Li J, Quan ZS. Piperazine skeleton in the structural modification of natural products: a review. J Enzyme Inhib Med Chem 2021; 36:1165-1197. [PMID: 34080510 PMCID: PMC8183565 DOI: 10.1080/14756366.2021.1931861] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Piperazine moiety is a cyclic molecule containing two nitrogen atoms in positions 1 and 4, as well as four carbon atoms. Piperazine is one of the most sought heterocyclics for the development of new drug candidates with a wide range of applications. Over 100 molecules with a broad range of bioactivities, including antitumor, antibacterial, anti-inflammatory, antioxidant, and other activities, were reviewed. This article reviewed investigations regarding piperazine groups for the modification of natural product derivatives in the last decade, highlighting parameters that affect their biological activity.
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Affiliation(s)
- Run-Hui Zhang
- College of Pharmacy, Yanbian University, Yanji, Jilin, 133002, China
| | - Hong-Yan Guo
- College of Pharmacy, Yanbian University, Yanji, Jilin, 133002, China
| | - Hao Deng
- College of Pharmacy, Yanbian University, Yanji, Jilin, 133002, China
| | - Jinzi Li
- Affiliated Hospital of Yanbian University, Yanji, Jilin, China
| | - Zhe-Shan Quan
- College of Pharmacy, Yanbian University, Yanji, Jilin, 133002, China
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9
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Mayer S, Keglevich P, Keglevich A, Hazai L. New Anticancer Vinca Alkaloids in the Last Decade - A Mini-Review. CURR ORG CHEM 2021. [DOI: 10.2174/1385272825666210216123256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The chemistry and pharmacology of the important Vinca alkaloids such as vinblastine
and vincristine used in anticancer therapy are still investigated widely. Several new
derivatives, e.g., vinflunine, vinorelbine, and vindesine, have been synthesized and become
successful medicines in anti-cancer therapy. In 2012, we published a paper that reviewed the
Vinca derivatives. Nevertheless, the interest in the preparation of new modified structures is
not decreasing either in recent years. In this review, the vinblastine-type molecules with several
substituents, e.g., amide, nitrile, hydrazide, substituted side chains, etc. in different positions
of catharanthine and/or vindoline cores are presented. An important part of the review is
the derivatization of the monomer alkaloid vindoline, which possesses no antitumor effect.
Additionally, new hybrid molecules of these alkaloids are also discussed in this mini-review.
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Affiliation(s)
- Szabolcs Mayer
- Department of Organic Chemistry and Technology, University of Technology and Economics, Budapest, Hungary, H-1111 Budapest, Gellert ter 4,Hungary
| | - Péter Keglevich
- Department of Organic Chemistry and Technology, University of Technology and Economics, Budapest, Hungary, H-1111 Budapest, Gellert ter 4,Hungary
| | - András Keglevich
- Department of Organic Chemistry and Technology, University of Technology and Economics, Budapest, Hungary, H-1111 Budapest, Gellert ter 4,Hungary
| | - László Hazai
- Department of Organic Chemistry and Technology, University of Technology and Economics, Budapest, Hungary, H-1111 Budapest, Gellert ter 4,Hungary
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Faustova M, Nikolskaya E, Sokol M, Fomicheva M, Petrov R, Yabbarov N. Metalloporphyrins in Medicine: From History to Recent Trends. ACS APPLIED BIO MATERIALS 2020; 3:8146-8171. [PMID: 35019597 DOI: 10.1021/acsabm.0c00941] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The history of metalloporphyrins dates back more than 200 years ago. Metalloporphyrins are excellent catalysts, capable of forming supramolecular systems, participate in oxygen photosynthesis, transport, and used as contrast agents or superoxide dismutase mimetics. Today, metalloporphyrins represent complexes of conjugated π-electron system and metals from the entire periodic system. However, the effect of these compounds on living systems has not been fully understood, and researchers are exploring the properties of metalloporphyrins thereby extending their further application. This review provides an overview of the variety of metalloporphyrins that are currently used in different medicine fields and how metalloporphyrins became the subject of scientists' interest. Currently, metalloporphyrins utilization has expanded significantly, which gave us an opprotunuty to summarize recent progress in metalloporphyrins derivatives and prospects of their application in the treatment and diagnosis of different diseases.
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Affiliation(s)
- Mariia Faustova
- MIREA-Russian Technological University, Lomonosov Institute of Fine Chemical Technologies, 119454 Moscow, Russia.,N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119991 Moscow, Russia
| | - Elena Nikolskaya
- N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119991 Moscow, Russia
| | - Maria Sokol
- N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119991 Moscow, Russia.,JSC Russian Research Center for Molecular Diagnostics and Therapy, 117149 Moscow Russia
| | - Margarita Fomicheva
- N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119991 Moscow, Russia.,JSC Russian Research Center for Molecular Diagnostics and Therapy, 117149 Moscow Russia
| | - Rem Petrov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Moscow 117997, Russia
| | - Nikita Yabbarov
- N. M. Emanuel Institute of Biochemical Physics of Russian Academy of Sciences, 119991 Moscow, Russia.,JSC Russian Research Center for Molecular Diagnostics and Therapy, 117149 Moscow Russia
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11
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Results in Chemistry of Natural Organic Compounds. Synthesis of New Anticancer Vinca Alkaloids and Flavone Alkaloids. CHEMISTRY 2020. [DOI: 10.3390/chemistry2030046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The antitumor indole–indoline alkaloids of the evergreen Catharanthus roseus—namely vinblastine and vincristine—are widely used in chemotherapy of cancer. Many efforts were made to synthesize more efficient derivatives with less side-effect. The 14,15-cyclopropane derivative of vinblastine was synthesized successfully by a five-step procedure starting from vindoline. Vincristine, vinorelbine and several derivatives condensed with a cyclopropane ring were synthesized. Various hybrid molecules were prepared by the coupling reaction of vindoline and methyl ester of tryptophan, which were conjugated by carrier peptides of octaarginine. Studying the halogenation reactions of vindoline and catharanthine some fluorine derivatives were obtained which showed promising antitumor activity on various tumor types. The synthesis of the Aspidospermane alkaloid bannucine and 5′-epibannucine were carried out using N-acyliminium intermediates. The same intermediate was also applied in the first synthesis of sessiline. The research group have synthesized of flavonoid alkaloids: dracocephins A and B. Further three flavonoid alkaloids, namely 8-(2”-pyrrolidinon-5′′-yl)quercetin, 6-(2′′-pyrrolidinon-5′′-yl)-(−)- and 8-(2′′-pyrrolidinon-5′′-yl)-(−)-epicatechin were prepared by acid-catalyzed regioselective Mannich reaction starting from the corresponding flavonoid precursor. Vindoline was also coupled to synthetic pharmacophores, such as triphenylphosphine and various N-heterocycles. Some of these hybrid molecules showed significant antitumor activity. Furthermore, 7-OH and 7-NH modified flavonoid derivatives were synthesized by a regioselective alkylation followed by Smiles rearrangement and hydrolysis.
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