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Nawasreh M, Tahtamouni L. Performance of Green Desymmetrization Methods toward Bioactive Cephalostatin Analogues. Curr Med Chem 2024; 31:3327-3344. [PMID: 37157200 DOI: 10.2174/0929867330666230508145058] [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: 11/23/2022] [Revised: 03/14/2023] [Accepted: 03/27/2023] [Indexed: 05/10/2023]
Abstract
Since the discovery of cephalostatins, which have shown remarkable activity against human cancer cells, they have attracted the attention of researchers to target the synthesis of such impressive, complicated molecules using the green desymmetrization approach. In the current review, we report the progress in the desymmetrization of symmetrical bis-steroidal pyrazines (BSPs) as an approach toward potentially active anti-- cancer agents, namely cephalostatins/ ritterazines. The achievement of synthesizing a gram-scaled prodrug with comparable activity to the potent natural cephalostatins using green methods is our primary target. These synthetic methods can be scaled up based on the symmetrical coupling (SC) of two steroidal units of the same type. Our secondary target is the discovery of new green pathways that help in structural reconstruction programming toward the total synthesis of at least one potentially active family member. The strategy is based on functional group interconversions with high flexibility and brevity using green selective methods. The introduction of controlling groups using nontrivial reconstruction methodologies forms the backbone of our work. After certain modifications to the symmetrical BSP starting material, the resulting analogs underwent several chemoselective transformations through three main routes in rings F, D, and C. One of these routes is the chemoselective spiroketal opening (ring-F). The second route was the functionalization of the Δ14,15 bond (ring-D), including chlorination/dechlorination, in addition to epoxidation/ oxygenation processes. Finally, the introduction of the C-11 methoxy group as a directing group on ring-C led to several chemoselective transformations. Moreover, certain transformations on C-12 (ring-C), such as methylenation, followed by hydroboration- oxidation, led to a potentially active analog. The alignment of these results directs us toward the targets. Our efforts culminated in preparing effective anti-cancer prodrugs (8, 24, 30, and 31), which are able to overcome cancer drug resistance (chemoresistance) by inducing the atypical endoplasmic reticulum-mediated apoptosis pathway, which works through the release of Smac/Diablo and the activation of caspase-4.
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Affiliation(s)
- Mansour Nawasreh
- Scientific Basic Sciences Department, Faculty of Engineering Technology, Al-Balqa Applied University, Marka 11134, Amman, Jordan
| | - Lubna Tahtamouni
- Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa, Jordan
- Department of Biochemistry and Molecular Biology, College of Natural Sciences, Colorado State University, Fort Collins, Colorado, USA
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2
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Tomkiel AM, Majewski AD, Siergiejczyk L, Morzycki JW. Montmorillonite Catalyzed Synthesis of Novel Steroid Dimers. Molecules 2023; 28:7068. [PMID: 37894547 PMCID: PMC10609449 DOI: 10.3390/molecules28207068] [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: 09/28/2023] [Revised: 10/10/2023] [Accepted: 10/10/2023] [Indexed: 10/29/2023] Open
Abstract
The reactions of sterols (androst-5-en-3β-ol-17-one, diosgenin, and cholesterol) and their tosylates with hydroquinone aimed at the synthesis of O,O-1,4-phenylene-linked steroid dimers were studied. The reaction course strongly depended on the conditions used. The study has shown that the major reaction products are the elimination products and unusual steroid dimers resulting from the nucleophilic attack of the hydroquinone C2 carbon atom on the steroid C3 position, followed by an intramolecular addition to the C5-C6 double bond. A different reaction course was observed when montmorillonite K10 was used as a catalyst. The reaction of androst-5-en-3β-ol-17-one under the promotion of this catalyst afforded the O,O-1,4-phenylene-linked steroid dimer in addition to the disteroidal ether. The formation of the latter compound was suppressed by using 3-tosylate as a substrate instead of the free sterol. The reactions of androst-5-en-3β-ol-17-one tosylate and cholesteryl tosylate with hydroquinone catalyzed by montmorillonite K10 carried out under optimized conditions afforded the desired dimers in 31% and 67% yield, respectively.
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Affiliation(s)
- Aneta M. Tomkiel
- Faculty of Chemistry, University of Bialystok, Ciołkowskiego 1K, 15-245 Bialystok, Poland; (A.D.M.); (L.S.)
| | - Adam D. Majewski
- Faculty of Chemistry, University of Bialystok, Ciołkowskiego 1K, 15-245 Bialystok, Poland; (A.D.M.); (L.S.)
- Doctoral School of Exact and Natural Sciences, University of Bialystok, Ciołkowskiego 1K, 15-245 Bialystok, Poland
| | - Leszek Siergiejczyk
- Faculty of Chemistry, University of Bialystok, Ciołkowskiego 1K, 15-245 Bialystok, Poland; (A.D.M.); (L.S.)
| | - Jacek W. Morzycki
- Faculty of Chemistry, University of Bialystok, Ciołkowskiego 1K, 15-245 Bialystok, Poland; (A.D.M.); (L.S.)
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3
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Vazquez-Chavez J, Aguilar-Granda A, Iglesias Arteaga MA. Synthesis and characterization of a fluorescent steroid dimer linked through C-19 by a 1,4-Bis(phenylethynyl)phenylene fragment. Steroids 2022; 187:109098. [PMID: 35964795 DOI: 10.1016/j.steroids.2022.109098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Revised: 07/27/2022] [Accepted: 08/09/2022] [Indexed: 11/20/2022]
Abstract
The synthesis and characterization of a dimer in which two nuclei of 3β-acetoxy-19-hydroxyandrost-5-en-17-one are linked by the fluorescent 1,4-bis(phenylethynyl)phenylene bridge attached to the oxygenated functions at positions C-19 of each steroid fragment is described. The compound was obtained in five steps and 23 % overall yield and showed a strong blue emission with a quantum yield of 0.66.
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Affiliation(s)
- Josué Vazquez-Chavez
- Facultad de Química, Universidad Nacional Autónoma de México. CDMX, 04510, México
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Nawasreh MM. Novel Epoxidation/Oxygenation Method toward Bioactive Cephalostatins Using Common Alkaline Metals. ChemistrySelect 2022. [DOI: 10.1002/slct.202103756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- M. M. Nawasreh
- Scientific Basic Sciences Dept./Faculty of Engineering Technology-Al-Balqa Applied University P.B. 15008, Marka 11134 Amman Jordan
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5
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Huang Y, Li G, Hong C, Zheng X, Yu H, Zhang Y. Potential of Steroidal Alkaloids in Cancer: Perspective Insight Into Structure-Activity Relationships. Front Oncol 2021; 11:733369. [PMID: 34616681 PMCID: PMC8489381 DOI: 10.3389/fonc.2021.733369] [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: 06/30/2021] [Accepted: 08/12/2021] [Indexed: 11/13/2022] Open
Abstract
Steroidal alkaloids contain both steroidal and alkaloid properties in terms of chemical properties and pharmacological activities. Due to outstanding biological activities such as alkaloids and similar pharmacological effects to other steroids, steroidal alkaloids have received special attention in anticancer activity recently. Substituted groups in chemical structure play markedly important roles in biological activities. Therefore, the effective way to obtain lead compounds quickly is structural modification, which is guided by structure-activity relationships (SARs). This review presents the SAR of steroidal alkaloids and anticancer, including pregnane alkaloids, cyclopregnane alkaloids, cholestane alkaloids, C-nor-D-homosteroidal alkaloids, and bis-steroidal pyrazine. A summary of SAR can powerfully help to design and synthesize more lead compounds.
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Affiliation(s)
- Ying Huang
- Key Laboratory of Computational Chemistry-Based Natural Antitumor Drug Research & Development, Liaoning Province, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, China
| | - Gen Li
- School of Chinese Materia Medica, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Chong Hong
- Key Laboratory of Computational Chemistry-Based Natural Antitumor Drug Research & Development, Liaoning Province, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, China
| | - Xia Zheng
- The Second Affiliated Hospital of Liaoning University of Traditional Chinese Medicine, Shenyang, China
| | - Haiyang Yu
- State Key Laboratory of Component-Based Chinese Medicine, Tianjin University of Traditional Chinese Medicine, Tianjin, China
| | - Yan Zhang
- Key Laboratory of Computational Chemistry-Based Natural Antitumor Drug Research & Development, Liaoning Province, School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, China
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6
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Wang Z, Hui C. Contemporary advancements in the semi-synthesis of bioactive terpenoids and steroids. Org Biomol Chem 2021; 19:3791-3812. [PMID: 33949606 DOI: 10.1039/d1ob00448d] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Many natural products have intriguing biological properties that arise from their fascinating chemical structures. However, the intrinsic complexity of the structural skeleton and the reactive functional groups on natural products pose tremendous challenges to chemical syntheses. Semi-synthesis uses chemical compounds isolated from natural sources as the starting materials to produce other novel compounds with distinct chemical and medicinal properties. In particular, advancements in various types of sp3 C-H bond functionalization reactions and skeletal rearrangement methods have contributed to the re-emergence of semi-synthesis as an efficient approach for the synthesis of structurally complex bioactive natural products. Here, we begin with a brief discussion of several bioactive natural products that were obtained via a semi-synthetic approach between 2008 and 2015 and we then discuss in-depth contemporary advancements in the semi-synthesis of bioactive terpenoids and steroids reported during 2016-2020.
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Affiliation(s)
- Zhuo Wang
- Southern University of Science and Technology, School of Medicine, Shenzhen, 518055, People's Republic of China.
| | - Chunngai Hui
- Division of Life Science, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 999077, China
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8
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Nakayama Y, Maser MR, Okita T, Dubrovskiy AV, Campbell TL, Reisman SE. Total Synthesis of Ritterazine B. J Am Chem Soc 2021; 143:4187-4192. [PMID: 33689345 DOI: 10.1021/jacs.1c01372] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The first total synthesis of the cytotoxic alkaloid ritterazine B is reported. The synthesis features a unified approach to both steroid subunits, employing a titanium-mediated propargylation reaction to achieve divergence from a common precursor. Other key steps include gold-catalyzed cycloisomerizations that install both spiroketals and late stage C-H oxidation to incorporate the C7' alcohol.
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Affiliation(s)
- Yasuaki Nakayama
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Michael R Maser
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Tatsuya Okita
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Anton V Dubrovskiy
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Taryn L Campbell
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Sarah E Reisman
- The Warren and Katharine Schlinger Laboratory for Chemistry and Chemical Engineering, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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Nawasreh MM, Alzyoud EI, Al-Mazaydeh ZA, Rammaha MS, Yasin SR, Tahtamouni LH. Biological activity and apoptotic signaling pathway of C 11-functionalized cephalostatin 1 analogues. Steroids 2020; 158:108602. [PMID: 32092307 DOI: 10.1016/j.steroids.2020.108602] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 01/07/2020] [Accepted: 01/27/2020] [Indexed: 02/06/2023]
Abstract
Cephalostatin 1, a potent anti-cancer agent, is a natural bis-steroidal alkaloid that causes cell death in the subnanomolar to picomolar ranges via an atypical apoptosis pathway. Although cephalostatin 1 is a highly effective anticancer drug, its availability limits its utilization. We previously reported the synthesis of two 12'α-hydroxy derivatives of cephalostatin 1 that induce cell death by activating the ER stress apoptosis signaling pathway. For the current work, we synthesized six C11-functionalized cephalostatin 1 analogues (CAs) to evaluate their biological activity. For the cytotoxic compounds, the induced apoptotic pathway was investigated. The C11-functionalized cephalostatin 1 analogues 5 and 6 (CA5 and CA6) were found to exhibit cytotoxic activity against K-562 leukemia cells, MCF-7 breast cancer cells and DU-145 prostate cancer cells, while the remaining four analogues did not show anti-tumor activities against any of the cell lines. Our results indicated that CA5 and CA6 induced cell death via the atypical ER-dependent apoptosis pathway; they increased the expression of Smac/DIABLO, an inhibitor of inhibitors of apoptosis (IAPs), which in turn facilitated the activation of different caspases including the ER-caspase 4 without cytochrome c release from mitochondria. CA5 and CA6 are promising anticancer agents due to their low GI50, the remarkable apoptosis pathway they induce which can overcome chemoresistance, and their very low toxicity to normal cells making them cephalostatin 1 utilizable alternatives.
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Affiliation(s)
- Mansour M Nawasreh
- Applied Sciences Department, Faculty of Engineering Technology, Al-Balqa Applied University, Amman 11134, Jordan
| | - Elham I Alzyoud
- Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa 13115, Jordan; Department of Genetics, University of Szeged, H-6720 Szeged, Hungary
| | - Zainab A Al-Mazaydeh
- Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa 13115, Jordan
| | - Majdoleen S Rammaha
- Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa 13115, Jordan
| | - Salem R Yasin
- Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa 13115, Jordan
| | - Lubna H Tahtamouni
- Department of Biology and Biotechnology, Faculty of Science, The Hashemite University, Zarqa 13115, Jordan; Department of Biochemistry and Molecular Biology, College of Natural Sciences, Colorado State University, Fort Collins 80523, CO, USA.
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10
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Design, Synthesis, and Biological Evaluation of Two Series of Novel A-Ring Fused Steroidal Pyrazines as Potential Anticancer Agents. Int J Mol Sci 2020; 21:ijms21051665. [PMID: 32121303 PMCID: PMC7084598 DOI: 10.3390/ijms21051665] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Increasingly, different heterocyclic systems have been introduced into the steroid nucleus to significantly enhance the antitumor activities of steroid molecules. However, in this study, few literature precedents describing the pyrazine heterocyclic-condensed modification to an A-ring of steroid monomers were found, although the pyrazine group is thought to be essential for the potent anticancer activity of clinically relevant drugs and natural steroid dimers. METHODS AND RESULTS Two series of novel A-ring fused steroidal pyrazines were designed and efficiently synthesized from commercially available progesterone via key α-ketoenol intermediates. Through a cell counting kit-8 cytotoxic assay of 36 derivatives for three tumor cells, 14 compounds displayed significant antiproliferative activity compared to 5-fluorouracil, especially for human prostatic tumor cells (PC-3) in vitro. Further mechanistic studies indicated that the most active compound, 12n (IC50, 0.93 μM; SI, 28.71), could induce the cell apoptosis of PC-3 cells in a dose-dependent manner and cause cell cycle arrest in the G2/M phase. The molecular docking study suggested that compound 12n fitted the active sites of cytochrome P450 17A1 (6CIZ) well. CONCLUSIONS 12n might serve as a promising lead compound for the development of novel anticancer drugs. This facile ring-closing strategy may provide a novel and promising avenue for the cycloaddition reaction of the steroidal skeleton through α-ketoenol intermediates.
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11
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Novel double functional protection of cephalostatin analogues using a gas-free chlorination method. Heliyon 2020; 6:e03025. [PMID: 31909240 PMCID: PMC6938862 DOI: 10.1016/j.heliyon.2019.e03025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 11/26/2019] [Accepted: 12/06/2019] [Indexed: 12/02/2022] Open
Abstract
Herewith, we report on a method that allows to simultaneously protect both the ∆14,15 bond and the carbonyl group of the symmetrical bis-steroidal diketone 2. We found that environmentally friendly and gas-free chlorination is ideally suited to achieve this goal. This method was discovered during our efforts to methoxylate 2 in a solution of dichloromethane and basic methanol in the presence of diacetoxy iodobenzene. Unexpectedly, the ∆14,15 bonds were chlorinated once as well as twice in a statistical manner. Interestingly, the singly dichlorinated desymmetrized product is an ideal precursor for conduction a series of position selective transformations. Importantly, the carbonyl group present in the nonchlorinated hemisphere can be selectively reduced, olefinated or oximated, while the other carbonyl group stays unaltered. A structurally related “monomeric” steroid derivative undergoes ∆14,15 chlorination and 11-position methoxylation under same conditions. These findings represent a powerful entry for preparing new nonsymmetrical cephalostatin derivatives.
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12
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Dey P, Kundu A, Chakraborty HJ, Kar B, Choi WS, Lee BM, Bhakta T, Atanasov AG, Kim HS. Therapeutic value of steroidal alkaloids in cancer: Current trends and future perspectives. Int J Cancer 2019; 145:1731-1744. [PMID: 30387881 PMCID: PMC6767045 DOI: 10.1002/ijc.31965] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2018] [Revised: 10/04/2018] [Accepted: 10/19/2018] [Indexed: 12/21/2022]
Abstract
Discovery and development of new potentially selective anticancer agents are necessary to prevent a global cancer health crisis. Currently, alternative medicinal agents derived from plants have been extensively investigated to develop anticancer drugs with fewer adverse effects. Among them, steroidal alkaloids are conventional secondary metabolites that comprise an important class of natural products found in plants, marine organisms and invertebrates, and constitute a judicious choice as potential anti-cancer leads. Traditional medicine and modern science have shown that representatives from this compound group possess potential antimicrobial, analgesic, anticancer and anti-inflammatory effects. Therefore, systematic and recapitulated information about the bioactivity of these compounds, with special emphasis on the molecular or cellular mechanisms, is of high interest. In this review, we methodically discuss the in vitro and in vivo potential of the anticancer activity of natural steroidal alkaloids and their synthetic and semi-synthetic derivatives. This review focuses on cumulative and comprehensive molecular mechanisms, which will help researchers understand the molecular pathways involving steroid alkaloids to generate a selective and safe new lead compound with improved therapeutic applications for cancer prevention and therapy. In vitro and in vivo studies provide evidence about the promising therapeutic potential of steroidal alkaloids in various cancer cell lines, but advanced pharmacokinetic and clinical experiments are required to develop more selective and safe drugs for cancer treatment.
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Affiliation(s)
- Prasanta Dey
- School of PharmacySungkyunkwan UniversitySuwonRepublic of Korea
| | - Amit Kundu
- School of PharmacySungkyunkwan UniversitySuwonRepublic of Korea
| | | | - Babli Kar
- Bengal Homoeopathic Medical College and HospitalAsansolIndia
| | - Wahn Soo Choi
- School of MedicineKonkuk UniversityChungjuRepublic of Korea
| | - Byung Mu Lee
- School of PharmacySungkyunkwan UniversitySuwonRepublic of Korea
| | - Tejendra Bhakta
- Regional Institute of Pharmaceutical Science & TechnologyTripuraIndia
| | - Atanas G. Atanasov
- Institute of Genetics and Animal Breeding of the Polish Academy of SciencesJastrzebiecPoland
- Department of PharmacognosyUniversity of ViennaViennaAustria
| | - Hyung Sik Kim
- School of PharmacySungkyunkwan UniversitySuwonRepublic of Korea
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Şotowski Z, Gryszkiewicz A, Borowiecka JB, Nikitiuk A, Morzycki JW. A Facile Synthesis of Symmetrical Dimeric Steroid-pyrazines. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.1177/174751989902301113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The reaction of steroidal 2α-bromo-3-ketones ( e.g. 2α-bromocholestan-3-one 2) with ammonia followed by hydrolysis and air-oxidation affords the easily separable mixture of the trans and cis dimeric steroid-pyrazines (3 and 4, respectively).
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Affiliation(s)
- Zenon Şotowski
- Institute of Chemistry, University of Bialystok, Pilsudskiego 11/4, 15-443 Bialystok, Poland
| | - Agnieszka Gryszkiewicz
- Institute of Chemistry, University of Bialystok, Pilsudskiego 11/4, 15-443 Bialystok, Poland
| | - Jolanta B. Borowiecka
- Institute of Chemistry, University of Bialystok, Pilsudskiego 11/4, 15-443 Bialystok, Poland
| | - Agnieszka Nikitiuk
- Institute of Chemistry, University of Bialystok, Pilsudskiego 11/4, 15-443 Bialystok, Poland
| | - Jacek W. Morzycki
- Institute of Chemistry, University of Bialystok, Pilsudskiego 11/4, 15-443 Bialystok, Poland
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14
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Shi Y, Xiao Q, Lan Q, Wang DH, Jia LQ, Tang XH, Zhou T, Li M, Tian WS. A synthesis of cephalostatin 1. Tetrahedron 2019. [DOI: 10.1016/j.tet.2018.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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15
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Kumar RN, Lee S. Synthesis and bioactivity of bis-steroidal pyrazine 23-deoxy-25-epi ritterostatin G N1 N. Steroids 2017; 126:74-78. [PMID: 28778629 DOI: 10.1016/j.steroids.2017.07.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Revised: 07/17/2017] [Accepted: 07/24/2017] [Indexed: 01/03/2023]
Abstract
Cephalostatins, ritterazines and their hybrid bis-steroidal pyrazine analogs such as 25-epi-rittereostatin GN1N show unusually high potency against a wide range of cancer cell lines. Herein, we report the synthesis and bioactivity of 23-deoxy-25-epi ritterostatin GN1N, which lacks the 23-hydroxyl group of 25-epi rittereostatin GN1N. The less oxygenated bis-steroidal pyrazine was ∼50- to 1000-fold less potent than 25-epi ritterostatin GN1N, highlighting the importance of the 23-hydroxyl group for the antiproliferative activity of the cephalostatin/ritterazine class of drugs.
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Affiliation(s)
- Rayala Naveen Kumar
- The Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA
| | - Seongmin Lee
- The Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA.
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17
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Ambrose AJ, Santos EA, Jimenez PC, Rocha DD, Wilke DV, Beuzer P, Axelrod J, Kumar Kanduluru A, Fuchs PL, Cang H, Costa-Lotufo LV, Chapman E, La Clair JJ. Ritterostatin G N 1 N , a Cephalostatin-Ritterazine Bis-steroidal Pyrazine Hybrid, Selectively Targets GRP78. Chembiochem 2017; 18:506-510. [PMID: 28074539 PMCID: PMC5562448 DOI: 10.1002/cbic.201600669] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Indexed: 01/25/2023]
Abstract
Natural products discovered by using agnostic approaches, unlike rationally designed leads or those obtained through high-throughput screening, offer the ability to reveal new biological pathways and, hence, serve as an important vehicle to unveil new avenues in drug discovery. The ritterazine-cephalostatin family of natural products displays robust and potent antitumor activities, with sub-nanomolar growth inhibition against multiple cell lines and potent activity in xenograft models. Herein, we used comparative cellular and molecular biological methods to uncover the ritterazine-cephalostatin cytotoxic mode of action (MOA) in human tumor cells. Our findings indicated that, whereas ritterostatin GN 1N , a cephalostatin-ritterazine hybrid, binds to multiple HSP70s, its cellular trafficking confines activity to the endoplasmic reticulum (ER)-based HSP70 isoform, GRP78. This targeting results in activation of the unfolding protein response (UPR) and subsequent apoptotic cell death.
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Affiliation(s)
- Andrew J Ambrose
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, P. O. Box 210207, Tuscon, AZ, 85721, USA
| | - Evelyne A Santos
- Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, CE, 60.430-270, Brazil
| | - Paula C Jimenez
- Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, CE, 60.430-270, Brazil
- Instituto do Mar, Universidade Federal de São Paulo, Santos, SP, 11.070-100, Brazil
| | - Danilo D Rocha
- Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, CE, 60.430-270, Brazil
| | - Diego V Wilke
- Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, CE, 60.430-270, Brazil
| | - Paolo Beuzer
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Sciences, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Josh Axelrod
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Sciences, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Ananda Kumar Kanduluru
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
- Present address: On Target Laboratories, 1281 Win Hentschel Boulevard, West Lafayette, IN, 47907, USA
| | - Philip L Fuchs
- Department of Chemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Hu Cang
- Waitt Advanced Biophotonics Center, The Salk Institute for Biological Sciences, 10010 North Torrey Pines Road, La Jolla, CA, 92037, USA
| | - Letícia V Costa-Lotufo
- Departamento de Fisiologia e Farmacologia, Universidade Federal do Ceará, Fortaleza, CE, 60.430-270, Brazil
- Departamento de Farmacologia, Universidade de São Paulo, São Paulo, SP, 05508-900, Brazil
| | - Eli Chapman
- Department of Pharmacology and Toxicology, College of Pharmacy, University of Arizona, 1703 East Mabel Street, P. O. Box 210207, Tuscon, AZ, 85721, USA
| | - James J La Clair
- Xenobe Research Institute, P. O. Box 3052, San Diego, CA, 92163-1052, USA
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18
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Wu JJ, Shi Y, Tian WS. Synthesis of the aglycon of aspafiliosides E and F via a spiroketal-forming cascade. Tetrahedron Lett 2017. [DOI: 10.1016/j.tetlet.2017.01.067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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19
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Kumar RN, Lee S. Synthesis of 23-deoxy-25-epi north unit of cephalostatin 1 via reductive and oxidative modifications of hecogenin acetate. Steroids 2017; 118:68-75. [PMID: 28041952 DOI: 10.1016/j.steroids.2016.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2016] [Revised: 11/29/2016] [Accepted: 12/20/2016] [Indexed: 12/01/2022]
Abstract
An efficient synthesis of the 23-deoxy-25-epi north unit of cephalostatin 1 has been achieved in 17 steps via reductive and oxidative functionalizations of hecogenin acetate with an overall yield of 3.8%. This synthesis features transetherification-mediated E-ring opening, D-ring oxidation, hemiketalization-mediated E-ring closure, and stereoselective 5/5-spiroketalization.
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Affiliation(s)
- Rayala Naveen Kumar
- The Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA
| | - Seongmin Lee
- The Division of Chemical Biology and Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA.
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20
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Affiliation(s)
- Yong Shi
- CAS Key Laboratory
of Synthetic
Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Xiao-Ling Jiang
- CAS Key Laboratory
of Synthetic
Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Wei-Sheng Tian
- CAS Key Laboratory
of Synthetic
Chemistry of Natural Substances, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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21
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Li H, Chen Q, Lu Z, Li A. Total Syntheses of Aflavazole and 14-Hydroxyaflavinine. J Am Chem Soc 2016; 138:15555-15558. [DOI: 10.1021/jacs.6b10880] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Hailong Li
- State Key Laboratory of Bioorganic
and Natural Products Chemistry, Collaborative Innovation Center of
Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Qifeng Chen
- State Key Laboratory of Bioorganic
and Natural Products Chemistry, Collaborative Innovation Center of
Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Zhaohong Lu
- State Key Laboratory of Bioorganic
and Natural Products Chemistry, Collaborative Innovation Center of
Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
| | - Ang Li
- State Key Laboratory of Bioorganic
and Natural Products Chemistry, Collaborative Innovation Center of
Chemistry for Life Sciences, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, China
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22
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Qiu Y, Gao S. Trends in applying C-H oxidation to the total synthesis of natural products. Nat Prod Rep 2016; 33:562-81. [PMID: 26847167 DOI: 10.1039/c5np00122f] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Covering: 2006 to 2015C-H functionalization remains one of the frontier challenges in organic chemistry and drives quite an active area of research. It has recently been applied in various novel strategies for the synthesis of natural products. It can dramatically increase synthetic efficiency when incorporated into retrosynthetic analyses of complex natural products, making it an essential part of current trends in organic synthesis. In this Review, we focus on selected case studies of recent applications of C-H oxidation methodologies in which the C-H bond has been exploited effectively to construct C-O and C-N bonds in natural product syntheses. Examples of syntheses representing different types of C-H oxidation are discussed to illustrate the potential of this approach and inspire future applications.
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Affiliation(s)
- Yuanyou Qiu
- Shanghai Key Laboratory of Green Chemistry and Chemical Processes, School of Chemistry and Molecular Engineering, East China Normal University, 3663N Zhongshan Road, Shanghai 200062, P. R. China.
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23
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Wu JJ, Gao R, Shi Y, Tian WS. Direct amination of EF spiroketal in steroidal sapogenins: an efficient synthetic strategy and method for related alkaloids. Tetrahedron Lett 2015. [DOI: 10.1016/j.tetlet.2015.10.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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24
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25
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Davies-Coleman MT, Veale CGL. Recent Advances in Drug Discovery from South African Marine Invertebrates. Mar Drugs 2015; 13:6366-83. [PMID: 26473891 PMCID: PMC4626695 DOI: 10.3390/md13106366] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2015] [Revised: 09/28/2015] [Accepted: 09/29/2015] [Indexed: 01/14/2023] Open
Abstract
Recent developments in marine drug discovery from three South African marine invertebrates, the tube worm Cephalodiscus gilchristi, the ascidian Lissoclinum sp. and the sponge Topsentia pachastrelloides, are presented. Recent reports of the bioactivity and synthesis of the anti-cancer secondary metabolites cephalostatin and mandelalides (from C. gilchristi and Lissoclinum sp., respectively) and various analogues are presented. The threat of drug-resistant pathogens, e.g., methicillin-resistant Staphylococcus aureus (MRSA), is assuming greater global significance, and medicinal chemistry strategies to exploit the potent MRSA PK inhibition, first revealed by two marine secondary metabolites, cis-3,4-dihydrohamacanthin B and bromodeoxytopsentin from T. pachastrelloides, are compared.
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Affiliation(s)
- Michael T Davies-Coleman
- Department of Chemistry, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, South Africa.
| | - Clinton G L Veale
- Faculty of Pharmacy, Rhodes University, Grahamstown 6140, South Africa.
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26
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Pereira DM, Valentão P, Correia-da-Silva G, Teixeira N, Andrade PB. Translating endoplasmic reticulum biology into the clinic: a role for ER-targeted natural products? Nat Prod Rep 2015; 32:705-22. [PMID: 25703279 DOI: 10.1039/c4np00102h] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
ER stress has been identified as a hallmark, and sometimes trigger, of several pathologies, notably cancer, inflammation and neurodegenerative diseases like Alzheimer's and Parkinson's. Among the molecules described in literature known to affect ER function, the majority are natural products, suggesting that natural molecules may constitute a significant arsenal of chemical entities for modulating this cellular target. In this review, we will start by presenting the current knowledge of ER biology and the hallmarks of ER stress, thus paving the way for presenting the natural products that have been described as being ER modulators, either stress inducers or ER protectors. The chemistry, distribution and mechanism of action of these compounds will be presented and discussed.
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Affiliation(s)
- David M Pereira
- REQUIMTE/LAQV, Laboratório de Farmacognosia, Departamento de Química, Faculdade de Farmácia, Universidade do Porto, Rua de Jorge Viterbo Ferreira, no. 228, 4050-313 Porto, Portugal.
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27
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Pettit GR, Xu JP, Chapuis JC, Melody N. The Cephalostatins. 24. Isolation, Structure, and Cancer Cell Growth Inhibition of Cephalostatin 20. JOURNAL OF NATURAL PRODUCTS 2015; 78:1446-50. [PMID: 26042639 DOI: 10.1021/acs.jnatprod.5b00129] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
For the purpose of advancing knowledge of the structural variations available in the natural cephalostatins contained in the marine worm Cephalodiscus gilchristi, the isolation and structure of the 20th member (1) has been accomplished (10(-7) % yield). In turn cephalostatin 20 (1) proved to be enough for an initial SAR study comprising six important human cancer cell lines. A parallel objective was aimed at the possible discovery of a natural cephalostatin with a more accessible structure for total synthesis and/or synthetic modifications, but with powerful cancer cell growth inhibition.
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Affiliation(s)
- George R Pettit
- Cancer Research Institute and Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Jun-Ping Xu
- Cancer Research Institute and Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Jean-Charles Chapuis
- Cancer Research Institute and Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Noeleen Melody
- Cancer Research Institute and Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
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28
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Pettit GR, Moser BR, Herald DL, Knight JC, Chapuis JC, Zheng X. The Cephalostatins. 23. Conversion of Hecogenin to a Steroidal 1,6-Dioxaspiro[5.5]nonane Analogue for Cephalostatin 11. JOURNAL OF NATURAL PRODUCTS 2015; 78:1067-1072. [PMID: 25915559 DOI: 10.1021/np501033u] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Cephalostatin 1 (1) has proved to be a remarkably potent cancer cell growth inhibitor. Since this steroidal alkaloid constituent of the marine worm Cephalodiscus gilchristi possesses a complex structure, providing preclinical supplies by total synthesis continues to be challenging. Therefore, syntheses of less complex structural modifications of this important pyrazine have also received substantial attention. Herein are summarized the synthesis of [5.5]spiroketal 5, a simplified right-side steroidal unit of 1, in seven steps from hecogenin acetate (11) with an overall yield of 4.6%. Consistent with other SAR studies, such reduction in structural complexity compared to 1 led to loss of cancer cell growth inhibitory activity against the P388 lymphocytic leukemia cell line.
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Affiliation(s)
- George R Pettit
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Bryan R Moser
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Delbert L Herald
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - John C Knight
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Jean-Charles Chapuis
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Xing Zheng
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
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29
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Pettit GR, Melody N, Hempenstall F, Chapuis JC, Groy TL, Williams L. Antineoplastic agents. 595. Structural modifications of betulin and the X-ray crystal structure of an unusual betulin amine dimer. JOURNAL OF NATURAL PRODUCTS 2014; 77:863-72. [PMID: 24694263 PMCID: PMC4010298 DOI: 10.1021/np400947d] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Indexed: 05/04/2023]
Abstract
The lupane-type triterpene betulin (1) has been subjected to a series of structural modifications for the purpose of evaluating resultant cancer cell growth inhibitory activity. The reaction sequence 7→11→12 was especially noteworthy in providing a betulin-derived amine dimer. Other unexpected synthetic results included the 11 and 13/14→17 conversions, which yielded an imidazo derivative. X-ray crystal structures of dimer 12 and intermediate 25 are reported. All of the betulin modifications were examined for anticancer activity against the P388 murine and human cell lines. Significant cancer cell growth inhibition was found for 4, 8, 9, 15/16, 19, 20, 24, and 26, which further defines the utility of the betulin scaffold.
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Affiliation(s)
- George R. Pettit
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Noeleen Melody
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Frank Hempenstall
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Jean-Charles Chapuis
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
| | - Thomas L. Groy
- Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, United States
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30
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Da Silva PPJ, Bendjeddou LZ, Meijer L. [Search for natural substances with therapeutic activity: George R. Pettit]. Med Sci (Paris) 2014; 30:319-28. [PMID: 24685224 DOI: 10.1051/medsci/20143003021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
This series of brief reviews covers the "life and work" of famous and iconic researchers who discovered major therapeutics from natural products: their life history, the circumstances of their discoveries, the molecules and their molecular, cellular and physiological mechanisms of action, and their biomedical applications. Dedicated to George R. Pettit, the second article reviews the life of the famous researcher, his worldwide exploration of natural products, especially of marine origin, in search of promising anticancer leads, his discovery and structural elucidation of very potent drug candidates, their synthesis and the launch of some of them on the pharmaceutical market. An extraordinary scientific career which lead George R. Pettit from exploration of Nature to state-of-the-art analytical and synthetic chemistry and from clinical trials to therapeutic successes.
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Affiliation(s)
- Pierre P J Da Silva
- Association « Jardin de plantes anticancéreuses », place de l'Évêché, 29250 Saint-Pol-de-Léon, France
| | - Lyamin Z Bendjeddou
- Association « Jardin de plantes anticancéreuses », place de l'Évêché, 29250 Saint-Pol-de-Léon, France - ManRos Therapeutics, centre de Perharidy, 29680 Roscoff, France - Laboratoire de chimie et biochimie pharmacologiques et toxicologiques (LCBPT), unité de pharmacologie génétique et chimique, Inserm U1022, université Paris Descartes, 45, rue des Saints Pères, 75006 Paris, France
| | - Laurent Meijer
- Association « Jardin de plantes anticancéreuses », place de l'Évêché, 29250 Saint-Pol-de-Léon, France - ManRos Therapeutics, centre de Perharidy, 29680 Roscoff, France
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31
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Kanduluru AK, Banerjee P, Beutler JA, Fuchs PL. A convergent total synthesis of the potent cephalostatin/ritterazine hybrid -25-epi ritterostatin GN1N. J Org Chem 2013; 78:9085-92. [PMID: 23899273 PMCID: PMC7511990 DOI: 10.1021/jo401171q] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The convergent synthesis of 25-epi ritterostatin GN1N is described for the first time, starting from hecogenin acetate (HA). Stereoselective dihydroxylation employing the chiral ligand (DHQ)2PHAL was used as the key step to introduce the C25 epi-stereocenter on the north 1 segment. The title compound was obtained through a coupling reaction between the C3-keto-azide (cstat North 1) and North G.
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Affiliation(s)
- Ananda Kumar Kanduluru
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Prabal Banerjee
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - John A Beutler
- Molecular Targets Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702, United States
| | - Philip L Fuchs
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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Sánchez-Flores J, Romero-Ávila M, Rosado-Abón A, Flores-Álamo M, Iglesias-Arteaga MA. Diacetoxyiodobenzene-mediated synthesis of unnatural furospirostane sapogenins derived from diosgenin and tigogenin. Steroids 2013; 78:798-802. [PMID: 23707570 DOI: 10.1016/j.steroids.2013.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2013] [Revised: 04/29/2013] [Accepted: 05/16/2013] [Indexed: 10/26/2022]
Abstract
Two unnatural steroid sapogenins bearing a furospirostane side chain were prepared starting from the readily available spirostane sapogenins, tigogenin and diosgenin following a synthetic protocol that included: (i) introduction of a carbonyl group at position C-23, (ii) diacetoxyiodobenzene-induced F-ring contraction and (iii) LiAlH4 reduction of the newly emerged methoxycarbonyl moiety. The structures of the new compounds were corroborated by NMR and X-ray studies.
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Affiliation(s)
- Jacqueline Sánchez-Flores
- Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México D.F., Mexico
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Macías-Alonso M, Flores-Álamo M, Iglesias-Arteaga MA. Mechanistic insights on the reactivity of furospirostanes with the 16β,22:22,25-diepoxy-23-acetoxymethyl-24-methyl side chain. Steroids 2013; 78:787-97. [PMID: 23707575 DOI: 10.1016/j.steroids.2013.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2013] [Revised: 04/16/2013] [Accepted: 05/09/2013] [Indexed: 11/27/2022]
Abstract
F-ring opening in spirostanes with the 16β,22:22,25-diepoxy-23-acetoxymethyl-24-methyl side chain produces a Δ(22)-intermediate with an allylic acetoxy group. For this reason the reactivity profile of these compounds deviates from that observed in other naturally occurring or synthetic spirostanes and furospirostanes.
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Affiliation(s)
- Mariana Macías-Alonso
- Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 México, DF, Mexico
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34
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Cheun Y, Kou Y, Stevenson B, Kim HK, Koag MC, Lee S. Synthesis of C17-OH-north unit of ritterazine G via "Red-Ox" modifications of hecogenin acetate. Steroids 2013; 78:639-43. [PMID: 23500411 DOI: 10.1016/j.steroids.2013.02.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2012] [Revised: 02/16/2013] [Accepted: 02/26/2013] [Indexed: 01/18/2023]
Abstract
The C17-OH-north unit of ritterazine G was prepared in 13 steps from hecogenin acetate. This synthesis features a highly efficient and stereoselective introduction of the C17-OH via E-ring cleavage/F-ring formation, D-ring oxidation, and F-ring cleavage/E-ring formation.
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Affiliation(s)
- Young Cheun
- The Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA
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35
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Kou Y, Cheun Y, Koag MC, Lee S. Synthesis of 14',15'-dehydro-ritterazine Y via reductive and oxidative functionalizations of hecogenin acetate. Steroids 2013; 78:304-11. [PMID: 23238516 DOI: 10.1016/j.steroids.2012.10.021] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 10/05/2012] [Accepted: 10/29/2012] [Indexed: 11/24/2022]
Abstract
An analog of ritterazine Y was synthesized from hecogenin acetate in 23 steps via functional group manipulations of hecogenin acetate. Preparation of the north G and south Y units and the late stage Guo-Fuchs asymmetric coupling of the both units afforded the ritterazine Y analog.
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Affiliation(s)
- Yi Kou
- The Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, USA
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36
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Iglesias-Arteaga MA, Morzycki JW. Cephalostatins and ritterazines. THE ALKALOIDS. CHEMISTRY AND BIOLOGY 2013; 72:153-279. [PMID: 24712099 DOI: 10.1016/b978-0-12-407774-4.00002-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
This review article is a tribute to the numerous chemists whose relentless effort for the last quarter of a century resulted in the isolation, identification, and finally the chemical synthesis of a family of bis-steroidal pyrazine alkaloids of marine origin. In the task of defeating cancer, the search for bioactive substances among the naturally occurring compounds is, without any doubt, a preferential approach. The remarkable contribution of Petitt, Fusetani, and their coworkers allowed to discover this family of marine alkaloids that emerge as potential therapeutic anticancer agents, although there is still a long way to go. The challenging and dangerous task of collecting living organisms from deep-waters was followed by a laborious isolation, elucidation of the complicated structures and biological tests. The outcome of this paramount effort was the identification of 45 compounds that stand, to date, as some of the most potent anticancer agents. The intriguing structures of the isolated alkaloids drew the attention of synthetic chemists, valiant enough to undertake the challenging task of synthesizing some of the most active members of the family. Fuchs, Heathcock, Winterfeldt, Suarez, Shair, and their associates pioneered in the establishment of feasible synthetic routes for the preparation of some of the naturally occurring compounds and a large number of synthetic analogs, allowing to establish SAR criteria that have guided the design of new synthetic analogs. Numerous analogs have been prepared to investigate the mechanism of action of bis-steroidal pyrazines, e.g. cephalostatin analogs bearing a strained spiroketal moiety. However, the mechanism of action and the biological target of these compounds remain far from being understood. Therefore, the rational design of simpler, yet highly active analogs seems at the current stage elusive. It is still 1 to clear why these compounds need to be dimeric to show high biological activity. Furthermore, it is not known whether the central pyrazine ring is simply a linker or has some additional function. This could be tested by examining the biological activity of steroidal dimers with other linkers, e.g. with a benzene ring. Such analogs have been actually prepared but without functional groups necessary for biological activity. The clinical trials of cephalostatins have got stuck due to a shortage of material. There is an urgent need to provide highly active, yet not too complex analogs, which could be available in substantial amounts for advanced pharmacological studies.
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Tlais SF, Dudley GB. On the proposed structures and stereocontrolled synthesis of the cephalosporolides. Beilstein J Org Chem 2012; 8:1287-92. [PMID: 23019461 PMCID: PMC3458751 DOI: 10.3762/bjoc.8.146] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2012] [Accepted: 07/14/2012] [Indexed: 11/23/2022] Open
Abstract
The synthesis of four candidate stereoisomers of cephalosporolide H is described, made possible by a zinc-chelation strategy for controlling the stereochemistry of oxygenated 5,5-spiroketals. The same strategy likewise enables the first stereocontrolled synthesis of cephalosporolide E, which is typically isolated and prepared admixed with its spiroketal epimer, cephalosporolide F.
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Affiliation(s)
- Sami F Tlais
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390 USA
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38
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Pettit GR, Moser BR, Mendonça RF, Knight JC, Hogan F. The cephalostatins. 22. synthesis of bis-steroidal pyrazine pyrones (1). JOURNAL OF NATURAL PRODUCTS 2012; 75:1063-9. [PMID: 22607450 PMCID: PMC3409868 DOI: 10.1021/np300069z] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Cephalostatin 1 (1), a remarkably strong cancer cell growth inhibitory trisdecacyclic, bis-steroidal pyrazine isolated from the marine tube worm Cephalodiscus gilchristi, continues to be an important target for practical total syntheses and a model for the discovery of less complex structural modifications with promising antineoplastic activity. In the present study, the cephalostatin E and F rings were greatly simplified by replacement at C-17 with an α-pyrone (in 12), typical of the steroidal bufodienolides, and by a dihydro-γ-pyrone (in 16). The synthesis of pyrazine 12 from 5α-dihydrotestosterone (nine steps, 8% overall yield) provided the first route to a bis-bufadienolide pyrazine. Dihydro-γ-pyrone 16 was synthesized in eight steps from ketone 13. While only insignificant cancer cell growth inhibitory activity was found for pyrones 12 and 16, the results provided further support for the necessity of more closely approximating the natural D-F ring system of cephalostatin 1 in order to obtain potent antineoplastic activity.
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Affiliation(s)
- George R Pettit
- Cancer Research Institute, Department of Chemistry and Biochemistry, Arizona State University, P.O. Box 871604, Tempe, Arizona 85287-1604, USA.
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Ruíz-Pérez KM, Romero-Ávila M, Tinajero-Delgado V, Flores-Álamo M, Iglesias-Arteaga MA. BF₃·Et₂O-induced stereoselective aldol reaction with benzaldehyde, and steroid sapogenins and its application to a convenient synthesis of dinorcholanic lactones. Steroids 2012; 77:819-28. [PMID: 22449388 DOI: 10.1016/j.steroids.2012.02.016] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 02/21/2012] [Accepted: 02/22/2012] [Indexed: 11/16/2022]
Abstract
Treatment of steroid sapogenins with benzaldehyde and BF(3)·Et(2)O cleanly produces E-23(23')-benzylidenspirostanes in good yields in a reaction pathway which consists on an aldol reaction followed by a dehydration step. The obtained E-23(23')-benzylidenspirostanes can be easily converted to dinorcholanic lactones by treatment with CrO(3) in acetic acid. The synthetic sequence to dinorcholanic lactones is compatible with the presence of double bonds and carbonyl groups in the steroid framework.
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Affiliation(s)
- Karen M Ruíz-Pérez
- Departamento de Química Orgánica, Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Mexico, DF, Mexico
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40
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Cheun Y, Koag MC, Kou Y, Warnken Z, Lee S. Transetherification-mediated E-ring opening and stereoselective "Red-Ox" modification of furostan. Steroids 2012; 77:276-81. [PMID: 22198526 DOI: 10.1016/j.steroids.2011.12.015] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 01/15/2023]
Abstract
We have developed a novel E-ring opening method for furostan, and applied it to prepare D-ring modified steroids, which can be used to synthesize cephalostatin analogs.
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Affiliation(s)
- Young Cheun
- The Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Austin, TX 78712, United States
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41
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Greszler SN, Reichard HA, Micalizio GC. Asymmetric synthesis of dihydroindanes by convergent alkoxide-directed metallacycle-mediated bond formation. J Am Chem Soc 2012; 134:2766-74. [PMID: 22235773 DOI: 10.1021/ja2105043] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A convergent synthesis of highly substituted and stereodefined dihydroindanes is described from alkoxide-directed Ti-mediated cross-coupling of internal alkynes with substituted 4-hydroxy-1,6-enynes (substrates that derive from 2-directional functionalization of readily available epoxy alcohol derivatives). In addition to describing a new and highly stereoselective approach to bimolecular [2 + 2 + 2] annulation that delivers products not available with other methods in this area of chemical reactivity, evidence is provided to support annulation by way of regioselective alkyne-alkyne coupling, followed by metal-centered [4 + 2] rather than stepwise alkene insertion and reductive elimination. Overall, the reaction proceeds with exquisite stereochemical control and defines a convenient, convergent, and enantiospecific entry to fused carbocycles of great potential value in target-oriented synthesis and medicinal chemistry.
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Affiliation(s)
- Stephen N Greszler
- Department of Chemistry, The Scripps Research Institute, Scripps Florida, Jupiter, Florida 33458, USA
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42
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Lee JS, Kim BS, Shin JH, Lee YJ, Shin HJ, Lee HS. Mild Isomerative Opening of Tetrahydrofuranyl Subunits in Steroids Using TFAT (trifluoroacetyl trifluoromethanesulfonate): Application to Synthesis of C17-OH Rockogenin Acetate. B KOREAN CHEM SOC 2012. [DOI: 10.5012/bkcs.2012.33.1.76] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Pettit GR, Mendonça RF, Knight JC, Pettit RK. The cephalostatins. 21. Synthesis of bis-steroidal pyrazine rhamnosides (1). JOURNAL OF NATURAL PRODUCTS 2011; 74:1922-30. [PMID: 21899266 PMCID: PMC3251514 DOI: 10.1021/np200411p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The synthesis of bis-steroidal pyrazines derived from 3-oxo-11,21-dihydroxypregna-4,17(20)-diene (4) and glycosylation of a D-ring side chain with α-L-rhamnose have been summarized. Rearrangement of steroidal pyrazine 10 to 14 was found to occur with boron triflouride etherate. Glycosylation of pyrazine 10 using 2,3,4-tri-O-acetyl-α-L-rhamnose iodide led to 1,2-orthoester-α-L-rhamnose pyrazine 17b. By use of a persilylated α-L-rhamnose iodide as donor, formation of the orthoester was avoided. Bis-steroidal pyrazine 10 and rhamnosides 17b and 21c were found to significantly inhibit cancer cell growth in a murine and human cancer cell line panel. Pyrazine 9 inhibited growth of the nosocomial pathogen Enterococcus faecalis.
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Affiliation(s)
- George R. Pettit
- Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, Arizona 85287-1604
| | - Ricardo F. Mendonça
- Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, Arizona 85287-1604
| | - John C. Knight
- Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, Arizona 85287-1604
| | - Robin K. Pettit
- Department of Chemistry and Biochemistry, Arizona State University, PO Box 871604, Tempe, Arizona 85287-1604
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Macías-Alonso M, Flores-Álamo M, Iglesias-Arteaga MA. On the reactivity of 23-methoxycarbonyl furospirostanes. Steroids 2011; 76:1021-31. [PMID: 21515298 DOI: 10.1016/j.steroids.2011.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 03/31/2011] [Accepted: 04/01/2011] [Indexed: 11/26/2022]
Abstract
Brønsted and Lewis acid-catalysed reactions of the 23-methoxycarbonyl furospirostanic side chain are described. While bromination, deuteration and BF(3)·Et(2)O/AcOH treatment involve regioselective F-ring opening with exclusive participation of Δ(22)-furostenic intermediates, BF(3)·Et(2)O/Ac(2)O treatment leads to irreversible E- or F-ring cleavage.
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Affiliation(s)
- Mariana Macías-Alonso
- Facultad de Química, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510 Mexico, DF, Mexico
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45
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Geoffroy P, Ressault B, Marchioni E, Miesch M. Norrish-Prins reaction as a key step in the synthesis of 14β-hydroxy-5α (or 5β or Δ(5,6))-pregnane derivatives. Steroids 2011; 76:1166-75. [PMID: 21645535 DOI: 10.1016/j.steroids.2011.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Revised: 05/09/2011] [Accepted: 05/13/2011] [Indexed: 11/30/2022]
Abstract
Numerous bioactive glycosteroids are characterized by aglycones bearing a 14β-hydroxy pregnane skeleton like boucerin and isoramanone. In general, the syntheses of the latter are achieved by acidic hydrolysis of the corresponding glycosteroids. These aglycones were also obtained by a combined Norrish type I-Prins reaction starting from the corresponding 12-keto-pregnane derivatives. However, for the Norrish-Prins reaction, no reports describe the influence of the A/B ring junction (cis or trans or Δ(5,6) double bond) or the influence of the substitution pattern at position 20. Herein, we describe the use of Norrish type I-Prins reactions to synthesize isoramanone and boucerin derivatives and their A/B cis and trans analogs. The influence of the parameters mentioned above is also presented. These studies showed that the A/B ring junction has little influence on the Norrish type I-Prins reaction but that the substitution pattern at position 20 is important. The presence of a dioxolane group induced not only the formation of the desired 14β-hydroxy pregnane derivatives in the highest yields but also the formation of new spiro derivatives.
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Affiliation(s)
- Philippe Geoffroy
- Université de Strasbourg, Institut de Chimie, Université, UMR 7177, Laboratoire de Chimie Organique Synthétique, 1 rue Blaise Pascal, BP 296/R8, 67008 Strasbourg-Cedex, France
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46
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Koag M, Lee S. Discovery of Hypoiodite-Mediated Aminyl Radical Cyclization Lacking a Nitrogen Radical-Stabilizing Group: Application to Synthesis of an Oxazaspiroketal-Containing Cephalostatin Analog. Org Lett 2011; 13:4766-9. [DOI: 10.1021/ol2017033] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Myong Koag
- The Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Texas 78712, United States
| | - Seongmin Lee
- The Division of Medicinal Chemistry, College of Pharmacy, University of Texas at Austin, Texas 78712, United States
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47
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Geoffroy P, Ressault B, Marchioni E, Miesch M. Synthesis of Hoodigogenin A, aglycone of natural appetite suppressant glycosteroids extracted from Hoodia gordonii. Steroids 2011; 76:702-8. [PMID: 21473873 DOI: 10.1016/j.steroids.2011.03.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2011] [Revised: 03/24/2011] [Accepted: 03/25/2011] [Indexed: 11/17/2022]
Abstract
14β-hydroxy pregnane glycosides extracted from Hoodia gordonii, a succulent plant isolated from Apocynaceae are suggested to have appetite suppressant properties in animals and humans. However, limited reports on biological studies concerning the appetite suppressant properties are available in the open literature. One reason for that is the poor availability of these glycosteroids because H. gordonii is a protected plant and the yield of extraction lies between 0.003% and 0.02%. Starting from 3α,12α-diacetoxy-pregnanone 1, we disclose in this report the synthesis of Hoodigogenin A, the aglycone of the natural 14β-hydroxy pregnane glycosides extracted from H. Gordonii.
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Affiliation(s)
- Philippe Geoffroy
- Université de Strasbourg-Institut de Chimie, UMR 7177-Laboratoire de Chimie Organique Synthétique-1, rue Blaise Pascal, BP 296/R8, 67008 Strasbourg-Cedex, France
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48
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Abstract
Terpenes and alkaloids are ever-growing classes of natural products that provide new molecular structures which inspire chemists and possess a broad range of biological activity. Terpenoid-alkaloids originate from the same prenyl units that construct terpene skeletons. However, during biosynthesis, a nitrogen atom (or atoms) is introduced in the form of β-aminoethanol, ethylamine, or methylamine. Nitrogen incorporation can occur either before, during, or after the cyclase phase. The outcome of this unique biosynthesis is the formation of natural products containing unprecedented structures. These complex structural motifs expose current limitations in organic chemistry, thus providing opportunities for invention. This review focuses on total syntheses of terpenoid-alkaloids and unique issues presented by this class of natural products. More specifically, it examines how these syntheses relate to the way terpenoid-alkaloids are made in Nature. Developments in chemistry that have facilitated these syntheses are emphasized, as well as chemical technology needed to conquer those that evade synthesis.
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Affiliation(s)
- Emily C. Cherney
- Department of Chemistry, The Scripps Research Institute 10550 N. Torrey Pines Rd, La Jolla, CA 92037 phone: (+1) 858-784-7370 fax: (+1) 858-784-7375
| | - Phil S. Baran
- Department of Chemistry, The Scripps Research Institute 10550 N. Torrey Pines Rd, La Jolla, CA 92037 phone: (+1) 858-784-7370 fax: (+1) 858-784-7375
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49
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Shi Y, Jia L, Xiao Q, Lan Q, Tang X, Wang D, Li M, Ji Y, Zhou T, Tian W. A Practical Synthesis of Cephalostatin 1. Chem Asian J 2011; 6:786-90. [DOI: 10.1002/asia.201000882] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Indexed: 11/07/2022]
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50
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Shawakfeh KQ, Al-Said NH. Synthesis of new symmetrical bis-steroidal pyrazine analogues from diosgenin. Steroids 2011; 76:232-7. [PMID: 20951717 DOI: 10.1016/j.steroids.2010.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Revised: 10/04/2010] [Accepted: 10/06/2010] [Indexed: 11/16/2022]
Abstract
New symmetrical bis-steroidal pyrazine dimers that are cephalostatins/ritterazines analogues have been prepared easily from a cheap, readily available natural steroid (diosgenin). These dimers were obtained by classical, condensation of α-amino ketones in order to construct the pyrazine rings. The three dimers differ in the functionalized diosgenin: (25R)-5α,6β-dihydroxy-5α-spirosta-3-one, (25R)-4,5α-epoxy-5β-spirosta-3,6-dione and (25R)-5α-hydroxy-5α-spirosta-3,6-dione respectively.
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Affiliation(s)
- Khaled Q Shawakfeh
- Department of Applied Chemical Sciences, Jordan University of Science and Technology, Irbid, Jordan.
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