New Alkaloids from<i>Margaritopsis carrascoana</i>(Rubiaceae)

Nascimento, Raimundo R. G.; Pimenta, Antônia Torres Ávila; Lima‐Neto, Pedro de; Júnior, José Roberval Cândido; Costa-Lotufo, Letı́cia V.; Ferreira, Elthon G.; Tinoco, Luzineide W.; Braz-Filho, Raimundo; Silveira, Edilberto R.; Lima, Mary Anne Sousa

doi:10.5935/0103-5053.20150079

Cited by 4 publications

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“…Originally isolated in 1961 from Hodgkinsonia frutescens , 19 alkaloid (−)- 4 was found to show a strong dose-dependent analgesic activity against capsaicin-induced pain 9f as well as cytotoxicity against human cancer cell lines HCT-116, SF-295 and OVACR-8. 9g …”

Section: Resultsmentioning

confidence: 99%

“…First isolated in 1987 from an extract of Psychotria oleoides , 21a (−)-quadrigemine C ( 7 ) is reported to be an antagonist of the somatostatin receptor (SRIF), 9d an inhibitor of human platelet aggregation 9a and has displayed cytotoxicity against two invasive cancer cell lines DU145 and A2058. 2m Overman’s synthesis of (−)-quadrigemine C ( 7 ) stands as a superb demonstration of a challenging double enantioselective Heck cyclization (diastereoselection 9.3:2.0:1.0, 90% ee for major isomer) in a complex setting.…”

Section: Resultsmentioning

confidence: 99%

“…9 However, a dearth of synthetic solutions to these alkaloids has hampered further evaluation of their properties. Amongst the existing solutions, Overman’s synthesis of oligocyclotryptamine alkaloids including (−)-hodgkinsine B ( 3 ), (−)-hodgkinsine ( 4 ) and (−)-quadrigemine C ( 7 ), elegantly establishes the key C3a–C7' stereocenter via a catalyst-controlled asymmetric intramolecular Heck cyclization to give α-aryl oxindoles.…”

Section: Introductionmentioning

confidence: 99%

“…The oligomeric cyclotryptamine alkaloids have been found to possess a variety of biological activities ranging from analgesic, antibacterial, antifungal, and anticandidal properties, to cytotoxicity against human cancer cell lines . However, a dearth of synthetic solutions to these alkaloids has hampered further evaluation of their properties.…”

Section: Introductionmentioning

confidence: 99%

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Concise Synthesis of (−)-Hodgkinsine, (−)-Calycosidine, (−)-Hodgkinsine B, (−)-Quadrigemine C, and (−)-Psycholeine via Convergent and Directed Modular Assembly of Cyclotryptamines

Lindovska

Movassaghi

2017

J. Am. Chem. Soc.

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The enantioselective total synthesis of (−)-hodgkinsine, (−)-calycosidine, (−)-hodgkinsine B, (−)-quadrigemine C, and (−)-psycholeine through a diazene-directed assembly of cyclotryptamine fragments is described. Our synthetic strategy enables multiple and directed assembly of intact cyclotryptamine subunits for convergent synthesis of highly complex bis- and tris-diazene intermediates. Photoextrusion of dinitrogen from these intermediates enables completely stereoselective formation of all C3a–C3a' and C3a–C7' carbon–carbon bonds and all the associated quaternary stereogenic centers. In a representative example, photoextrusion of three dinitrogen molecules from an advanced intermediate in a single-step led to completely controlled introduction of four quaternary stereogenic centers and guided the assembly of four cyclotryptamine monomers en route to (−)-quadrigemine C. The synthesis of these complex diazenes was made possible through a new methodology for synthesis of aryl-alkyl diazenes using electronically attenuated hydrazine-nucleophiles for a silver-promoted addition to C3a-bromocyclotryptamines. The application of Rh- and Ir-catalyzed C–H amination reactions in complex settings were used to gain rapid access to C3a- and C7-functionalized cyclotryptamine monomers, respectively, used for diazene synthesis. This convergent and modular assembly of intact cyclotryptamines offers the first solution to access these alkaloids through completely stereoselective union of monomers at challenging linkages and the associated quaternary stereocenters as illustrated in our synthesis of five members of the oligocyclotryptamine family of alkaloids.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Concise Synthesis of (−)-Hodgkinsine, (−)-Calycosidine, (−)-Hodgkinsine B, (−)-Quadrigemine C, and (−)-Psycholeine via Convergent and Directed Modular Assembly of Cyclotryptamines

Lindovska

Movassaghi

2017

J. Am. Chem. Soc.

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“…The oligomeric cyclotryptamine alkaloids are a subset of pyrroloindoline natural products comprised of multiple C–C linked cyclotryptamine units . This structurally fascinating family of alkaloids possesses a range of intriguing biological activities, such as analgesic and antifungal properties and cytotoxicity against human cancer cell lines. , Notably, these alkaloids pose a considerable challenge to chemical synthesis due to the C3a–C3a′ and C3a–C7′ linkages, the corresponding C3a quaternary stereocenters on each cyclotryptamine subunit, and the presence of multiple basic nitrogen atoms . While several polycyclotryptamine alkaloids have been prepared through chemical synthesis using innovative strategies, other complex members with unspecified stereochemistry, such as (−)-psychotridine ( 4 , Figure ), have not been accessed .…”

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confidence: 99%

Total Synthesis and Stereochemical Assignment of (−)-Psychotridine

2022

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We report the first enantioselective total synthesis and stereochemical assignment of (−)-psychotridine. The application of our diazene-directed assembly of enantiomerically enriched cyclotryptamines afforded a highly convergent synthesis of the pentameric alkaloid, allowing its detailed structural assignment. Highlights of the synthesis include the introduction of four quaternary stereocenters with complete stereochemical control in a single step via the photoextrusion of three molecules of dinitrogen from an advanced intermediate and metal-catalyzed C−H amination reactions in challenging settings.

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A revised classification of the sister tribes Palicoureeae and Psychotrieae (Rubiaceae) indicates genus-specific alkaloid accumulation

et al. 2021

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Tribes Palicoureeae and Psychotrieae (Rubiaceae, Gentianales) are complex and speciose sister groups with a pantropical distribution. Since the initial studies on ipecacuanha more than two centuries ago, species of the group have been subject to numerous phytochemical studies yielding diverse specialized ("secondary") metabolites, most of them alkaloids. However, the generic limits within the tribes have long been unclear and only recently, monophyletic genera have been delimited and segregated from a once broadly circumscribed Psychotria. Thus, a phylogeny-based and taxonomically updated review of phytochemical literature was performed which allowed assigning the bulk of phytochemical data previously reported for Psychotria to various segregate genera such as Carapichea, Eumachia and Palicourea. This review not only challenges the common perception of Psychotria as a monoterpene-indole alkaloid-rich genus. It also highlights that each of its relatives differs by accumulating specific groups of alkaloids, which is of major importance for understanding animal-plant interactions such as herbivory, as well as for drug discovery. The alkaloid complement of each of these genera is here enumerated and discussed, which should provide a framework for future studies addressing the biosynthesis, evolution, ecological and pharmacological significance of specialized metabolite differentiation in this abundant, ecologically and ethnopharmacologically important group.

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New Alkaloids fromMargaritopsis carrascoana(Rubiaceae)

Cited by 4 publications

References 0 publications

Concise Synthesis of (−)-Hodgkinsine, (−)-Calycosidine, (−)-Hodgkinsine B, (−)-Quadrigemine C, and (−)-Psycholeine via Convergent and Directed Modular Assembly of Cyclotryptamines

Concise Synthesis of (−)-Hodgkinsine, (−)-Calycosidine, (−)-Hodgkinsine B, (−)-Quadrigemine C, and (−)-Psycholeine via Convergent and Directed Modular Assembly of Cyclotryptamines

Total Synthesis and Stereochemical Assignment of (−)-Psychotridine

A revised classification of the sister tribes Palicoureeae and Psychotrieae (Rubiaceae) indicates genus-specific alkaloid accumulation

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