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Klintworth R, Morgans GL, Scalzullo SM, de Koning CB, van Otterlo WAL, Michael JP. Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones. Beilstein J Org Chem 2021; 17:2543-2552. [PMID: 34760023 PMCID: PMC8551872 DOI: 10.3762/bjoc.17.170] [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: 08/02/2021] [Accepted: 09/29/2021] [Indexed: 01/02/2023] Open
Abstract
A wide range of N-(ethoxycarbonylmethyl)enaminones, prepared by the Eschenmoser sulfide contraction between N-(ethoxycarbonylmethyl)pyrrolidine-2-thione and various bromomethyl aryl and heteroaryl ketones, underwent cyclization in the presence of silica gel to give ethyl 6-(hetero)aryl-2,3-dihydro-1H-pyrrolizine-5-carboxylates within minutes upon microwave heating in xylene at 150 °C. Instead of functioning as a nucleophile, the enaminone acted as an electrophile at its carbonyl group during the cyclization. Yields of the bicyclic products were generally above 75%. The analogous microwave-assisted reaction to produce ethyl 2-aryl-5,6,7,8-tetrahydroindolizine-3-carboxylates from (E)-ethyl 2-[2-(2-oxo-2-arylethylidene)piperidin-1-yl]acetates failed in nonpolar solvents, but occurred in ethanol at lower temperature and microwave power, although requiring much longer time. A possible mechanism for the cyclization is presented, and further functionalization of the newly created pyrrole ring in the dihydropyrrolizine core is described.
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Affiliation(s)
- Robin Klintworth
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa
| | - Garreth L Morgans
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa
| | - Stefania M Scalzullo
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa
| | - Charles B de Koning
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa
| | - Willem A L van Otterlo
- Department of Chemistry and Polymer Science, Stellenbosch University, Matieland 7602, Stellenbosch, South Africa
| | - Joseph P Michael
- Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, PO Wits 2050, Johannesburg, South Africa
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Barny LA, Tasca JA, Sanchez HA, Smith CR, Koptur S, Livshultz T, Minbiole KPC. Chemotaxonomic investigation of Apocynaceae for retronecine-type pyrrolizidine alkaloids using HPLC-MS/MS. PHYTOCHEMISTRY 2021; 185:112662. [PMID: 33774572 DOI: 10.1016/j.phytochem.2021.112662] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2020] [Revised: 01/03/2021] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Apocynaceae are well known for diverse specialized metabolites that are distributed in a phylogenetically informative manner. Pyrrolizidine alkaloids (PAs) have been reported sporadically in one lineage in the family, the APSA clade, but few species have been studied to date. We conducted the first systematic survey of Apocynaceae for retronecine-type PAs, sampling leaves from 231 species from 13 of 16 major lineages within the APSA clade using HPLC-MS/MS. We also followed up preliminary evidence for infra-specific variation of PA detectability in Echites umbellatus Jacq. Four precursor ion scans (PREC) were developed for a high-throughput survey for chemicals containing a structural moiety common to many PAs, the retronecine core. We identified with high confidence PAs in 7 of 8 sampled genera of tribe Echiteae, but not in samples from the closely related Odontadenieae and Mesechiteae, confirming the utility of PAs as a taxonomic character in tribal delimitation. Occurrence of PAs in Malouetieae is reported with moderate confidence in Galactophora schomburgkiana Woodson and Eucorymbia alba Stapf, but currently we have low confidence of their presence in Holarrena pubescens Wall. ex G. Don (the one Malouetieae species where they were previously reported), as well as in Holarrena curtisii King & Gamble and in Kibatalia macrophylla (Pierre ex Hua) Woodson. Candidate PAs in some species of Wrightia R. Br. (Wrightieae) and Marsdenia R. Br. (Marsdenieae) are proposed with moderate confidence, but a subset of the compounds in these taxa presenting with a PA-like fragmentation pattern are more likely to be aminobenzoyl glycosides. Candidate PAs are reported in species with predicted (VXXXD) and unexpected (IXXXN) amino acid motifs in their homospermidine synthase-like genes. Detectability of PAs varies among samples of Echites umbellatus and intra-individual plasticity contributes to this variation. Of toxicological importance, novel potential sources of human exposure to pro-toxic PAs were identified in the medicinal plant, Wrightia tinctoria R.Br., and the food plants, Marsdenia glabra Cost. and Echites panduratus A. DC., warranting immediate further research to elucidate the structures of the candidate PAs identified. Method development and limitations are discussed.
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Affiliation(s)
- Lea A Barny
- Department of Chemistry, Villanova University, Villanova, PA, 19085, USA.
| | - Julia A Tasca
- Department of Chemistry, Villanova University, Villanova, PA, 19085, USA; Department of Biochemistry and Molecular Biophysics, Perelman School of Medicine at the University of Pennsylvania, 3400 Civic Center Blvd, Philadelphia, PA, 19104, USA.
| | - Hugo A Sanchez
- Department of Chemistry, Villanova University, Villanova, PA, 19085, USA.
| | - Chelsea R Smith
- Department of Biodiversity Earth and Environmental Sciences, Drexel University, PA, 19104, USA.
| | - Suzanne Koptur
- Department of Biology, Florida International University, 11200 SW 8th St, Miami, FL, 33199, USA.
| | - Tatyana Livshultz
- Department of Biodiversity Earth and Environmental Sciences, Drexel University, PA, 19104, USA; Department of Botany, Academy of Natural Sciences of Drexel University, 1900 Benjamin Franklin Parkway, Philadelphia, PA, 19103, USA.
| | - Kevin P C Minbiole
- Department of Chemistry, Villanova University, Villanova, PA, 19085, USA.
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Colegate SM, Gardner DR, Betz JM, Fischer OW, Liede-Schumann S, Boppré M. Pro-toxic 1,2-Dehydropyrrolizidine Alkaloid Esters, Including Unprecedented 10-Membered Macrocyclic Diesters, in the Medicinally-used Alafia cf. caudata and Amphineurion marginatum (Apocynaceae: Apocynoideae: Nerieae and Apocyneae). PHYTOCHEMICAL ANALYSIS : PCA 2016; 27:257-276. [PMID: 27432636 DOI: 10.1002/pca.2624] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Revised: 04/01/2016] [Accepted: 04/07/2016] [Indexed: 06/06/2023]
Abstract
INTRODUCTION Within the Apocynoideae (Apocynaceae) pro-toxic dehydropyrrolizidine alkaloids have been reported only in Echiteae. However, attraction of pyrrolizidine alkaloid-pharmacophagous insects suggested their presence in Alafia cf. caudata Stapf (Nerieae: Alafiinae) and Amphineurion marginatum (Roxb.) D.J. Middleton (Apocyneae: Amphineuriinae), both used as medicinal plants. OBJECTIVE To confirm the presence of dehydropyrrolizidine alkaloids in Alafia cf. caudata and Amphineurion marginatum and identify their structures. METHODS Methanol extracts of air-dried roots, stems and leaves of non-flowering plants were analysed using HPLC-ESI(+)MS and MS/MS or collision-induced dissociation MS in low and/or high resolution modes. Pyrrolizidine alkaloids were tentatively identified based on the mass spectrometry data. Solid phase extraction combined with semi-preparative HPLC were used to isolate major alkaloids. Structures were elucidated using NMR spectroscopy. RESULTS Monoesters of retronecine with senecioic, hydroxysenecioic or syringic acids were identified in roots of Alafia cf. caudata. Two unprecedented 10-membered macrocyclic dehydropyrrolizidine alkaloid diesters were isolated from roots of Amphineurion marginatum. Pyrrolizidine alkaloids were detected in root and leaf material of Alafia cf. caudata at 0.34 and 0.01% dry weight (DW), and 0.13, 0.02 and 0.09% DW in root, leaf and stem material of Amphineurion marginatum. CONCLUSIONS The presence of pro-toxic dehydropyrrolizidine alkaloids suggests that medical preparations of these plants pose potential health risks to consumers. Dehydropyrrolizidine alkaloids are evidently more widespread in Apocynoideae than previously assumed, and it would seem rewarding to study other members of this family for the presence of pyrrolizidines, dehydropyrrolizidines and dihydropyrrolizines. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Steven M Colegate
- USDA, ARS, Poisonous Plant Research Laboratory, Logan, UT, 84341, USA
- Department of Animal, Dairy and Veterinary Sciences, Utah State University, Logan, UT, 84322, USA
| | - Dale R Gardner
- USDA, ARS, Poisonous Plant Research Laboratory, Logan, UT, 84341, USA
| | - Joseph M Betz
- Office of Dietary Supplements, National Institutes of Health, 6100 Executive Blvd., Room 3B01, Bethesda, MD, 20892, USA
| | - Ottmar W Fischer
- Forstzoologie und Entomologie, Albert-Ludwigs-Universität, D-79085, Freiburg, Germany
| | | | - Michael Boppré
- Forstzoologie und Entomologie, Albert-Ludwigs-Universität, D-79085, Freiburg, Germany
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New sources of lycopsamine-type pyrrolizidine alkaloids and their distribution in Apocynaceae. BIOCHEM SYST ECOL 2015. [DOI: 10.1016/j.bse.2015.02.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Schulz S, Beccaloni G, Brown KS, Boppré M, Freitas AVL, Ockenfels P, Trigo JR. Semiochemicals derived from pyrrolizidine alkaloids in male ithomiine butterflies (Lepidoptera: Nymphalidae: Ithomiinae). BIOCHEM SYST ECOL 2004. [DOI: 10.1016/j.bse.2003.12.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Röder E, Bartkowski JPB, Bourauel T. Synthesis of 2,3-Dihydro-7-hydroxymethyl-1H-pyrrolizin-1-one, the Alkaloid Loroquine. European J Org Chem 1993. [DOI: 10.1002/jlac.1993199301116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Edgar JA. Pyrrolizidine alkaloids in insect-plant co-evolution. Toxicon 1983. [DOI: 10.1016/0041-0101(83)90164-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Robins DJ. The pyrrolizidine alkaloids. FORTSCHRITTE DER CHEMIE ORGANISCHER NATURSTOFFE = PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS. PROGRES DANS LA CHIMIE DES SUBSTANCES ORGANIQUES NATURELLES 1982; 41:115-203. [PMID: 7049874 DOI: 10.1007/978-3-7091-8656-5_4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Curtain CC, Edgar JA. The binding of dehydroheliotridine to DNA and the effect of it and other compounds on repair synthesis in main and satellite band DNA. Chem Biol Interact 1976; 13:243-56. [PMID: 1269045 DOI: 10.1016/0009-2797(76)90078-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
This study was aimed at elucidating the mechanisms of the preferential depression of satellite DNA synthesis by dehydroheliotridine (DHH). DHH was found to induce repair synthesis to the same extent in both main and satellite band DNA in cultured sheep lymphocytes. This was also the case with acridine orange, nitrogen mustard (HN2) and ethyl methane-sulphonate (EMS). Using analytical equilibrium ultracentrifugation no difference was found between the extents of in vitro binding of DHH by main and satellite band DNA. From these results it was concluded that the depression of the synthesis of satellite DNA could not be explained by either its preferential binding of DHH or by less effective repair mechanisms. Radiolabelled DHH when added to synchronized cultures of ovine kidney cells was found to be preferentially bound to the satellite DNA (one DHH molecule to 6000 nucleotides) compared with the main band DNA (one to 10 000). When 5-bromodeoxyuridine (BUdR) was added to the cultures no DHH label was found in the heavy, semiconservatively replicated DNA band. From these findings it is suggested that attack may occur during mitosis where all of the satellite DNA may be undergoing synthesis at the same time, thus explaining the increased amount of DHH bound to the satellite.
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Pyrrolizidine alkaloids inParsonsia species (family apocynaceae) which attract Danaid butterflies. ACTA ACUST UNITED AC 1975. [DOI: 10.1007/bf02026335] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Edgar JA, Culvenor CC, Pliske TE. Coevolution of Danaid butterflies with their host plants. Nature 1974; 250:646-8. [PMID: 4851069 DOI: 10.1038/250646a0] [Citation(s) in RCA: 44] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Dihydropyrrolizine derivatives in the ‘hair-pencil’ secretions of danaid butterflies. ACTA ACUST UNITED AC 1971. [DOI: 10.1007/bf02136849] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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