Dissertations / Theses: 'Alkaloid'

1

Mathews, C. J. "Alkaloid synthesis." Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238202.

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2

Atkinson, Jonathan D. M. "Alkaloid synthesis." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302885.

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3

Callaghan, Owen. "Synthetic and mechanistic studies in free radical." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366957.

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4

Ali, Naji M. "Studies in alkaloid synthesis." Thesis, University of East Anglia, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327933.

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5

Walsma, J. "Tropane alkaloid production by Datura." Thesis, De Montfort University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.383103.

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6

Glenn, Weslee S. (Weslee Sinclair). "Understanding and manipulating alkaloid biosynthesis." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84374.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2013.
Cataloged from PDF version of thesis. Vita.
Includes bibliographical references.
Humans have exploited plant alkaloids as medicines since at least the Neolithic Era. Today, alkaloids such as vinblastine (isolated from Catharanthus roseus) and morphine (isolated from Papaver somniferum) are prescribed to treat various cancers and relieve pain, respectively. Despite this storied use and palpable presence in the current pharmacopeia, relatively little is known about the biosynthesis, regulation and transport of these molecules. For example, monoterpene indole alkaloid (MIA) biosynthesis, a set of metabolic pathways that produces hundreds of bioactive natural products, has not been fully elucidated in any organism. Here we examine the biosynthesis of secologanin, which contributes the monoterpene moiety to all MIAs. Specifically, we excavate C. roseus transcriptomic datasets to identify 1 0-hydroxygeraniol oxidoreductase, a missing step in secologanin biosynthesis. 10-hydroxygeraniol oxidoreductase catalyzes the oxidation of both hydroxyl moieties of 10-hydroxygeraniol to form 10-oxogeranial, which is the substrate for iridoid synthase, the reductive cyclase that assembles the characteristic iridoid scaffold. Despite having an incomplete understanding of MIA biosynthesis, several engineering strategies have been successfully deployed to incorporate halogenation into the MIA machinery and yield halogenated alkaloids. Although alkaloids and plant natural products have been used to treat various diseases, these compounds have not evolved specifically to do so. Therefore, these compounds frequently require editing to effectively tune their biological and pharmacological activities. We also describe efforts to reengineer tryptophan halogenase RebH to preferentially install chlorine onto tryptamine, the direct indole precursor for the MIAs. After reengineering RebH, we then overexpressed the tryptamine-specific mutant RebH Y455W and flavin reductase RebF in C. roseus and observed the de novo biosynthesis of a chlorinated unnatural natural product 12-chloro- 19,20-dihydroakuammicine. Lastly, we describe the serendipitous discovery of a P. somniferum codeine-Odemethylase mutant that selectively demethylates codeine, a benzylisoquinoline alkaloid involved in morphine biosynthesis, instead of both codeine and thebaine. This mutant may selectively disable a redundant route in the biosynthesis of morphine that has been associated with poor seed and licit opium quality.
by Weslee S. Glenn.
Ph.D.

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7

Boynton, Carole M. "Alkaloid synthesis via novel azabicycles." Thesis, Sheffield Hallam University, 1988. http://shura.shu.ac.uk/19384/.

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A basic introduction to pyrrolizidine and indolizidine alkaloids has been described along with a selection of recent syntheses of the said compounds. Cycloalkene synthesis by intramolecular Wittig reaction has been reviewed and we describe the utility of this strategy in the formation of nitrogen-bridgehead bicycles which can then be used in alkaloid synthesis. Our initial studies on the viability of this strategy in the synthesis of fused pyrrolidone systems employed a Wittig reaction between 5-acetylpyrrolidin-2-one and vinylphosphonium salts. A comparison was made between three different vinylphosphonium salts but in each case the bicycle formed was present as a mixture with the Wittig by-product triphenylphosphine oxide. Various solutions to this problem were investigated including modification of the bicycle and also the formation of a water soluble vinylphosphonium salt. The difficulties encountered led us to the use of a vinylphosphine oxide which resulted in the formation of 5,6,7,7a-tetrahydro-1-methyl-2-phenylthio-3H-pyrrolizin-5-one in good yields. Desulphurisation gave 5,6,7,7a-tetrahydro-1-methyl-3H-pyrrolizin-5-one which has previously been converted into (+/-)-supinidine. Thus our method constitutes a formal total synthesis of (+/-)-supinidine. Attempts at the preparation of analogues of 5-acetylpyrrolidin-2-one were unsuccessful but were in their preliminary stages at the close of the work. Reaction of 5-acetylpyrrolidin-2-one with cyclopropylphosphonium salts were attempted without success but it is felt that the use of cyclopropylphosphine oxides would solve this problem. Attempts at performing an intramolecular Wittig reaction on the imide carbonyl of succinimide using both cyclopropylphosphonium salts and butadienylphosphonium salts were unsuccessful but our investigations gave an insight into the cause of the failure forcing conditions need to be employed to effect the cyclisation.

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Kuschnir, R. V. "Koffein – alkaloid fur gute laune." Thesis, Київський національний університет технологій та дизайну, 2018. https://er.knutd.edu.ua/handle/123456789/11392.

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9

Ermayanti, Tri Muji. "Alkaloid production from root cultures." Thesis, Ermayanti, Tri Muji (1993) Alkaloid production from root cultures. PhD thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/51711/.

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Root culture was used as a method for swainsonine (1,2,8-trihydroxyoctaindolizine) production from the Australian native plant Sxvainsona galegifolia (Darling pea). Root cultures were established either from seedling roots or after infection of plant organs with Agrobacterium rhizogenes. Murashige and Skoog (MS) liquid medium with 5 µM IBA was the best medium for growth of untransformed isolated roots while MS liquid medium with no hormones was best for transformed roots. Swainsonine produced by root cultures of S. galegifolia reached a maximum 30 - 35 days after subculture, and the identity of the compound was confirmed by its GC retention time and mass spectrum in comparison to swainsonine from intact plants and the swainsonine standard (Sigma Co., USA). Roots and shoots from glasshousegrown plants had a similar swainsonine concentration to shoots of plants grown in vitro. The concentration of swainsonine in transformed roots was higher than in untransformed roots. Tests of the effect of plant genotype and A. rhizogenes strain LBA 9402 showed that plant genotype influences swainsonine level in transformed roots, but that different transformation events in one genotype resulted in equally large differences in the level of swainsonine. Polyploid roots might be expected to show higher levels of secondary metabolites than diploids, but attempts to induce polyploidy through use of colchicine, transformation of cotyledons, or differentiation of roots from callus was unsuccessful. Roots from callus showed lowered swainsonine levels concomitant with a reduction in modal chromosome number from 32 to 18. In normal cultures of untransformed or transformed roots, the level of swainsonine in the medium was negligible. Stimulation of production of swainsonine and its release into the medium was attempted using CUSO4, reduction of medium pH, and supply of swainsonine precursors. Addition of 0.5 - 2.0 mM CUSO4 for 1 - 4 days to the culture medium for transformed roots increased swainsonine level and stimulated release of swainsonine to the medium. The maximum swainsonine concentration was achieved after treatment with 2.0 mM CUSO4 for 2 days. Reduction of medium pH from 5.7 to 2.7 for 1 day also increased swainsonine level in transformed roots and in the medium. The precursors pipecolic acid and malonic acid at 0.005 - 2.0 mM given for 1 - 12 days in MS liquid medium increased root growth and swainsonine level. The maximum swainsonine level was found in transformed roots with 2 mM of pipecolic acid for 6 days. Addition of 1 mM malonic acid for each of 4 successive days also increased growth of transformed roots and swainsonine level but the increase did not exceed that achieved by a single supplementation. This report adds to the evidence that roots transformed with A. rhizogenes show high and stable levels of secondary metabolite production. Transformed roots of S. galegifolia had a swainsonine production almost 10-fold that measured in intact plants grown under glasshouse condition. The addition of precursors increased the level to almost 20-fold. Root culture was also attempted for castanospermine production by Castanospermum australe. Growth of untransformed root cultures was unsuccessful. Untransformed roots grew in solid medium but failed to grow in liquid medium. It was not possible to induce transformed roots. No roots were obtained after infection using a range of A. rhizogenes strains or when the bacterium was pre-incubated with acetosyringone in the medium.

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10

Antropow, Alyssa Hope. "Synthesis and anticancer evaluation of agelastatin alkaloid derivatives and enantioselective total synthesis of aspidosperma alkaloids." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/118214.

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Thesis: Ph. D. in Organic Chemistry, Massachusetts Institute of Technology, Department of Chemistry, 2018.
Cataloged from PDF version of thesis. Vita.
Includes bibliographical references.
I. Synthesis and Evaluation of Agelastatin Derivatives as Potent Modulators for Cancer Invasion and Metastasis The synthesis of new agelastatin alkaloid derivatives and their anticancer evaluation in the context of the breast cancer microenvironment is described. A variety of Ni -alkyl and C5-ether agelastatin derivatives were accessed via application of our strategy for convergent imidazolone synthesis. We have discovered that agelastatin alkaloids are potent modulators for cancer invasion and metastasis at non-cytotoxic doses. We discuss the increased potency of (-)-agelastatin E as compared to (-)-agelastatin A in this capacity, in addition to identification of new agelastatin derivatives with activity that is statistically equivalent to (-)-agelastatin E. II. Enantioselective Synthesis of (-)-Vallesine: Late-stage C17-Oxidation via Complex Indole Boronation The first enantioselective total synthesis of (-)-vallesine via a strategy that features a late-stage regioselective C17-oxidation followed by a highly stereoselective transannular cyclization is described. The versatility of this approach is highlighted by divergent synthesis of the archetypal alkaloid of this family, (+)-aspidospermidine, and an A-ring oxygenated derivative (+)- deacetylaspidospermine, the precursor to (-)-vallesine, from a common intermediate. III. Enantioselective Total Synthesis of (-)-Jerantinine A from (-)-Melodinine P via Bio-Inspired A-Ring Oxidation The first enantioselective synthesis of (-)-melodinine P and its direct conversion to related alkaloid (-)-jerantinine A is described. A key para-aza-quinone methide pentacyclic intermediate enables A-ring to C-ring oxidation state transfer. Our synthesis is streamlined through the development of two multi-step single-pot procedures which proceed with high efficiency. We further demonstrate the utility ofpara-aza-quinone methide intermediates in our strategy for CI6-methoxylation which provides entry to the (-)-jerantinine alkaloid family.
by Alyssa Hope Antropow.
Ph. D. in Organic Chemistry

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11

Sedlock, Andrea B. "Ergot alkaloids and herbivory in model animals and variation in an ergot alkaloid biosynthesis gene." Morgantown, W. Va. : [West Virginia University Libraries], 2003. http://etd.wvu.edu/templates/showETD.cfm?recnum=3190.

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Thesis (M.S.)--West Virginia University, 2003.
Title from document title page. Document formatted into pages; contains viii, 62 p. : ill. (some col.) Vita. Includes abstract. Includes bibliographical reference.

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12

Coufal-Majewski, Stephanie. "Characterising the impact of ergot alkaloids on digestibility and growth performance of lambs." Thesis, The University of Sydney, 2017. http://hdl.handle.net/2123/17226.

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The negative impacts of ergot contamination of grain on the health of humans and animals were first documented during the fifth century AD. Although ergotism is now rare in humans, cleaning contaminated grain concentrates ergot bodies in screenings which are used as livestock feed. Ergot is found worldwide, with even low concentrations of alkaloids in the diet (<100 ppb total), reducing the growth efficiency of livestock. Extended periods of increased moisture and cold during flowering promote the development of ergot in cereal crops. Furthermore, the unpredictability of climate change may have detrimental impacts to important cereal crops, such as wheat, barley, and rye, favoring ergot production. Allowable limits for ergot in livestock feed are confusing as they may be determined by proportions of ergot bodies or by total levels of alkaloids, measurements that may differ widely in their estimation of toxicity. The proportion of individual alkaloids, including ergotamine, ergocristine, ergosine, ergocornine, and ergocryptine is extremely variable within ergot bodies and the relative toxicity of these alkaloids has yet to be determined. This raises concerns that current recommendations on safe levels of ergot in feeds may be unreliable. Furthermore, the total ergot alkaloid content is greatly dependent on the geographic region, harvest year, cereal species, variety and genotype and can vary greatly depending on the chosen analytical method. Considerable animal-to-animal variation in the ability of the liver to detoxify ergot alkaloids also exists and the impacts of factors, such as pelleting of feeds or use of binders to reduce bioavailability of alkaloids require study. Accordingly, unknowns greatly outnumber the knowns for cereal ergot and further study to help better define allowable limits for livestock would be welcome.

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13

Romeril, Stuart P. "Synthesis and structural elucidation of the Bis-3-alkylpyridine alkaloid pyrinodemin A and other monomeric alkaloids." Thesis, University of Oxford, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288526.

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14

Bennett, P. A. R. "Synthetic approaches to the alkaloid himbacine." Thesis, University of Oxford, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.233479.

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15

Faulkner, Jerome Ralph. "INTERMEDIATE STEPS OF LOLINE ALKALOID BIOSYNTHESIS." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/209.

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Epichloë species and their anamorphs, Neotyphodium species, are fungal endophytes that inhabit cool-season grasses and often produce bioprotective alkaloids. These alkaloids include lolines, which are insecticidal and insect feeding deterrents. Lolines are exo-1-aminopyrrolizidines with an oxygen bridge between carbons 2 and 7, and are usually methylated and formylated or acetylated on the 1-amine. In previously published studies lolines were shown to be derived from the amino acids L-proline and L-homoserine. In addition the gene cluster involved in loline-alkaloid biosynthesis has also been characterized. In this dissertation a survey of plant-endophyte symbioses revealed a phenotype with only N-acetylnorloline. This phenotype provided insights into loline alkaloid production. This dissertation focuses on determining the steps to loline biosynthesis after the amino acid precursors. The study involves feeding isotopically labeled potential precursors to loline-alkaloid-producing cultures of Neotyphodium uncinatum, as well as RNA interference (RNAi) of N. uncinatum genes for steps in the pathway. Synthesized deuterated compounds were fed to loline-alkaloid-producing cultures of N. uncinatum to test their possible roles as precursors or intermediates in the loline-alkaloid pathway. N-Formylloline was extracted from the cultures and assayed by GCMS for incorporation of the deuterium label. The results indicated that N-(3-amino, 3-carboxy)propylproline and exo-1-aminopyrrolizidine are intermediates in the loline-alkaloid biosynthetic pathway. Plasmids were also designed for expression of double-stranded RNA homologous to loline-alkaloid biosynthesis genes, and introduced by transformation into N. uncinatum. This RNAi strategy resulted in fungal transformants altered in loline-alkaloid profiles. The RNAi results indicated that N-acetyl-1-aminopyrrolizidine is the intermediate before oxygen bridge formation. Based on the results of this study and the likely roles of the loline-alkaloid biosynthesis genes inferred from signature sequences of their predicted protein products, I propose a pathway of bond formation steps in loline-alkaloid biosynthesis.

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16

Zhao, Bo. "Alkaloid Production by Hairy Root Cultures." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3884.

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In the present research, nicotine alkaloid production by Nicotiana tabacum (tobacco) hairy roots and tropane alkaloid production by Hyoscyamus niger hairy roots were investigated. The first objective of this research was to improve the oxygen mass transfer in hairy root cultures with microbubbles. Oxygen was shown as a critical nutrient for the growth of tobacco and H. niger hairy roots. In a 1-liter fermentor, microbubble dispersion improved the oxygen mass transfer, tobacco hairy root growth, and nicotine production in the medium. In a novel ground-joint column bioreactor, microbubbles enhanced the oxygen mass transfer and the growth of H. niger hairy roots. The second objective of this research was to enhance the release of alkaloids from the hairy roots into the culture medium. In a l-liter fermentor, nicotine concentration in medium was improved by adjusting the medium pH to 6. Unlike the nicotine alkaloid, hyoscyamine concentration in medium was not detectable at medium pH 6, whereas hyoscyamine in medium increased to 42 mg l-1 at medium pH 3. Similar to the hyoscyamine, scopolamine in medium increased from 0.1 to 11 mg l-1 when the medium pH was adjusted from 6 to 3. The release of alkaloids into culture medium provides opportunities to isolate a high-value alkaloid directly from the culture fluid, and reduces the cost of product recovery.

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17

Padmanabhan, Padma. "Biosynthetic studies on the indolizidine alkaloid cyclizidine." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304387.

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18

Meheux, Phillip Antony. "Enantioselective hydrogenation catalysed by alkaloid-modified platinum." Thesis, University of Hull, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359924.

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19

Murphy, James P. "Synthesis of azabicyclic intermediates for alkaloid synthesis." Thesis, Queen's University Belfast, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394528.

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20

Roe, Caroline. "1-arylcyclohexadienyliron complexes in alkaloid in synthesis." Thesis, University of East Anglia, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445209.

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21

Jones, Clifford David. "Asymmetric synthesis of the frog alkaloid epibatidine." Thesis, University of Nottingham, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262966.

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22

Ewin, Richard Andrew. "Applications of radical chemistry to alkaloid synthesis." Thesis, King's College London (University of London), 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261811.

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23

Burbridge, Alan. "Tropane alkaloid production by genetically manipulated Datura." Thesis, De Montfort University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.303319.

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24

Callis, David John. "Synthetic studies towards the indole alkaloid, aspidospermidine." Thesis, University of Sussex, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340832.

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25

Endo, Tsuyoshi. "ALKALOID BIOSYNTHESIS IN CULTURED TISSUES OF DUBOISIA." Kyoto University, 1989. http://hdl.handle.net/2433/78202.

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26

Tholen, Niels T. H. "New sulfone-assisted strategies for alkaloid synthesis." Thesis, Imperial College London, 2010. http://hdl.handle.net/10044/1/6081.

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This thesis is divided into three chapters. Chapter 1 provides brief reviews on the subjects of previous total syntheses of suaveoline, alstonerine and cytisine. In addition, a review concerning the Pictet–Spengler reaction mechanism and its application to the total syntheses of isoquinoline containing natural products has been included as well. Chapter 2 focuses on the research findings in the past three years. Two routes were investigated towards the total synthesis of (±)-suaveoline involving the decarboxylative Claisen rearrangement (dCr), N-sulfonylaziridine chemistry and subsequent nucleophilic ringopening of the latter by various sulfone-anions. Route A focused on the use of oxo-lithio chelation during aziridine ring-opening while route B employed selective weakening of the aziridine C–N bond proximal to the olefin by PiC–C→Sigma* C–N overlap (Scheme 0.1). Attempts towards total synthesis of (±)-alstonerine involved the preparation and subsequent screening of various sulfone-anions against the indolic hydroxy aziridine, followed by an interesting E1cB / Michael addition, cis-Pictet–Spengler cyclization and an ambitious global reduction step. Furthermore progress towards total synthesis of (–)-cytisine involved investigation towards the application of regioselective sulfone-anion hydroxy-aziridine opening mediated by oxolithio- chelation. Chapter 3 provides the experimental details and characterization data.

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27

Lu, Pengfei. "Aziridine-metathesis based approaches to alkaloid synthesis." Thesis, Imperial College London, 2009. http://hdl.handle.net/10044/1/4392.

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The aim of the project is to synthesise (–)-morphine utilising aziridine and metathesis chemistry. The thesis is divided into three chapters. Chapter 1 provides brief reviews on the subjects of total synthesis of morphine; ringrearrangement metathesis (RRM) and regioselective ring-opening of aziridines. Chapter 2 focuses on the research findings in the past three years. Two routes, A and B, were investigated in attempts to synthesise morphine (Scheme 1). In route A, sulfonyl cyclopentene II was prepared from ring-closing metathesis of a diene precursor, which was synthesised from lithiated cinnamylsulfone and butadiene monoxide. Subsequently, RRM reactions of several α-SO2Ph allyl derivatives of II were investigated and some interesting results were obtained. The synthesis of 2,3-trans vinylaziridine III was achieved in seven steps beginning with a Grignard reaction of (4- methoxyphenyl)magnesium bromide with butadiene monoxide. Subsequently, some highly regioselective ring-opening reactions of III with sulfur-stabilised anionic nucleophiles were achieved. However, in an attempt to synthesise compound I from II and III, no reaction was observed. This led to the investigation of route B, in which five methods for the synthesis of compound IV were investigated. The practical approach deployed a novel Al-mediated substitution of the 4-tosyl group of the tosyl tetrahydropyridine counterpart of IV, prepared from V and III, with a phenylthio group. Chapter 3 provides the experimental details and characterisation data.

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Lam, Kwun Ting. "Chiral acetylenic sulfoxide in asymmetric alkaloid synthesis." HKBU Institutional Repository, 2004. http://repository.hkbu.edu.hk/etd_ra/509.

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Conrad, Rosemary McCutcheon. "Synthetic studies on the norditerpenoid alkaloid aconitine /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.

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Crapnell, Katherine Mary. "Preparation of polycyclic amines and studies towards manzamine." Thesis, University of Exeter, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324717.

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31

Gericke, N., and AM Viljoen. "Sceletium—A review update." Elsevier, 2008. http://encore.tut.ac.za/iii/cpro/DigitalItemViewPage.external?sp=1000168.

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It is probable that plants of the genus Sceletium (Mesembryanthemaceae) have been used as masticatories and for the relief of thirst and hunger, to combat fatigue, as medicines, and for social and spiritual purposes by San hunter-gatherers (historically referred to as Bushmen) and Khoi pastoralists (historically referred to as Hottentots) for millennia before the earliest written reports of the uses of these plants by European explorers and settlers. The oral-tradition knowledge of the uses of Sceletium by indigenous peoples has largely been eroded over the last three centuries due to conflicts with settlers, genocidal raids against the San, loss of land, the ravages of introduced diseases, and acculturation. Wild resources of Sceletium have also been severely diminished by over-harvesting, poor veld-management, and possibly also by plant diseases. Sceletium was reviewed almost a decade ago and new results have emerged substantiating some of the traditional uses of one of South Africa’s most coveted botanical assets, and suggesting dietary supplement, phytomedicine and new drug applications. This review aims to collate the fragmented information on past and present uses, the alkaloid chemistry and pharmacological evidence generated on Sceletium.

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Leach, Stuart Grahame. "Diversity-Oriented Synthesis of Alkaloid-like Unnatural Products." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.485593.

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This thesis describes the development of a novel methodology to allow the synthesis of skeletally diverse alkaloid-like unnatural compounds. Enantiomerically enriched building blocks are iteratively assembled onto a purification handle using reliable coupling reactions. Subsequently, ring-opening-ring-closing metathesis cascade reactions are used as a complexity generating step to restitch the molecular framework. Chapter 1 introduces the concept of diversity-oriented synthesis, with particular emphasis on strategies used to introduce skeletal diversity. The conceptual idea behind the project is explained, and placed into context using leading examples as the benchmark for success in diversity-oriented synthesis. Chapter 2 describes the synthesis of a range of building blocks, many of which are enantiomerically enriched, on multigram scale. The design of a solid phase 'linker' is described in Chapter 3, as are the solution phase studies used to explore suitable methodologies to couple the building blocks. The use of solid phase chemistry is described in Chapter 4, as well as the use of light fluorous tags as an alternative purification handle. Chapter 5 describes the synthesis and subsequent metathesis of a range of fluorous-tagged metathesis substrates using one building block iteration. The Thesis concludes with the preparation of 45 metathesis precursors using combinations of two building blocks assembled onto a fluoroustagged linker in Chapter 6. Metathesis cascades were carried out, allowing the isolation of 33 complex and skeletally diverse products.

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Murrison, Sarah Louise. "Diversity-oriented synthesis of polycyclic alkaloid-like compounds." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531520.

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34

Börger, Carsten, Micha P. Krahl, Margit Gruner, Olga Kataeva, and Hans-Joachim Knölker. "First total synthesis of the biscarbazole alkaloid oxydimurrayafoline." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-139201.

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We report the first total synthesis of oxydimurrayafoline via nucleophilic substitution at the benzylic position at C-3 of the carbazole framework
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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35

Owen, David Alan. "Aryl substituted cyclohexanienyl iron complexes in alkaloid synthesis." Thesis, University of East Anglia, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278063.

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36

Ouali, Dehimi. "Enantioselective synthesis of novel corynanthe indole alkaloid synthons." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315329.

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37

Barbey, Sabine. "A novel approach to the ergot alkaloid skeleton." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294855.

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38

Ho, Tim Chien Ting. "Novel applications of aryl radicals in alkaloid synthesis." Thesis, King's College London (University of London), 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264981.

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39

Salih, Rebin M. "Investigations of carbocyclisation reactions in prodiginine alkaloid biosynthesis." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/107843/.

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Prodiginine alkaloids, including streptorubin B, metacycloprodigiosin and roseophilin, are a family of red-pigmented pyrrole-containing specialised metabolites with immunosuppressive, anticancer and antimalarial properties. The final steps in streptorubin B and metacycloprodigiosn biosynthesis are oxidative carbocyclisations catalysed by Rieske oxygenases RedG and McpG respectively. These enzymes utilize the same substrate (undecylprodigiosin) to give cyclised products with different regio and stereochemistry. In order to further investigate the McpG catalysed reaction and to develop a system that could be used to probe the mechanism, mcpG was expressed in S. albus and S. coelicolor M511. Cyclic compound was observed following feeding of undecylprodigiosin to S. albus/mcpG. Since production was low, the role of McpH in forming a complex with McpG was investigated. Unfortunately, whilst McpH was shown to catalyse the condensation of 2-undeyclpyrrole (2-UP) and 4-methoxy-2, 2’ bipyrrole-5-carboxaldehyde (MBC), co-expression of mcpH with mcpG did not improve production of metacycloprodigiosin. Since whole genome sequencing showed that the mcpG expression construct originally used to prove the function of this gene contained a 5' truncation due to a sequencing error, full length mcpG was expressed in a redG mutant of S. coelicolor. This resulted in production of metacyloprodigiosin, which was confirmed by mass spectrometry and 1H and 13C NMR spectroscopy. The rph gene cluster reported to be responsible for the biosynthesis of prodigiosin R1 and roseophilin in S. griseoviridis contains four redG orthologues (rphG, rphG2, rphG3 and rphG4). Unfortunately, neither expression of the rphG genes in the redG mutant of S. coelicolor, nor the feeding of 11-methyldodecylprodigiosin to S. albus separately expressing each of the rphG genes resulted in the production of carbocylic products. Bioinformatics analysis of the S. longispororuber genome sequence revealed several cryptic natural product biosynthetic gene clusters. The likely products of some of these clusters are discussed in the light of predictive sequence analysis.

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40

Ronan, Jade L. "Elucidating molecular mechanisms of actinobacterial polyketide alkaloid biosynthesis." Thesis, University of Warwick, 2017. http://wrap.warwick.ac.uk/97197/.

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Coelimycin P1 is a yellow-pigmented alkaloid with a unique 1,5-oxathiocane ring, produced by Streptomyces coelicolor M145. Recently, it was demonstrated that a type I modular polyketide synthase (PKS) with a C-terminal thioester reductase (TR) domain is involved in its assembly. Due to its unusual biosynthetic origin, unprecedented structure and the antibiotic activity likely associated with coelimycin A, its biosynthesis is of great interest. To investigate the roles of the putative post-PKS tailoring enzymes (CpkG, CpkH, CpkD, ScF, CpkE and CpkI), the recombinant proteins were overproduced in E. coli, purified and incubated with various commercial and synthetic substrates. CpkG was characterised as an (S)-selective ω-transaminase with a broad substrate tolerance, responsible for the incorporation of nitrogen into the six-membered ring of coelimycin P1. Crystal structures of CpkG revealed a rare tri-domain architecture, key active site residues and provided insight into the transamination mechanism. CpkH, CpkD and ScF were all subsequently characterised as flavoproteins. Specifically, CpkH was demonstrated to catalyse an (R)-specific FAD-dependent dehydrogenation, while CpkD was shown to catalyse two FMN-dependent epoxidations. The roles of ScF, CpkE and CpkI in coelimycin biosynthesis remain to be elucidated. Bioinformatics searches identified 22 additional actinobacterial gene clusters, which also encode modular PKSs with a TR domain and a homologue of CpkG. These have been predicted to direct the biosynthesis of both known and novel polyketide alkaloids, suggesting that reductive chain release and transamination constitute a conserved mechanism for the biosynthesis of such metabolites.

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Hatzios, Stavroula K. (Stavroula-Artemis K. ). "Human alkaloid biosynthesis : chemical inducers of Parkinson's disease?" Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/36162.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.
Includes bibliographical references (leaves 26-29).
The occurrence of certain alkaloids in the human brain appears to be associated with the onset of Parkinson's disease (PD). Recently, a human protein bearing homology to an alkaloid synthase in plants was identified. This protein, termed BSCv, may catalyze alkaloid formation in humans. If such activity is confirmed, regulation of BSCv through the use of small molecule inhibitors could provide novel drug therapies for PD patients. This paper describes the first heterologous expression and purification of this transmembrane protein and examines its biological function through a series of enzyme assays. The assays used to evaluate enzyme activity were modeled after the Pictet-Spengler condensation catalyzed by the plant enzyme. Substrates were selected based on their potential to form alkaloids previously identified in central nervous system tissue. Product formation was monitored via high-performance liquid chromatography. Preliminary data suggest that BSCv does not function as an alkaloid synthase. However, further studies are needed to ascertain such conclusions. Alternative detergents should be evaluated to assess their influence on enzyme activity. The use of an expanded substrate pool may also provide insight into protein function since substrate specificity may have restricted product formation in the performed assays. Finally, incubation of BSCv with rat brain extract, which contains another species homologue of the protein, could provide insight into its natural substrates. If these studies are unsuccessful, consideration should be given to the possibility that BSCv may function as a receptor. Once the mechanistic and structural properties of the plant enzyme are elucidated, it may be possible to take a more direct approach to the characterization of its human homologue.
by Stavroula K. Hatzios.
S.B.

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Pett, Richard. "Total synthesis of the macroline-related alkaloid (±)-alstonerine." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/17842.

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This thesis examines the total synthesis of the macroline-related indole alkaloid alstonerine and related compounds. It is divided into three sections: The first section provides a review of the total synthesis efforts reported by Cook, Martin, Kuethe, and Kwon, as well previous work within the Craig group. The second section discusses the results of our investigations. The optimisation of the synthesis of key intermediate α,β-unsaturated lactam alcohol via directed-aziridine ring-opening is presented in detail. Our progress towards the synthesis of macroline-related alkaloids macroline, alstolactone, anhydromacrosalhine-methine and alstonerinal, as well as their N4-tosyl derivatives, from the key intermediate is discussed. The findings from these studies are presented en route to the total synthesis of alstonerine. The third section contains experimental procedures and characterisation data for compounds synthesised.

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43

Collinge, Margaret Ann. "Tropane alkaloid production in immobilized plant cell cultures." Thesis, University of Edinburgh, 1987. http://hdl.handle.net/1842/16965.

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44

Börger, Carsten, Micha P. Krahl, Margit Gruner, Olga Kataeva, and Hans-Joachim Knölker. "First total synthesis of the biscarbazole alkaloid oxydimurrayafoline." Royal Society of Chemistry, 2012. https://tud.qucosa.de/id/qucosa%3A27812.

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We report the first total synthesis of oxydimurrayafoline via nucleophilic substitution at the benzylic position at C-3 of the carbazole framework.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

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45

Jaunbergs, Janis. "AROMATIC RADICAL CATION COUPLING IN BIOMIMETIC ALKALOID SYNTHESIS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1024673469.

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Irie, Kazuhiro. "STRUCTURE-ACTIVITY STUDIES OF INDOLE ALKALOID TUMOR PROMOTERS." Kyoto University, 1988. http://hdl.handle.net/2433/78193.

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47

Brown, Ammon W. "Relative Toxicity of Select Dehydropyrrolizidine Alkaloids and Evaluation of a Heterozygous P53 Knockout Mouse Model for Dehydropyrrolizidine Alkaloid Induced Carcinogenesis." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4519.

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Dehydropyrrolizidine alkaloids (DHPAs) are a large group of globally important plant-derived pro-toxins that can contaminate or are naturally present in animal feed and the human food supply as well as herbal supplements. Their bioactive metabolites are potentially hepatotoxic, pneumotoxic, genotoxic and carcinogenic. Due to the difficulty in obtaining sufficient quantities of purified DHPAs, toxicity studies have largely relied on single intraperitoneal injections in rodent models, and carcinogenicity studies have been limited to a small handful of the hundreds of isolated DHPAs. To assess the relative toxicity of structurally diverse DHPAs in a more biologically relevant manner, male California White chicks were dosed orally with 0.01, 0.04, 0.13, or 0.26 mmol of seven different DHPAs and three DHPA N-oxides kg-1 bodyweight for 7 days. DHPAs were grouped in relation to their toxicity based on clinical, serum biochemical, and histopathological evaluations as well as tissue adduct accumulation rates. Using the same model, a reduced extract from comfrey, a commonly used DHPA containing herb, was compared to its two major constituent DHPAs, intermedine and lycopsamine. Based on the same parameters, the comfrey extract was more toxic than pure lycopsamine or intermedine. Addressing the need for a more sensitive carcinogenicity model, male heterozygous p53 knockout mice were treated with riddelliine 5, 15 or 45 mg kg–1 bodyweight day-1 by oral gavage for 14 days, or given a long-term treatment of riddelliine 1 mg kg-1 bodyweight day–1 in pelleted feed for 12 months. Exposure to riddelliine increased the odds of tumor development in a dose-responsive manner (odds ratio 2.05 and Wald 95% confidence limits between 1.2 and 3.4). The most common neoplasm was hepatic hemangiosarcoma, which is consistent with previously published lifetime rodent studies. The results of this research demonstrate that the California White chick model is sensitive for comparison of DHPA toxicity, and data obtained from this research can be used to validate previous DHPA toxicity research. It also demonstrates that comfrey toxicity may have been previously underestimated. The heterozygous p53 knockout mouse model is beneficial for further investigation of comparative carcinogenesis of structurally and toxicologically different DHPAs and their N-oxides.

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Gassner, Cemena, Ronny Hesse, Arndt W. Schmidt, and Hans-Joachim Knölker. "Total synthesis of the cyclic monoterpenoid pyrano[3,2-a]carbazole alkaloids derived from 2-hydroxy-6-methylcarbazole." Royal Society of Chemistry, 2014. https://tud.qucosa.de/id/qucosa%3A28532.

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Fortune, Grady Thomas Jr. "Structure-activity relationships in semisynthetic pyrrolizidine alkaloid antitumor agents." Diss., Georgia Institute of Technology, 1989. http://hdl.handle.net/1853/27371.

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Machado, Caroline. "STUDIES OF ERGOT ALKALOID BIOSYNTHESIS GENES IN CLAVICIPITACEOUS FUNGI." UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_diss/433.

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Neotyphodium species, endophytic fungi associated with cool-season grasses, enhance host fitness and stress tolerance, but also produce biologically active alkaloids including ergot alkaloids associated with fescue toxicosis in grazing animals. One approach to reduce fescue toxicosis is to manipulate genes in the ergot alkaloid pathway. The gene, dmaW, encoding the first pathway-specific step in ergot alkaloid biosynthesis, was cloned previously from Claviceps spp. and its function was demonstrated by expression in yeast. Putative homologs have been cloned from Neotyphodium coenophialum (from tall fescue) and Neotyphodium sp. Lp1 (from perennial ryegrass). In order to confirm the function of dmaW in ergot alkaloid production, dmaW in Neotyphodium sp. isolate Lp1 was knocked out by gene replacement. The dmaW knockout mutant produced no detectable ergovaline or simpler ergot alkaloids. Complementation with Claviceps fusiformis dmaW restored ergovaline production. These results confirmed that the cloned endophyte gene was dmaW, and represented the first genetic experiments to show the requirement of dmaW for ergot alkaloid biosynthesis. Neotyphodium coenophialum, endophyte of the grass tall fescue (Lolium arundinaceum) has two homologs of dmaW. Considering the possible field applications in future, the Cre/lox site-specific recombination system was chosen because of the potential to sequentially knock out both homologs and obtain marker-free dmaW mutants of N. coenophialum. One homolog, dmaW-2, was disrupted by marker exchange, and the marker was eliminated by Cre, thus demonstrating the application of Cre/lox system in N. coenophialum to eliminate a marker gene. The dmaW-2 knockout did not eliminate ergovaline production, indicating that the dmaW-1 was probably also active in N. coenophialum. A putative ergot alkaloid biosynthesis gene cluster was identified in Claviceps purpurea and C. fusiformis. C. purpurea and C. fusiformis produce different subsets of ergot alkaloids. Identification of nine common genes between them suggests the possible role of these genes in the early part of the ergot alkaloid biosynthetic pathway.

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Dissertations / Theses on the topic 'Alkaloid'

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