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Richardson AT, Cameron RC, Stevenson LJ, Singh AJ, Lukito Y, Berry D, Nicholson MJ, Parker EJ. Biosynthesis of Nodulisporic Acids: A Multifunctional Monooxygenase Delivers a Complex and Highly Branched Array. Angew Chem Int Ed Engl 2022; 61:e202213364. [PMID: 36199176 PMCID: PMC10098816 DOI: 10.1002/anie.202213364] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Indexed: 11/11/2022]
Abstract
Nodulisporic acids (NAs) are structurally complex potent antiinsectan indole diterpenes. We previously reported the biosynthetic gene cluster for these metabolites in Hypoxylon pulicicidum and functionally characterised the first five steps of the biosynthetic pathway. Here we reveal a highly complex biosynthetic array, furnishing multiple end products through expression of cluster components in Penicillium paxilli. We show that seven additional cluster-encoded gene products comprise the biosynthetic machinery that elaborate precursor NAF in this highly branched pathway. The combined action of these enzymes delivers 37 NA congeners including four major end products, NAA, NAA1 , NAA2 and NAA4 . The plethora of intermediates arises due to modification of the carboxylated prenyl tail by a single promiscuous P450 monooxygenase, NodJ, a pivotal branchpoint enzyme which produces four distinct biosynthetic products giving rise to the complex metabolic grid that characterises NA biosynthesis.
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Affiliation(s)
- Alistair T. Richardson
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
| | - Rosannah C. Cameron
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
| | - Luke J. Stevenson
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
| | - A. Jonathan Singh
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
| | - Yonathan Lukito
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
| | - Daniel Berry
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
| | - Matthew J. Nicholson
- Wellington Univentures Victoria University of Wellington Wellington 6012 New Zealand
| | - Emily J. Parker
- Ferrier Research Institute Victoria University of Wellington Wellington 6012 New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery New Zealand
- Centre for Biodiscovery School of Biological Sciences Victoria University of Wellington Wellington 6012 New Zealand
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2
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Zou Y, Li X, Yang Y, Berritt S, Melvin J, Gonzales S, Spafford M, Smith AB. Total Synthesis of (-)-Nodulisporic Acids D, C, and B: Evolution of a Unified Synthetic Strategy. J Am Chem Soc 2018; 140:9502-9511. [PMID: 30028603 PMCID: PMC6085755 DOI: 10.1021/jacs.8b04053] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A unified synthetic strategy leading to the total synthesis of (-)-nodulisporic acids D, C, and B is described. Key synthetic transformations include a nickel-chromium-mediated cyclization, an aromatic ring functionalization employing a novel copper-promoted alkylation, a palladium-catalyzed cross-coupling cascade/indole ring construction, and a palladium-mediated regio- and diastereoselective allylic substitution/cyclization reaction, the latter to construct ring D.
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Affiliation(s)
- Yike Zou
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Xiangqin Li
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Yun Yang
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Simon Berritt
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Jason Melvin
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Stephen Gonzales
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Matthew Spafford
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Amos B. Smith
- Department of Chemistry, Laboratory for Research on the Structure of Matter, and Monell Chemical Senses Center, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
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3
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Bills GF, González-Menéndez V, Martín J, Platas G, Fournier J, Peršoh D, Stadler M. Hypoxylon pulicicidum sp. nov. (Ascomycota, Xylariales), a pantropical insecticide-producing endophyte. PLoS One 2012; 7:e46687. [PMID: 23056404 PMCID: PMC3467290 DOI: 10.1371/journal.pone.0046687] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Accepted: 08/30/2012] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Nodulisporic acids (NAs) are indole diterpene fungal metabolites exhibiting potent systemic efficacy against blood-feeding arthropods, e.g., bedbugs, fleas and ticks, via binding to arthropod specific glutamate-gated chloride channels. Intensive medicinal chemistry efforts employing a nodulisporic acid A template have led to the development of N-tert-butyl nodulisporamide as a product candidate for a once monthly treatment of fleas and ticks on companion animals. The source of the NAs is a monophyletic lineage of asexual endophytic fungal strains that is widely distributed in the tropics, tentatively identified as a Nodulisporium species and hypothesized to be the asexual state of a Hypoxylon species. METHODS AND RESULTS Inferences from GenBank sequences indicated that multiple researchers have encountered similar Nodulisporium endophytes in tropical plants and in air samples. Ascomata-derived cultures from a wood-inhabiting fungus, from Martinique and closely resembling Hypoxylon investiens, belonged to the same monophyletic clade as the NAs-producing endophytes. The hypothesis that the Martinique Hypoxylon collections were the sexual state of the NAs-producing endophytes was tested by mass spectrometric analysis of NAs, multi-gene phylogenetic analysis, and phenotypic comparisons of the conidial states. We established that the Martinique Hypoxylon strains produced an ample spectrum of NAs and were conspecific with the pantropical Nodulisporium endophytes, yet were distinct from H. investiens. A new species, H. pulicicidum, is proposed to accommodate this widespread organism. CONCLUSIONS AND SIGNIFICANCE Knowledge of the life cycle of H. pulicicidum will facilitate an understanding of the role of insecticidal compounds produced by the fungus, the significance of its infections in living plants and how it colonizes dead wood. The case of H. pulicicidum exemplifies how life cycle studies can consolidate disparate observations of a fungal organism, whether from environmental sequences, vegetative mycelia or field specimens, resulting in holistic species concepts critical to the assessment of the dimensions of fungal diversity.
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Affiliation(s)
- Gerald F Bills
- Fundación MEDINA, Centro de Excelencia en Investigación de Medicamentos Innovadores en Andalucía, Parque Tecnológico de Ciencias de la Salud, Armilla, Granada, Spain.
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4
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Meinke PT, Colletti SL, Fisher MH, Wyvratt MJ, Shih TL, Ayer MB, Li C, Lim J, Ok D, Salva S, Warmke LM, Zakson M, Michael BF, Demontigny P, Ostlind DA, Fink D, Drag M, Schmatz DM, Shoop WL. Discovery of the development candidate N-tert-butyl nodulisporamide: a safe and efficacious once monthly oral agent for the control of fleas and ticks on companion animals. J Med Chem 2009; 52:3505-15. [PMID: 19445514 DOI: 10.1021/jm801334v] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nodulisporic acid A (1) is a structurally complex fungal metabolite that exhibits systemic efficacy against fleas via modulation of an invertebrate specific glutamate-gated ion channel. In order to identify a nodulisporamide suitable for monthly oral dosing in dogs, a library of 335 nodulisporamides was examined in an artificial flea feeding system for intrinsic systemic potency as well as in a mouse/bedbug assay for systemic efficacy and safety. A cohort of 66 nodulisporamides were selected for evaluation in a dog/flea model; pharmacokinetic analysis correlated plasma levels with flea efficacy. These efforts resulted in the identification of the development candidate N-tert-butyl nodulisporamide (3) as a potent and efficacious once monthly oral agent for the control of fleas and ticks on dogs and cats which was directly compared to the topical agents fipronil and imidacloprid, with favorable results obtained. Multidose studies over 3 months confirmed the in vivo ectoparasiticidal efficacy and established that 3 lacked overt mammalian toxicity. Tissue distribution studies in mice using [(14)C]-labeled 3 indicate that adipose beds serve as ligand depots, contributing to the long terminal half-lives of these compounds.
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Affiliation(s)
- Peter T Meinke
- Merck Research Laboratories, Rahway, NJ 07065-0900, USA.
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5
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Concellón JM, Rodríguez-Solla H, Díaz P. Sequential Reactions Promoted by Manganese: Completely Stereoselective Synthesis of (E)-α,β-Unsaturated Amides, Ketones, Aldehydes, and Carboxylic Acids. J Org Chem 2007; 72:7974-9. [PMID: 17887705 DOI: 10.1021/jo701417z] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A complete E-selective synthesis of alpha,beta-unsaturated amides through a sequential reaction of a range of dichloroamides with a variety of aldehydes promoted by Rieke manganese (Mn*) is reported. A mechanism based on a sequential aldol-type reaction and a completely stereoselective beta-elimination is proposed to explain these results. The unsaturated amides obtained are readily and efficiently transformed into alpha,beta-unsaturated ketones, aldehydes, or carboxylic acids without loss of the diastereoisomeric purity of the C-C double bond.
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Affiliation(s)
- José M Concellón
- Departamento de Química Orgánica e Inorgánica, Universidad de Oviedo, Julián Clavería 8, 33071 Oviedo, Spain.
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6
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Feuillet FJP, Cheeseman M, Mahon MF, Bull SD. Stereoselective synthesis of (E)-trisubstituted α,β-unsaturated amides and acids. Org Biomol Chem 2005; 3:2976-89. [PMID: 16186928 DOI: 10.1039/b503633j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Potassium alkoxides of N-acyl-oxazolidin-2-one-syn-aldols undergo stereoselective elimination reactions to afford a range of trisubstituted (E)-alpha,beta-unsaturated amides in >95% de, that may be subsequently converted into their corresponding (E)-alpha,beta-unsaturated acids or (E)-alpha,beta-unsaturated oxazolines in good yield. syn-Aldols derived from alpha,beta-unsaturated aldehydes gave their corresponding trisubstituted (E)-alpha,beta-unsaturated-amides with poorer levels of diastereocontrol, whilst there was a similar loss in (E)-selectivity during elimination of syn-aldols derived from chiral aldehydes. These elimination reactions proceed via rearrangement of the potassium alkoxide of the syn-aldol to a 1,3-oxazinane-2,4-dione enolate intermediate that subsequently eliminates carbon dioxide to afford a trisubstituted (E)-alpha,beta-unsaturated amide. The (E)-selectivity observed during the E1cB-type elimination step has been rationalised using a simple conformational model that employs a chair-like transition state to explain the observed stereocontrol.
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7
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Singh SB, Ondeyka JG, Jayasuriya H, Zink DL, Ha SN, Dahl-Roshak A, Greene J, Kim JA, Smith MM, Shoop W, Tkacz JS. Nodulisporic acids D-F: structure, biological activities, and biogenetic relationships. JOURNAL OF NATURAL PRODUCTS 2004; 67:1496-1506. [PMID: 15387649 DOI: 10.1021/np0498455] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nodulisporic acids D, E, and F are the newest members of a family of nontremorogenic indole-diterpenoids that are potent, orally bioavailable, antiflea agents derived from a fungus belonging to the genus Nodulisporium. The four members of the D series are each devoid of an isoprene residue that is present at C-26 in the three nodulisporic acids described originally (the A series). Nodulisporic acid E (11a) has a simpler structure, which lacks not only the isoprene residue at C-26 but also two that form the A/B rings. Nodulisporic acid F is the simplest of all nodulisporic acids and is devoid of all three isoprene residues of the indole unit; as such, it represents the earliest biosynthetic intermediate in this series. A biogenetic grid based on mutation studies is proposed that encompasses all the known nodulisporic acids. Structure-activity relationships of the known natural nodulisporic acids have been elucidated. Within a series the most active compound possesses a dienoic acid chain, and overall, the end product of the biogenetic grid, i.e., nodulisporic acid A, exhibits the most potent antiflea activity. Additionally, the stereochemistries of C-3' ' and C-4' ' of nodulisporic acid D(2) and therefore of nodulisporic acids A(2), B(2), and C(2) have been assigned.
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Affiliation(s)
- Sheo B Singh
- Merck Research Laboratories, P.O. Box 2000, Rahway, New Jersey 07065, USA.
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8
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Chakravarty PK, Shih TL, Colletti SL, Ayer MB, Snedden C, Kuo H, Tyagarajan S, Gregory L, Zakson-Aiken M, Shoop WL, Schmatz DM, Wyvratt M, Fisher MH, Meinke PT. Nodulisporic acid side-chain modifications: access to the 2", 3", 4", and 6" registers. Bioorg Med Chem Lett 2003; 13:147-50. [PMID: 12467636 DOI: 10.1016/s0960-894x(02)00826-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Efficient routes to access the 2", 3", 4", and 6" registers of the nodulisporic acid (NsA) side chain are disclosed. A mild one-carbon, Ph(2)CdoublebondNCH(2)CtriplebondN mediated homologation of NsA's 3"-aldehyde permitted access to the 4"-register. Curtius reaction of NsA's 3"-acid yielded the corresponding 2"-aldehyde 4 from which the unnatural Delta(2",3")-olefin isomer 2b was obtained. In addition, Arndt-Eistert reactions of the parent NsA permitted a one-carbon homologation to the 6" register. These efforts identified new analogues with significant flea activity and illustrated the biological significance of unsaturation at the 1",2" register.
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Affiliation(s)
- Prasun K Chakravarty
- Merck Research Laboratories, PO Box 2000, RY800-B101, Rahway, NJ 07065-0900, USA
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9
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Sings H, Singh S. Tremorgenic and nontremorgenic 2,3-fused indole diterpenoids. THE ALKALOIDS. CHEMISTRY AND BIOLOGY 2003; 60:51-163. [PMID: 14593856 DOI: 10.1016/s0099-9598(03)60002-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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10
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Ondeyka JG, Dahl-Roshak AM, Tkacz JS, Zink DL, Zakson-Aiken M, Shoop WL, Goetz MA, Singh SB. Nodulisporic acid B, B1, and B2: a series of 1′-deoxy-nodulisporic acids from Nodulisporium sp. Bioorg Med Chem Lett 2002; 12:2941-4. [PMID: 12270179 DOI: 10.1016/s0960-894x(02)00621-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
During the re-isolation of the lead compound nodulisporic acid A (1a) and targeted chemical screening for related compounds, we discovered a series of 1'-deoxy congeners named herein nodulisporic acids B (1b), B1 (2b), and B2 (3b). In comparison with nodulisporic acid A, these compounds were less active and were chemically unstable resulting into formation of delta23 dehydro derivatives. Therefore, these compounds were stabilized and isolated as sodium salts and methyl ester. Nodulisporic acid B is 100-fold less active than nodulisporic acid A against fleas. The isolation, structure elucidation, and biological activities of these compounds are described.
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Affiliation(s)
- John G Ondeyka
- Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA.
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11
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Ok D, Li C, Shih TL, Salva S, Ayer MB, Colletti SL, Chakravarty PK, Wyvratt MJ, Fisher MH, Gregory L, Zakson-Aiken M, Shoop WL, Schmatz DM, Meinke PT. Side-chain homologation of nodulisporic acid: synthesis of potent new dienyl derivatives. Bioorg Med Chem Lett 2002; 12:1751-4. [PMID: 12067553 DOI: 10.1016/s0960-894x(02)00284-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
A series of new, diene-modified nodulisporic acid analogues (2) bearing diverse functionality at the 3"- and 4"-sites was efficiently prepared from the 3"-aldehyde 3. Biological evaluation of these synthetic nodulisporic acid analogues for systemic flea efficacy identified potent compounds and further clarified the structural requirements for ectoparasite activity.
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Affiliation(s)
- Dong Ok
- Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065-0900, USA
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12
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Ludmerer SW, Warren VA, Williams BS, Zheng Y, Hunt DC, Ayer MB, Wallace MA, Chaudhary AG, Egan MA, Meinke PT, Dean DC, Garcia ML, Cully DF, Smith MM. Ivermectin and nodulisporic acid receptors in Drosophila melanogaster contain both gamma-aminobutyric acid-gated Rdl and glutamate-gated GluCl alpha chloride channel subunits. Biochemistry 2002; 41:6548-60. [PMID: 12009920 DOI: 10.1021/bi015920o] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
35S-labeled derivatives of the insecticides nodulisporic acid and ivermectin were synthesized and demonstrated to bind with high affinity to a population of receptors in Drosophila head membranes that were previously shown to be associated with a glutamate-gated chloride channel. Nodulisporic acid binding was modeled as binding to a single population of receptors. Ivermectin binding was composed of at least two kinetically distinct receptor populations, only one of which was associated with nodulisporic acid binding. The binding of these two ligands was modulated by glutamate, ivermectin, and antagonists of invertebrate gamma-aminobutyric acid (GABA)ergic receptors. Because solubilized nodulisporic acid and ivermectin receptors comigrated as 230-kDa complexes by gel filtration, antisera specific for both the Drosophila glutamate-gated chloride channel subunit GluCl alpha (DmGluCl alpha) and the GABA-gated chloride channel subunit Rdl (DmRdl) proteins were generated and used to examine the possible coassembly of these two subunits within a single receptor complex. DmGluCl alpha antibodies immunoprecipitated all of the ivermectin and nodulisporic acid receptors solubilized by detergent from Drosophila head membranes. DmRdl antibodies also immunoprecipitated all solubilized nodulisporic receptors, but only approximately 70% of the ivermectin receptors. These data suggest that both DmGluCl alpha and DmRdl are components of nodulisporic acid and ivermectin receptors, and that there also exists a distinct class of ivermectin receptors that contains the DmGluCl alpha subunit but not the DmRdl subunit. This co-association of DmGluCl alpha and DmRdl represents the first biochemical and immunological evidence of coassembly of subunits from two different subclasses of ligand-gated ion channel subunits.
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Affiliation(s)
- Steven W Ludmerer
- Department of Parasite Biochemistry and Molecular Biology, Merck Research Laboratories, Rahway, New Jersey 07065, USA
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13
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Chakravarty PK, Tyagarajan S, Shih TL, Salva S, Snedden C, Wyvratt MJ, Fisher MH, Meinke PT. Synthesis of side chain truncated 3"-aldehyde, 3"-carboxylic acid, and 1"-aldehyde from nodulisporic acid A. Org Lett 2002; 4:1291-4. [PMID: 11950345 DOI: 10.1021/ol025766d] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An efficient synthesis of the truncated 3"-aldehyde (3) from nodulisporic acid A (1) under mild conditions is described. Further oxidation of 3 to 3"-carboxylic acid (4) and its subsequent oxidative degradation produced 1"-aldehyde (5). These new derivatives are versatile intermediates for the preparation of new, side chain modified derivatives of nodulisporic acid A. [reaction: see text]
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Affiliation(s)
- Prasun K Chakravarty
- Department of Medicinal Chemistry, Merck Research Laboratories, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065-0900, USA.
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14
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Felcetto T, Ondeyka J, Colletti SL, Meinke PT, Shoop WL. Comparison of nodulisporic acid analogs in a Lucilia sericata in vitro assay and a Ctenocephalides felis membrane feeding system. J Parasitol 2002; 88:223-6. [PMID: 12053989 DOI: 10.1645/0022-3395(2002)088[0223:conaai]2.0.co;2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
A medicinal chemistry program on the nodulisporic acid chemical class, guided by an artificial membrane flea-feeding assay, has recently identified permissive and nonpermissive regions of the pharmacophore for exploitation against fleas. This pathway was validated when several promising compounds from this program were administered orally to dogs at 15.0 mg/kg and found to have >90% flea activity for 2 wk. To determine if a surrogate insect assay would have provided the same guidance, a nodulisporic acid analog series was examined in both a Lucilia sericata larval assay and an artificial membrane flea-feeding assay using Ctenocephalides felis. Results from both insect assays were concordant in that even subtle chemical modification or substitution to the left-hand side of the nodulisporic acid pharmacophore resulted in substantial loss of insecticidal activity. Both assays were also in general agreement that the only modifications to the pharmacophore that did not result in loss of activity occurred to the C-8 side chain on the right-hand side of the molecule. Although there was good agreement between the 2 assays on the general regions of the pharmacophore, there was variance on individual compounds in the mono- and disubstituted amide series from the C-8 side chain. For example, the L. sericata assay showed several analogs from this subclass to possess similar activity to the parent acid, whereas the membrane assay indicated superior activity against fleas relative to the same parent. Consequently, although there was substantial general agreement between the assays, it was concluded that finer optimization of a lead compound should be done against the target parasite, even if it is ex vivo, as early as possible in a medicinal chemistry program.
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Affiliation(s)
- T Felcetto
- Merck Research Laboratories, Merck and Co., Inc., Rahway, New Jersey 07065, USA
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15
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Smith AB, Cho YS, Ishiyama H. Nodulisporic acid A synthetic studies. 2. Construction of an eastern hemisphere subtarget. Org Lett 2001; 3:3971-4. [PMID: 11720582 DOI: 10.1021/ol016888t] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this, the second of two Letters, we describe an effective assembly of (+)-4, an eastern hemisphere subtarget comprising the FGH rings of (+)-nodulisporic acid A (1) (17 steps, 9% overall yield). Central to the synthesis is a Koga three-component conjugate addition-alkylation sequence which secures the trans orientation of the vicinal quaternary methyl groups. [reaction: see text]
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Affiliation(s)
- A B Smith
- Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104, USA.
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16
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Berger R, Shoop WL, Pivnichny JV, Warmke LM, Zakson-Aiken M, Owens KA, deMontigny P, Schmatz DM, Wyvratt MJ, Fisher MH, Meinke PT, Colletti SL. Synthesis of nodulisporic acid 2' '-oxazoles and 2' '-thiazoles. Org Lett 2001; 3:3715-8. [PMID: 11700120 DOI: 10.1021/ol016651x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction--see text] The semisynthetic conversion of nodulisporic acid A (1) into a set of three heterocyclic side chain derivatives provided compounds, highlighted by 6, with an improved spectrum of ectoparasiticidal activity and pharmacokinetic profile relative to the natural product.
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Affiliation(s)
- R Berger
- Merck Research Laboratories, Merck & Co., Inc., Rahway, New Jersey 07065, USA
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17
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Shoop WL, Zakson-Aiken M, Gregory LM, Michael BF, Pivnichny J, Meinke PT, Fisher MH, Wyvratt MJ, Pikounis B, Schmatz DM. Systemic efficacy of nodulisporamides against fleas on dogs. J Parasitol 2001; 87:1150-4. [PMID: 11695382 DOI: 10.1645/0022-3395(2001)087[1150:seonaf]2.0.co;2] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Nodulisporic acid A (NSA) has been shown previously to be safe in dogs and to deliver >90% flea control for 4 days following a single oral administration. Three newly prepared nodulisporamide derivatives were subsequently identified from an artificial membrane flea feeding system as exhibiting potency substantially greater than NSA. To determine if they have superior in vivo activity, these 3 nodulisporamides, as well as NSA, were evaluated in dogs at 15 mg/kg/os. Parasite challenges were made by placing 100 live Ctenocephalides felis fleas onto the dorsum of dogs every 48 hr and examining efficacy at each of those intervals over a 22-day period. Results showed that NSA produced >90% efficacy at day 2 and 81% efficacy at day 4, and its residual flea killing fell to approximately 50% by day 6 posttreatment. All dogs treated with the 3 new experimental nodulisporamides were 100% protected from flea challenges to day 8 posttreatment, and 2 of the compounds continued to produce >90% residual activity to 2 wk posttreatment. Pharmacokinetic analysis showed that plasma profiles and half-lives of NSA and these 3 new compounds correlated closely with flea efficacy. These results demonstrate that specific substitutions to the pharmacophore of NSA can substantially increase the duration of activity against fleas.
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Affiliation(s)
- W L Shoop
- Merck Research Laboratories, Merck & Co., Inc., Rahway, New Jersey 07065, USA.
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Shoop WL, Gregory LM, Zakson-Aiken M, Michael BF, Haines HW, Ondeyka JG, Meinke PT, Schmatz DM. Systemic efficacy of nodulisporic acid against fleas on dogs. J Parasitol 2001; 87:419-23. [PMID: 11318575 DOI: 10.1645/0022-3395(2001)087[0419:seonaa]2.0.co;2] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Nodulisporic acid A (NSA) is a novel natural product from a new structural class that was shown previously to have insecticidal activity against blowfly larvae. To determine if there was useful systemic efficacy against fleas (Ctenocephalides felis). NSA was evaluated in an artificial membrane flea feeding device and in dogs. In the artificial membrane flea feeding device, adult C. felis were allowed to feed on bovine blood containing various concentrations of NSA through a Parafilm membrane. NSA killed the fleas with a 50% lethal concentration of 0.68 microg/ml and was approximately 10-fold more potent than the systemic insecticide ivermectin. In the initial probe dog test, a single beagle was challenged with 100 C. felis before oral dosing with 15 mg/kg of NSA. Flea counts conducted at 72 hr postdosing showed an 88% reduction relative to control. Re-challenge of the same dog at 5 days postdosing showed 50% reduction of fleas at day 7, demonstrating some residual flea activity. In a confirmatory study, 8 dogs were challenged with 100 fleas just before oral dosing with 15 mg/kg of NSA (4 dogs) or vehicle (4 dogs). There was 99% reduction of fleas at 48 hr postdosing in the NSA-treated dogs relative to control. Additional challenges with 100 fleas were performed on these 8 dogs at 48-hr intervals to determine the duration of efficacy, and there was 97, 51, and 0% reduction of fleas relative to control on days 4, 6, and 8, respectively. No adverse effects were observed in the dogs in these studies. These data show that NSA has potent oral activity in the dog for the control of fleas, while lacking overt mammalian toxicity.
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Affiliation(s)
- W L Shoop
- Merck Research Laboratories, Merck & Co, Inc, Rahway, New Jersey, USA
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Affiliation(s)
- P T Meinke
- Department of Medicinal Chemistry, Merck Research Laboratories, P.O. Box 2000, RY800-B101, Rahway, New Jersey 07065-0900, USA.
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Kane NS, Hirschberg B, Qian S, Hunt D, Thomas B, Brochu R, Ludmerer SW, Zheng Y, Smith M, Arena JP, Cohen CJ, Schmatz D, Warmke J, Cully DF. Drug-resistant Drosophila indicate glutamate-gated chloride channels are targets for the antiparasitics nodulisporic acid and ivermectin. Proc Natl Acad Sci U S A 2000; 97:13949-54. [PMID: 11095718 PMCID: PMC17681 DOI: 10.1073/pnas.240464697] [Citation(s) in RCA: 128] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The fruit fly Drosophila melanogaster was used to examine the mode of action of the novel insecticide and acaricide nodulisporic acid. Flies resistant to nodulisporic acid were selected by stepwise increasing the dose of drug in the culture media. The resistant strain, glc(1), is at least 20-fold resistant to nodulisporic acid and 3-fold cross-resistant to the parasiticide ivermectin, and exhibited decreased brood size, decreased locomotion, and bang sensitivity. Binding assays using glc(1) head membranes showed a marked decrease in the affinity for nodulisporic acid and ivermectin. A combination of genetics and sequencing identified a proline to serine mutation (P299S) in the gene coding for the glutamate-gated chloride channel subunit DmGluClalpha. To examine the effect of this mutation on the biophysical properties of DmGluClalpha channels, it was introduced into a recombinant DmGluClalpha, and RNA encoding wild-type and mutant subunits was injected into Xenopus oocytes. Nodulisporic acid directly activated wild-type and mutant DmGluClalpha channels. However, mutant channels were approximately 10-fold less sensitive to activation by nodulisporic acid, as well as ivermectin and the endogenous ligand glutamate, providing direct evidence that nodulisporic acid and ivermectin act on DmGluClalpha channels.
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Affiliation(s)
- N S Kane
- Merck Research Laboratories, Merck & Co., Inc., PO Box 2000, R80Y-250, Rahway, NJ 07065, USA
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