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Luck VL, Richards DP, Shaikh AY, Franzyk H, Mellor IR. The Effects of Structural Alterations in the Polyamine and Amino Acid Moieties of Philanthotoxins on Nicotinic Acetylcholine Receptor Inhibition in the Locust, Schistocerca gregaria. Molecules 2021; 26:molecules26227007. [PMID: 34834099 PMCID: PMC8622278 DOI: 10.3390/molecules26227007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/16/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022] Open
Abstract
Alterations in the polyamine and amino acid (tyrosine) moieties of philanthotoxin-343 (PhTX-343) were investigated for their effects on the antagonism of nicotinic acetylcholine receptors (nAChRs) isolated from the locust (Schistocerca gregaria) mushroom body. Through whole-cell patch-clamp recordings, the philanthotoxin analogues in this study were shown to cause inhibition of the inward current when co-applied with acetylcholine (ACh). PhTX-343 (IC50 = 0.80 μM at -75 mV) antagonised locust nAChRs in a use-dependent manner, suggesting that it acts as an open-channel blocker. The analogue in which both the secondary amine functionalities were replaced with methylene groups (i.e., PhTX-12) was ~6-fold more potent (IC50 (half-maximal inhibitory concentration) = 0.13 μM at -75 mV) than PhTX-343. The analogue containing cyclohexylalanine as a substitute for the tyrosine moiety of PhTX-343 (i.e., Cha-PhTX-343) was also more potent (IC50 = 0.44 μM at -75 mV). A combination of both alterations to PhTX-343 generated the most potent analogue, i.e., Cha-PhTX-12 (IC50 = 1.71 nM at -75 mV). Modulation by PhTX-343 and Cha-PhTX-343 fell into two distinct groups, indicating the presence of two pharmacologically distinct nAChR groups in the locust mushroom body. In the first group, all concentrations of PhTX-343 and Cha-PhTX-343 inhibited responses to ACh. In the second group, application of PhTX-343 or Cha-PhTX-343 at concentrations ≤100 nM caused potentiation, while concentrations ≥ 1 μM inhibited responses to ACh. Cha-PhTX-12 may have potential to be developed into insecticidal compounds with a novel mode of action.
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Affiliation(s)
- Victoria L. Luck
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; (V.L.L.); (D.P.R.)
| | - David P. Richards
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; (V.L.L.); (D.P.R.)
| | - Ashif Y. Shaikh
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark; (A.Y.S.); (H.F.)
| | - Henrik Franzyk
- Department of Drug Design and Pharmacology, University of Copenhagen, Jagtvej 162, 2100 Copenhagen, Denmark; (A.Y.S.); (H.F.)
| | - Ian R. Mellor
- School of Life Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK; (V.L.L.); (D.P.R.)
- Correspondence: ; Tel.: +44-1159-513257
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Kachel HS, Franzyk H, Mellor IR. Philanthotoxin Analogues That Selectively Inhibit Ganglionic Nicotinic Acetylcholine Receptors with Exceptional Potency. J Med Chem 2019; 62:6214-6222. [PMID: 31244109 DOI: 10.1021/acs.jmedchem.9b00519] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Philanthotoxin-433 (PhTX-433) is an active component of the venom from the Egyptian digger wasp, Philanthus triangulum. PhTX-433 nonselectively inhibits several excitatory ligand-gated ion channels, and we recently showed that its synthetic analogue, PhTX-343, exhibits strong selectivity for neuronal over muscle-type nicotinic acetylcholine receptors (nAChRs). Here, we examined the action of 17 analogues of PhTX-343 against ganglionic (α3β4) and brain (α4β2) nAChRs expressed in Xenopus oocytes by using a two-electrode voltage clamp at -100 mV. IC50 values for PhTX-343 inhibition of α3β4 and α4β2 receptors were 7.7 and 80 nM, respectively. All the studied analogues had significantly higher potency at α3β4 nAChRs with IC50 values as low as 0.16 nM and with up to 91-fold selectivity for α3β4 over α4β2 receptors. We conclude that PhTX-343 analogues displaying both a saturated ring and an aromatic moiety in the hydrophobic headgroup of the molecule demonstrate exceptional potency and selectivity for α3β4 nAChRs.
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Affiliation(s)
- Hamid S Kachel
- School of Life Sciences , University of Nottingham , University Park , Nottingham NG7 2RD , U.K
| | - Henrik Franzyk
- Department of Drug Design and Pharmacology , University of Copenhagen , Jagtvej 162 , Copenhagen DK-2100 , Denmark
| | - Ian R Mellor
- School of Life Sciences , University of Nottingham , University Park , Nottingham NG7 2RD , U.K
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Kachel HS, Buckingham SD, Sattelle DB. Insect toxins - selective pharmacological tools and drug/chemical leads. CURRENT OPINION IN INSECT SCIENCE 2018; 30:93-98. [PMID: 30553492 DOI: 10.1016/j.cois.2018.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 10/01/2018] [Indexed: 06/09/2023]
Abstract
Insect toxins comprise a diverse array of chemicals ranging from small molecules, polyamines and peptide toxins. Many target nervous system and neuromuscular ion channels and so rapidly affect the behaviour of animals to which the toxin is applied or injected. Other modes of action have also been identified. Wasps, bees, flies, beetles and ants generate a rich arsenal of channel-active toxins, some of which offer selective pharmacological probes that target particular ion channels, while others act on more than one type of channel. Philanthotoxins from the digger wasp have been fruitful in adding to our understanding of ligand-gated ion channels both in the nervous system and at neuromuscular junctions. Fire ants produce the toxic alkaloid solenopsin, a molecule which has stimulated attempts to generate synthetic compounds with insecticidal activity. Apamin from bee venom targets calcium-activated potassium channels, which can in turn influence the release of neuropeptides. Melittin, another bee venom component, is a membrane-acting peptide. The saliva of the assassin bug contains toxins that target the voltage-gated calcium channels of their insect prey. Certain beetles produce diamphotoxin, a haemolytic peptide toxin with traditional use as an arrow poison and others generate leptinotarsin with similar properties. Mastoparan is a powerful peptide toxin present in the venom of wasps. Its toxic actions can be engineered out leaving a potent antimicrobial molecule of interest. In this short review we describe the actions of selected insect toxins and evaluate their potential as neuroactive pharmacological tools, candidate lead molecules for insect control and therapeutic candidates with potential antimicrobial, antiviral and anti-cancer applications.
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Affiliation(s)
- Hamid S Kachel
- General Science Department, College of Basic Education, University of Zakho, Zakho, Kurdistan Region, Iraq
| | - Steven D Buckingham
- Centre for Respiratory Biology, UCL Respiratory, University College London, Rayne Building, 5 University Street, London WC1E 6JF, UK
| | - David B Sattelle
- Centre for Respiratory Biology, UCL Respiratory, University College London, Rayne Building, 5 University Street, London WC1E 6JF, UK.
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Franzyk H, Grzeskowiak JW, Tikhonov DB, Jaroszewski JW, Mellor IR. The effects of conformational constraints in the polyamine moiety of philanthotoxins on AMPAR inhibition. ChemMedChem 2014; 9:1725-31. [PMID: 25044789 DOI: 10.1002/cmdc.201402109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Indexed: 11/06/2022]
Abstract
Philanthotoxin-433 (PhTX-433) is a known potent inhibitor of ionotropic glutamate receptors, and analogues have been synthesised to identify more potent and selective antagonists. Herein we report the synthesis of four PhTXs with a cyclopropane moiety introduced into their polyamine chain, and their inhibition of an α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor subtype by using two-electrode voltage-clamp assays on Xenopus oocytes expressing the GluA1flop subunit. All analogues were found to be more potent than PhTX-343, with trans-cyclopropyl-PhTX-343 being the most potent (∼28-fold) and cis-cyclopropyl-PhTX-343 least potent (∼4-fold). Both cis- and trans-cyclopropyl-PhTX-444 had intermediate potency (both∼12-fold). Molecular modelling indicates that a cyclopropane moiety confers a favourable steric constraint to the polyamine part, but this is compromised by a cis conformation due to enhanced intramolecular folding. Elongated PhTX-444 analogues alleviate this to some extent, but optimal positioning of the amines is not permitted.
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Affiliation(s)
- Henrik Franzyk
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100 Copenhagen (Denmark)
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Poulsen MH, Lucas S, Bach TB, Barslund AF, Wenzler C, Jensen CB, Kristensen AS, Strømgaard K. Structure-activity relationship studies of argiotoxins: selective and potent inhibitors of ionotropic glutamate receptors. J Med Chem 2013; 56:1171-81. [PMID: 23320429 DOI: 10.1021/jm301602d] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Argiotoxin-636 (ArgTX-636), a natural product from the spider Argiope lobata, is a potent but nonselective open-channel blocker of ionotropic glutamate (iGlu) receptors. Here, three series of analogues were designed to exploit selectivity among iGlu receptors, taking advantage of a recently developed solid-phase synthetic methodology for the synthesis of ArgTX-636 and analogues. Initially, the importance of secondary amino groups in the polyamine chain was studied by the synthesis of systematically modified ArgTX-636 analogues, which were evaluated for pharmacological activity at NMDA and AMPA receptors. This led to the identification of two compounds with preference for NMDA and AMPA receptors, respectively. These were further elaborated by systematically changing the aromatic headgroup and linker amino acid leading to compounds with increased potency and selectivity for NMDA and AMPA receptors, respectively. Thus, the first structure-activity relationship study of ArgTX-636 has been carried out and has provided lead compounds for probing the ion channel region of iGlu receptors.
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Affiliation(s)
- Mette H Poulsen
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Frølund S, Bella A, Kristensen AS, Ziegler HL, Witt M, Olsen CA, Strømgaard K, Franzyk H, Jaroszewski JW. Assessment of Structurally Diverse Philanthotoxin Analogues for Inhibitory Activity on Ionotropic Glutamate Receptor Subtypes: Discovery of Nanomolar, Nonselective, and Use-Dependent Antagonists. J Med Chem 2010; 53:7441-51. [DOI: 10.1021/jm100886h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Sidsel Frølund
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Angelo Bella
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Anders S. Kristensen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Hanne L. Ziegler
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Matthias Witt
- Bruker Daltonik GmbH, Fahrenheitstrasse 4, D-28359 Bremen, Germany
| | - Christian A. Olsen
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Kristian Strømgaard
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Henrik Franzyk
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
| | - Jerzy W. Jaroszewski
- Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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Dossey AT. Insects and their chemical weaponry: New potential for drug discovery. Nat Prod Rep 2010; 27:1737-57. [DOI: 10.1039/c005319h] [Citation(s) in RCA: 132] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Solvent-free Ugi four-component condensation: application to synthesis of philanthotoxins-12 analogues. Tetrahedron 2008. [DOI: 10.1016/j.tet.2008.02.051] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Buchanan MS, Carroll AR, Fechner GA, Boyle A, Simpson MM, Addepalli R, Avery VM, Hooper JN, Su N, Chen H, Quinn RJ. Spermatinamine, the first natural product inhibitor of isoprenylcysteine carboxyl methyltransferase, a new cancer target. Bioorg Med Chem Lett 2007; 17:6860-3. [DOI: 10.1016/j.bmcl.2007.10.021] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Revised: 10/04/2007] [Accepted: 10/05/2007] [Indexed: 12/30/2022]
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Olsen CA, Witt M, Franzyk H, Jaroszewski JW. Solid-phase synthesis of neuroactive spider–wasp hybrid toxin analogues using a backbone amide linker. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2006.11.074] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Strømgaard K, Piazzi L, Olsen CA, Franzyk H, Jaroszewski JW. Protolytic properties of polyamine wasp toxin analogues studied by 13C NMR spectroscopy. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2006; 44:1013-22. [PMID: 16941578 DOI: 10.1002/mrc.1890] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Acid-base properties of the natural polyamine wasp toxin PhTX-433 (1) and seven synthetic analogues [PhTX-343 (2), PhTX-334 (3), PhTX-443 (4), PhTX-434 (5), PhTX-344 (6), PhTX-444 (7), and PhTX-333 (8)], each having four protolytic sites, were characterized by 13C NMR spectroscopy. Nonlinear, multiparameter, simultaneous fit of all chemical shift data obtained from the NMR titration curves yielded macroscopic pKa values as well as intrinsic chemical shift data of all differently protonated macrospecies. Analyses of the chemical shift data demonstrated strong interactions between all four sites and provided information about complex relationships between chemical shift values and protonation state. Deprotonation of fully protonated forms starts at the central amino group of the polyamine moiety, and the extent of this trend depends on the distance to the flanking, protonated amino groups. The pKa1 values of 1-8 are in the range 8.2-9.4. Hence, some of the toxins are incompletely protonated at the pH and ionic strength conditions used for assessment of their interactions with ionotropic glutamate and nicotinic acetylcholine receptors, and the degree of protonation is expected to have pharmacological importance in the ion-channel binding event.
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Affiliation(s)
- Kristian Strømgaard
- Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark
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