The development of novel solid phase methodologies for the synthesis of atypical peptides and non-peptide entities

Solid phase peptide synthesis (SPPS) of branched/cyclic peptides, multiple antigenic peptides (MAPs), pseudopeptide toxins etc. requires amine protection orthogonal to the established Fmoc/Boc protocols. It was envisaged that progression from Dde to N-1-(4-Nitro-l,3-dioxoindan-2-ylidene)ethyl (Nde) amino acid protection would maintain the stipulated orthogonality, whilst improving the hydrazine mediated deprotection. A selection of Nα-Nde-amino acids were efficiently synthesised and their compatibility with SPPS conditions demonstrated by the synthesis of a number of peptides. The Nde group displayed a faster and more easily monitored deprotection profile and similar orthogonality when compared with the Dde group. The selective primary amine protecting characteristics of the Nde group was illustrated by the synthesis of N¹N⁸-bis Nde-spermidine which was subsequently utilised in the solid phase synthesis of the natural product, dihydrotrypanothione. Large peptides synthesised by SPPS often demand elaborate, expensive and cumbersome purification protocols. Dde based reversible amine protecting groups incorporating hydrophobic and affinity probes have been developed. Their ease of preparation and efficacy in the purification of synthetic peptides has been demonstrated. Intercellular communication in various Gram-negative microorganisms is often mediated by small signalling molecules, e.g. N-(3-oxohexanoyl)-L-homoserine lactone (OHHL). Detection of these molecules is often extremely difficult. To address this, SPPS procedures have been employed to couple N-β-ketoacyl-L-homoserine lactone containing haptens to a dendritic lysine scaffolding, and the resultant macromolecule evaluated for its ability to raise anti-N-β-ketoacyl-L-homoserine lactone antibodies. 1-Carbapen-2-em-3-carboxylic acid is a broad spectrum antibiotic produced by the Gram-negative Erwinia and Serratia microorganisms. Some key intermediates for the putative synthetic precursors have been successfully prepared in order to study the biosynthetic pathways by feeding blocke mutants of the above bacteria, and also to transpose the methodologies to a solid phase to construct carbapenem libraries. NB. This ethesis has been created by scanning the typescript original and may contain inaccuracies. In case of difficulty, please refer to the original text

The development of novel solid phase methodologies for the synthesis of atypical peptides and non-peptide entities

Solid phase peptide synthesis (SPPS) of branched/cyclic peptides, multiple antigenic peptides (MAPs), pseudopeptide toxins etc. requires amine protection orthogonal to the established Fmoc/Boc protocols. It was envisaged that progression from Dde to N-1-(4-Nitro-l,3-dioxoindan-2-ylidene)ethyl (Nde) amino acid protection would maintain the stipulated orthogonality, whilst improving the hydrazine mediated deprotection. A selection of Nα-Nde-amino acids were efficiently synthesised and their compatibility with SPPS conditions demonstrated by the synthesis of a number of peptides. The Nde group displayed a faster and more easily monitored deprotection profile and similar orthogonality when compared with the Dde group. The selective primary amine protecting characteristics of the Nde group was illustrated by the synthesis of N¹N⁸-bis Nde-spermidine which was subsequently utilised in the solid phase synthesis of the natural product, dihydrotrypanothione. Large peptides synthesised by SPPS often demand elaborate, expensive and cumbersome purification protocols. Dde based reversible amine protecting groups incorporating hydrophobic and affinity probes have been developed. Their ease of preparation and efficacy in the purification of synthetic peptides has been demonstrated. Intercellular communication in various Gram-negative microorganisms is often mediated by small signalling molecules, e.g. N-(3-oxohexanoyl)-L-homoserine lactone (OHHL). Detection of these molecules is often extremely difficult. To address this, SPPS procedures have been employed to couple N-β-ketoacyl-L-homoserine lactone containing haptens to a dendritic lysine scaffolding, and the resultant macromolecule evaluated for its ability to raise anti-N-β-ketoacyl-L-homoserine lactone antibodies. 1-Carbapen-2-em-3-carboxylic acid is a broad spectrum antibiotic produced by the Gram-negative Erwinia and Serratia microorganisms. Some key intermediates for the putative synthetic precursors have been successfully prepared in order to study the biosynthetic pathways by feeding blocke mutants of the above bacteria, and also to transpose the methodologies to a solid phase to construct carbapenem libraries. NB. This ethesis has been created by scanning the typescript original and may contain inaccuracies. In case of difficulty, please refer to the original text

Meeting report: 27th Annual GP2A Medicinal Chemistry Conference

The 27th annual GP2A (Groupement des Pharmacochimistes de l′Arc Atlantique/Group of Medicinal Chemists in the Atlantic Arc) conference took place from 21 to 23 August 2019, at the East Midlands Conference Centre (University Park, Nottingham, United Kingdom) and was hosted by the Division of Biomolecular Science and Medicinal Chemistry (BSMC), within the School of Pharmacy at the University of Nottingham. The event brought together an international delegation of researchers with interests in medicinal chemistry and interfacing disciplines. In addition, a pre-conference workshop provided an opportunity for younger researchers to develop their theoretical knowledge in quantitative pharmacology. Abstracts of presentations by the 14 invited speakers and 6 young researchers, in addition to 41 posters, are included in this report

Kinetic analysis of antagonist-occupied adenosine-A3 receptors within membrane microdomains of individual cells provides evidence of receptor dimerization and allosterism

In our previous work, using a fluorescent adenosine-A3 receptor (A3AR) agonist and fluorescence correlation spectroscopy (FCS), we demonstrated high-affinity labeling of the active receptor (R*) conformation. In the current study, we used a fluorescent A3AR antagonist (CA200645) to study the binding characteristics of antagonist-occupied inactive receptor (R) conformations in membrane microdomains of individual cells. FCS analysis of CA200645-occupied A3ARs revealed 2 species, τD2 and τD3, that diffused at 2.29 ± 0.35 and 0.09 ± 0.03 μm2/s, respectively. FCS analysis of a green fluorescent protein (GFP)-tagged A3AR exhibited a single diffusing species (0.105 μm2/s). The binding of CA200645 to τD3 was antagonized by nanomolar concentrations of the A3 antagonist MRS 1220, but not by the agonist NECA (up to 300 nM), consistent with labeling of R. CA200645 normally dissociated slowly from the A3AR, but inclusion of xanthine amine congener (XAC) or VUF 5455 during washout markedly accelerated the reduction in the number of particles exhibiting τD3 characteristics. It is notable that this effect was accompanied by a significant increase in the number of particles with τD2 diffusion. These data show that FCS analysis of ligand-occupied receptors provides a unique means of monitoring ligand A3AR residence times that are significantly reduced as a consequence of allosteric interaction across the dimer interfac

Drug-like antagonists of P2Y receptors — from lead identification to drug development

P2Y receptors are expressed in virtually all cells and tissue types and mediate an astonishing array of biological functions, including platelet aggregation, smooth muscle cell proliferation, and immune regulation. The P2Y receptors belong to the G protein-coupled receptor superfamily and are composed of eight members encoded by distinct genes that can be subdivided into two groups on the basis of their coupling to specific G-proteins. Extensive research has been undertaken to find modulators of P2Y receptors, although to date only a limited number of small-molecule P2Y receptor antagonists have been approved by drug/medicines agencies. This Perspective reviews the known P2Y receptor antagonists, highlighting oral drug-like receptor antagonists, and considers future opportunities for the development of small molecules for clinical evaluation

Subtle modifications to a thieno[2,3-d]pyrimidine scaffold yield negative allosteric modulators and agonists of the dopamine D2 receptor

We recently described a structurally novel series of negative allosteric modulators (NAMs) of the dopamine D2 receptor (D2R) based on thieno[2,3-d]pyrimidine 1, showing it can be structurally simplified to reveal low molecular weight, fragment-like NAMs that retain robust negative cooperativity, such as 3. Herein, we report the synthesis and functional profiling of analogues of 3, placing specific emphasis on examining secondary and tertiary amino substituents at the 4-position, combined with a range of substituents at the 5/6-positions (e.g. aromatic/aliphatic carbocycles). We identify analogues with diverse pharmacology at the D2R including NAMs (19fc) with sub-?M affinity (9h) and, surprisingly, low efficacy partial agonists (9d and 9i)

Adenosine-A3 receptors in neutrophil microdomains promote the formation of bacteria-tethering cytonemes

The A3‐adenosine receptor (A3AR) has recently emerged as a key regulator of neutrophil behaviour. Using a fluorescent A3AR ligand, we show that A3ARs aggregate in highly polarized immunomodulatory microdomains on human neutrophil membranes. In addition to regulating chemotaxis, A3ARs promote the formation of filipodia‐like projections (cytonemes) that can extend up to 100 μm to tether and ‘reel in’ pathogens. Exposure to bacteria or an A3AR agonist stimulates the formation of these projections and bacterial phagocytosis, whereas an A3AR‐selective antagonist inhibits cytoneme formation. Our results shed new light on the behaviour of neutrophils and identify the A3AR as a potential target for modulating their function