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- Andréasson, Måns, 1994-
(författare)
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Redefining the essential molecular aspects that drive interactions between small molecules and G-quadruplex DNA
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- G-Quadruplex (G4) structures are secondary nucleic acid structures located in guanine-rich regions of DNA and RNA sequences, involved in gene regulation and cellular maintenance. Efforts to target G4s in a therapeutic setting are scarce, mainly due to vague details about the binding interactions between the ligands and the G4 structure combined with the lack of emphasis on drug-like properties early in the ligand development process. Furthermore, the ability to target specific G4 structures with small drug-like molecules remains a big challenge to overcome in the field. In this thesis, extensive organic synthesis developments coupled with computational-aided design and orthogonal in vitro assays has been used in tandem to reveal in-depth knowledge about ligand-to-G4 interactions. First, a macrocyclic approach was applied to design and discover novel G4 ligands which showed that macrocycles offer a solid foundation for ligand design. Next, computational tools to optimise the macrocyclic molecular conformation were used based on the macrocycles' abilities to stack on the G4 surface. In addition, macrocyclic, and non-macrocyclic ligands that bound G4 with high potency were shown to correlate with electron-deficient electrostatic potential (ESP) maps. The frequent inclusion of cationic residues in G4 ligands and their enhancement on ligand-to-G4 binding was, thereof, ascribed to their impact on the electrostatic character of the ligands' arene-arene interactions with the G4 surface, and not through direct electrostatic ionic interactions. In addition, the dispersion energetic component in the arene-arene interactions between the G4 ligand and the G4 was discovered to be paramount for ligand-to-G4 binding. The implementation of these descriptors in practice resulted in the discovery of potent G4 binders with adequate pharmacokinetic (PK) properties, accentuating the significance of understanding the molecular interactions between ligands and G4s in rational ligand design. Finally, a G4 ligand conjugated to an oligonucleotide was demonstrated as a modular approach to achieve selective binding of a ligand to a specific G4 structure.
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| 2. |
- Kulén, Martina, 1988-
(författare)
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New alternatives to combat Listeria monocytogenes and Chlamydia trachomatis : Design, synthesis, and evaluation of substituted ring-fused 2-pyridones as anti-virulent agents
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibiotic resistance has become a global health burden with the number of resistant bacteria continuously increasing. Antibiotic drugs act by being either bactericidal (killing bacteria) or bacteriostatic (inhibiting growth of bacteria). However, these modes of action increase the selective pressure on the bacteria. An alternative treatment strategy to antibiotics is anti-virulence therapies that inhibits virulence of the pathogenic bacteria. The term “virulence” summarises a number of factors that the bacteria need to colonise a new niche and as a consequence its ability to infect and cause diseases. By inhibiting virulence, instead of killing, the selective pressure on the bacteria can be reduced and consequently decreases the rapid development of resistance. This thesis describes two projects focusing on development of anti-virulence agents, with the ring-fused 2-pyridone scaffold as the central character, targeting the bacteria Listeria monocytogenes and Chlamydia trachomatis.The first project is targeting L. monocytogenes, which is the cause for listeriosis in humans. This can develop into life-threatening encephalitis and meningitis as well as cause severe complications for developing fetus. The target in L. monocytogenes is the transcriptional regulator PrfA that control almost all virulence factors in this bacterium. We have designed and synthesised potent substituted ring-fused 2-pyridones, which at low micromolar concentrations block activation of the virulence regulator PrfA and thus attenuate the bacterial infection. Co-crystallisation of the active ring-fused 2-pyridones with PrfA resulted in determination of the exact substance interaction site in the protein. This facilitated further structure-based design that resulted in improved compounds capable of attenuating L. monocytogenes in an in vivo model.The second project targets C. trachomatis, which is the causative agent behind the most common sexually transmitted infection as well as the eye infection trachoma. By structure-activity relationship analysis of previously tested ring-fused 2-pyridones, we have designed and synthesised non-hydrolysable ring-fused 2-pyridone amide isosteres. The most potent analogues inhibit C. trachomatis infectivity at low nanomolar concentrations, without showing host cell toxicity or affecting the viability of commensal microbiota. Introduction of heteroatom substituents at specific sites of the ring-fused 2-pyridone scaffold, resulted in improved pharmacokinetic properties of the analogues and further evaluation in vivo was performed.
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