Neurodegenerative diseases, such as Alzheimer's, Parkinson's disease, amyotrophic lateral sclerosis, and others, affect different neurons in disease-specific regions of the central nervous system. Despite varying clinical signs and pathophysiological mechanisms, all these diseases feature chronic neuroinflammation, which was initially perceived just as a consequence of the disease. However, new research suggests that neuroinflammation might be the primary cause of their onset. Damage-associated molecular patterns (DAMPs) and pathogen-associated molecular patterns (PAMPs) activate inflammasomes, which in turn activate caspase-1. Caspase-1 then activates pro-inflammatory cytokines, which cause neuroinflammation through various mechanisms and, with chronic activation, also lead to neurodegeneration. The caspase-1 inhibitor, VX-765 or belnacasan, successfully reduced neuroinflammation, improved episodic and spatial memory, and prevented amyloid β deposition in the brain in numerous in vivo mouse models of Alzheimer’s disease. Moreover, belnacasan also prevented axonal degeneration and reduced disease-associated increased secretion of the pro-inflammatory cytokine IL-1β.
In the thesis, we prepared analogs of belnacasan, replacing the aldehyde warhead with other electrophiles – oxirane, carbamoyl fluoride, terminal alkyne, propargylamine, and 3-bromo-4,5-dihydroisoxazole. The products of individual reactions were isolated using normal and reverse-phase chromatography, and the identity of the compounds was confirmed by mass spectrometry and nuclear magnetic resonance. Using recombinant human caspase-1, we then determined the inhibitory activity of the synthesized belnacasan analogs. For a deeper understanding of the binding and interactions between the inhibitor and caspase-1, we also performed molecular docking. In most cases, the prepared compounds did not inhibit caspase-1, with the exception of the oxirane derivatives 42a and 42b, which inhibited caspase-1 activity at a concentration of 100 µM. The reason for the inactivity of the compounds could be the absence of the archetypal carboxylic acid – aspartyl residue at the P1 position of the inhibitor. Therefore, in designing new analogs, it would be sensible to place greater emphasis on interactions in the S1 pocket, where placing various bioisosteric replacements of the carboxylate could improve binding and subsequently also inhibitory activity.
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