Spirooxindoles as Disruptors of Preformed Hen Egg White Lysozyme Fibrils as a Model for Neurodegenerative Diseases

Formation of fibrils from the misfolding of proteins has been associated with being the root cause of many neurodegenerative diseases. The highly ordered structure of fibrils formed from stacked β-sheet, makes the deposition of the structures and resultant development of neurodegeneration extremely difficult to treat. The importance of effective treatments against these conditions led to the highlighted study. Synthesized spirooxindole compounds labeled Hd-63, Hd-66, and Hd-74, indicated potent abilities to perturb the structure of hen egg white lysozyme (HEWL) fibrils. The spectroscopic analyses, centered around the use of Raman spectroscopy and the changes in key protein marker bands, known as the amide I and amide III bands, show that the addition of Hd-63, Hd-66, and Hd-74 to solutions of preformed HEWL fibrils leads to morphological changes that indicate a breakdown of the highly ordered β-sheet scaffold, and result in the formation of highly disordered aggregates, which do not suggest a fibril-like nature. The formation of these disordered aggregates suggests the progression in the mechanism of fibrillation away from the saturation of fibrils in solution and instead toward the formation of off-pathway oligomers.