Unravelling the inhibitory and cytoprotective potential of diuretics towards amyloid fibrillation

Abstract

Protein misfolding and deposition of aggregated proteins inside as well as outside of the cells have been associated with several neurotoxic and neurodegenerative disorders like Alzheimer’s, Parkinson’s and familial amyloid polyneuropathy etc. that could be controlled by anti-aggregation methodologies employing either inhibition or disaggregation of toxic aggregates. Also, the Alzheimer’s disease develops in later life is somehow related to the high mid-life blood pressure. Therefore the present work targets the amyloid inhibiting potential of diuretics (a class of antihypertensive drugs) – Indapamide (INDP) and Hydrochlorothiazide (HCTZ) against human serum albumin (HSA) and human lysozyme (HL) fibrillogenesis. The effect of both INDP and HCTZ on the kinetics of amyloid formation of HSA and HL was illustrated and various biophysical techniques like Thioflavin T (ThT) and 8-Anilinonaphthalene-1-sulfonic acid (ANS) fluorescence measurement, Congo red measurements and circular dichroism (CD) measurements depicted the inhibitory action of both INDP and HCTZ in a dose dependent manner. Transmission Electronic Microscopy (TEM) confirmed the absence of fibrillar structures when HSA and HL were co-incubated with INDP and HCTZ. In addition, molecular docking results revealed that both the drugs interacts with HSA and HL through hydrophobic interactions as well as hydrogen bonding, and also showed non-hemolytic activity on human RBCs demonstrated by the Hemolytic assay. Thus, both INDP and HCTZ could be propitious as a therapeutic agent and aid in the cure of amyloid related diseases.