Integrated green chemistry approaches for the development of PCSK9 inhibitors with multiple pharmacological applications

This thesis integrates green chemistry principles with the development of novel small-molecule PCSK9 inhibitors, in a sustainable medicinal chemistry effort. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a critical drug target, widely recognized for its role in hypercholesterolemia treatment and increasingly investigated for its involvement in other pathological conditions, including infections, neurodegenerative diseases, and cancer. Despite its significant therapeutic potential, no small-molecule PCSK9 inhibitors are currently available on the market, underscoring the challenges in their development and emphasizing the importance of the research objectives pursued in this work. In the work herein described, I have employed both phenotypic and target-based drug discovery (PDD and TBDD) approaches to identify and optimize novel PCSK9i chemotypes. A sustainable medicinal chemistry perspective has guided the synthesis of these compounds, utilizing green methodologies such as late-stage functionalization (LSF), electrochemistry, multicomponent reactions (MCR), and microwave-assisted synthesis. The resulting compounds were evaluated for their pharmacological applications as lipid-lowering and neuroprotective agents. The PDD studies were conducted at the University of Parma and led to the identification of the 4-amino-2-pyridone as a promising anti-PCSK9 chemotype through phenotypic screening. This was followed by a hit-expansion campaign, early lead identification, and subsequent lead optimization to improve the metabolic stability. Lead optimization was supported by different green chemistry tools, such as electrochemistry and MCR to perform LSF of the early lead compound. Moreover, scaffold hopping based on the early lead led to the discovery of 2-aminothiazoles as a novel promising anti-PCSK9 scaffold. The in silico TBDD studies were conducted as Remote Company Training from the University of Pisa under the supervision of Prof. Tiziano Tuccinardi, with remote supervision by Dr. Sharon Bryant, CEO of InteLigand. These efforts involved a virtual screening protocol comprising docking studies, molecular dynamics simulations, and pharmacophore generation. This process resulted in the identification of a third active chemotype that was chemically expanded at the University of Parma. To further advance the understanding and application of electrochemistry as a green chemistry methodology, I undertook a three-month research placement in the laboratory of Prof. Kevin Lam at the University of Greenwich (UK). During this period, I worked on the development and scope exploration of an electrochemical protocol for the hydrogenation and deuteration of organic compounds.