Analysis of the Physicochemical Properties of Anti-Schistosomal Compounds to Identify Next-Generation Leads

To investigate the physicochemical properties of anti-schistosomal compounds reported between 2008 and 2023, a simple but extensive literature scrutiny was conducted. Keywords were searched in Chemical Abstracts Service (CAS) SciFinder and primary medicinal chemistry and pharmacology literature to locate publications with compounds displaying ex vivo and/or in vivo anti-schistosomal activity. A total of 57 repurposed U.S. Food and Drug Administration (FDA)-approved drugs, hits and their derivatives were manually extracted, curated and compared to known anti-schistosomal oral drugs in view of establishing trends of calculated critical molecular properties. From this analysis, it was determined that more than 65% of the compounds display cLogD_7.4 > 3 values, whereas oxamniquine, metrifonate and praziquantel (PZQ), previous and currently used oral anti-schistosomal drugs, possess lower cLogD_7.4 values (≤2.5). Furthermore, the lipophilicity associated with PZQ corresponds to a highly permeable and sparingly soluble compound, characteristics that favor drug absorption and compound penetration in the parasite. These physicochemical properties together with PZQ's anti-schistosomal activity make PZQ an essential medicine for the treatment of schistosomiasis and demonstrate the importance of finding the right balance among potency (e.g., EC₅₀ < 5 and 0.5 μM), cell permeability (e.g., P_app > 2 × 10⁶ cm/s) and kinetic aqueous solubility (e.g., >10 μM) to provide high-quality hits and/or leads for the discovery of new oral anti-schistosomal therapeutics.