Aminoalkoxycarbonyloxymethyl Ether Prodrugs with a pH-Triggered Release Mechanism: A Case Study Improving the Solubility, Bioavailability, and Efficacy of Antimalarial 4(1<i>H</i>)‑Quinolones with Single Dose Cures

Preclinical and clinical development of numerous small molecules is prevented by their poor aqueous solubility, limited absorption, and oral bioavailability. Herein, we disclose a general prodrug approach that converts promising lead compounds into aminoalkoxycarbonyloxymethyl (amino AOCOM) ether-substituted analogues that display significantly improved aqueous solubility and enhanced oral bioavailability, restoring key requirements typical for drug candidate profiles. The prodrug is completely independent of biotransformations and animal-independent because it becomes an active compound via a pH-triggered intramolecular cyclization–elimination reaction. As a proof-of-concept, the utility of this novel amino AOCOM ether prodrug approach was demonstrated on an antimalarial compound series representing a variety of antimalarial 4­(1H)-quinolones, which entered and failed preclinical development over the last decade. With the amino AOCOM ether prodrug moiety, the 3-aryl-4­(1H)-quinolone preclinical candidate was shown to provide single-dose cures in a rodent malaria model at an oral dose of 3 mg/kg, without the use of an advanced formulation technique.