Synthesis and Evaluation of β-Carbolinium Cations as New Antimalarial Agents Based on π-Delocalized Lipophilic Cation (DLC) Hypothesis

Abstract

Several β-carbolines including naturally occurring substances and their corresponding cationic derivatives were synthesized and evaluated for antimalarial (antiplasmodial) activity in vitro and in vivo. A tetracyclic carbolinium salt was elucidated for antileishmanial and antitrypanosomal activities in vitro as well as antiplasmodial activity. Quarternary carbolinium cations showed much higher potencies in vitro than electronically neutral β-carbolines and a good correlation was observed between π-delocalized lipophilic cationic (DLC) structure and antimalarial efficacy. β-Carbolinium compounds exhibit medium suppressive activity in vivo against rodent malaria.