Isolation, structure elucidation, and synthesis of antiplasmodial quinolones from Crinum firmifolium

Abstract Antiplasmodial bioassay guided fractionation of a Madagascar collection of Crinum firmifolium led to the isolation of seven compounds. Five of the seven compounds were determined to be 2-alkylquinolin-4(1 H )-ones with varying side chains. Compounds 1 and 4 were determined to be known compounds with reported antiplasmodial activities, while 5 was believed to be a new branched 2-alkylquinolin-4(1 H )-one, however, it was isolated in limited quantities and in admixture and therefore was synthesized to confirm its structure as a new antiplasmodial compound. Along with 5 , two other new and branched compounds 6 and 7 were synthesized as well. Accompanying the five quinolones were two known compounds 2 and 3 which are inactive against Plasmodium falciparum . The isolation, structure elucidation, total synthesis, and biological evaluation of these compounds are discussed in this article.