Growth inhibition of asexual erythrocytic forms of Plasmodium falciparum and P-berghei in vitro by naphthylisoquinoline alkaloid-containing extracts of Ancistrocladus and Triphyophyllum species

Naphthylisoquinoline alkaloid-containing extracts [1-20] of four species of the genus Ancistrocladus (A. barteri, A. heyneanus, A. robertsoniorum, and A. tectorius) and of Triphyophyllum peltatum have been examined for their antiplasmodial activity against asexual erythrocytic forms of Plasmodium falciparum (NF 54, clone A1A9) and P. berghei (Anka) in vitro. Incorporation of H-3-hypoxanthine was measured in the presence of the test substances. The above mentioned plant species are used in several countries of the pantropical area against fevers and malaria. Five of the examined extracts displayed high growth inhibiting activity in the P. falciparum system: CH2Cl2/NH3 bark extract of T. peltatum [20], EtOH leaf extract of A. barteri [4], CH2Cl2 leaf [14] and CH2Cl2/NH3 bark [15] extracts of A. tectorius, and CH2Cl2 leaf [17] extract of T. peltatum). These extracts (IC50 < 1 mu g/ml) [4, 14, 15, 17, and 20] were further examined in the P. berghei system. Two of them (the CH2Cl2/NH3 bark extracts of A. tectorius [15] and T. peltatum [20]) were proven to be highly active in both test systems. These findings confirm that extracts of species belonging to the Ancistrocladaceae and the Dioncophyllaceae have a considerable antiplasmodial capacity.