formazans and Parasitemia

Extracts from Holostylis reniformis were tested in vivo against Plasmodium berghei and in vitro against a chloroquine-resistant strain of Plasmodium falciparum. The hexane extract of the roots was the most active, causing 67% reduction of parasitemia in vivo. From this extract, six lignans, including a new (7'R,8S,8'S)-3',4'-methylenedioxy-4,5-dimethoxy-2,7'-cyclolignan-7-one, were isolated and tested in vitro against P. falciparum. The three most active lignans showed 50% inhibitor concentrations of < or =0.32 microM. An evaluation of minimum lethal dose (30%) values showed low toxicity for these lignans in a hepatic cell line (Hep G2A16). Therefore, these compounds are potential candidates for the development of antimalarial drugs.

Topics: Animals; Antimalarials; Aristolochiaceae; Cell Line, Tumor; Chromatography, High Pressure Liquid; Circular Dichroism; Formazans; Humans; Inhibitory Concentration 50; Lignans; Mice; Molecular Conformation; Molecular Structure; Nuclear Magnetic Resonance, Biomolecular; Parasitemia; Plant Extracts; Plant Roots; Plasmodium berghei; Plasmodium falciparum; Spectrophotometry, Ultraviolet; Tetralones