HPLC-based activity profiling for antiprotozoal compounds in Croton gratissimus and Cuscuta hyalina

In a screening of Sudanese medicinal plants for antiprotozoal activity, the chloroform fractions obtained by liquid-liquid partitioning from ethanolic extracts of fruits of; Croton gratissimus; var.; gratissimus; and stems of; Cuscuta hyalina; Roth ex Schult. exhibited; in vitro; activity against axenically grown; Leishmania donovani; amastigotes. This antileishmanial activity was localized by HPLC-based activity profiling. Targeted preparative isolation afforded flavonoids; 1; -; 6; , 3-methoxy-4-hydroxybenzoic acid (; 7; ), and benzyltetrahydroisoquinoline alkaloids laudanine (; 8; ) and laudanosine (; 9; ) from; C. gratissimus; , and pinoresinol (; 10; ), isorhamnetin (; 11; ), (-)-pseudosemiglabrin (; 12; ), and kaempferol (; 13; ) from; C. hyalina.; The antiprotozoal activity of; 1; -; 13; against; L. donovani; (axenic and intracellular amastigotes),; Trypanosoma brucei rhodesiense; (bloodstream forms), and; Plasmodium falciparum; (erythrocytic stages), and the cytotoxicity in L6 murine myoblast cells were determined; in vitro; . Quercetin-3,7-dimethylether (; 6; ) showed the highest activity against axenic; L. donovani; (IC; 50,; 4.5 µM; selectivity index [SI], 12.3),; P. falciparum; (IC; 50,; 7.3 µM; SI, 7.6), and; T. b. rhodesiense; (IC; 50; , 2.4 µM; SI, 23.2). The congener ayanin (; 2; ) exhibited moderate antileishmanial (IC; 50; , 8.2 µM; SI, 12.2), antiplasmodial (IC; 50; , 7.8 µM; SI, 12.9), and antitrypanosomal activity (IC; 50; , 11.2 µM; SI, 8.9). None of the compounds showed notable activity against the intramacrophage form of; L. donovani; .