Screening in vitro of natural products against blood forms of Trypanosoma cruzi.

Transmission of Chagas disease by blood transfusion is a major health problem in Central and South America. The annual incidence of transfusion-transmitted Chagas disease in Brazil is about 20,000 cases. Crystal violet is the only trypanosomicidal agent available at present, but there are some restrictions on its use. In a search for possible new chemoprophylactic agents, several natural products of different structural types were tested in vitro against infective blood trypomastigotes of Trypanosoma cruzi. Four compounds had high activity at a concentration of 5 x 10(-4) M: the diarylpropanoids (3R)-claussequinone, (R)-4-methoxydalbergione and (S)-4,4'-dimethoxy-dalbergione, and 15-deoxygoyazensolide, a sesquiterpenelactone. Haemoculture and serology of mice inoculated with infected blood treated with these active compounds were negative after 3 and 6 months. The benzoquinone moiety seemed to be important for this activity since lapachol and related naphthoquinones are known to be trypanosomicidal. 15-Deoxygoyazensolide has previously been recognized as a schistosomicide.