TY - JOUR
T1 - Antitrypanosomal activity of camptothecin analogs. Structure-activity correlations
AU - Bodley, Annette L.
AU - Wani, Mansukh C.
AU - Wall, Monroe E.
AU - Shapiro, Theresa A.
PY - 1995/9/28
Y1 - 1995/9/28
N2 - African trypanosomes (Trypanosoma brucei species) are parasitic protozoa that cause lethal diseases in humans and cattle. Previous studies showed that camptothecin, a potent and specific inhibitor of DNA topoisomerase I, is cytotoxic to African trypanosomes and related pathogenic hemoflagellates (Bodley AL and Shapiro TA, Proc Natl Acad Sci USA 92: 3726-3730, 1995). In this study, a series of camptothecin analogs was tested against axenically cultured, bloodstream form, T. brucei. Modifications to the pentacyclic nucleus of camptothecin ablated antiparasitic activity. In contrast, activity could be increased by substituents added to the parent ring system (e.g. 10,11-methylenedioxy or ethylenedioxy groups; alkyl additions to carbon 7; or 9-amino or 9-chloro substituents). Cytotoxicity was correlated with the level of cleavable complexes in trypanosomes, implicating topoisomerase I as the intracellular target for these compounds. To obtain some indication of selective toxicity, ten compounds were also tested against L1210 mouse leukemia cells. The 9-substituted-10, 11-methylenedioxy analogs caused a disproportionate increase in antiparasitic activity, compared with mammalian cell toxicity. These findings provide a basis for designing further structural modifications and for selecting camptothecin analogs to test in animal models of trypanosomiasis.
AB - African trypanosomes (Trypanosoma brucei species) are parasitic protozoa that cause lethal diseases in humans and cattle. Previous studies showed that camptothecin, a potent and specific inhibitor of DNA topoisomerase I, is cytotoxic to African trypanosomes and related pathogenic hemoflagellates (Bodley AL and Shapiro TA, Proc Natl Acad Sci USA 92: 3726-3730, 1995). In this study, a series of camptothecin analogs was tested against axenically cultured, bloodstream form, T. brucei. Modifications to the pentacyclic nucleus of camptothecin ablated antiparasitic activity. In contrast, activity could be increased by substituents added to the parent ring system (e.g. 10,11-methylenedioxy or ethylenedioxy groups; alkyl additions to carbon 7; or 9-amino or 9-chloro substituents). Cytotoxicity was correlated with the level of cleavable complexes in trypanosomes, implicating topoisomerase I as the intracellular target for these compounds. To obtain some indication of selective toxicity, ten compounds were also tested against L1210 mouse leukemia cells. The 9-substituted-10, 11-methylenedioxy analogs caused a disproportionate increase in antiparasitic activity, compared with mammalian cell toxicity. These findings provide a basis for designing further structural modifications and for selecting camptothecin analogs to test in animal models of trypanosomiasis.
KW - Trypanosoma brucei
KW - antitrypanosomal activity
KW - camptothecin
KW - structure-activity relationship
KW - topoisomerase I
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U2 - 10.1016/0006-2952(95)00215-L
DO - 10.1016/0006-2952(95)00215-L
M3 - Article
C2 - 7575676
AN - SCOPUS:0028818612
VL - 50
SP - 937
EP - 942
JO - Biochemical Pharmacology
JF - Biochemical Pharmacology
SN - 0006-2952
IS - 7
ER -