Neolignans inhibit Trypanosoma cruzi infection of its triatomine insect vector, Rhodnius prolixus

Two neolignans, burchellin and nordihydroguaiaretic acid (NDGA), were toxic only to Trypanosoma cruzi clone Dm28c maintained in brain heart infusion ( BHI) medium at a concentration of 100 mu g/ml, nor 10 mu g/ml. When Rhodniu s prolixus was fed with epimastigotes of T. cruzi and treated simultaneousl y with a single dose of burchellin or NDGA at 10 mu g/ml of blood meal the number of parasites in the gut decreased. Whereas burchellin was only parti ally active, NDGA drastically reduced the number of epimastigotes and metac yclic trypomastigotes of T. cruzi in the excreta (urine plus feces). When t he insect larvae were pretreated with burchellin or NDGA at 20 days before the infection with T. cruzi a significant reduction in the number of parasi tes in the gut occurred. However, when both compounds were applied at 20 da ys after the establishment of T. cruzi infection. although burchellin signi ficantly reduced the gut infection. neither compound could abolish the infe ction entirely within the subsequent 15 days.