Fig. 3.

A lactone ring is associated with the dual anthelmintic activity of the two most effective triterpenoids. (A) The structural elucidation of triterpenoids 700015 and 700234 revealed a tetracyclic steroid-like nucleus core, a keto- (700015) or hydroxyl- (700234) group and a conserved lactone ring. ‘A, B, C, D’ represent the classic lettering system for steroids (Moss, 1989). Carbon numbering is derived from the ¹³C NMR structural elucidation of each triterpenoid. (B) Representative images of F. hepatica NEJs co-cultivated with DMSO (0.1%, negative control), TCBZ (10 μM in 0.1% DMSO, positive control), 700015 (10 μM in 0.1% DMSO) and 700234 (10 μM in 0.1% DMSO) obtained by bright field microscopy (20× objective) compared to representative images of S. mansoni schistosomula co-cultivated with DMSO (0.625%, negative control), PZQ (10 μM in 0.625% DMSO, positive control), 700015 (10 μM in 0.625% DMSO) and 700234 (10 μM in 0.625% DMSO) obtained by the high content imaging platform (10× objective). All parasite images were acquired at 72 h post parasite/compound co-cultivation.