Ultrastructural study of morphological changes in Schistosoma mansoni after in vitro exposure to the monoterpene rotundifolone

ABSTRACT

ABSTRACT INTRODUCTION: Schistosomiasis, a parasitic disease caused by trematode flatworms of the genus Schistosoma, affects more than 200 million people worldwide, and its control is dependent on a single drug, praziquantel. Here, we report the in vitro effect of rotundifolone, a monoterpene isolated from Mentha x villosa (Lamiaceae), on Schistosoma mansoni adult worms. METHODS: The in vitro effect of rotundifolone on adult Schistosoma mansoni was evaluated by analysis of behavior and mortality and through a scanning electron microscopic analysis of ultrastructural changes in the tegument of the worms. RESULTS: At concentrations of 3.54 and 7.09μg/mL-1 rotundifolone, no worm mortality was observed at any of the sampling intervals. A minor reduction in movement of the tail, suckers, and gynecophoral canal membrane was observed after 96 h of exposure to 7.09μg/mL-1 rotundifolone. At 70.96μg/mL-1, a lack of movement was observed from 72h onwards and all worms were deemed dead; similar effects were observed at 48h with 177.4μg/mL-1, and at 24h with 354.8μg/mL-1 and 700.96μg/mL-1. Rotundifolone also caused death of all parasites and separation of coupled pairs into individual males and females after 24h at 354.8μg/mL-1. CONCLUSIONS: The main changes in the tegument induced by the different ROT treatments were after 24h incubation, bubble lesions spread over the entire body and loss of tubercles occurred in some regions of the ventral region.