Synthesis, in vitro schistosomicidal activity and ultrastructural alterations caused by thiosemicarbazones and thiazolidinones against juvenile and adult Schistosoma mansoni worms (Sambon, 1907)

Schistosomiasis is a neglected disease that affects about 258 million people worldwide. Caused by Schistosoma mansoni, helminth which, in Brazil, it is present on 19 states and capital. Praziquantel (PZQ) treatment presents low efficacy and adverse effects in parasites juvenile stages. Thiosemicarbazones and thiazolidinones are rising as potent chemical groups that have biological activity wide spectrum, and with radical modifications, they may become more effective and selective. Aiming to evaluate the action of these molecules against S. mansoni, JF series thiosemicarbazones and thiazolidinones (LqIT/UFPE) were synthesized: JF30, JF31, JF33, JF34, JF35, JF36, JF38, JF39, JF42 and JF43. Several parameters were evaluated, such as: their cytotoxicity in VERO cells, in vitro schistosomicidal activity for juvenile and adult worms and their action on worms through ultrastructural changes. Cytotoxicity indices ranged from 272 µM to 725 µM. When evaluating mortality rate, adult and juvenile worms showed 100 % mortality rate within 24 h and 48 h, respectively, when exposed to the compounds JF31 and JF43 at a dose of 200 µM. Also, motility, mortality and oviposition parameters were evaluated: JF31 and JF43 presented a score of 0 in 24 h, meaning total absence of movement, whereas no eggs and soft tissue damage were observed under optical microscopy. Through scanning electron microscopy, integumentary alterations caused by the compounds JF31 and JF43 were observed, such as: exposure of the musculature, formation of integumentary bubbles, integuments with abnormal morphology and destruction of tubercles and spikes. The results shoerd that the compound JF31 was 2.39 times more selective for adult worms and JF43 was 3.74 times more selective for juvenile worms. Thus, the compounds JF43 and JF31 are the most promising for presenting schistosomicidal activity of S. mansoni.