In Vitro Anthelminthic Activity and Ultrastructural Analysis of Barbatic Acid against Schistosomulae and Juvenile Worms of Schistosoma mansoni.

Schistosomiasis affects about 260 million people worldwide and the search for new schistosomicidal compounds is urgent. In this study we evaluated the in vitro effect of barbatic acid against schistosomulae and young worms of Schistosoma mansoni. The barbatic acid was evaluated through the bioassay of motility and mortality, cellular viability and ultrastructural analysis of juvenile stages through Scanning Electron Microscopy. Barbatic acid showed a schistosomicidal effect against schistosomulae and young worms of S. mansoni after 3 h of exposure. At the end of 24 h, barbatic acid showed 100 %, 89.5 %, 52 % and 28.5 % of lethality for schistosomulae at the concentrations of 200, 100, 50 and 25 µM, respectively. For young worms, barbatic acid showed 100 % and 31.7 % of lethality at the concentrations of 200 and 100 µM, respectively. Motility changes were observed at all sublethal concentrations. There was a significant reduction in the viability of young worms after exposure to barbatic acid at 50, 100 and 200 µM. Extensive damage to the schistosomulae and young worm's tegument, was observed from 50 µM. This report provides data showing the schistosomicidal effect of barbatic acid on schistosomulae and young worms of S. mansoni, causing death, motility changes and ultrastructural damage to worms.

Studies on Toxicity of Suspensions of CdTe Quantum Dots to Biomphalaria glabrata Mollusks.

Quantum dots have generated great interest because of their optical properties, both to life sciences and electronics applications. However, possible risks to the environment associated with these nanoparticles are still under investigation. The present study aimed to evaluate the toxicity of suspensions of cadmium telluride (CdTe) quantum dots to Biomphalaria glabrata mollusks, a very sensitive aquatic environmental bioindicator for physical and chemical agents. Toxicity was examined by using embryos and adult mollusks as well as hemocytes. The distribution of cadmium in the organs of adults was also assessed. Effects of the stabilizing agent of the quantum dots were also evaluated. Animals were exposed to suspensions of quantum dots for 24 h, at concentrations varying from 1.2 to 20 nM for embryos and from 50 to 400 nM for adult mollusks. Results showed that suspensions of quantum dots induced malformations and mortality in embryos and mortality in adults, depending on the concentration applied. In the cytotoxicity study, hemocyte apoptosis was observed in adults exposed to the highest concentration of quantum dots applied as well as to the stabilizing agent. Cell binucleation and micronucleus frequencies were not significative. Bioaccumulation evaluation revealed that quantum dots targeted the digestive gland (hepatopancreas). Taken together, outcomes suggested that specific nano-effects related directly not only to composition but also to the aggregation of quantum dots may be mediating the observed toxicity. Thus B. glabrata was determined to be a very sensitive species for interpreting possible nano-effects in aquatic environments. Environ Toxicol Chem 2019;38:2128-2136. © 2019 SETAC.