Toxic, cytotoxic and genotoxic effect of plumbagin in the developmental stages of Biomphalaria glabrata (Say, 1818-intermediate host) and cercaricidal activity against the infectious agent of schistosomiasis mansoni

Developmental toxicity and environmental risk assessment of chlorothalonil: A comprehensive study using biomphalaria as a model gastropod

The threat of pesticide pollution to aquatic ecosystems is severe. Chlorothalonil, a broad-spectrum fungicide, causes toxic effects on non-target organisms. While previous studies have focused on mussels, clams, and fish, research on gastropods remains limited despite their critical ecological roles. This study systematically evaluated the toxicity of chlorothalonil across different developmental stages of B. glabrata, with B. straminea (Red) adults serving as a comparative reference. Results showed that the median lethal concentration (LC50) was 0.3396 mg/L for B. glabrata embryos and 3.598 mg/L for adults, while the LC50 for B. straminea (Red) adults was 2.315 mg/L. Chronic exposure (21 days) to sublethal concentrations significantly inhibited shell growth, reduced egg production, and increased abnormal egg masses concentration-dependently. Histopathological analysis revealed severe tissue damage at 0.8 mg/L, including reduced hemocyte density, hepatopancreatic acinar disintegration, and ovotestis vacuolation. These findings provide critical evidence of chlorothalonil's environmental risks and emphasize the importance of evaluating pesticide effects on different developmental stages of non-target organisms.

Genotoxicity, mutagenicity, and immunotoxicity assessment of green silver nanoparticles from Croton urucurana on neotropical snails Biomphalaria glabrata

Green silver nanoparticles (G-Ag NPs) have been indicated as safer nanotechnology in nanomedicine, especially for controlling microorganisms, vectors, and gastropods of medical importance. However, their mechanisms of action and ecotoxicity in aquatic organisms remain unknown. Thus, the current study aimed to investigate the effects of G-Ag NPs synthesized through Croton urucurana leave aqueous extract on the neotropical freshwater snail Biomphalaria glabrata after in vivo exposure using multi-biomarker responses in hemocytes. Adult snails were exposed to G-Ag NPs (0.05 and 0.14 mg L-1) or leave aqueous extract (5.4 mg L-1) for 7 days. Genotoxicity (comet assay), mutagenicity (micronucleus test and nuclear abnormality assay), and immunotoxicity (phagocytosis assay by flow cytometry) were analyzed in hemocytes. Results showed that G-Ag NPs induced high mortality and genotoxic effects (DNA damage) compared to leave aqueous extract and negative control groups. G-Ag NPs also induced mutagenic effects (nuclear alterations), mainly notched and blebbed nuclei. Also, G-Ag NPs and extract did not change the phagocytic activity and cell viability of hemocytes. These findings contribute to understanding the toxicity of green nanoparticles in freshwater gastropods and represent a pioneering effort to evaluate the effects of G-Ag NPs and the C. urucurana aqueous extract in B. glabrata hemocytes. Overall, the immune system of gastropods is a target of green nanoparticle toxicity.

Bisphenol A effects on the host Biomphalaria alexandrina and its parasite Schistosoma mansoni

Bisphenol A (BPA) is one of the most potent endocrine-disrupting chemicals (EDCs) that adversely affect aquatic organisms. The present investigation explored the effects of exposure to BPA at 0.1 and 1 mgL-1 concentrations on the fecundity of Biomphalaria alexandrina, snail's infection with Schistosoma mansoni, and histology of the ovotestis and topographical structure of S. mansoni cercariae emerged from exposed snails. The 24 h LC50 and LC90 values of BPA against B. alexandrina were 8.31 and 10.88 mgL-1 BPA, respectively. The exposure of snails to 0.1 or 1 mgL-1 BPA did not affect the snail's survival. However, these concentrations caused an increase in the reproductive rate (Ro) of infected snails. A slight decrease in egg production was observed in snails exposed to 0.1 mgL-1 BPA after being infected (infected then exposed). However, a significant increase in egg production was noted in snails exposed to 1 mgL-1 BPA after infection with S. mansoni. Histopathological investigations indicated a clear alteration in the ovotestis tissue structure of exposed and infected-exposed groups compared to the control snails. Chronic exposure to BPA caused pathological alterations in the gametogenic cells. SEM preparations of S. mansoni cercariae emerged from infected-exposed snails showed obvious body malformations. From a public health perspective, BPA pollution may negatively impact schistosomiasis transmission, as indicated by the disturbance in cercarial production and morphology. However, it has adverse effects on the reproduction and architecture of reproductive organs of exposed snails, indicating that B. alexandrina snails are sensitive to sublethal BPA exposure.

Plumbagin: A Promising In Vivo Antiparasitic Candidate against Schistosoma mansoni and In Silico Pharmacokinetic Properties (ADMET)

Schistosomiasis, a potentially fatal chronic disease whose etiological agents are blood trematode worms of the genus Schistosoma spp., is one of the most prevalent and debilitating neglected diseases. The treatment of schistosomiasis depends exclusively on praziquantel (PZQ), a drug that has been used since the 1970s and that already has reports of reduced therapeutic efficacy, related with the development of Schistosoma-resistant or -tolerant strains. Therefore, the search for new therapeutic alternatives is an urgent need. Plumbagin (PLUM), a naphthoquinone isolated from the roots of plants of the genus Plumbago, has aroused interest in research due to its antiparasitic properties against protozoa and helminths. Here, we evaluated the in vivo schistosomicidal potential of PLUM against Schistosoma mansoni and the in silico pharmacokinetic parameters. ADMET parameters and oral bioavailability were evaluated using the PkCSM and SwissADME platforms, respectively. The study was carried out with five groups of infected mice and divided as follows: an untreated control group, a control group treated with PZQ, and three groups treated orally with 8, 16, or 32 mg/kg of PLUM. After treatment, the Kato-Katz technique was performed to evaluate a quantity of eggs in the feces (EPG). The animals were euthanized for worm recovery, intestine samples were collected to evaluate the oviposition pattern, the load of eggs was determined on the hepatic and intestinal tissues and for the histopathological and histomorphometric evaluation of tissue and hepatic granulomas. PLUM reduced EPG by 65.27, 70.52, and 82.49%, reduced the total worm load by 46.7, 55.25, and 72.4%, and the female worm load by 44.01, 52.76, and 71.16%, for doses of 8, 16, and 32 mg/kg, respectively. PLUM also significantly reduced the number of immature eggs and increased the number of dead eggs in the oogram. A reduction of 36.11, 46.46, and 64.14% in eggs in the hepatic tissue, and 57.22, 65.18, and 80.5% in the intestinal tissue were also observed at doses of 8, 16, and 32 mg/kg, respectively. At all doses, PLUM demonstrated an effect on the histopathological and histomorphometric parameters of the hepatic granuloma, with a reduction of 41.11, 48.47, and 70.55% in the numerical density of the granulomas and 49.56, 57.63, and 71.21% in the volume, respectively. PLUM presented itself as a promising in vivo antiparasitic candidate against S. mansoni, acting not only on parasitological parameters but also on hepatic granuloma. Furthermore, in silico, PLUM showed good predictive pharmacokinetic profiles by ADMET.

Antiparasitic Activity of Plumbago auriculata Extracts and Its Naphthoquinone Plumbagin against Trypanosoma cruzi

Chagas disease (CD) caused by the protozoan Trypanosoma cruzi affects more than six million people worldwide. Treatment is restricted to benznidazole (Bz) and nifurtimox (Nf) that display low activity in the later chronic stage besides triggering toxic events that result in treatment abandonment. Therefore, new therapeutic options are necessary. In this scenario, natural products emerge as promising alternatives to treat CD. In the family Plumbaginaceae, Plumbago sp. exhibits a broad spectrum of biological and pharmacological activities. Thus, our main objective was to evaluate, in vitro and in silico, the biological effect of crude extracts of root and of aerial parts of P. auriculata, as well as its naphthoquinone Plumbagin (Pb) against T. cruzi. The phenotypic assays revealed potent activity of the root extract against different forms (trypomastigote and intracellular forms) and strains (Y and Tulahuen), with a compound concentration that reduced 50% of the number of the parasite (EC₅₀) values ranging from 1.9 to 3.9 µg/mL. In silico analysis showed that Pb is predicted to have good oral absorption and permeability in Caco2 cells, besides excellent probability of absorption by human intestinal cells, without toxic or mutagenic potential effects, not being predicted as a substrate or inhibitor of P-glycoprotein. Pb was as potent as Bz against intracellular forms and displayed a superior trypanosomicidal effect (about 10-fold) in bloodstream forms (EC₅₀ = 0.8 µM) as compared to the reference drug (8.5 µM). The cellular targets of Pb on T. cruzi were evaluated using electron microscopy assays and the findings on bloodstream trypomastigotes showed several cellular insults related to the autophagic process. Regarding toxicity in mammalian cells, the root extracts and the naphthoquinone present a moderate toxic profile on fibroblasts and cardiac cell lines. Then, aiming to reduce host toxicity, the root extract and Pb were tested in combination with Bz, and the data showed additive profiles with the sum of the fractional inhibitory concentration indexes (ΣFICIs) being 1.45 and 0.87, respectively. Thus, our work reveals the promising antiparasitic activity of Plumbago auriculata crude extracts and its purified naphthoquinone Plumbagin against different forms and strains of Trypanosoma cruzi in vitro.