José Augusto Albuquerque dos Santos

Schistosomiasis remains a critically neglected tropical disease, and its control relies on the suppression of vector snails of the genus Biomphalaria. The extensive use of niclosamide is limited by its high cost, poor water solubility, and ecotoxicity. In this study, the molluskicidal, ovicidal, ecotoxicological, and biosafety properties of fractions obtained from the ethanolic seed extract of Abelmoschus esculentus were evaluated. Soxhlet extraction and liquid–liquid partitioning yielded five fractions of increasing polarity. LC–QTOF–MS analysis of the active fractions: crude ethanolic extract in ethyl acetate, crude ethanolic extract in acetone, and crude ethanolic extract in ethanol revealed bioactive polyphenols, including glycosylated flavonols, astilbin, catechin/epicatechin, procyanidin dimers, and protocatechuic acid. The ethyl acetate fraction showed the highest molluskicidal activity against adult Biomphalaria glabrata (48 h LC₅₀ = 41.76 mg/L; LC₉₀ = 61.25 mg/L), while crude ethanolic extract in acetone and crude ethanolic extract in ethanol also met the World Health Organization (WHO) efficacy threshold (LC₉₀ < 100 mg/L). Strong ovicidal activity was observed, particularly for the crude ethanolic extract in ethanol (LC₅₀ = 37.82 mg/L) and crude ethanolic extract in ethyl acetate (LC₅₀ = 40.56 mg/L) fractions. The crude ethanolic extract in ethanol and crude ethanolic extract in dichloromethane fractions caused no mortality in Physella acuta or Biomphalaria tenagophila. Biosafety assays demonstrated low cytotoxicity, minimal hemolysis, and no acute toxicity in mice. These findings highlight A. esculentus seed fractions, especially crude ethanolic extract in ethyl acetate, as promising, biodegradable botanical molluskicides for schistosomiasis control.

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects mainly peripheral joints because of inflammation of the synovial membrane. Current treatments, such as nonsteroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids, although effective, are associated with high costs and several adverse effects. In this context, natural products have emerged as promising alternatives because of their potential therapeutic effects and lower toxicity. The objective of this review was to identify and evaluate natural substances with potential applications in RA treatment on the basis of studies published between 2015 and 2020. A literature search was conducted in SciELO, PubMed, and Google Scholar using the keywords “rheumatoid arthritis”, “treatment”, “toxicity”, and “natural products”. Additionally, we applied in silico methods to predict pharmacokinetic and toxicological parameters using ADMET Predictor^® (Simulation Plus) and compared the results with those of commercial drugs such as diclofenac, ibuprofen, and naproxen. Target fishing (reverse docking) was also performed to identify possible molecular targets related to RA. Seven natural compounds were identified, mostly evaluated through in vivo studies. Among them, paeoniflorin, quercetin, resveratrol, and celastrol are in clinical phases and present potential as RA treatments. In silico analysis highlighted curcumin, tetramethylpyrazine, and resveratrol as the most promising candidates, with ADMET profiles comparable or superior to those of current NSAIDs. In conclusion, natural products represent viable alternatives for RA therapy. However, further studies are essential to better understand their safety, pharmacokinetics, and drug interactions to ensure their clinical applicability.

Fasciolosis is one of the neglected tropical diseases, transmitted by the freshwater snails of the Lymnaea genus. In recent years, the control of these transmitters has been prioritized, and the search for effective and natural molluscicides aims to achieve a viable and eco-friendly alternative. In this sense, nanoemulsions are formulations that enhance the stability of active compounds, improve their delivery to their target site, and promote efficient dispersion of insoluble/immiscible substances. The development of a nanoemulsion containing a flavonoid-rich extract from Eugenia pruniformis for the biological control of Lymnaea sp. involved pre-formulation studies, as well as assessments of chemical and physicochemical stability. Biological assays evaluating the mortality of adult species of Lymnaea sp. upon contact with the most stable nanoemulsion during 72 h were performed. Additionally, the chemical composition of the extract was analyzed through UPLC-ESI-MS/MS, revealing a predominance of kaempferol, quercetin, and their derivatives, as well as gallic and ellagic tannins and chlorogenic acid isomers. The most stable formulation exhibited molluscicidal activity with LC₅₀/LC₉₀ values at 72 h of 20.38 ± 5.67 and 44.93 ± 9.06 ppm, respectively. These findings suggest the feasibility of employing a stable, active, biodegradable, and low-cost nanoformulation for the biological control of fascioliasis vectors.

The mollusk Achatina fulica, commonly known as the giant African snail, is a terrestrial gastropod native to East Africa that is spreading worldwide because of its high adaptability and reproductive capacity. This invasive species causes agricultural damage, negatively affects biodiversity, and poses risks to public and veterinary health by acting as an intermediate host of nematodes such as Aelurostrongylus abstrusus and Angiostrongylus cantonensis, the latter of which are responsible for eosinophilic meningitis in humans. Conventional control methods include manual collection and the use of synthetic molluskicides such as carbamate pesticides and metaldehyde. However, environmental concerns related to these substances have encouraged the search for alternative control strategies, including natural products with molluskicidal potential. This study aimed to evaluate the effects of plant extracts, fractions, and commercial fertilizer salts on A. fulica. Bioassays were performed using niclosamide, coarse salt, fractions of Abelmoschus esculentus, and extracts of Piper nigrum through a spraying method. In addition, bait formulations were prepared using fertilizer salts with agricultural applications, including salts A (potassium chloride - KCl), B (potassium nitrate - KNO3), and C (calcium sulfate - CaSO4). The results indicate that the tested fractions of A. esculentus did not present molluskicidal activity against A. fulica. Extracts of P. nigrum resulted in 11% mortality under the conditions tested. Salts B and C were active at a concentration of 2000 mg/L in the spraying protocol, with the highest mortality rate (33.3%) observed for salt C at 50,000 mg/L. In the bait experiments, the formulations were not consumed and were buried in the substrate by the mollusks.

Several natural products have been tested on mollusks of medical importance aiming to control these animals. Diverse scientific groups have demonstrated interest in finding new molluskicides from natural origin. In the literature, many promising studies have examined the molluskicidal activity of natural products on freshwater mollusks with medical importance. We used the keywords "natural products" and "molluskicidal activity" in diverse scientific databanks. A total of 301 articles were found, 25 of which were used in this letter. Most of these articles did not present ecotoxicity test reports. Some studies have reported ecotoxicity assays using nontarget organisms that do not represent freshwater ecosystems. Few articles showed ecotoxicity test reports using appropriate nontarget organisms, and only 1 presented test with more than 1 representative organism. The present work demonstrates the need to realize ecotoxicity tests using representative organisms in studies with natural products on freshwater mollusks of medical importance.

As the second most common infectious parasitic disease in the world, schistosomiasis is present in Brazil, mainly in the Northeast and Southeast regions. Currently, the recommended form of prevention is controlling this disease’s intermediate host, mollusks of the Biomphalaria genus, using the chemical molluscicide Bayluscide WP 70^®. This synthetic molluscicide is expensive, has low selectivity for Biomphalaria glabrata species, and is toxic to the environment. In this context, the use of natural products such as molluscicides represents a sustainable control method. The objective of this study was to evaluate the molluscicidal effects of a crude ethanolic extract of the leaves and stems and fractions of the species Myrsine parvifolia on the mollusk Biomphalaria glabrata. Methods: The methodology was adapted from standards defined by the World Health Organization (WHO), where the molluscicidal activity of Myrsine parvifolia was investigated as an alternative for the population control of Biomphalaria glabrata and That’s right. environmental toxicity was evaluated using the Physella sp. The results revealed that the stem ethanolic crude extract exhibited activity after 24 h of exposure, with an LC₅₀ of 207.4 mg/L and an LC₉₀ of 256.2 mg/L. Conclusions: Myrsine parvifolia can be used as a sustainable biological alternative for the population control of Biomphalaria glabrata snails, especially for poor populations and inaccessible regions.

Background/objectives: Schistosomiasis is caused by flatworms of the genus Schistosoma, for which mollusks of the genus Biomphalaria are intermediate hosts. Niclosamide (NCL) is a molluscicide recommended by the World Health Organization (WHO) for control of Biomphalaria. Although effective, it is expensive and environmentally toxic, which raises concerns regarding its widespread use. As a result, we explored new synthetic substances as alternative strategies for controlling Biomphalaria glabrata. We evaluated the molluscicidal activity of 2-(1H-py-razol-1-yl)-1,3,4-thiadiazole and 2-(4,5-dihydro-1H-pyrazol-1-yl)-1,3,4-thiadiazole derivatives against B. glabrata snails and embryos, as well as Schistosoma cercariae (infective larvae). Methods: Adult and young snails were added to 24-well plates containing 20 synthetic compounds from the PDAN series for initial screening over 96 h at a concentration of 100 ppm. Water and NCL (2 ppm) were used as the negative and positive controls, respectively. Active compounds in the adult B. glabrata assay were selected for the tests vs. embryos and cercariae. Results: In the initial screen, only PDAN 52 (63 ± 4%) and 79 (12 ± 3%) showed molluscicidal activity at a concentration of 100 ppm up to 48 h. Consequently, we selected only PDAN 52. The LC₅₀ value found in the tests on embryos after 24 h of treatment was 20 ± 2 ppm and, after 48 h, it was 4 ± 0.5 ppm. Against cercariae, we measured an LC₅₀ value of 68 ± 5 ppm after 4 h of treatment. PDAN 52 did not induce marked toxicity against a second mollusk, Physella acuta, after 48 h of exposure. Conclusions: We highlight the promising molluscicidal activity of PDAN 52 against different developmental stages of the mollusk, B. glabrata, as well the infective larvae of Schistosoma mansoni.

Topical administration of Moringa oleifera leaf and seed ethanolic extracts concentrations (5, 10, 25, 50, 75, and 100 mg/L) were screened for insecticide activities against Chrysomya putoria (Diptera: Calliphoridae). Results showed that all tested leaf and seed extractconcentrations were toxic, delayed post-embryonic larval development, and reduced weight. As for C. putoria mortality, from newly hatched larvae to the adult period, all concentrations showed larvicidal power. However, above 20% of the mortality rate occurred in those treated with both leaf and seed extract concentrations. The ones treated with M. oleifera leaf extract concentrations presented the respective mortality rates: 50 mg/L (23%), 75 mg/L (29 %), and 100 mg/L (30%). While those treated with M. oleifera seed extract concentrations, the mortality rate observed was 25 mg/L (20%), 50 mg/L (27%), 75 mg/L (30%), and 100 mg/L (32%). The medicinal plant M. oleifera leaf and seed extracts proved to be a viable alternative for the population control of the medical veterinary and sanitary important blowfly C. putoria .

Schistosomiasis is a neglected tropical disease caused by parasitic worms of the genus Schistosoma. In Brazil, there are reports of infection by the Schistosoma mansoni species, which has the Biomphalaria glabrata snail as one of its intermediate hosts. The present work aimed to test the effects of different Abelmoschus esculentus seed extracts and fractions on adults and embryos of B. glabrata and S. mansoni cercariae. A total of four crude extracts and thirteen fractions with different organic solvents were used for the bioassays. The extracts were analyzed using high-performance liquid chromatography coupled to mass spectrometry. Molluscicidal activity was assessed in 24-well plates, after which the LC₅₀ and LC₉₀ were calculated. Assays with B. glabrata embryos and S. mansoni cercariae were also performed. These findings indicate the presence of flavanoids in the hexane, ethyl acetate, and ethanol crude extracts. For the molluscicidal activity assays, eight fractions had an LC₉₀ value less than that recommended by the WHO. The methanol fraction of the dichloromethane extract (FrMeOH EDM) had the most promising results, with an LC90 of 37.15 mg/L and 100% mortality in embryos of B. glabrata and cercariae. FrMeOH, EDM, and other fractions are possible candidates for new drugs for the combat of schistosomiasis.

Achatina fulica is a terrestrial mollusk known as the giant African snail that is related to environmental, economic, urban, and public health problems. As control measures for this mollusk, cooking salt (NaCl) and calcium oxide (CaO) are used, and baits are composed of metaldehyde. However, these measures have environmental toxicity and impact the soil. In this way, natural products have been tested on this mollusk to discover and develop a substance to combat this urban and agricultural pest. This article aims to evaluate studies involving natural products to control the population of Achatina fulica. Articles and works published in books were included in the present work. A total of 1,103 works were found during the search. Of these, 14 works met the objective of these review and were included in this article. The tests do not possess methodological standardization, do not have a maximum concentration to be considered active, or a maximum exposure time. A lack of standardization in the methodology of tests on A. fulica was observed. The performance of tests on other life stages of the mollusk, as well as tests that analyze other parameters, are essential. Only one article analyzed presented phytochemical analysis. No ecotoxicity tests were reported either. Some extracts showed promising results, highlighting the aqueous extract of Capsicum frutescens. More studies investigating the molluscicidal activity of natural products on A. fulica are needed. It is very relevant that the new studies present a phytochemical analysis of the tested extracts, as well as ecotoxicity studies.