Molluscicidal Activity Research Articles

Marine Cyanobacteria: A Rich Source of Structurally Unique Anti-Infectives for Drug Development

Marine cyanobacteria represent a promising yet underexplored source of novel natural products with potent biological activities. Historically, the focus has been on isolating cytotoxic compounds from marine cyanobacteria, but a substantial number of these photosynthetic microorganisms also produce diverse specialized molecules with significant anti-infective properties. Given the global pressing need for new anti-infective lead compounds, this review provides a concise yet comprehensive overview of the current knowledge on anti-infective secondary metabolites derived from marine cyanobacteria. A majority of these molecules were isolated from free-living filamentous cyanobacteria, while several examples were derived from marine cyanobacterial symbionts. In addition, SAR studies and potent synthetic analogs based on selected molecules will be featured. With more than 200 molecules, this review presents their antibacterial, antifungal, antiviral, antiprotozoal, and molluscicidal activities, with the chemical and biological information covered in the literature up to September 2024.

Conchocarpus J. C. Mikan (Rutaceae): Chemical Constituents and Biological Activities.

Rutaceae Juss. stands out as a botanical family recognized for its remarkable diversity in taxonomy, worldwide distribution, chemical composition, and biological activity exhibited by its compounds. Conchocarpus J. C. Mikan is one of the main genera of this family, comprising 50 species distributed throughout the Neotropical America. Brazil is the main center of diversity for this genus, hosting 66 % of the species as endemic. This is the first review concerning the genus Conchocarpus, emphasizing its chemical composition and biological activities. The selected papers for this review cover studies on 11 species, of which were identified 88 compounds. Among these, quinoline and acridone alkaloids predominate (57 %), followed by flavonoids, amides, coumarins and terpenoids. The biological activities of extracts and compounds indicate trypanocidal and leishmanicidal actions, as well as cytotoxic, fungicidal, molluscicidal, insecticidal, anticholinesterase and antioxidant activities.

Molluscicidal property of symbiotic bacteria associated with entomopathogenic nematodes against Indoplanorbis exustus and Radix rubiginosa, the intermediate hosts of trematode parasites

Indoplanorbis exustus and Radix rubiginosa act as intermediate hosts for veterinary and medical trematode parasites. Snail control is a strategy used to decrease the number of snails and interrupt the life cycle of parasites. The objective of this study was to evaluate the efficacy of Xenorhabdus and Photorhabdus extracts against I. exustus and R. rubiginosa in the laboratory. Ethyl acetate extracts of selected symbiotic bacteria were tested for their molluscicidal activities according to World Health Organization guidelines. Additionally, pathological changes in the snails were observed after treatment with the LC50 values under a light microscope. Indoplanorbis exustus and R. rubiginosa were susceptible to all ethyl acetate extracts of symbiotic bacteria. The lowest LC50 and LC90 at 24 h for I. exustus after exposure to Photorhabdus laumondii subsp. laumondii (bALN18.2_TH) extracts were 81.66 and 151.02 ppm, respectively. Similarly, the lowest LC50 and LC90 at 24 h for R. rubiginosa after exposure to Photorhabdus luminescence subsp. akhurstii (bAPY3.5_TH) extracts were 49.21 and 147.66 ppm, respectively. Photorhabdus species had more substantial molluscicidal effects than Xenorhabdus on these snails. The ethyl acetate extracts of these bacteria are effective when contacting the epithelial cells and foot muscle of the snails. To our knowledge, this is the first report on using Xenorhabdus and Photorhabdus extracts to evaluate molluscicidal activities. These symbiotic bacteria, Xenorhabdus and Photorhabdus, may be useful for controlling snail intermediate hosts.

Molluscicidal activity and biochemical impacts of borrelidins against an aquatic invasive snail Pomacea canaliculata for crop protection

The invasive golden apple snail Pomacea canaliculata is one of the devastating threats to aquatic ecosystems and wetland agriculture worldwide. Macrolides from microbes display various advantages over other compounds in controlling snails. However, emergence of antibiotic-resistant phenotypes against certain macrolides in the field appeals for exploring more effectively molluscicidal macrolides. Here, two borrelidins, borrelidin BN1 and BN2, from the extract of a Streptomyces strain fermentation were evaluated for molluscicidal potential against P. canaliculata using both immersion and contact bioassay methods. Borrelidin BN1 (borrelidin A) presented a significant molluscicidal activity comparable to the chemical pesticide metaldehyde, and had a much lower median lethal concentration value (LC50, 522.984 μg·ml−1) than avermectin B1 at 72 h of contact-killing treatment. Snail growth was inhibited by borrelidin BN1 more than by metaldehyde at sublethal concentrations, consistent with responses of key biochemical parameters. Exposure to borrelidin BN1 decreased the activity of acetylcholinesterase (AChE), glutathione S-transferase (GST), aspartate aminotransferase (AST), alanine aminotransferase (ALT) as well as the levels of energy reserves and sex steroids in snail tissues, while increased the activity of superoxide dismutase (SOD), catalase (CAT), lactate dehydrogenase (LDH) and the level of lipid peroxidation (LPO). Further application assay confirmed that borrelidin BN1 protected crop plant Zizania latifolia from P. canaliculata damage via suppressing snail population density. These findings suggest great potential of borrelidin BN1 as a molluscicide. Additionally, its higher activity than the stereoisomeric borrelidin BN2 (borrelidin F) implied better molluscicidal borrelidins could be acquired through structural optimization.

Evaluation of the Effects of Papain on Schistosoma mansoni: Miracidial Infection Capacity, Infection Prevalence, Cercarial Shedding and Molecular Changes in Biomphalaria alexandrina.

The aim of the present study is to assess the molluscicidal, larvicidal and genotoxicological activities of papain and how it can affect the host-parasite interactions. Toxicity of papain on snails by making series of concentrations to calculate LC50, and then study its larvicide effect on the free larval stages of S. mansoni and infection rate of snails. Papain has a molluscicidal activity on adult snails of Biomphalaria alexandrina with a lethal concentration LC50 equals to 43.1mg/L. In addition, it has activity on miracidia with half Lethal time (LT50) of 16.11min., and on cercariae with 12.1min. compared to control ones. The sub lethal concentration LC10 and LC25 (6.9 or 24.1mg/L, respectively) decreased the survival rate of snails at the first cercarial shedding, the rate of infection, the average total number of cercariae per snail, the shedding period and the life span of snails, while the prepatent period was significantly increased than the control ones. The morphological alterations in cercariae after exposure to papain were occurred where the cercariae lacked motility and some had a dark tail with complete detachment of head and tail. Compared to the control group, the levels of cytochrome oxidase subunit I (COI) and (ND1) genes significantly decreased in snails after exposure to papain. Papain could be used as a potential molluscicide for elimination of schistosomiasis and decrease its transmission and deterioration of host-parasite interaction.

In vitro molluscicidal activity and biochemical impacts of some thiophene derivatives against the glassy clover snail, Monacha obstructa (Pfeiffer)

BackgroundThe glassy clover snail, Monacha obstructa (Pfeiffer), is considered one of the major agricultural pests that ruin many field crops, vegetables, orchards of fruits, plants of ornament as well as many other plantations. Synthesis of the Schiff base ligand, namely bis-[4-benzylidene-thiophene-2′-yl] methane (L), produced from the reaction between thiophene-2-carboxaldehyde and diaminodiphenylmethane (MDA), alongside its copper complex were conducted. The output chemical compounds were evaluated in vitro for their molluscicidal activity against the glassy clover snail, M. obstructa by performing the contact technique. Stock solutions were prepared via using (distilled water + DMF) mixture. Furthermore, the impact of these compounds on some critical biochemical indicators: cholesterol, total protein, and acetylcholinesterase (AChE), was evaluated.ResultsThe outcome results demonstrated the significantly higher molluscicidal activity of the Cu(II) chelate compared to its free ligand (L), which in turn reveals the importance of metal chelation in enhancing toxicity against the target species. Particularly, the LC25 and LC50 values are (27.25, 34.65) and (17.88, 25.31) ppm for the ligand (L) and its copper construction, respectively. Additionally, the data confirmed the significant effectiveness of the tested compounds on the assessed biochemical indicators of treated snails. Total protein and cholesterol levels were elevated after treatment with both the ligand (L) and its copper complex while AChE activity increased after treatment with the ligand (L) and reduced upon the exposure to the Cu(II) chelate.ConclusionsThe findings established that the copper complex exhibited a markedly higher molluscicidal activity compared to the free ligand (L). Also, the results confirmed the significant effects of the investigated compounds on the assessed biochemical indicators of treated M. obstructa snails.

Main active constituents and mechanism of toxicity of raphides from Arisaema erubescens against Oncomelania hupensis

To find a high-efficiency and environment-friendly biogenic molluscicide against Oncomelania hupensis, and prevent aquatic ecosystem from being contaminated by chemical molluscicides and being toxic. We extracted and purified raphides from the tubers of Arisaema erubescent, and determined the active constituents and molluscicidal activity of the raphides, detoxification enzyme activity, and liver damage. The results showed that the raphides had a strong molluscicidal activity. O. hupensis snails were exposed to the lethal concentration (LC50) of 70.95 mg/L and 44.25 mg/L for treatment with raphides for 48 h and 72 h, respectively. The raphides of molluscicidal activity of the main constituents was as follows: intact raphides > calcium oxalate crystals > AEL (Arisaema erubescens Lectin). The activities of peroxidase (POD), superoxide dismutase (SOD) and catalase (CAT) in the snail livers increased significantly at the early stage of treatment (24 h), but decreased sharply in the later stage (120 h), compared with that in the control group. The results indicated that after treatment with 1/2 LC50 raphides for 120 h, the activities of POD, SOD, and CAT in the snail livers decreased by 82.5 %, 62.9 %, and 84.7 %, respectively. In addition, electron micrographs have shown that the raphides were needle-shaped crystals and tended to be sharp at both ends (with a groove down both sides) and some were barbed, which caused damage to the snail livers to different extent. Overall, our results indicate that the mechanism of toxicity of raphides against O. hupensis may be that the calcium oxalate crystals pricked the liver surface of snail and produced mechanical damage; and then the harmful protease AEL in the raphides was injected into the liver, which reduced the activities of detoxification enzymes, produced severe toxic reactions and eventually killed the O. hupensis snails.

Microscopic and histochemical characterization applied to quality control of Anacardium occidentale: Anacardium occidentale microanalyses

Anacardium occidentale belongs to the Anacardiaceae family and is popularly known as cashew. It is provided with several pharmacological activities, described in the National List of Medicinal Plants of Interest to the Unified Health System. Its anti-inflammatory, antioxidant, antimicrobial, antidiabetic, molluscicidal, and larvicidal activities stand out. As it is a plant of great economic and medicinal importance, it is necessary to characterize the pharmacobotanical profile of this species. Thus, the present work aims to carry out a microscopic and histochemical characterization applied to the quality control of A. occidentale. Cross-sections of the stem, petiole and leaf blade were performed, as well as longitudinal sections of the stem and paradermal sections of the leaf blade. Anatomical studies were performed under light, polarization and scanning electron microscopy. For histochemical analysis, different reagents were used according to the metabolite under investigation. Among the anatomical structures that provide a detailed diagnosis of the studied parts of this species, the presence of resin ducts, druse crystals, glandular trichomes, paracytic stomata, and isobilateral mesophyll stand out. Histochemistry identified the location of different substances, such as starch, phenolic compounds, lipophilic compounds, lignin, essential oils, tannins, triterpenes, steroids, and calcium oxalate crystals in the leaf blade. Through the analysis of ultra-anatomical images by SEM-EDS, it was also possible to verify that the crystals found in the leaf blade are calcium oxalate. Its elemental composition was shown in detail. In view of the results, the importance of this study is justified because important characteristics of the anatomical structure of the stem and leaves of this medicinal species of wide distribution in Brazil are now identified. They are essential parameters for the determination of botanical authenticity.

Chemical structure of steroidal saponin isolated from the leaves of Dracaena draco L.

Saponins are naturally occurring compounds ubiquitously present in various organisms, predominantly in plants. They are noted for forming colloidal solutions in water, which foam on shaking and precipitate cholesterol. Several in vitro and in vivo tests on mixtures and individual saponins have revealed a broad spectrum of biological and pharmacological activities, including cancer-related activity, antiphlogistic and antiallergic, immunomodulating, antihepatotoxic, antiviral, hypoglycemic, antifungal and molluscicidal activities. The Dracaena genus is renowned for an abundance of steroidal saponins utilized in treating digestive and hematological disorders. Previous studies on this genus revealed the presence of steroidal saponins, some of which showed cytotoxic activities against cultured tumor cells and interesting biological activities. This study procured steroidal saponin from the foliage of D. dracoL. using various chromatographic techniques and 1D and 2D nuclear magnetic resonance (NMR) spectroscopic analysis. The structure was deduced as 26-O-β-D-glucopyranosyl-22-O-methylfurosta-5,25(27)-diene-1β,3β,22α,26-tetrol 1-O-{O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl}; a compound previously isolated from the underground parts of Ruscusaculeatus in Japan. Future evaluation of the saponin’s biological activity is imperative to enhance chemotaxonomic data concerning the chemical composition and biological functionality of D. draco L. and, by extension, the Dracaena genus.

Research on the Mechanism of Metaldehyde on Pomacea canaliculata.

Golden apple snail (Pomacea canaliculata), a major alien invasive organism in China, affects food production and poses a threat to human health. Metaldehyde is a highly effective, commonly used snail killer with low toxicity. Virulence determination, tissue section, iTRAQ and RNA interference were used to systematically study the toxicity of metaldehyde on P. canaliculata. The molluscicidal activity tests showed that metaldehyde exhibits strong toxicity against P. canaliculata. Physiological and biochemical data indicate that metaldehyde can cause damage to the gills, liver, pancreas, and kidneys of snails, also reduce the oxygen consumption rate and ammonia excretion rate of golden apple snails, and cause neurological diseases. The proteome of the gill region of the golden apple snail after exposure to metaldehyde was analyzed by using iTRAQ technology. A total of 360 differential proteins were identified, and four target proteins were screened, namely, alpha-protein kinase 1 (ALPK1), cubilin (CUBN), sodium- and chloride-dependent GABA transporter 2 (GAT2), and acetylcholinesterase (AChE). RNAi was used to target the four proteins. After the ALPK1 and CUBN protein genes were interfered with by metaldehyde treatment, it was found that the mortality rate of the golden apple snail significantly increased. However, interference of GAT2 and AChE protein genes by metaldehyde led to no significant change in the mortality rates of the snails. The histopathological observation of the gill showed that the rate of cilia shedding in the gill decreased after the interference of ALPK1 and CUBN protein genes.

Novel synthesis of some heterocycles and their molluscicidal activity against the destructive land snail, Theba pisana

BackgroundTerrestrial snails, specifically Theba pisana, represent significant agricultural pests in the Mediterranean region, particularly in Egypt. They are gastropods that cause substantial damage to a variety of vegetation, rendering them important agricultural pests that result in economic losses. In response, we have developed unique and non-toxic molluscicides. The study assessed nine novel heterocycles compared with methomyl as a reference compound, to study their molluscicidal effects on T. pisana. These heterocycles include 2-pyrazolines, 2-oxocyclohex-3-ene, and 3-cyano-2-ethoxypyridine.ResultsThe obtained data revealed that the majority of the produced chemicals were remarkably effective against T. pisana snails, exhibiting different degrees of toxicity seven days post-treatment. Methomyl exhibited the highest toxicity, followed by prop-2-en-1-one and 1-thiocarbamoyl-2-pyrazoline derivatives, with LC50 values of 44.14, 59.54, and 72.00 ppm, respectively.ConclusionsThese findings will inform the potential of these synthetic compounds as one of the sources for molluscicide development and their integration into pest management strategies.Graphical

Molluscicidal Activity and Inhibition of Acetylcholinesterase Activity of Azadirachta Indica Extract on Pomacea Canaliculata

The Golden Apple Snail, Pomacea canaliculata, is a notorious pest in Malaysia, leading to substantial agricultural and economic losses, while, the neem tree, Azadirachta indica has been identified as alternative source for bio-pesticides. There is currently limited information on A. indica as natural molluscicide against P. canaliculata. This study aims to evaluate the effects of A. indica on P. canaliculata at various life stages (eggs, juvenile and adult). The bioactive compound, azadirachtin in A. indica extracts was quantified using high-performance liquid chromatography (HPLC). Egg hatchability was determined using spot spraying on egg clusters while the molluscicidal activity of A. indica on juvenile and adult specimens was evaluated using the immersion bioassay approach. The snail's acetylcholinesterase (AChE) inhibition was assessed using Ellman assay. The azadirachtin content in the ethanolic extract of A. indica leaves at a concentration of 1 µg/mL was found to be 45.42%. Increasing the concentration of A. indica extracts resulted in lower egg hatchability and increased mortality of juvenile and adult snails. Azadirachta indica extracts showed the highest effectiveness against adult P. canaliculata with an LC50 value of 0.52 mg/mL, compared to 0.92 mg/mL for juveniles and 0.74 mg/mL for eggs. Additionally, A. indica extract exhibited greater inhibition of AChE in adult specimens compared to juvenile specimens and eggs. The IC50 for adult is 0.60 μg/mL, which is the lowest while the IC50 for juvenile is 0.68 μg/mL, the highest. Taken together, A. indica shows immerse potential as natural pesticide for managing the population of P. canaliculata.

Antiparasitic activities of medicinal plants: An overview

Several of the parasites have become resistant to chemotherapy, so alternatives are urgently required. Natural products still play an important role in therapy: between 1981 and 2006, 1,184 new drugs were registered of which 28% were natural products or their derivatives. Another 24% of the new drugs had pharmacophores (functional groups with pharmacological activity) derived from natural products. In this review, PubMed, Google Scholar, Web of Science, EBSCO, Science Direct, and Scopus were searched for medicinal plants with antiparasitic, antiprotozoal, molluscicidal and insecticidal activity to encourage identification of the active ingredients, determination of clinical efficacy, studying of pharmacokinetic characteristics, investigation of the mode of action and safety.

Screening the Efficacy and Safety of Molluscicides from Three Leaf Extracts of Chimonanthus against the Invasive Apple Snail, Pomacea canaliculata.

Pomacea canaliculata, the invasive snail, is a host of the parasitic nematode Angiostrongylus cantonensis, which has adverse effects on the agriculture system and human health. This work evaluated the molluscicidal activity of petroleum ether extracts (PEEs) from three species of Chimonanthus against the snail P. canaliculate. Pcp (PEE of C. praecox) showed the most effective molluscicide activity. Sixty-one compounds were identified by GC-MS and the main components were terpenoids and fatty acids. The half-lethal concentration (LC50) of Pcp at 24 h (0.27 mg/mL) and 48 h (0.19 mg/mL) was used to evaluate the biochemical alterations in snail tissue. These sublethal concentrations caused the levels of alkaline phosphatase (ALP), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) activity to increase, while acetylcholinesterase (AChE) activity decreased. Also, under LC50 treatment, several histological changes were observed in the hepatopancreas and foot of the snail compared with the control group. Moreover, the toxic test in rice demonstrated that Pcp has low toxicity. These results suggest that Pcp could be developed as an effective molluscicide for P. canaliculata control.

Phyto-synthesized silver nanoparticles from Sargassum subrepandum: anticancer, antimicrobial, and molluscicidal activities.

In the realm of nanotechnology, the use of algae to produce nanoparticles is an environmentally friendly, sustainable, and economically viable strategy. In the present study, the brown macroalgae Sargassum subrepandum was utilized to effectively produce silver nanoparticles (AgNPs). Through various characterization techniques, the AgNPs' structural integrity was confirmed. AgNPs exhibited significant antimicrobial activity against Pseudomonas aeruginosa and Fusarium equiseti. AgNPs showed cytotoxic effects on the MCF-7 breast adenocarcinoma cell line with an IC50 of 12.5 µg/ml. Treatment with AgNPs resulted in a marked reduction in cell viability, alongside evident apoptotic and necrotic morphological changes in the cancer cells. Through molecular docking studies, a deeper understanding of the interaction between AgNPs and crucial proteins related to cancer has been achieved, AgNPs showed a promising molluscicidal action on Biomphalaria alexandrina snails, a Schistosoma mansoni intermediate host. The half-lethal dose (LC50) of AgNPs was determined to be 0.84 mg/L. The potential consequences of its administration include potential disruptions to the glycolysis profile, as well as potential impacts on the steroidal hormone's estrogen and testosterone and certain kidney function tests. This study highlights the diverse uses of algae-synthesized AgNPs, ranging from healthcare to environmental management, demonstrating their importance in advancing nano-biotechnological solutions.

Molluscicide screening and identification of novel targets against Pomacea canaliculata.

Owing to the nonavailability of any clear targets for molluscicides against Pomacea canaliculata, target-based screening strategy cannot be employed. In this study, the molluscicidal effects of typical pesticides on P. canaliculata were evaluated to obtain the molluscicide target. A series of arylpyrrole compounds were synthesized based on the discovered target, and their structure-activity relationships explored. A preliminary strategy for screening molluscicides based on specific targets was also developed. A laboratory colony of P. canaliculata was developed, which showed no difference in sensitivity to niclosamide compared with the wild group, while exhibiting a higher stability against pesticide response. Mitochondrial adenosine triphosphate (ATP) synthase inhibitors and mitochondrial membrane potential uncouplers were identified and validated as potential targets for molluscicide screening against P. canaliculata. A series of arylpyrrole compounds were designed and synthesized. The median lethal concentration of 4-bromo-2-(4-chlorophenyl)-5-(trifluoromethyl)-1H-pyrrole-3-carbonitrile (Compound 102) was 10-fold lower than that of niclosamide. New molluscicide targets were discovered and validated, and preliminary strategies were explored for pesticide screening based on these targets. Compound 102 exhibited a high molluscicidal activity and had a great potential value for exploring a molluscicide to control P. canaliculata. © 2024 Society of Chemical Industry.

Green synthesis of silver nanoparticles using Croton urucurana and their toxicity in freshwater snail species Biomphalaria glabrata

Green silver nanoparticles (G-Ag NPs) have contributed to the development of ecological technologies with low environmental impact and safer for human health, as well as demonstrating potential for the control of vectors and intermediate hosts. However, knowledge about its toxicity in the early stages of gastropod development remains scarce. Therefore, the current study aimed to investigate the toxicity of G-Ag NPs synthesized from Croton urucurana leaf extracts in snail species Biomphalaria glabrata, which is an intermediate host for Schistosoma mansoni parasite. G-Ag NPs were synthesized using two types of plant extracts (aqueous and hydroethanolic) and characterized using multiple techniques. Bioassays focused on investigating G-Ag NPs and plant extracts were carried out with embryos and newly hatched snails, for 144 h and 96 h, respectively; toxicity was analyzed based on mortality, hatching, development inhibition, and morphological changes. Results have shown that both G-Ag NPs were more toxic to embryos and newly hatched snails than the investigated plant extracts. G-Ag NPs deriving from aqueous extract have higher molluscicidal activity than those deriving from hydroethanolic extract. Both G-Ag NPs induced mortality, hatching delay, development inhibition, and morphological changes (i.e., hydropic embryos), indicating their molluscicidal activities. Moreover, embryos were more sensitive to G-Ag NPs than newly hatched snails. Thus, the toxicity of G-Ag NPs to freshwater snails depends on the type of extracts and the snail's developmental stages. These findings can contribute to the development of green nanobiotechnologies applicable to control snails of medical importance.

Potential molluscicidal activity of the aqueous extracts of some plants and their powders against terrestrial snail Monacha obstructa (L. Pfeiffer, 1842) under laboratory and field conditions

As it is known that the excessive use of pesticides causes many environmental problems, the effects of four aqueous plant extracts and their powders [Solanum nigrum L., Withania somnifera (L.) Dunal, Salix mucronata Thunb. and Lawsonia inermis L.] were evaluated as natural molluscicides on the land snail Monacha obstructa (Family: Hygromiidae) under laboratory conditions. Three different bioassay methods were used: contact, leaf-dipping and bait techniques. The results indicated that, using all methods, S. Nigrum extract was the most toxic extract for the terrestrial snail M. obstructa. The contact technique of the tested plant extracts was the most effective method of application compared to other methods. Moreover, using plant extracts was better than using powders of these plants for controlling the terrestrial snail M. obstructa. In addition, the results indicated that the aqueous extract of S. nigrum gave the highest percentage of reduction in the snail population when assessed under field conditions. The obtained data showed that plant extracts were significantly effective against the terrestrial snail and could be used as alternatives to pesticides in integrated pest management.

Effects of Abelmoschus esculentus Extracts and Fractions on Embryos and Adult Individuals of Biomphalaria glabrata (Say, 1818) and on Schistosoma mansoni Cercariae

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.

Molluscicidal effect mechanism study on metaldehyde to Pomacea canaliculate at low temperature.

Metaldehyde is a molluscicide commonly used to control Pomacea canaliculate. Its efficacy is significantly impacted by water temperature, although the underlying mechanisms have not been fully explored. In this study, we systematically investigated the temperature effect and molecular mechanisms of metaldehyde on P. canaliculata. The molluscicidal effect at various temperatures indicated that metaldehyde's molluscicidal activity significantly decreases with a drop in temperature. The LC50 value was only 458.8176 mg/L at 10 °C, while it surged to a high of 0.8249 mg/L at 25 °C. The impact of low temperature (10 °C) on metaldehyde's molluscicidal activity was analyzed via transcriptomics. The results revealed that the effect of low temperature primarily influences immunity, lipid synthesis, and oxidative stress. The expression of stress and immune-related genes, such as MANF, HSP70, Cldf7, HSP60, and PclaieFc, significantly increased. Furthermore, we studied the function of five target genes using RNA interference (RNAi) and discovered that Cldf7 and HSP70 could notably affect metaldehyde's molluscicidal effect. The mortality of P. canaliculata increased by 36.17% (72 h) after Cldf7 interference and by 48.90% (72 h) after HSP70 interference. Our findings demonstrate that low temperature can induce the extensive expression of the Cldf7 and HSP70 genes, resulting in a substantial reduction in metaldehyde's molluscicidal activity. © 2024 Society of Chemical Industry.