Experimental study on the molluscicidal activity of surfactin against Oncomelania hupensis / 中国血吸虫病防治杂志

Objective To evaluate the molluscicidal activity of surfactin against Oncomelania hupensis, so as to provide the experimental basis for use of Bacillus for killing O. hupensis. Methods O. hupensis snails were collected from schistosomiasisendemic foci of Wuhu City on September 2022, and Schistosoma japonicum-infected snails were removed. Then, 60 snails were immersed in surfactin at concentrations of 2, 1, 0.5, 0.25, 0.125 mg/mL and 0.062 5 mg/mL for 24, 48, 72 hours at 26 °C, while ultrapure water-treated snails served as controls. The median lethal concentration (LC50) of surfactin against O. hupensis snails was estimated. O. hupensis snails were immersed in surfactin at a concentration of 24 h LC50 and ultrapure water, and then stained with propidium iodide (PI). The PI uptake in haemocyte was observed in O. hupensis snails using fluorescence microscopy. Results The mortality of O. hupensis was 5.0% following immersion in surfactin at a concentration of 0.062 5 mg/mL for 24 h, and the mortality was 100.0% following immersion in surfactin at a concentration of 2 mg/mL for 72 h, while no snail mortality was observed in the control group. There were significant differences in the mortality of O. hupensis in each surfactin treatment groups at 24 (χ2 = 180.150, P < 0.05), 48 h (χ2 = 176.786, P < 0.05) and 72 h (χ2 = 216.487, P < 0.05), respectively. The average mortality rates of O. hupensis were 38.9% (140/360), 62.2% (224/360) and 83.3% (300/360) 24, 48 h and 72 h post-immersion in surfactin, respectively (χ2 = 150.264, P < 0.05), and the 24, 48 h and 72 h LC50 values of surfactin were 0.591, 0.191 mg/mL and 0.054 mg/mL against O. hupensis snails. Fluorescence microscopy showed more numbers of haemocytes with PI uptake in 0.5 mg/mL surfactintreated O. hupensis snails than in ultrapure water-treated snails for 24 h, and there was a significant difference in the proportion of PI uptake in haemocytes between surfactin-and ultrapure water-treated snails (χ2 = 6.690, P < 0.05). Conclusion Surfactin is active against O. hupensis snails, which may be associated with the alteration in the integrity of haemocyte membrane.

Molluscicidal activity of the Bacillus velezensisis Y6 strain against Oncomelania hupensis and its preliminary mechanisms of molluscicidal actions / 中国血吸虫病防治杂志

Objective To assess the molluscicidal activity of the of Bacillus Y6 strain against Oncomelania hupensis in laboratory, and to preliminarily investigate its mechanisms of molluscicidal actions. Methods Biological identification of the Y6 strain was performed based on analysis of its morphological and physiochemical features and homology analysis of the 16S rDNA gene sequence. Bacillus Y6 suspensions were formulated at concentrations of 0.005, 0.010 g/mL and 0.015 g/mL, and the molluscicidal activity of Bacillus Y6 suspensions against O. hupensis was tested in laboratory using the immersion method. In addition, the Bacillus Y6 content and glycogen content were detected in O. hupensis following exposure to Bacillus Y6 suspensions to preliminarily explore the molluscicidal mechanism of the Bacillus Y6 strain against O. hupensis. Results The colony of the Bacillus Y6 strain appeared non-transparent milky white, and mycoderma was produced on the surface of the nutrient agar liquid medium. The Y6 stain was Gram positive and rod-shaped, and the endospore was located at the center of the Bacillus Y6 strain and appeared an achromatic, transparent and refractive body, which was encapsulated by the Y6 strain. The Y6 strain was positive for the lecithinase test, and the 16S rDNA gene sequence showed a 100% homology with those of multiple B. velezensisis strains, B. amyloliquefaciens and B. subtilis. The Y6 strain was therefore identified as B. velezensisis. Following immersion in the Bacillus Y6 suspensions at concentrations of 0.005, 0.010 g/mL and 0.015 g/mL for 24, 48 h and 72 h, the mortality rates of Oncomelania snails were 28.3%, 31.7% and 81.6%, 43.3%, 58.3% and 93.3%, and 63.3%, 78.3% and 98.3%, respectively. The molluscicidal activity of the Bacillus Y6 suspensions increased with the suspension concentration and duration of immersion. Microscopy and colony counting revealed the highest Y6 content in dead snails and the lowest in living snails following immersion in Bacillus Y6 suspensions, and the mean glycogen contents were (0.68 ± 0.06), (1.09 ± 0.16) μg/mg and (2.56 ± 0.32) μg/mg in the soft tissues of dead, dying and living snails following immersion in Bacillus Y6 suspensions (F = 59.519, P < 0.05), and the mean glycogen content was significantly higher in living snails than in dead (t = 14.073, P < 0.05) and dying snails (t = 10.027, P < 0.05), while the mean glycogen content was significantly higher in dying snails than in dead snails (t = 5.983, P < 0.05). Conclusion The B. velezensisis Y6 strain shows a high molluscicidal activity against O. hupensis snails, and its invasion may cause glycogen metabolism disorders, leading to snail death.

MOLLUSCICIDAL AND LARVICIDAL ACTIVITIES OF Atriplex inflata AERIAL PARTS AGAINST THE MOLLUSK Galba truncatula, INTERMEDIATE HOST OF Fasciola hepatica / Atividade moluscicida e larvicida das partes aéreas de Atriplex inflata contra o molusco Galba truncatula, hospedeiro intermediário da Fasciola hepatica

Fasciolosis is a widespread parasitosis of farm live-stock in many developing countries. For this reason, it is necessary to search for new substances against parasitic diseases caused by flukes. Indeed, a wide variety of terrestrial plants have been subjected to chemical and pharmacological screening in order to discover their potential for human medicinal use. The molluscicidal and larvicidal activities of Atriplex inflata were tested on Galba truncatula and Fasciola hepatica larval stages infecting this snail in Tunisia. Phytochemical tests were conducted on extracts in order to establish a meaningful relationship with molluscicidal and larvicidal activities. The molluscicidal activity was evaluated by subjecting snails to sample aqueous solutions. Accordingly, hexane, ethyl acetate, methanol and methanol-water (8:2, v-v) were used as extraction solvents. As a result, hexane and ethyl acetate extracts showed potent activity, according to the World Health Organization, giving LC50 = 7.59 mg/L and 6.69 mg/L for hexane extracts of leaves and fruits, respectively. Ethyl acetate extracts gave LC50 = 5.90 mg/L and 7.32 mg/L for leaves and fruits, successively. Molluscicidal activities of powders were less potent on snails, but active according to the World Health Organization. Hexane and ethyl acetate extracts from leaves and fruits gave potent larvicidal activities with a delay rate exceeding 45.50% (45.50- 98.92%). Phytochemical tests showed that these activities may be attributed to the presence of triterpenoids and/or sterols.

Fasciolose é uma parasitose generalizada que ocorre em animais de fazendas em muitos países em desenvolvimento. Por esta razão, é necessária a busca de novas substâncias contra as doenças parasitárias causadas por vermes. De fato, uma grande variedade de plantas terrestres foi objeto de testes farmacológicos e químicos a fim de descobrir o seu potencial para utilização em terapêutica humana. As atividades moluscicida e larvicida de Atriplex inflata foram testadas contra estágios larvários de Galba truncatula e Fasciola hepatica infectando este caracol na Tunísia. Testes fitoquímicos foram realizados com extratos a fim de estabelecer uma relação significativa com as atividades moluscicida e larvicida. A atividade moluscicida foi avaliada submetendo os caracóis a soluções aquosas. Conforme o caso, hexano, acetato de etilo, metanol e metanol-água (8:2, v-v) foram utilizados como solventes de extração. Como resultado, hexano e extratos de acetato apresentaram atividades potentes de acordo com a Organização Mundial de Saúde, resultando em LC50 = 7,59 mg/L e 6,69 mg/L para extratos de hexano de folhas e frutos, respectivamente. Extratos de acetato de etilo resultaram em LC50 = 5,90 mg/L e 7,32 mg/L para as folhas e frutos sucessivamente. Atividades moluscicidas das substâncias sob a forma de pó foram menos potentes em caracóis, mas ativas de acordo com a Organização Mundial de Saúde. Hexano e extratos de acetato de folhas e frutos apresentaram atividade larvicida potente, com uma taxa de atraso superior a 45,50% (45,50-98,92%). Testes fitoquímicos mostraram que estas atividades podem ser atribuídas à presença de triterpenóides e/ou esteróis.

GC/MS-based dynamic analysis of Eucalyptus camaldulensis extract on corre-lation of chromatography-activity against Oncomelania hupensis / 中国血吸虫病防治杂志

Objective To determine the contributions of main chemical compositions of extracts of Eucalyptus camaldulensis represented by GC/MS elute peaks to the molluscicidal activities,and explore a shortcut of looking for the effective components from natural products. Methods E. camaldulensis leaves were collected consecutively in 12 months at the same place,extracted with dichloromethane,analyzed by GC/MS,and their LC50(s)of molluscicidal activities were tested according to the method rec-ommended by WHO. The correlation of the main components in 12 extracts and their molluscicidal activities were analyzed by the grey relative correlation analysis model with software GTMS 3.0. Result All the dichloromethane extracts of eucalyptus leaves showed excellent molluscicidal activities with the highest LC50 of 0.257mg/L and 0.242mg/L for the samples in June and July and the lowest LC50 of 6.802 mg/L and 5.406 mg/L in December and January respectively. The structures of 16 main chemical compo-nents were elucidated by GC/MS and NIST Mass Spectral Library,most of which were monoterpenes and sesquiterpenoids. The gray correlation coefficients with activity were all over 0.5,the first five over 0.9 were 4,4,8-Trimethyltricyclo[6.3.1.0(1,5)]do-decane-2,9-diol,(-)-Spathulenol,a structural isomer of(-)-Spathulenol,Eucalyptol and Ledol. Conclusion The most main in-gredients in the dichloromethane extracts of E. camaldulensis leaves show good correlations with the molluscicidal activity,which suggests that the molluscicidal role is synergistically played by the multiple components together.

Optimization of fermentation conditions of molluscicidal endophyte LL3026 from Buddleia lindleyana / 中国血吸虫病防治杂志

Objective To optimize the fermentation conditions of molluscicidal endophyte LL3026 from Buddleia lindleyana. Method The medium composition and cultivation conditions were optimized by orthogonal and single factor experiments. Re-sults The experiments showed that the conditions of initial pH 3,fermentation temperature 30℃,volume of liquid 100 ml(250 ml Erlenmeyer flask),and 3D-xylitol 0.5 g/L were optimum,and the molluscicidal activity of the fermentation filtrate reached 95%. After three hatches of cultivation,the predicted values were verified by validation experiments. Conclusion Endophyte LL3026 from Buddleia lindleyana has a good molluscicidal activity after the optimization.

Characterization of the molluscicidal activity of Bauhinia variegata and Mimusops elengi plant extracts against the fasciola vector lymnaea acuminata / Caracterização da atividade moluscicida dos extratos das plantas Bauhinia variegata e Mimusops elengi contra o vetor da Fasciola, Lymnaea acuminata

The molluscicidal activity of Bauhinia variegata leaf and Mimusops elengi bark was studied against vector snail Lymnaea acuminata. The toxicity of both plants was time and concentration-dependent. Among organic extracts, ethanol extracts of both plants were more toxic. Toxicity of B. variegata leaf ethanolic extract (96h LC50- 14.4 mg/L) was more pronounced than M. elengi bark ethanolic extract (96h LC50-15.0 mg/L). The 24h LC50 of column purified fraction of B. variegata and M. elengi bark were 20.3 mg/L and 18.3 mg/L, respectively. Saponin and quercetin were characterized and identified as active molluscicidal component. Co-migration of saponin (Rf 0.48) and quercetin (Rf 0.52) with column purified bark of M. elengi and leaf of B. variegata on thin layer chromatography demonstrate same Rf value i.e. 0.48 and 0.52, respectively. The present study clearly indicates the possibility of using M. elengi and/or B. variegata as potent molluscicide.

A atividade moluscicida das folhas da Bauhinia variegata e da casca do Mimusops elengi foi testada contra o vetor caracol, Limnaea acuminata. A toxicidade de ambas as plantas é dependente do tempo e da concentração. Entre os extratos orgânicos, os extratos de etanol de ambas as plantas foi mais tóxico. A toxicidade do extrato etanólico da folha da B. variegata (96 h LC50 - 14,4 mg/L) foi mais pronunciada do que o extrato etanólico da casca do M. elengi (96h - LC50 - 15,0 mg/L). As frações purificadas em coluna durante 24 h LC50 do B. variegata e da casca do M. elengi foram 20,3 mg/L e 18,3 mg/L, respectivamente. A saponina e a quercentina foram caracterizadas e identificadas como os componentes ativos moluscicidas. A co-migração da saponina (Rf 0,48) e da quercentina (Rf 0,52) com a casca purificada por coluna do M. elengi e as folhas da B. variegata na cromatografia demonstraram o mesmo valor Rf isto é, 0,48 e 0,52 respectivamente. O presente estudo indica claramente a possibilidade de usar M. elengi e/ou B. variegata como moluscicidas potentes.

Molluscicidal activities of medicinal plants from eastern China against Oncomelania hupensis, the intermediate host of Schistosoma japonicum / Atividades moluscicida de plantas medicinais do leste da China contra Oncomelania hupensis, o hospedeiro intermediário da Schistosoma japonicum

In a search for natural products that could be used to control schistosomiasis, nineteen extracts of eleven medicinal plants from eastern China have been tested for molluscicidal activity against snail Oncomelania hupensis. The n-butanol fraction of the fresh leaf from Buddleja lindleyana Fortune, Buddlejaceae, showed significant activity against the snails. Statistical analysis revealed that the LC50 and LC90 values for the n-butanol fraction were 39.91 mg L-1 and 59.28 mg L-1 for 48 h, respectively. Otherwise, the LC50 values for the n-butanol fraction to zebrafish was 403.24 mg L-1 for 48 h. Therefore, the n-butanol fraction of the fresh leaf from B. lindleyana may be a potent and safe molluscicides.

Na busca por produtos naturais que podem ser utilizados para controle da esquistossomose, dezenove extratos de onze plantas medicinais do leste da China foram testados para atividade moluscicida contra o caramujo Oncomelania hupensis. A fração n-butanol das folhas frescas de Buddleja lindleyana Fortune, Buddlejaceae, mostrou atividade significativa contra os caracóis. A análise estatística revelou que os valores de CL50 e CL90 para a fração n-butanol foram 39,91 mg L-1 e 59,28 mg L-1 por 48 h, respectivamente. Por outro lado, a CL50 para a fração n-butanol para peixe-zebra foi 403,24 mg L-1 por 48 h. Portanto, a fração n-butanol das folhas frescas de B. lindleyana poderá vir a ser um moluscicidas potente e seguro.

Avaliação da bioatividade dos extratos de cúrcuma (Curcuma longa L., Zingiberaceae) em Artemia salina e Biomphalaria glabrata / Bioactivity evaluation of the turmeric (Curcuma longa L., Zingiberaceae) extracts in Artemia salina and Biomphalaria glabrata

A cúrcuma é o rizoma limpo, em boas condições, seco e moído da Curcuma longa L., uma planta herbácea da família Zingiberaceae. Visando novas alternativas para o controle da esquistossomose, os extratos de Curcuma longa L. foram testados para a avaliação da atividade moluscicida contra caramujos adultos da espécie Biomphalaria glabrata, e toxicidade (ensaio de letalidade com Artemia salina). A oleoresina e o óleo essencial de cúrcuma foram ativos contra Artemia salina (CL50 = 80,43 e CL50 = 319,82 μg/mL, respectivamente) e também ativos contra os indivíduos adultos de Biomphalaria glabrata (CL50 = 58,3 e CL50 = 46,73 μg/mL, respectivamente). A partir dos resultados obtidos pôde ser concluído que ambos os extratos podem constituir uma alternativa no controle da população desses caramujos e na redução da esquistossomose.

The turmeric is the clean rhizome at good conditions, dried and powdered of Curcuma longa L., an herbaceous plant of Zingiberaceae family. Aiming new alternatives for Schistosomiasis control, the Curcuma longa L. extracts were tested for molluscicidal activity evaluation against adult snails of Biomphalaria glabrata specie, and the toxicity (Brine Shrimp Lethality-BSL-bioassay). The oleoresin and the essential oil of turmeric were active against Artemia salina (CL50 = 80.43 and CL50 = 319.82 μg.mL-1, respectively) and also active against the adult snails of Biomphalaria glabrata (CL50 = 58.3 and CL50 = 46.73 μg.mL-1, respectively). From the obtained results it was concluded that both extracts can constitute an alternative to population control of these snails and in the reduction of Schistosomiasis.

Molluscicidal activity of Hammada scoparia (Pomel) Iljin leaf extracts and the principal alkaloids isolated from them against Galba truncatula

The molluscicidal activity of Hammada scoparia leaf extracts and the principal alkaloids isolated from them (carnegine and N-methylisosalsoline) were tested against the mollusc gastropod, Galba truncatula, the intermediate host of Fasciola hepatica in Tunisia. The results indicated that the molluscicidal activity was correlated with the presence of alkaloids. A significant molluscicidal value, according to the World Health Organization, was found with the methanol extract (LC50 = 28.93 ppm). Further fractionation of the methanolic extract led to the isolation of two principal alkaloids: carnegine and N-methylisosalsoline. These alkaloids are isoquinolines that have not previously been characterised for their molluscicidal activity. The N-methylisosalsoline possesses the highest molluscicidal activity (LC50 = 0.47 ìM against G. truncatula).

Molluscicidal activity of 2-hydroxy-[1, 4]naphthoquinone and derivatives

The toxic profile of lawsone (2-hydroxy-[1,4]naphthoquinone) and a series of [1,4]naphthoquinone derivatives was evaluated against the brine shrimp Artemia salina and against the mollusk Biomphalaria glabrata, the main transmitting vector of schistosomiasis in Brazil. Of the seventeen compounds tested nine fell below the threshold of 100 µg/mL set for potential molluscicidal activity by the World Health Organization. As a general rule derivatives with non-polar substituents presented the highest molluscicidal activities. These substances showed significant toxicity in A. salina lethality bioassay.

A toxicidade da lausona (2-hidroxi-1,4)-naftoquinona e de diversos derivados foi avaliada frente à Artemia salina e ao molusco Biomphalaria glabrata, o principal vetor de transmissão da esquistossomose no Brasil. Entre os dezessete compostos testados, nove apresentaram um perfil de toxicidade menor que 100 µg/mL, sendo potenciais agentes moluscicidas de acordo com as designações da Organização Mundial da Saúde. No presente estudo, os compostos contendo substituintes apolares exibiram as maiores atividades. Estes compostos também se mostraram significantemente tóxicos frente à A. salina.

Avaliação da atividade tóxica em Artemia salina e Biomphalaria glabrata de extratos de quatro espécies do gênero Eleocharis (Cyperaceae) / Toxic evaluation of four species of the genus Eleocharis (Cyperaceae) in Artemia salina and Biomphalaria glabrata

O gênero Eleocharis R. Br. compreende cerca de 200 espécies, ocorrendo em ambientes úmidos tais como brejos e margens de rios e lagos. Procurando novos agentes moluscicidas, os extratos de Eleocharis acutangula (Roxb.) Schult., Eleocharis interstincta (Vahl) Roem. & Schult., Eleocharis maculosa (Vahl) Roem. & Schult. e Eleocharis sellowiana Kunth foram testados para atividade moluscicida, contra caramujos adultos e desovas, e toxicidade (ensaio de letalidade com Artemia salina). O extrato hexânico de Eleocharis acutangula (parte subterrânea fresca) foi ativo contra Artemia salina (CL50 = 476,00 mg/mL), enquanto os demais extratos apresentaram CL50 >> 10³ mg/mL, sugerindo baixa toxicidade. O extrato hidro-etanólico de Eleocharis sellowiana (parte subterrânea fresca) foi ativo contra desovas de Biomphalaria glabrata (CL50 = 24,27 mg/mL) mas inativo contra indivíduos adultos. Os demais extratos testados não apresentaram atividade moluscicida.

The genus Eleocharis R. Br. comprises about 200 species, occurring in wet environments like swamps, lakes and river margins. In the search for new molluscicides, extracts from Eleocharis acutangula (Roxb.) Schult., Eleocharis interstincta (Vahl) Roem. & Schult., Eleocharis maculosa (Vahl) Roem. & Schult. and Eleocharis sellowiana Kunth were tested for molluscicidal activity (spawns and adult snails) and toxicity (Brine Shrimp Lethality - BSL - bioassay). The hexane extract of Eleocharis acutangula (fresh subterraneous parts) was active in the BSL bioassay (LC50 = 476 mg/mL), while the other extracts showed LC50 >> 10³ mg/mL, suggesting they have low toxicity. The aqueous ethanol extract of Eleocharis sellowiana (fresh subterraneous parts) was active against Biomphalaria glabrata spawns (LC50 = 24.27 mg/mL) but it was not lethal to adult snails. No other plant extract tested in this study showed molluscicidal activity.

Screening of chemical compounds for molluscicidal activity against Oncomelania quadrasi

In view of the inherent problems associated with the medical, sanitary and educational approach to the control of schistosomiasis, it is the consensus that the control of the small intermediate host offers a better and more effective means of reducing the transmission of the disease. Having achieved some degree of success in the ecological control of the snail host (Oncomelania quadrasi) in the Philippines as shown by the evaluation done in 1962 by Hairston, a WHO Consultant it has nevertheless been noted that due to the varied hopographic characteristics of small areas, complete eradication may not be attained in certain instances. For it was noted that snails had continued to thrive in small pockets after ecological control measures had been applied. Molluscicides at this stage, therefore, could be used to great advantage as a terminal measure. (Author)