Comparative toxicity of Paraquat herbicide and some plant extracts in Lymnaea natalensis snails.

Paraquat has been shown to be a highly toxic compound for humans and animals, and many cases of acute poisoning and death have been reported over the past few decades. The present study was undertaken to evaluate comprehensively herbicides (Paraquat) and some plant extracts to biochemical aspects of Lymnaea natalensis snails. It was found that the exposure of L. natalensis to Paraquat and plant extracts led to a significant reduction in the infectivity of Fasciola gigantica miracidia to the snail. The glucose level in hemolymph of exposed snails was elevated, while the glycogen showed a decrease in soft tissues when compared with the control group. In addition, the activity level of some enzymes representing glycolytic enzymes as hexokinase (HK), pyruvate kinase (PK), phosphofructokinase (PFK), lactate dehydrogenase (LDH), and glucose phosphate isomerase (GPI) in snail's tissues were reduced in response to the treatment. It was concluded that the pollution of the aquatic environment by herbicide would adversely affect the metabolism of the L. natalensis snails. Snails treated with Agave attenuate, Ammi visnaga, and Canna iridiflora plant had less toxic effect compared to snails treated with Paraquat.

In vitro phytotherapy of vector snails by binary combinations of larvicidal active components in effective control of fascioliasis.

A food-borne trematode infection fascioliasis is one among common public health problems worldwide. It caused a great economic loss for the human race. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. The life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria inside of the snail Lymnaea acuminata. In vitro toxicity of different binary combinations (1:1 ratio) of plant-derived larvicidal active components such as citral, ferulic acid, umbelliferone, azadirachtin and allicin against Fasciola redia and cercaria were tested. The mortality of larvae was observed at 2h, 4h, 6h and 8h of treatment. In in vitro condition azadirachtin + allicin (1:1 ratio) was highly toxic against redia and cercaria (8h LC50 0.006 and 0.005 mg/L). Toxicity of citral + ferulic acid was lowest against redia and cercaria larvae.

In vitro PHYTOTHERAPY OF VECTOR SNAILS BY BINARY COMBINATIONS OF LARVICIDAL ACTIVE COMPONENTS IN EFFECTIVE CONTROL OF FASCIOLIASIS / Fitoterapia in vitro de caramujos vetores por combinações binárias de componentes ativos larvicidas como controle efetivo de fasciolíase

SUMMARY A food-borne trematode infection fascioliasis is one among common public health problems worldwide. It caused a great economic loss for the human race. Control of snail population below a certain threshold level is one of the important methods in the campaign to reduce the incidence of fascioliasis. The life cycle of the parasite can be interrupted by killing the snail or Fasciola larva redia and cercaria inside of the snail Lymnaea acuminata. In vitro toxicity of different binary combinations (1:1 ratio) of plant-derived larvicidal active components such as citral, ferulic acid, umbelliferone, azadirachtin and allicin against Fasciola redia and cercaria were tested. The mortality of larvae was observed at 2h, 4h, 6h and 8h of treatment. In in vitro condition azadirachtin + allicin (1:1 ratio) was highly toxic against redia and cercaria (8h LC50 0.006 and 0.005 mg/L). Toxicity of citral + ferulic acid was lowest against redia and cercaria larvae. .

RESUMO A infecção alimentar pelo trematóide da fasciolíase é uma dentre os mais comuns problemas de saúde pública mundiais, causando grande prejuízo econômico para a humanidade. Controle da população de caramujos abaixo de determinado nível é um dos métodos no campo mais importantes para a redução da incidência da fasciolíase. O ciclo de vida do parasita pode ser interrompido pela morte do caramujo ou da larva redia e cercária da Fasciola dentro da Lymnaea acuminata. Foi testada a toxicidade in vitro das diferentes combinações binárias (relação 1:1) entre os vários componentes larvicidas ativos da planta tais como citral, ácido ferúlico, umbeliferone, azadiractina, e alicina contra a Fasciola redia e a cercária. A mortalidade das larvas foi observada após duas, quatro, seis e oito horas de tratamento. A condição in vitro azadiractina + alicina (relação 1:1) foi altamente tóxica contra redia e cercária (8h LC50 0,006 e 0,005 mg/L). Toxicidade do citral + ácido ferúlico foi a mais baixa contra redia e larvas de cercária. .

Molecular cloning and characterization of leucine aminopeptidase from Fasciola gigantica.

M17 leucine aminopeptidase (LAP) is one of a family of metalloexopeptidases, of which short peptide fragments are cleaved from the N-terminals. In this study, the full length of cDNA encoding Fasciola gigantica LAP (FgLAP) was cloned from adult parasites. The amino acid sequences of FgLAP showed a high degree of identity (98%) with that from Fasciola hepatica and a low degree of identities (11% and 9%) with those from cattle and human. Phylogenetic analysis revealed that the FgLAP was closely related and grouped with F. hepatica LAP (FhLAP). Northern analysis showed that FgLAP transcriptional products have 1800 base pairs. Analysis by RNA in situ hybridization indicated that LAP gene was expressed in the cecal epithelial cells of adult parasites. A polyclonal antibody to a recombinant FgLAP (rFgLAP) detected the native LAP protein in various developmental stages of the parasite. In a functional test, this rFgLAP displayed aminolytic activity using a fluorogenic Leu-MCA substrate, and was significantly inhibited by bestatin. Its maximum activity was at pH 8.0 and enhanced by Mn(2+) ions. Localization of LAP proteins by immunohistochemistry and immunofluorescence techniques indicated that the enzyme was distributed in the apical cytoplasm of cecal epithelial cells. Because of its important metabolic role and fairly exposed position, FgLAP is a potential drug target and a possible vaccine candidate against fasciolosis.

Alterations in carbohydrates and the protein metabolism of the harmful freshwater vector snail Lymnaea acuminata induced by the Euphorbia tirucalli latex extract.

To know the short- as well as long-term effect of aqueous latex extracts of Euphorbia tirucalli on carbohydrate and protein metabolism, the snail Lymnaea acuminata was exposed to sublethal doses of 0.37 and 0.55 mg/L for a 24-h and 0.20 and 0.31 mg/L for a 96-h exposure period. Significant (P<0.05) alterations in the glycogen, pyruvate, lactate, total protein, and free amino acid level, as well as in the activity of enzyme lactic dehydrogenase, succinic dehydrogenase, cytochrome oxidase, protease, aspartate aminotransaminase, and alanine aminotransaminase were observed in the nervous, hepatopancreatic, and ovotestis tissues of the freshwater vector snail L. acuminata exposed to sublethal doses of E. tirucalli latex extract. The alterations in all biochemical parameters were significantly (P<0.05) time and dose dependent. After the 7th day of the withdrawal of treatment, there was significant (P<0.05) recovery in glycogen, pyruvate, lactate, total protein, and the free amino acid level and in the activity of the lactic dehydrogenase, succinic dehydrogenase, cytochrome oxidase, protease, aspartate aminotransaminase and alanine aminotransaminase enzymes in all three of the studied tissues of the snail, which supports the view that the plant product is safe for use as a molluscicide for the control of harmful freshwater vector snails in the aquatic environment.

Toxicological effect and biochemical alterations induced by different fractions of Euphorbia royleana latex in freshwater harmful vector snail Lymnaea acuminata.

Laboratory evaluation was made to assess the molluscicidal activity of different fractions of Euphorbia royleana (Family- Euphorbiaceae) latex obtained through sephadex gel column against freshwater snail Lymnaea (Radix) acuminata Lamarack. This snail is the vector of liver fluke, Fasciola hepatica Linnaeus and Fasciola gigantica Cobbold, which causes endemic fascioliasis in cattle and livestock. The toxic effect of the different fractions was time dependent and fifth fraction obtained through benzene: ethyl acetate (5:5) had maximum molluscicidal activity against Lymnaea acuminata. There was a significant negative correlation between LC values and exposure periods thus increase in exposure time, the LC50 value of V fraction of Euphorbia royleana latex was decreased from 14.28 mg/l (24 hr) to 9.28 mg/l (96 hr) against Lymnaea acuminata. After exposure to sub-lethal concentrations of this fraction there were significant time and dose dependent alterations observed in pyruvate, lactate levels, ALAT, AAT, AChE and cytochrome oxidase enzyme activities in different body tissues of Lymnaea acuminata. It is proposed that the fifth fraction of E. royleana latex can be used as a molluscicide for controlling the harmful snail population from aquatic ecosystem without any harm due to their reversible toxic action.

Molluscicidal activity of Lawsonia inermis and its binary and tertiary combinations with other plant derived molluscicides.

Molluscicidal activity of leaf, bark and seed of Lawsonia inermis against Lymnaea acuminata and Indoplanorbis exustus was studied. Highest toxicity was observed in the seed of Lawsonia inermis. Toxicity of binary (1:1) and tertiary (1:1:1) combinations of the essential oil of cedar (Cedrus deodara Roxh) and neem (Azadirachta indica A. Juss), powder from bulb of garlic (Allium sativum Linn), and oleoresin extracted from rhizome of ginger (Zingiber officinale Rosc) with Lawsonia inermis and Embelia ribes fruit powder were studied against L. acuminata and I. exustus. L. inermis seed powder in combination with Cedrus deodara oil and Azadirachta indica oil was more toxic than their individual components and other combinations.

[Molluscacidal activity of Paraiso (Melia azedarach L.) (Meliaceae) on Lymnaea cubensis, host snail of fascioliasis]. / Actividad molusquicida del Paraiso (Melia azedarach L.) (Meliaceae) sobre Lymnaea cubensis, molusco vector de Fasciolosis.

INTRODUCTION: Fasciolosis is a source of serious economic loss in various regions of Brazil and when control measures of its host (molluscs) are not taken under favorable ecological conditions, isolated cases of human Fasciolosis may occur. Among the alternative measures for its control is the use of vegetable extracts and the purpose of this project is the assessment of the use of juice extracted from the fruit and seeds of the Paraiso plant (Melia azedarach L.) in the control of Lymnaea cubensis, the main vector of Fasciolosis in Cuba. MATERIAL AND METHOD: Various concentrations of the juice extracted from the Paraiso fruit (Melia azedarach L.) were tested to determine the average and maximum lethal doses (DL50 and DL90' respectively) used in a computerized PROBIT-LOG program. Seven experimental series were undertaken, 72 molluscs being used in each of them. Three groups of ten molluscs were tested to determine the effect on cardiac frequency, two of them being treated with CL50 = 0.88627 and CL90 = 1.7641, respectively, the third being used as control. RESULTS AND CONCLUSIONS: A considerable effect of both doses on the cardiac frequency of the mollusc studied was observed. The results were encouraging, for they demonstrated the potential use of this plant in the control of undesirable molluscs.

Molluscicidal activity of neem (Azadirachta indica A. Juss).

Molluscicidal property of Azadirachta indica A. Juss (neem) against the snails Lymnaea acuminata and Indoplanorbis exustus was studied. It was observed that the molluscicidal activity of the leaf, bark, cake, neem oil and the neem-based pesticides, achook and nimbecidine, was both time- and dose-dependent. The toxic effect of pure azadirachtin against both the snails was greater than the synthetic molluscicides.

The uptake and distribution of radioselenium in the larvae of Fasciola hepatica and its snail host Lymnaea columella.

Radiolabeled metacercariae of Fasciola hepatica were obtained in vivo by incubating infected Lymnaea columella snails with 20 muCi radioselenomethione (75Se-M) per snail in 5 ml of water for 5 h, or in vitro by incubating a batch of unlabeled F. hepatica metacercariae with 75Se-M for 24 h. Radioassay showed that only 5% of the 75Se-M was incorporated into maritas (juvenile flukes) from the in vivo labeled metacercariae. The inner cyst wall of in vivo labeled metacercariae contained 46% of the total activity, of which 21% was dissolved in the excysting medium. The outer, tan-colored cyst wall contained 49% of the radioactivity. Through diffusion/attachment, maritas from in vitro labeled metacercariae could occasionally be labeled with 0.4% of the total radioactivity. However, the activity was lost after inoculation into the body of mice. The outer and inner cyst walls of in vitro labeled metacercariae contained 92% and 7.6%, respectively, of the total activity. Microautoradiography demonstrated that 75Se-M was evenly distributed in the body of marita and the cyst wall of inner and outer layers from an in vivo labeled metacercaria. A 9 X 4 micron rectangularly-shaped aggregate of Ag degree grains was present on the outer periphery of the inner cyst wall. Microautoradiography of in vitro labeled metacercariae demonstrated a significant concentration of Ag degree grains on the cyst walls. The ventral plug contained fewer Ag degree grains per unit area compared to the other portion of the inner cyst wall. Uptake and distribution of 75Se-M in the snail host were also studied. It appeared that rediae and cercariae tended to concentrate the label in the foot, the mantle and the digestive gland. Little or no radioactivity was present in the areas where F. hepatica larvae were not found.

A technique for in vivo labelling of Fasciola hepatica miracidia with radioselenium.

Radioactivity is incorporated in Fasciola hepatica and its eggs when 75Semethionine is administered intraperitoneally in chronically infected mice. Maximum egg-bound radioactivity is achieved 2-3 days after the administration of the labelled aminoacid. Seventy-three per cent of the radioactivity of the egg is recovered in the free-swimming miracidium. There appears to be no altered motility or infectivity to snails of miracidia made radioactive at a level corresponding to 6 pCi per larva. Suggestions are made for the application of labelled larvae in studies on various aspects of the parasite-snail contact.