Laboratory assessment of molluscicidal and cercariacidal effects of Glinus lotoides fruits.

BACKGROUND: The negative impact of synthetic molluscicides on the environment and their high cost necessitated search for an alternative approach of using plant extracts for the control of schistosomiasis. The objective of this study was, therefore, to evaluate aqueous and ethyl acetate crude extracts of Glinus lotoides fruits for their cercariacidal activity and molluscicidal effect against schistosome snail intermediate hosts. METHODS: Assessment of the molluscicidal activity against Biomphalaria pfeifferi was made by immersion method in accordance with WHO guideline. The results of mortality were statistically analyzed using probit analysis. The attenuating effect of the plant on Schistosoma mansoni cercariae was determined using establishment of adult worms as a parasitological parameter post exposure. RESULTS: The 24 and 48 hour-LC50 values for the aqueous extract of G. lotoides fruits were 47.1 and 44.1 mg/L, respectively, whereas that of ethyl acetate were 66.1 and 59.6 mg/L, respectively. The 24 and 48 hour LC90 values for the aqueous extract of G. lotoides fruits were 56.96 and 51.0 mg/L, respectively, while that of ethyl acetate were 77.2 and 70.0 mg/L, respectively. The in vitro cercariacidal activity was determined after 2 hrs of exposure to the aqueous plant extract. It was found out that the LC50 and LC90 values were 18.7 and 41.7 mg/L, respectively. Besides, infectivity of Schistosoma mansoni cercariae to mice was determined by exposing mice to cercariae pre-treated with the sub-lethal concentrations (3.7, 11.6 and 18.7 mg/L) of the aqueous extract. A significant reduction in worm burden in mice was obtained at 11.6 mg/L (p < 0.05). Moreover, the reduction in number of worms recovered was highly significant at 18.7 mg/L (p < 0.001). CONCLUSIONS: The results showed that G. lotoides has molluscicidal activity against B. pfeifferi snails and cercariacidal activity against S. mansoni. Yet, further comprehensive evaluation is recommended for the possible use of G. lotoides against B. pfeifferi and the schistosome parasite.

Correlation between steroid sex hormones, egg laying capacity and cercarial shedding in Biomphalaria alexandrina snails after treatment with Haplophyllum tuberculatum.

Schistosomiasis is considered the second most pre-valiant worldwide parasitic disease ranked next to malaria. It has significant economic and public health consequences in many developing countries. Several ways have been practiced in order to bring the disease under an adequate control through the breakage of the life cycle of the parasite. Snail control could be regarded as a rapid and efficient of reducing or eliminating transmission and remains among the methods of choice for schistosomiasis control. The aim of this work is to evaluate the role of Haplophyllum tuberculatum (family Rutaceae) as a plant molluscicide. The mortality rate of Biomphalaria alexandrina snails were monitored after treatment with three extracts of the plant aerial parts; petroleum ether, chloroform and ethanol. Chloroform extract that recorded the most potent effect was further evaluated through measuring the toxicity pattern against B. alexandrina snails, egg laying capacity, cercarial shedding, phenol oxidase enzyme and the levels of steroid sex hormones. Histopathological examination of hepatopancreas and ovotestis of treated snails were also done for result confirmation. Treatment of snails by chloroform extract recorded reduction in egg laying capacity, decrease in cercarial shedding, diminution in phenol oxidase enzyme, disturbance in steroid sex hormones and sever alternation of the histopathological picture of snails tissue. In conclusion, H. tuberculatum recorded molluscicidal potency against B. alexandrina snails. Further studies are needed for its environmental applications.

Reproductive activity alterations on the Biomphalaria glabrata exposed to Euphorbia splendens var. hislopii latex.

The reproductive activity of Biomphalaria glabrata exposed to Euphorbia splendens var. hislopii latex was evaluated. Parameters related to fecundity and fertility were observed. The snails were exposed to the LD50 (1 mg/l) of crude latex. At the first week post exposure (p.e.), the egg laying was reduced. After the fourth week p.e., an increase of the number of eggs/snail occurred. The results showed a marked reduction in the hatching of the snails, revealing an interference of latex exposure with the reproductive process of B. glabrata of E. splendens var. hislopii. The LD50 of the latex may be used as an alternative method to control the size of the populations of B. glabrata in field.

Reproductive activity alterations on the Biomphalaria glabrata exposed to Euphorbia splendens var. hislopii latex

The reproductive activity of Biomphalaria glabrata exposed to Euphorbia splendens var. hislopii latex was evaluated. Parameters related to fecundity and fertility were observed. The snails were exposed to the LD50 (1 mg/l) of crude latex. At the first week post exposure (p.e.), the egg laying was reduced. After the fourth week p.e., an increase of the number of eggs/snail occurred. The results showed a marked reduction in the hatching of the snails, revealing an interference of latex exposure with the reproductive process of B. glabrata of E. splendens var. hislopii. The LD50 of the latex may be used as an alternative method to control the size of the populations of B. glabrata in field.

Effect of Commiphora molmol on adults, egg masses and egg-deposition of Biomphalaria arabica under laboratory conditions.

Commiphora molmol (Myrrh) has molluscicidal effect on Biomphalaria arabica snails at low concentration (40 ppm) after 48 hours exposure. The number of dead-snails increased with increasing the time of exposure. One day-old egg masses were more susceptible (death 100% with 80ppm) to the ovicidal effect of C. molmol than the five-day old ones (Death 95% with 80ppm). However, the eggs were more resistant to the C. molmol effect than the adult snails, embryogenesis began to stop at 20 ppm and eggs were all killed at 60 & 80 ppm. B. arabica fecundity decreased at 1 ppm. Based on safety to man and animals, C. molmol is recommended as a safe molluscidide.

Physiological changes in Biomphalaria glabrata Say, 1818 (Pulmonata: Planorbidae) caused by sub-lethal concentrations of the latex of Euphorbia splendens var. hislopii N.E.B (Euphorbiaceae).

Molluscides have been used as one of the strategies to control schistosomiasis. Many plant extracts with molluscidal effects have been tested, but the action of the latex of Euphorbia splendens var. hislopii is considered the most promising because it meets the recommendations of the World Health Organization (WHO). The objective of this study was to determine the lethal dose and identify the effects of the different doses of latex of E. splendens var. hislopii on the physiology of Biomphalaria glabrata submitted to treatment for 24 h. The concentrations of glucose, uric acid and total proteins in the hemolymph and of glycogen in the digestive gland and cephalopodal mass were determined. The LD50 value was 1 mg/l. The highest escape index was found to be at a concentration of 0.6 mg/l. The results showed that the latex of E. splendens var. hislopii caused a sharp reduction in the reserves of glycogen in the digestive gland and elevation of the protein content in the hemolymph of B. glabrata.

Physiological changes in Biomphalaria glabrata say, 1818 (Pulmonata: Planorbidae) caused by sub-lethal concentrations of the latex of Euphorbia splendens var. hislopii N.E.B (Euphorbiaceae)

Molluscides have been used as one of the strategies to control schistosomiasis. Many plant extracts with molluscidal effects have been tested, but the action of the latex of Euphorbia splendens var. hislopii is considered the most promising because it meets the recommendations of the World Health Organization (WHO). The objective of this study was to determine the lethal dose and identify the effects of the different doses of latex of E. splendens var. hislopii on the physiology of Biomphalaria glabrata submitted to treatment for 24 h. The concentrations of glucose, uric acid and total proteins in the hemolymph and of glycogen in the digestive gland and cephalopodal mass were determined. The LD50 value was 1 mg/l. The highest escape index was found to be at a concentration of 0.6 mg/l. The results showed that the latex of E. splendens var. hislopii caused a sharp reduction in the reserves of glycogen in the digestive gland and elevation of the protein content in the hemolymph of B. glabrata.

The effects of myrrh (Commiphora molmol) on the infected snails of Schistosoma sp. and their egg masses: effect on shedding of cercariae and on snail fecundity.

Myrrh has molluscicidal effect on infected Bulinus truncatus and Biomphalaria alexandrina snails at low concentrations (10 & 20 ppm respectively) after 24 hours exposure. The number of dead-snails increased with prolongation of exposure time. All Schistosoma free cercariae were killed by 2.5 ppm within 15 minutes. One day-old egg masses were more susceptible to the ovicidal effect of Myrrh than the five-day old ones. Both types of eggs were more resistant to the effect of Myrrh than the adult snails, embryogenesis began to stop at 20 ppm and eggs were all killed at 60 & 80 ppm. Shedding of cercariae of Schistosoma mansoni from infected B. alexandrina stopped at 1 ppm and was suppressed at 0.8 ppm. Snail fecundity decreased at 1 ppm.

Molluscicidal effect of fungicide, herbicide and plant extract on some biological and physiological parameters of Biomphalaria alexandrina.

In was found that the exposure of B. alexandrina to LC25 of fungicide (Isoprothiolane), herbicide (Anilofos) and plant extract (Euphorbia lactea) led to highly significantly elevated in the number of abnormal egg masses laid by treated snails in comparison with the control ones. The LC25 caused reduction in infection rate of B. alexandrina. It caused reduction in number of cercariae per snail during the patent period and reduction in the period of cercarial shedding. The results obtained showed that adenosine triphosphatase (ATPase) activity of tissue of snails was significantly increased in response to tested substances. The activity level of lactate dehydrogenase (LDH). pyruvate kinase (PK) and phosphoenolpyruvate carboxy kinase (PEPCK) was significantly reduced in response to treatment. This reduction does not reflect on both D. lactate and pyruvate concentrations.

The molluscicidal activity of the latex of Euphorbia splendens var. hislopii on Melanoides tuberculata (Thiaridae), a snail associated with habitats of Biomphalaria glabrata (Planorbidae).

The use of the latex of Euphorbia splendens var. hislopii was considered as an effective control method for Biomphalaria glabrata in Sumidouro, Rio de Janeiro. However, the appearance and expansion of the snail Melanoides tuberculata since August 1997, with the concomitant reduction of the population of B. glabrata suggest that competitive exclusion might be taking place. Depending on the susceptibility of the thiarid to the E. splendens toxin, the natural control that is occurring could be interrupted by the employment of the latex if the planorbid were less susceptible to the toxin. The aim of this study is to investigate the molluscicidal activity of the latex on M. tuberculata. We used 420 M. tuberculata, from Sumidouro. Fourteen different latex concentrations were tested using World Health Organization general methodology. Probit analysis was used for LD90 and LD50 determination. The LD50 was 3.57 mg/l and LD90 was 6.22 mg/l. At the highest concentration (10 mg/l) there was no survival. No significant differences among replicas (chi2 = 8.31; gl = 13; p > 0.05) were found. The LD90 dose for M. tuberculata was 13.8 times greater than that for B. glabrata, so that the molluscicide in the presence of the thiarid may have a synergic effect on reduction of Biomphalaria populations.

Potential effect of Allium cepa and Allium sativum on haemolymph of Biomphalaria alexandrina, the intermediate host of Schistosoma mansoni.

Biomphalaria alexandrina were fed on either Allium cepa or A. sativum to study their effects on some biochemical parameters such as total proteins, free amino acids and liver enzymes (ALT, ALP and AST) on egg laying activity of the snails. The results revealed that ALP was highly significantly reduced in haemolymph of snails that fed on either Allium cepa or A. sativum. Also, ALT and AST were highly significantly reduced in haemolymph of snails that were fed on A. cepa while those fed on A. sativum showed no change in ALT activity and a high significant increase in AST activity. Total proteins were significantly decreased in haemolymph of all treated snails whereas variations in free amino acids contents were also observed. The reproductive activity of snails fed on either Allium cepa or A. sativum was highly affected. In addition, growth rate of newly hatched snails fed on either A. cepa or A. sativum was affected. Exposure of snails to water containing either A. cepa or A. sativum caused snail toxicity which may result from alterations in the snails' habitat.

Molluscicidal constituents of Marsypianthes chamaedrys.

Marsypianthes chamaedrys is a common herb that occurs in the North and Northeast regions of Brazil. Phytochemical studies showed this plant to be rich in triterpenoids. The hexane extract of M. chamaedrys yielded, after chromatographic separations, two mixtures: the first containing monohydroxylated-compounds (alpha-amyrin, beta-amyrin, lupeol and germanicol) and the second, dihydroxylated compounds (chamaedrydiol, castanopsol, 2alpha-hydroxylupeol and epigermanidiol). Molluscicidal tests were performed for the crude hexane extract and for mixtures I and II. Mixture II showed high activity.

Molluscicidal acridone alkaloids from Angostura paniculata: isolation, structures, and synthesis.

Two novel acridone alkaloids, cuspanine [1] and cusculine [2], were isolated from the CH2Cl2 extract of the leaves of Angostura paniculata (Rutaceae). Their structures were established as 1-hydroxy-2,3,5,6-tetramethoxy-9-acridone for 1 and 1,2,3,5,6-pentamethoxy-9-acridone for 2 by means of spectroscopic studies, in particular nmr. These structural assignments were confirmed by synthesis, using a direct metallation method as a key reaction. Both alkaloids exhibited moderate molluscicidal activity against an aquatic snail, Biomphalaria glabrata, and cytotoxicity against several types of carcinoma cell lines.

Evaluation of the molluscicidal properties of Euphorbia splendens var. hislopii (N. E. B.) (Euphorbiaceae)--1. Experimental test in a lentic habitat.

The latex of Euphorbia splendens var. hislopii, at concentrations between 5 to 12 mg/l, kills 100% of the population of Biomphalaria glabrata in a lentic habitat, after 24 h. The lyophilized latex, stocked for 18 months, killed only 34.2% of the snails, at the concentration of 5 mg/l, and 96.0% at 12 mg/l. No lethal effect was observed among Pomacea haustrum exposed to the same concentrations of the molluscicide.

Ecdysteroids as regulators of host and parasite interactions: a study of interrelationships between Schistosoma mansoni and the host snail, Biomphalaria glabrata.

Ecdysteroids have been detected in trematode parasites and in several species of gastropod snails. The potential role of these and other hormones as regulators of host/parasite interactions is discussed. This study considers the role of ecdysteroids in the host parasite interactions between Schistosoma mansoni and Biomphalaria glabrata interactions. beta-Ecdysterone was found to be effective in stimulating host location activities in S. mansoni miracidia and in enhancing growth and egg production in B. glabrata. However, plant extracts rich in phytoecdysteroids were not attractive to miracidia and did not affect growth and egg production in snails. The potential role of ecysteroids in the process of parasitism and snail physiological processes is discussed. Plants rich in phytoecdysteroids do not appear to be of value in process which may interfere with the host parasite interactions in schistosomes.

Preference of Biomphalaria tenagophila among macrophytes and their periphytons determined through the degree of attractiveness

Em presença de extratos de seis macrófitas a Biomphalaria tenagophila apresentou maior atraçäo por quatro delas, na seguinte ordem: Nasturtium pumilum > Polygonum acre > Commelina sp = Echinocloa crusgalli. Para o perifíton destas macrófitas a B. tenagophila foi atraída, sem mostrar preferência entre eles. Na discussäo, tal comportamento é avaliado sob o ponto de vista da co-evoluçäo entre moluscos e plantas

[Chemoprophylaxis of schistosomiasis: molluscacidal activity of natural products--assays with adult snails and oviposition]. / Quimioprofilaxia da esquistossomose: atividade moluscicida de produtos naturais--ensaios com caramujos adultos e desovas.

Data concerning the molluscicidal activity of 159 extracts from 84 Brazilian plants on Biomphalaria glabrata, the most important intermediate host of Schistosoma mansoni in Brazil, are presented. Seventy eight extracts (49,0%) showed activity against snails or eggs, but only twenty nine (18.2%) were active on both, snails and eggs. Extracts of two species (Mikania hirsutissima and Qualea multiflora) have shown to be lethals to adult snails at 10 ppm concentration.