Article

Effect of Agave attenuata extracts on detoxification enzymes of Biomphlaria alexandrina

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Abstract

The toxicity and rising costs of synthetic molluscicides have led to interest in compounds derived from locally growing plants that can be used as molluscicides. The aim of the present work was to study the effect of extracts of some Egyptian plants having lethal effect on snails of medical importance (Biomphlaria alexandrina) as well as on antioxidant and glutathione detoxification enzymes. Ethanolic extracts of locally growing plants Agave attenuata, Agave sislana, Phytolaca dodecandra and Euphorbia spllendens were applied as a contact poison to B. alexandrina, the intermediate host of Schistosoma mansoni. The LC50 of A. attenuata, A. sislana, P. dodecandra and E. spllendens are 82, 101, 98 and 98 mg/L, respectively. Glutathione and the enzymes involved in protection of the snail from reactive oxygen species namely, glutathione peroxidase, glutathione reductase, glutathione S-transferase, catalase, gamma glutamyl transferase increased in the survival snails exposed to high concentrations of A. attenuata. Glucose-6-phosphate dehydrogenase indirectly affecting glutathione reductase and the oxidation, reduction of glutathione significantly decreased in snails exposed to A. attenuata extracts. Superoxide dismutase level tend to decrease in snails exposed to A. attenuata of action. In conclusion A. attenuata is preferable when compared with synthetic molluscicides. The enzymes involved directly or indirectly in protection mechanism of the snail against A. attenuata are mainly responsible for snails survival.

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... Besides, the effective concentration decreased superoxide dismutase activity due to the oxidative stress produced by the phytochemicals of the extract. Similarly, Hamed et al. [97] observed a modification in the activity of the antioxidant enzymes within the effective molluscicide concentration range. Thus, it might have involved a defense response brought about by secondary metabolites. ...
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... This deterioration in may be due to snails immune system activation. This agreed with Hamed et al. (2006) who found that exposure of B. alexandrina to A. attenuate increased the activities of CAT and SOD. Rnhancement of oxygen free radicals production post snails exposure stimulated antioxidant activities to cope with increased oxidative stress and protect snails' cells from damage (Torres et al., 2002). ...
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A lethal concentration of a crude, aqueous extract of Agave attenuata was applied as a contact poison to Bulinus africanus, the intermediate host of Schistosoma haematobium, for a 24-h period. The gross histopathological effects of the extract on the epithelium of the digestive tract were then studied. A graded series of cellular injuries to the epithelial layer was observed along the length of the tract. These included the loss of cilia and brush border, disruption of the epithelial layer, cellular vacuolation, swelling and rupture, and the discharge of secretory products from mucous gland cells. The results of the microscopy show that epithelial tissue is probably a primary target of the molluscicide. The cytological injuries induced by extracts of A. attenuata indicate that the molluscicide acts by disrupting the osmoregulatory mechanisms of the epithelial cells, but further, detailed studies are required to confirm this.
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High glycolytic flux as an emergency pathway for generating ATP was recorded as the most important metabolic pathway required for the success of Biomphalaria-Schistosome sporocyst interaction. Effect of LC25 of dry powdered Ambrosia maritima (Damsissa) as plant molluscicide on hexokinase (HK), pyruvate kinase(PK), glucose phosphate isomerase(GPI) was tested. It resulted in a significant inhibition of the three investigated enzymes. Treatment of snails with LC10 concentrations of A. maritima reduced considerably the infection rate of Biomphalaria alexandrina with Schistosoma mansoni to be 34% compared to an infection rate of 80% in control non-treated snails. Longer prepatent period and remarkable decrease in cercarial production was also recorded in snails treated with the sublethal concentrations of this molluscicide.
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Synthetic steroids are obtainable cheaply and in abundance from sapogenins, substances originating from plants of the Discorea family. Some 40 years ago, Russell Marker, an American chemist, discovered this source, which grows abundantly in Mexican jungles and is now exploited and cultivated commercially. Today synthetic steroids prepared from extracts from a wide range of vegetable sources are used in the treatment of rheumatoid arthritis, allergies, inflammatory diseases, sterility, and various heart conditions, and form the basis of modern oral contraceptives. Nevertheless, oral contraceptives in current use are still fairly costly, and women have to be educated in their use. What is needed urgently is a cheaper contraceptive pill with a long-term effect, and research is continuing. For example, scientists from the People's Republic of China have reported significant anti-fertility effects associated with 2 substances, anordin and dinordin, prepared with steroids derived from the sisal plants Agave sisilana and Agave americana. These agents, whose anti-fertility properties have been confirmed by scientists in Sweden and the United States, constitute a new family of contraceptives with the great advantage of having to be taken only once or twice instead of 20 times per month necessary with the ordinary pill. Also from China, scientists have reported the effectiveness of gossypol as an orally administered male contraceptive, although gossypol is not a steroid. It may become, however, a leading candidate for a male contraceptive.
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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.
Glutathione and its Metabolizing Regulatory Enzymes in Some Egyptian Fresh Water Snails
  • R R Hamed
  • N S M Saleh
  • N M Farid
  • A M A Abdalla
  • R.R. Hamed
Mammal Toxicity of the Plant Molluscicide apodytes dimidiate (Icacinaceae) in South Africa
  • T D Brackenbury
  • C C Appleton
  • T.D. Brackenbury
Biochemical Studies on Glutathione and Related Enzymes in Fresh Water Snails
  • A M Abdalla
Evolution of Glutathione Metabolism
  • R C Fahey
  • A R Sundquist
  • R.C. Fahey
Evaluation of the Molluscicidal Properties of Euphorbia Splendens: Experimental Test in an Endemic Area in the State of Minas Gerais
  • N M Mendes
  • M C Vasconcellos
  • D F Baptisa
  • R S Rocha
  • V T Schall
  • N.M. Mendes
A Short Communication on the Molluscicidal Properties of Some Plants from Euphorbiaceae and Agavaceae
  • H A Shoeb
  • M M El-Sayed
  • H.A. Shoeb