الفهرس 
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Abstract
Schistosomiasis is a public health problem in many developing countries. The side effects of this disease could extend from the great effect on human health to cause a threat to the development of disease in infected countries. Snail control with molluscicides is considered one of the most effective methods for controlling schistosomiasis transmission.
The present study was carried out to improve the molluscicidal activity of plants extraction of Anagallis arvensis, Calendula micrantha and Punica granatum using copper oxide and zinc oxide nanoparticles against Biomphalaria alexandrina snails and tested their effect against the biological indicator Daphnia magna. Also, the effect of some environmental factors as temperature, pH, and TDS on the potency of these molluscicides were studied. Moreover, some biochemical parameters as total protein, ALT, AST and ALP enzymes were determined in the hemolymph of snails treated with A. arvensis–CuO nanocomposite. Histological changes in the hermaphrodite glands of B. alexandrina snails exposed to ACuO NC were evaluated.
In the present work, Anagalis arvensis and Calendula micrantha plants were collected from Orman garden, Giza Governorate, while Punica granatum was collected from Nubariya, Beheira Governorate. Plants washed with tap water to remove dust, powdered using an electric blender, ethanolic and water extracts were prepared.
Biomphalaria alexandrina, the intermediate host of Schistosoma mansoni were collected from three different canals in Giza Governorate (El-Saff, El-Gizawia, and El- Mansouria canals) during the spring season, 2017.
Copper and zinc oxides NPs were fabricated and characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM) and fourier transform infrared (FTIR) spectroscopy.
New nanocomposites were prepared from plants extracts and nanoparticles as: A. arvensis–CuO (ACuO), A. arvensis–ZnO (AZnO), C. micrantha–CuO (CCuO), C. micrantha–ZnO (CZnO), P. granatum–CuO (PCuO) and P. granatum–ZnO (PZnO) nanocomposites. They were fabricated and characterized using fourier transform infrared (FTIR) spectroscopy. This study evaluated the molluscicidal effect of nanocomposites on the activity of B. alexandrina snails. The degree of activity varied with the different nanocomposites and the used sublethal concentration.
Data indicated that, the ethanolic extracts of plants showed high molluscicidal activity against B. alexandrina snails than their water extracts. The LC50 values of the ethanolic extracts of Anagalis arvensis and Calendula micrantha plants were 33.08, 66.77 ppm, respectively.
Data represented that the highest percentage of infection was found in El-Saff canal with 2.3%, followed by El-Gizawia canal with 1.8%, while the lowest percentage of infection was found in El-Mansouria canal with 1.4%.
The molluscicidal activity of CuO NPs was higher than ZnO NPs against B. alexandrina. The LC50 values of CuO NPs and ZnO NPs were 1.5 and 144.3 ppm, respectively.
Comparing the molluscicidal potency of the nanocomposites revealed that plant–CuO NCs possessed higher molluscicidal activity than plant–ZnO NCs. A. arvensis–CuO nanocomposite has the highest activity against B. alexandrina snails.
Laboratory results revealed that LC50 of ACuO and AZnO NCs were 1.8 and 24.6 ppm, respectively, while of CCuO and CZnO NCs were 3.2 and 36.4 ppm, respectively. However, LC50 of PCuO and PZnO NCs against B. alexandrina were 13.0 and 43.0 ppm, respectively.
The effect of some environmental factors on ethanolic extracts of A. arvensis, C. micrantha, and ((pomegranate peels) plants, CuO, ZnO NPs and nanocomposites on B. alexandrina snails were studied. A positive relationships was found between mortality of snails exposed to these compounds and temperature. Higher temperature (30˚C) increased the molluscicidal activity of these tested materials, while their molluscicidal activity decreased at low temperature (15˚C) considerably. The best activity of these materials was recorded at 25˚C.
Different pH values exhibited different effects on the potency of the different tested materials. The activity of these compounds highly raised at acidic pH 5 and reduced at alkaline media pH 9. The most promising results of these compounds were recorded at pH 7.
Different TDS values were studied on the molluscicidal activity of these tested materials. Results highlighted the high toxicity of CuO NPs, ZnO NPs, and all nanocomposites particularly at low TDS (300 ppm), while at high TDS values (1200 ppm),NPs and NCs had high aggregation and low activities against B. alexandrina snails.
The biochemical parameters (Total protein, ALT, AST and ALP) were evaluated in hemolyph of B. alexandrina snails treated with sublethal concentrations (LC10 and LC25) of ACuO NC after two weeks.
The results revealed a significant reduction in total protein content compared with the control group. The concentration of total protein for snails exposed to LC10 and LC25 of ACuO NC were 5.35 and 4.57 g/l, respectively compared to 6.0 g/l of control snails.
The activities of ALT, AST and alkaline phosphatase (ALP) were elevated in hemolymph of snails treated with ACuO NC in comparison with control. At LC10 and LC25, ALT activities recorded 112.0 and 150.7 U/L, respectively, compared to control with 77.2 U/L, while for AST were 99.0 and 120.4 U/L, respectively, compared to the control with 87.0 U/L. Moreover, LC10 and LC25, ALP activities reached 103.0 and 107.0 U/L, respectively, compared to 82.5 U/L for the control.
The histopathological changes were observed in the hermaphrodite glands of snails exposed to LC10 and LC25 of ACuO NC, where ova and sperms were degenerated and there were losses of connective tissues between acini.
The results showed that nanocomposites were safe when tested against the biological indicator Daphnia magna. Different nanocomposites showed different effect against Daphnia magna, where ACuO NC was more safe and lead to low mortality rate aflter 96 hours by 4% in LC10 and 11% in LC25, while PZnO NC caused high mortality rate for D. magna after 96 hours by 20% in LC10 and 29% in LC25.
These observations proved that ACuO NC has potent molluscicidal activity against the intermediate hosts of Schistosoma mansoni with more safety for the aquatic environment.