Parasitological and biochemical parameters in Schistosoma mansoni-infected mice treated with methanol extract from the plants Chenopodium ambrosioides, Conyza dioscorides and Sesbania sesban.

This study aims to detect the antischistosomal properties of the plants' Chenopodium ambrosioides, Conyza dioscorides and Sesbania sesban methanol extract against Schistosoma mansoni in infected mice, including determination of total protein and albumin levels and the activities of alanine and aspartate transaminases (AlT, AsT) and acid and alkaline phosphatases (AcP and AkP) enzymes in the serum of infected treated mice. Male Swiss albino mice were infected with S. mansoni and orally treated with methanol extract of the plants C. ambrosioides (1250 mg/kg/day), C. dioscorides and S. sesban (1000 mg/kg/day from each) for 2 consecutive days 7 weeks post infection (PI). In addition, treatment of mice with the tested dose of each plant extract was successively done (i.e. the 1st extract followed by the 2nd and 3rd one with an hour interval). Parasitological and biochemical parameters were assessed. Nine weeks PI, the reduction rates of worm load/mouse treated with either C. dioscorides (1000 mg/kg), C. ambrosioides (1250 mg/kg) or S. sesban (1000 mg/kg) were 40.9%, 53.7% and 54.4%, respectively. Successive treatment raised the reduction rates of worm load/mouse to 66.3% and the ova/g tissue in liver to 76.9%. Moreover, serum total protein and albumin levels and activities of AlT, Ast, AcP and AkP enzymes of infected treated mice were improved in comparison with those of infected untreated ones. It is concluded that administration of C. dioscorides, C. ambrosioides and S. sesban methanol extract to infected mice exhibited a moderate antischistosomal effect. Successive treatment improved the antischistosomal properties of these plant species, hence ameliorated the liver functions of treated mice that may suggest degenerations of liver granulomas and regenerative changes.

Susceptibility of Biomphalaria alexandrina to the plant Azolla pinnata and some herbicides in relation to infection with Schistosoma mansoni miracidia.

Molluscicidal activity of the herebicides 2,4-D and Graminol, as well as both extracts and dry powder of the plant Azolla pinnata were evaluated against B. alexandrina snails. It was observed that 2,4-D proved to be the most toxic compound among he tested ones, showing LC90 of 52 ppm after 24 h of exposure. Ethanol extract of Azolla showed the highest molluscicidal activity against the tested snails compared with the other extracts and dry powder (LC90 = 3300 ppm). Ethanol extract at 6600 ppm after 3 h of exposure killed 100% and 19.4% of S. mansoni miracidia and cercariae, respectively. The molluscicidal activity of 2,4-D was not influenced by the presence of Azolla (900 plants/liter) for 7 days, while Graminol effect was significantly reduced. However, the infectivity of S. mansoni miracidia to B. alexandrina snails was not affected by Azolla existence.

Effect of the plant Azolla pinnata on survival, growth rate, fecundity and hatchability of egg-masses of Biomphalaria alexandrina snails.

Data indicated that Azolla pinnata plants variously reduce the growth rate of Biomphalaria alexandrina snails expressed as net increase in shell diameter (direct or indirect exposure). The plant density played an important role in this respect. The higher the plant density was the lower the growth rate and vice versa. Too, indirect exposure of newly hatched B. alexandrina resulted from exposed treated eggs reduced the growth rate of these snails. Data revealed that direct and/or indirect exposure to the abnormal high density (50,000 plants/L) resulted in complete kill of B. alexandrina snails after two weeks from continuous exposure. Snails exposed directly to Azolla at 50,000 and 25,000 plants/L failed to lay eggs. On the other hand, sanils exposed to 10,000 plants/L laid few eggs, resulted in low reproductive rate (57.94) compared with unexposed ones (110.6). The same trend of results was recorded with hatchability of Biomphalaria eggs.

Effect of Schistosoma mansoni infection, starvation and molluscicides on acid phosphate, transaminases and total protein in tissues and hemolymph of Biomphalaria alexandrina.

The activities of GOT and GPT in the hemolymph of B. alexandrina were significantly decreased by S. mansoni infection. However, the total protein concentration and AcP activity were increased. Although the snail starvation decreased AcP activity in the ovotestis, it increased GOT activity in the other organs of the snails. On the other hand, the snail feeding after starvation increased significantly AcP activity in ovotestis. Natural and synthetic molluscicides inhibited the activities of GOT and GPT, however, they increased the total protein concentrations and AcP activities in the examined organs.

The influence of temperature, darkness, and starvation on growth and survival of Helisoma duryi, Biomphalaria alexandrina and Bulinus truncatus.

The influence of 10 degrees, 18 degrees, 26 degrees, 28 degrees and 33 degrees C, different periods of complete darkness and starvation on growth and survival of H. duryi, B. alexandrina and B. truncatus were studied. The optimum temperature for the growth and survival was about 26 degrees C. Survivorship and growth rates decreased proportionately according to starvation period. However, darkness had no significant effect on the growth of B. truncatus and H. duryi. Under the chosen experimental conditions H. duryi revealed higher tolerance limits and survival rates than B. alexandrina and B. truncatus. The potential of H. duryi as biological control agent of Schistosome vector snails is discussed.

The molluscicidal properties of some Bayluscide homologues.

The molluscicidal properties of 5-nitro- and 3-nitro2',4'-dichloro salicylanilides and their mixture 5.5 : 1 were investigated against the intermediate hosts of schistosomes Bulinus truncatus and Biomphalaria alexandrina. Unlike Bayluscide, the activity of the new mulluscicides is not affected by strong sun radiation or by acidic pH. Their activity is resistant to storage, river-bed mud and lower temperature.

The molluscicidal properties of natural products from Ambrosia maritima.

The molluscicidal properties of Damsin "I", Ambrosin "II", and tribromodamsin "III" were investigated against the intermediate hosts of schistosomiasis Biomphalaria alexandrina and Bulinus truncatus. Although Damsin was to some extent more toxic against B. alexandrina than the other two compounds, it was less toxic than them against B. truncatus after 24 hr exposure periods. There is a flex relationship between concentration of Damsin and exposure period to prodce 100% mortality. The molluscicidal potency of Damsin remained stable over a wide range of pH values, but was affected by storage, sunlight and river bed-mud. Structure-activity relationship is included.