Little information is known about using citrus plants in the eradication of snails and infective stages of Schistosoma mansoni. The present study was conducted to evaluate the effect of mandarin (Citrus reticulata) peel extract on Biomphalaria alexandrina snails and S. mansoni cercariae as well as the ability of mandarin peel extract-attenuated cercariae to infect mice with schistosomiasis. The molluscicidal effect of various concentrations of air-dried mandarin peel extract was increased by increasing exposure time, and the more effective concentration was 500 ppm. This concentration led to 35, 60, 95 and 95 % mortality after 24, 48, 72 and 96 hours, respectively. Exposure of S. mansoni cercariae to ascending concentrations of mandarin peel extract (1000-2500 ppm) for different time intervals (15-120 min) displayed a significant level of cercaricidal potential in a concentration-time relationship pattern. Attenuation of schistosomal cercariae using 1/10 LC50 of mandarin peel extract for different time periods (30-150 min) impaired the cercarial ability to infect mice, even for a short time. In addition, the relative spleen and liver weights of mice exposed to mandarin peel extract-attenuated S. mansoni cercariae were significantly reduced compared to those of the non-attenuated infected control mice. Taken all together, it can be concluded that air-dried mandarin peel extract may be considered as a promising candidate for the control of S. mansoni transmission as it has molluscicidal and cercaricidal activities. These effects may be due to active flavonoids and other constituents that cause death and attenuate the ability of cercariae to infect the final host.
Key words: Biomphalaria alexandrina, cercariae, Citrus reticulate, flavonoids, Schistosoma mansoni.
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