Cystoseira barbata marine algae have a molluscicidal activity against Biomphalaria alexandrina snails supported by scanning electron microscopy, hematological and histopathological alterations, and larvicidal activity against the infective stages of Schistosoma mansoni

Abstract

Schistosomiasis is one of the neglected tropical diseases. Biomphalaria spp. is the intermediate host of Schistosoma mansoni. The aim of this study is to evaluate the molluscicidal activity of the ethanolic extract of Cystoseira barbata marine algae on Biomphalaria alexandrina snails. The present results indicated that HPLC of C. barbata ethanolic extract contained 20 flavonoids, 20 phenolic compounds and 10 saccharides. It has a molluscicidal activity on B. alexandrina snails at LC50 175.04 mg L− 1 after 48 h of exposure. Scanning electron microscope of the head foot region of B. alexandrina snails exposed to 2 LC50 (175.04 mg L− 1) of the ethanolic extract shows the rough surface and damaged cilia in the tentacles and the foot region; the mantle contained erosion in its tegmental surface. Exposure to LC50 of the ethanolic extract caused ovicidal, miracidicidal and cercaricidal effects. Examinations of the hemocytes monolayers of the exposed snails showed that hyalinocytes had a shrunken nucleus and granulocytes had irregular cell membrane, forming pseudopodia. Histopathological changes occurred in the head foot region after exposure to LC50 of the extracted algae, where, vacuoles, shrinkage in the mucous secreting glands and splitting of the oblique muscle fibers were present. Also, histopathological alterations occurred in the digestive gland where the digestive cells were ruptured, vacuolated and there was a marked increase in the number of the secretory cells and these alterations were concentration dependent. Conclusively, C. barbata ethanolic extract contains bioactive molecules that could be developed as molluscicides for the control of freshwater intermediate hosts for schistosomiasis.