Phytochemical screening and molluscicidal potency of some Zairean medicinal plants.

A total number of 48 plants used in the Zairean pharmacopoeia were tested against molluscan intermediate hosts of schistosomiasis and fascioliasis. Aqueous and ethanolic extracts from five plants: Maesa lanceolata, Chenopodium ugandae, Asparagus racemosus, Phyllanthus nummulariifolius and Crinum zeylanicum, exhibited high mortality rate (100%) against Biomphalaria pfeifferi and Lymnaea natalensis. Their LC50 was respectively 0.1, 5, 5, 10 and 50 mg ml-1 for B. pfeifferi and 0.5, 5, 1, 10 and 10 mg ml-1 for L. natalensis. The activities are attributed to the presence of terpenoids, steroids and saponins in the plant extracts. Except for the extracts from Ch. ugandae however, the plants have shown toxic effect on fishes and aquatic insects.