Molluscicidal properties of constituents from the liverwort Ricciocarpos natans and of synthetic lunularic acid derivatives.

Five new sesquiterpenoids, three monocyclofarnesane, and two cuparane derivatives, isolated from the liverwort Ricciocarpos natans (L.) Corda have been tested against Biomphalaria glabrata, one of the snail vectors of schistosomiasis (bilharzia). Molluscicidal activity is exhibited by four of the sesquiterpenoids with an LC100 of 11 ppm of the most toxic compound. Lunularic acid, a common growth inhibitor of liverworts, and five of its synthetic derivatives have also been tested, and two derivatives were found to be highly active.