Study On The Molluscicidal Activity Of Pachysandra Terminalis

Background of the research :Schistosomiasis is a serious public health disease that the governments have to face. The epidemic situation is rising in recent years . In our country, Oncomelania hupensis is the only host of schistosomiasis, so to kill it is the useful way to control the schistosomiasis. High effective, safe, cheap medicine is needed, so plant which have effect on schistosomiasis is to be seek, but there is no plant which can reach WHO's standards.Content and significance of the research:It is to study the effect on Oncomelania hupensis and the components of Pachysandra terminalis (PT), to offer an account for researching new pattern of molluscacides and establish standards for enterprise.Result of the research:The mortality of PT powder is 93.4% for 72h immersion and 100% for 120h at the concentration of 17.5mg/L; LC₅₀ of the PT powder to the snail for 72 and 120h were 7.20, 4.20mg/L. After immersion for 1, 2, 18, 42h with 35.0, 17.5, 8.75 and 4.38mg/L PT, the upward-climbing inhibition rate of the snail were 100%. The Brachydanio rerio mortality was zero at the concentration of 75.0mg/L for 168h.The mortality of succus WP of PT to the snail is 80% for 120h immersion at the concentration of 270mg/L; After immersion for 1h with 270mg/L WP, the upward-climbing inhibition rate of the snail were 100% in the field.After extraction and isolation, we get PT-I ingredient. The snail mortality were 36.7%, 73.3% , 96.7%, 96.7% and 100% when they were immersed in the solution of 1.40mg/L PT-I for 24, 48, 72, 96 and 120h.It is confirmed that PT-I is a steroidal alkaloid by EA, IR, UV, ¹³C-NMRand MS. The molecular of PT-I is C₂₉H₄₈N₂O₃ and the molecular weight is 472. The result indicate that PT is a new plant molluscicide . It has high effect and high climbing-upward inhibition rate on Oncomelania hupensis and low toxicity to Brachydanio rerio. PT-I is a steroidal alkaloid and has high effect on Oncomelania hupensis.