Study On Active Constituents From The Stems Of Spatholobus Suberectus Against Dactylogyrus Infecting Fish

Dactylogyrus is a common parasitic pathogen in aquaculture industry; it will cause high mortality of fish when present in large numbers, resulting in serious economic losses. Currently, some chemicals such as mebendazole, praziquantel were applied for the treatment of parasitic disease caused by dactylogyrus. However, long-term and/or over use of these chemicals has led to a series of drawbacks including environmental contamination, food safety and drug-resistant, which rise a demand that the risk of food and environment safety should be considered meantime. Plant-derived products have received increasing concern owing to the features such as degradable and eco-friendly. Therefore, it is important to search for novel bulk pharmaceutical chemicals meeting the demand of health breeding in aquaculture and further biomimetic synthesis, aiming to cope with the current issues including drug-resistant and aquatic products safety.Based on the above points, the present work on the selected active plant, spatholobus suberectus was performed including the screen of active part of S. suberectus, bio-guided isolation and identification of the active components, spectroscopy analysis and structure elucidation etc. The results obtained in this work were as follows:1. Study of active part against dactylogyrus of S. suberectus: Five solvents with different polarity including petroleum ether, chloroform, ethyl acetate, methanol, and water were applied for the extraction of plant samples. Anthelmintic efficacy of five different extracts was determined in vivo and the results indicated that: methanol extract of S. suberectus exhibited a 100% efficacy against dactylogyrus after 48h when tested at 150 mg ^L-1, it reached efficacy between 57.8%-98.2% when tested at 50-125 mg ^L-1, which showed that methanol extract of S. suberectus was the active part with potent anthelmintic activity.2. Bio-guided isolation and structural identification of active molecules of S. suberectus: Ethanol extract was successively partitioned with petroleum ether, chloroform, ethyl acetate, methanol and water, and the antiparasitic activity of parts in different solvent were investigated indicating that the part in methanol showed the best antiparasitic effects. Bio-guided isolation and identification of the methanol part using various isolation techniques such as column chromatograph, LH-20 and successive crystallization has resulted in isolation of the active compound B4-3-2, it exhibited 100% efficacy at 3.0 mg ^L-1. When tested at the concentrations between 0.5 mg ^L-1-2.0 mg ^L-1, the active compound showed the efficacy between 44.8%-96.6%. The structure of the active compound was elucidated by physicochemical properties, spectroscopy analysis and comparing the spectral data with the reported values, identified as ononin.3. Acute toxicity on goldfish: The acute toxicity of the methanol extract and active compound, ononin, were evaluated on goldfish and the results showed that: the LC50 of methanol extract of S. suberectus were 230.39（219.55-242.73）, 226.86（216.19-238.66）, 217.41（ 206.78-228.82）, 210.56（199.41-222.21） mg ^L-1 after 24 h, 48 h, 72 h, and 96 h, respectively; LC50 of the active compound, ononin, were 4.66（4.45-4.89）, 4.58（4.38-4.80）, 4.44（4.23-4.66）, 4.27（4.08-4.46） mg ^L-1 after 24 h, 48 h, 72 h, and 96 h, respectively.