title: Cynatratoside-C efficacy against theronts of Ichthyophthirius multifiliis, and toxicity tests on grass carp and mammal blood cells.
abstract: Infection by Ichthyophthirius multifiliis, a ciliated protozoan parasite, results in high fish mortality and causes severe economic losses in aquaculture. To find new, efficient anti-I. multifiliis agents, cynatratoside-C was isolated from Cynanchum atratum by bioassay-guided fractionation in a previous study. The present study investigated the anti-theront activity, determined the toxicity of cynatratoside-C to grass carp Ctenopharyngodon idellus and mammalian blood cells, and evaluated the protection of cynatratoside-C against I. multifiliis theront infection in grass carp. Results showed that all theronts were killed by 0.25 mg l-1 of cynatratoside-C in 186.7 ± 5.8 min. Cynatratoside-C at 0.25 mg l-1 was effective in treating infected grass carp and protecting naive fish from I. multifiliis infestation. The 96 h median lethal concentration (LC50) of cynatratoside-C to grass carp and 4 h median effective concentration (EC50) of cynatratoside-C to theront were 46.8 and 0.088 mg l-1, respectively. In addition, the hemolysis assay demonstrated that cynatratoside-C had no cytotoxicity to rabbit red blood cells. Therefore, cynatratoside-C could be a safe and effective potential parasiticide for controlling I. multifiliis.
authors.affiliation: Institute of Hydrobiology, Jinan University, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Engineering Research Center of Tropical and Subtropical Aquatic Ecological Engineering Ministry of Education, Guangzhou 510632, PR China.
authors.forename: Yao-Wu
authors.initials: YW
authors.lastname: Fu
authors.forename: Qi-Zhong
authors.initials: QZ
authors.lastname: Zhang
authors.forename: De-Hai
authors.initials: DH
authors.lastname: Xu
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Jing-Han
authors.initials: JH
authors.lastname: Liang
authors.forename: De-Jie
authors.initials: DJ
authors.lastname: Lin
mesh_terms: D000818:Animals; D002347:Carps / Q000097:blood*; D016798:Ciliophora / Q000187:drug effects*; D016770:Ciliophora Infections / Q000517:prevention & control / Q000662:veterinary*; D005393:Fish Diseases / Q000139:chemically induced / Q000188:drug therapy / Q000469:parasitology*; D006461:Hemolysis / Q000187:drug effects*; D011817:Rabbits; D012632:Secosteroids / Q000009:adverse effects* / Q000627:therapeutic use*; D014312:Trisaccharides / Q000009:adverse effects* / Q000627:therapeutic use*
chemical_list: D012632:Secosteroids; D014312:Trisaccharides; C000596149:cynatratoside-C