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United States Department of Agriculture

Agricultural Research Service

Research Project: Integrated Aquatic Animal Health Strategies

Location: Aquatic Animal Health Research

Title: Evaluation of an antiparasitic compound extracted from Galla chinensis against fish parasite Ichthyophthirius multifiliis

Authors
item Zhang, Qizhong -
item Xu, Dehai
item Klesius, Phillip

Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 19, 2013
Publication Date: October 10, 2013
Repository URL: http://handle.nal.usda.gov/10113/58446
Citation: Zhang, Q., Xu, D., Klesius, P.H. 2013. Evaluation of an antiparasitic compound extracted from Galla chinensis against fish parasite Ichthyophthirius multifiliis. Veterinary Parasitology. 198:45-53.

Interpretive Summary: The protozoan parasite Ichthyophthirius multifiliis (Ich) infests most species of fresh water fish and results in severe economic loss in aquaculture. Currently there is no chemotherapeutant available to treat Ich effectively and economically. There is an urgent need to discover effective and safe parasiticides to control Ich infestations. In this study, we evaluated a compound named pentagalloylglucose which was extracted from plants for its efficacy against Ich and determined its toxicity to channel catfish. Pentagalloylglucose can kill infective theronts of Ich at concentrations of 2.5 mg/L or higher and terminate reproduction of Ich at 40 mg/L. Pentagalloylglucose significantly reduced infective ability of theronts at 1-5 mg/L. The survival of naive channel catfish was 70% when treated with 10 mg/L and 100% when treated with 20 mg/L of pentagalloylglucose. The compound killed Ich by destroying the plasma membrane of the parasite. Overall results demonstrated pentagalloylglucose as a safe, effective potential parasiticide against I. multifiliis. The study results are important to the aquaculture industry and will help researchers to develop effective parasiticides against the parasite Ich.

Technical Abstract: Ichthyophthirius multifiliis (Ich) is an important ectoparasitic ciliate that parasitizes gills and skin of freshwater fish resulting in massive mortality of fish. Currently there is no chemotherapeutant available to treat Ich effectively and economically. There is an urgent need to discover effective and safe parasiticides to control ichthyophthiriasis. In this study, anti-Ich efficacy of pentagalloylglucose,a compound extracted from the plant Galla chinensis was evaluated and the toxicity of the compound to channel catfish was determined. Pentagalloylglucose can kill all theronts of Ich at concentrations of 2.5 mg/L to 20 mg/L during 5.6 to 233.9 min and terminate reproduction of tomonts at 40 mg/L. Pentagalloylglucose significantly reduced infective ability of theronts at 1, 2 and 5 mg/L. The survival of naive channel catfish was 70% when treated with 10 mg/L and 100% when treated with 20 mg/L of pentagalloylglucose. For Ich infected catfish, the survival was 53.3% when treated with 10 mg/L and 93.3% when treated with 20 mg/L of pentagalloylglucose. Pentagalloylglucose at 20 mg/L was effective for treating either Ich infected catfish or preventing naive catfish from Ich infestation. Median lethal concentration of the compound to catfish was 151.3 mg/L, which was 5 times the median effective concentration (30.5 mg/L) for killing tomonts. The compound killed Ich by destroying the plasma membrane of the parasite. The result demonstrated pentagalloylglucose as a safe, effective potential parasiticide against I. multifiliis.

Last Modified: 4/18/2014
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