Screening Medicinal Plants for Use against Dactylogyrus intermedius (Monogenea) Infection in Goldfish

Abstract Methanol extracts of 24 traditional medicinal plants with potential anthelmintic activity against Dactylogyrus intermedius (Monogenea) in Goldfish Carassius auratus were investigated. Abrus cantoniensis, Citrus medica, Dioscorea collettii, and Polygonum multiflorum exhibited 100% activity and were selected for further evaluation by applying five solvents (petroleum ether, chloroform, ethyl acetate, methanol, and water) for the extraction of the samples, followed by an in vivo bioassay. Among the plants tested, water, methanol, and ethyl-acetate extracts of P. multiflorum showed the highest efficacies; EC50 values (median concentration that results in 50% of its maximal effect) were 1.9, 5.4, and 9.1 mg/L, respectively, and extracts showed 100% efficacy against Dactylogyrus intermedius at 100, 12.5, and 25 mg/L. This was followed by ethyl-acetate, chloroform, and methanol extracts of Dioscorea collettii, which demonstrated 100% efficacy at 80, 80, and 120 mg/L and had EC50 values of 19.7, 27.1, and 37.8 mg/L, respectively, after 48 h of exposure. Chloroform and ethyl-acetate extracts of C. medica, which exhibited 100% efficacy against Dactylogyrus intermedius at 100 and 125 mg/L, revealed similar activity and had EC50 values of 58.7 and 51.3 mg/L, respectively. The ethyl-acetate and methanol extracts of A. cantoniensis exhibited the lowest activity and had EC50 values of 279.4 and 64.3 mg/L. Acute toxicities of these active extracts were investigated on Goldfish for 48 h. The findings indicated that extracts of the four plants can be developed as a preferred natural antiparasitic for the control of D. intermedius. Received June 15, 2013; accepted February 11, 2014.