In vivo anthelmintic activity of Dryopteris crassirhizoma, Kochia scoparia, and Polygala tenuifolia against Dactylogyrus intermedius (Monogenea) in goldfish (Carassius auratus).

In order to find natural agents against Dactylogyrus intermedius in goldfish, petroleum ether, chloroform, ethyl acetate, acetone, and methanol extracts of three medicinal plants (Dryopteris crassirhizoma, Kochia scoparia, and Polygala tenuifolia) were screened for antiparasitic properties using in vivo anthelmintic efficacy assay. Among these extracts investigated, methanolic extract of D. crassirhizoma was observed the most effective with EC₅₀ value of 22.97 mg L⁻¹ after 48 h of exposure, which exhibited a 100% efficacy against D. intermedius at 60.00 mg L⁻¹, followed by the methanolic extracts of K. scoparia and P. tenuifolia with EC₅₀ values of 31.28 and 154.79 mg L⁻¹, showing 100% efficacy against D. intermedius at 60.00 and 500.00 mg L⁻¹, respectively. In addition, acute toxicity assay indicated that 48-h LC₅₀ values of methanolic extracts of D. crassirhizoma, K. scoparia, and P. tenuifolia were 4.10-, 2.27-, and 5.00-fold higher than the corresponding EC₅₀. The obtained results demonstrated that methanolic extracts of D. crassirhizoma, K. scoparia, and P. tenuifolia have the potential for the development of novel therapy for the control of D. intermedius in aquaculture.