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With the aim of finding natural anthelmintic agents against Dactylogyrus intermedius (Monogenea) in goldfish ( Carassius auratus), 26 plants were screened for antiparasitic properties using in vivo anthelmintic efficacy assay. The results showed that Caesalpinia sappan, Lysima chiachristinae, Cuscuta chinensis, Artemisia argyi, and Eupatorium fortunei were found to have 100 % anthelmintic efficacy at 125, 150, 225, 300, and 500 mg L −1 after 48 h of exposure. Crude extract of the five plants were further partitioned with petroleum ether, chloroform, ethyl acetate, methanol, and water to obtain anthelmintically active fractions with various polarity. Among these fractions tested, the ethyl acetate extract of L. chiachristinae was found to be the most effective with a 50 % effective concentration (EC 50) value of 5.1 mg/L after 48 h of exposure. This was followed by ethyl acetate extract of C. chinensis (48 h-EC 50 = 8.5 mg L −1), chloroform extracts of C. sappan (48 h-EC 50 = 15.6 mg L −1), methanol extract of C. chinensis (48 h-EC 50 = 15.9 mg L −1), and chloroform and petroleum ether extract of L. chiachristinae (EC 50 values of 17.2 and 21.1 mg/L, respectively), suggesting that these plants, as well as the active fractions, provide potential sources of botanic drugs for the control of D. intermedius in aquaculture. [ABSTRACT FROM AUTHOR]

Ichthyophthiriasis is a widespread disease in aquaculture and causes mass mortalities of fish. The development of new antiprotozoal agents for the treatment of Ichthyophthirius multifiliis infections is of increasing interest. The aim of the present study was to investigate the efficacy of 30 medicinal plants against I. multifiliis. The results showed that the methanol extracts of Magnolia officinalis and Sophora alopecuroides displayed the highest antiprotozoal activity against theronts, with 4-h LC values estimated to be 2.45 and 3.43 mg L, respectively. Concentrations of 2.5, 5.0, 10.0, and 20.0 mg L of M. officinalis extracts resulted in tomont mortality of 9.7, 43.7, 91.3, and 100 % at 20 h, respectively. From 40 to 320 mg L of S. alopecuroides extracts, tomont mortality increased from 29.7 to 100 %. Antiprotozoal efficacy against settled tomonts (2 and 10 h) was also applied; the results indicated that encysted I. multifiliis tomonts were less susceptible to these plant extract treatments. In vivo experiments demonstrated that high concentrations of M. officinalis and S. alopecuroides extracts could kill tomonts, and M. officinalis significantly reduced its reproduction ( P < 0.05). These results suggested that the methanol extracts of M. officinalis and S. alopecuroides have the potential to be used as an eco-friendly approach for the control of I. multifiliis. [ABSTRACT FROM AUTHOR]