Search

Dactylogyrus intermedius is one of the most pathogenic monogenean parasites on the gills of captive fish and can cause serious problem in aquaculture. To attempt controlling this parasite and explore novel potential antiparasitic agents, the present study was designed to investigate the anthelmintic activity of Dioscorea zingiberensis C. H. Wright against D. intermedius in goldfish under in vivo conditions. Bioactivity-guided fractionation and isolation of the compounds responsible for anthelmintic activity was carried out with the ethanolic extract yielding two bioactive compounds. Using MS, H NMR, C NMR spectroscopic analyses, the two compounds were identified as trillin and gracillin. The results of in vivo anthelmintic efficacy assay showed that the 48-h median effective concentrations (EC) are 26.48 mg L for trillin and 0.18 mg L for gracillin. The 48-h acute toxicity tests (LD) of trillin and gracillin were found to be 73.11 and 1.40 mg L for goldfish, respectively. The resulting therapeutic indices for the two active compounds are 2.76 and 7.78, respectively. These data confirmed that both trillin and gracillin are effective against D. intermedius, and the gracillin exhibits more interesting perspectives for the development of a candidate antiparasitic agent. [ABSTRACT FROM AUTHOR]

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]