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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]

Abstract: The present study was designated to ascertain the anthelmintic activity of the dried fruits of Brucea javanica and to isolate and characterise the active constituents. The methanol extract from the fruits of B. javanica showed significant anthelmintic activity against Dactylogyrus intermedius (EC50 (median effective concentration) value=49.96mgl−1). Based on this finding, the methanol extract was fractionated on silica gel column chromatography in a bioassay-guided fractionation affording two known quassinoids showing potent activity, bruceine A and bruceine D. Both bruceine A and D exhibited significant activity against D. intermedius with EC50 values of 0.49mgl−1 and 0.57mgl−1, respectively, which were more effective than the positive control, mebendazole (EC50 value=1.25mgl−1). In addition, the 48-h median lethal concentration (LC50) for bruceine A and D against the host (Carassius auratus) was 10.6-fold and 9.7-fold higher than the EC50 for D. intermedius. These results provide evidence that the isolated compounds might be potential sources of new anti-parasitic drugs for the control of Dactylogyrus. This is the first report on an in vivo anthelmintic investigation for B. javanica against D. intermedius. [Copyright &y& Elsevier]

In search of a natural antiparasitic, in vivo anthelmintic activity of petroleum ether, chloroform, ethyl acetate, methanol, and aqueous extracts of Angelica pubescens roots ( Radix angelicae pubescentis), Brucea javanica fruits ( Fructus bruceae), Spatholobus suberectus stems ( Caulis spatholobi), Aesculus chinensis Bge. seeds ( Semen aesculi), and Pharbitis purpurea (L.) Voigt seeds ( Semen pharbitidis) were tested against Dactylogyrus intermedius (Monogenea) in goldfish ( Carassius auratus). Among the extracts tested, the methanolic and aqueous extracts of S. aesculi were observed to be more efficient than the other plant extracts with EC50 and EC90 values of 5.23 and 7.33 mg/L and 6.48 and 12.29 mg/L after 48 h, respectively, followed by methanolic extracts of Fructus bruceae, Radix angelicae pubescentis, Caulis spatholobi, and Semen pharbitidis with EC50 49.96, 57.45, 64.92, and 309.47 mg/L. The methanolic and aqueous extracts of S. aesculi exhibited potential results and can be exploited as a preferred natural antiparasitic for the control of D. intermedius. [ABSTRACT FROM AUTHOR]

Dactylogyrus is one of the most serious parasites in aquaculture, resulting in devastating disease for severe economic impacts. In order to further increase the anthelmintic activity of coumarins, statistically valid three-dimensional quantitative structure-activity relationship (3D-QSAR) models was conducted by comparative molecular field analysis (CoMFA) to obtain better novel and promising anthelmintic coumarins within a total of 52 compounds in this study. By served C24 and C41 as template molecules, the steric and electrostatic fields of comparative molecular field analysis (CoMFA) showed a good correlation and predictive power, which was verified the model reliable. Based on the models, eight newly coumarin derivatives Q1 - Q8 were designed and synthesized, and Q1 , Q2 , Q6 and Q7 showed better antiparasitic activities (the EC 50 values ranged from 0.18 to 0.26 mg/L) than that of coumarin C24 and C41 (the EC 50 values of 0.85 and 0.80 mg/L). By comparing the therapeutic index (TI), the order is the potency of Q4 > Q5 > Q7 > mebendazole > Q2 > Q6 > praziquantel > Q1 > Q3 , which suggests that Q4 should be a viable way for controlling Dactylogyrus infection. Meanwhile, Q4 with a high stability in aquacultural water in immersion suppressed horizontal transmission of Dactylogyrus. These results will be contributed to further improve drug potency on aquacultural parasite control. • 3D-QSAR models was conducted to obtain better novel and promising anthelmintic coumarins. • Four coumarins from the model exhibited excellent antiparasitic activity against Dactylogyrus infection. • Coumarin Q4 suppressed horizontal transmission of Dactylogyrus. [ABSTRACT FROM AUTHOR]

Dactylogyrus is one of the most serious parasites in aquaculture, resulting in devastating disease for severe economic impacts. In order to further increase the anthelmintic activity of coumarins, statistically valid three-dimensional quantitative structure-activity relationship (3D-QSAR) models was conducted by comparative molecular field analysis (CoMFA) to obtain better novel and promising anthelmintic coumarins within a total of 52 compounds in this study. By served C24 and C41 as template molecules, the steric and electrostatic fields of comparative molecular field analysis (CoMFA) showed a good correlation and predictive power, which was verified the model reliable. Based on the models, eight newly coumarin derivatives Q1 - Q8 were designed and synthesized, and Q1 , Q2 , Q6 and Q7 showed better antiparasitic activities (the EC 50 values ranged from 0.18 to 0.26 mg/L) than that of coumarin C24 and C41 (the EC 50 values of 0.85 and 0.80 mg/L). By comparing the therapeutic index (TI), the order is the potency of Q4 > Q5 > Q7 > mebendazole > Q2 > Q6 > praziquantel > Q1 > Q3 , which suggests that Q4 should be a viable way for controlling Dactylogyrus infection. Meanwhile, Q4 with a high stability in aquacultural water in immersion suppressed horizontal transmission of Dactylogyrus. These results will be contributed to further improve drug potency on aquacultural parasite control. • 3D-QSAR models was conducted to obtain better novel and promising anthelmintic coumarins. • Four coumarins from the model exhibited excellent antiparasitic activity against Dactylogyrus infection. • Coumarin Q4 suppressed horizontal transmission of Dactylogyrus. [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]