Antiparasitic efficacy of dihydrosanguinarine and dihydrochelerythrine from Macleaya microcarpa against Ichthyophthirius multifiliis in richadsin (Squaliobarbus curriculus).

Ichthyophthirius multifiliis is a holotrichous protozoan that invades the gills and skin surfaces of fish and can cause morbidity and high mortality in most species of freshwater fish worldwide. The present study was undertaken to investigate the antiparasitic activity of crude extracts and pure compounds from the leaves of Macleaya microcarpa. The chloroform extract showed a promising antiparasitic activity against I. multifiliis. Based on these finding, the chloroform extract was fractionated on silica gel column chromatography in a bioactivity-guided isolation affording two compounds showing potent activity. The structures of the two compounds were elucidated as dihydrosanguinarine and dihydrochelerythrine by hydrogen and carbon-13 nuclear magnetic resonance spectrum and electron ionization mass spectrometry. The in vivo tests revealed that dihydrosanguinarine and dihydrochelerythrine were effective against I. multifiliis with median effective concentration (EC(50)) values of 5.18 and 9.43 mg/l, respectively. The acute toxicities (LC(50)) of dihydrosanguinarine and dihydrochelerythrine for richadsin were 13.3 and 18.2mg/l, respectively. The overall results provided important information for the potential application of dihydrosanguinarine and dihydrochelerythrine in the therapy of serious infection caused by I. multifiliis.

In vivo anthelmintic activity of chelidonine from Chelidonium majus L. against Dactylogyrus intermedius in Carassius auratus.

Dactylogyrus intermedius is one of the most common and serious cause of parasitic diseases of freshwater fish in aquaculture, and can cause morbidity and high mortality in most species of freshwater fish worldwide. To attempt controlling this parasite and explore novel potential antiparasitic agents, the present study was designed to ascertain the anthelmintic activity of Chelidonium majus L. whole plant and to isolate and characterize the active constituents against D. intermedius. The ethanol extract from C. majus whole plant showed significant anthelmintic activity against D. intermedius [EC(50) (median effective concentration) value = 71.5 mg L(-1)] and therefore subjected to further isolation and purification using various chromatographic techniques. A quaternary benzo[c]phenanthridine alkaloid exhibited significant activity against D. intermedius was obtained and identified as chelidonine. In vivo anthelmintic efficacy tests exhibited that chelidonine was 100% effective against D. intermedius at a concentration of 0.9 mg L(-1), with EC(50) value of 0.48 mg L(-1) after 48 h of exposure, which is more effective than the positive control, mebendazole (EC(50) value = 1.3 mg L(-1)). In addition, the 48-h median lethal concentration (LC(50)) for chelidonine against the host (Carassius auratus) was 4.54 mg L(-1). The resulting therapeutic index for chelidonine was 9.46. These results provided evidence that chelidonine might be potential sources of new antiparasitic drugs for the control of Dactylogyrus.

Activity of the chelerythrine, a quaternary benzo[c]phenanthridine alkaloid from Chelidonium majus L. on Dactylogyrus intermedius.

Dactylogyrus intermedius is a significant monogenean parasite on the gills of cyprinid fishes and can cause severe economic losses in aquaculture and ornamental fish breeding. In the present study, bioactivity-guide fractionation was employed to identify active compound from Chelidonium majus L. against D. intermedius. In vivo anthelmintic activity of petroleum ether, ethyl acetate, chloroform, and n-butanol extracts of C. majus were tested. Among them, only the n-butanol extract exhibited promising anthelmintic efficacy, and therefore subjected to the further isolation and purification using various chromatographic techniques. A compound showing potent activity was obtained and identified by hydrogen, carbon-13 nuclear magnetic resonance spectrum and electron ionization mass spectrometry as chelerythrine. In vivo anthelmintic efficacy tests exhibited that chelerythrine was 100% effective against D. intermedius at a concentration of 1.60 mg L(-1), with LC(50) values of 0.68 mg L(-1) after 48 h of exposure. The 48-h LC(50) value (acute toxicity tests) of chelerythrine was found to be 3.59 mg L(-1) for grass carp. These results provided evidence that chelerythrine can be selected as a lead compound for the development of new drugs against D. intermedius.