In vivo anthelmintic activity of five alkaloids from Macleaya microcarpa (Maxim) Fedde against Dactylogyrus intermedius in Carassius auratus

The present study aims to evaluate the anthelmintic properties of aerial part of Macleaya microcarpa (Maxim) Fedde. Bioassay-guided fractionation and isolation of the compounds with anthelmintic activity were performed on the ethanolic extract of M. microcarpa yielding five bioactive alkaloids namely: sanguinarine, cryptopine, β-allocryptopine, protopine and 6-methoxyl-dihydro-chelerythrine by comparing spectral data (UV, NMR, and EI-MS) with literature values. According to in vivo anthelmintic assays, they were found to be 100% effective at the concentrations of 0.7, 8.0, 8.0, 16.0 and 7.0 mg l−1, and the median effective concentration (EC50) values for the five compounds were 0.37, 3.31, 4.64, 8.13 and 3.63 mg l−1, respectively. Additionally, the acute toxicity on goldfish for the five active compounds was also investigated with median lethal concentrations (LC50) values of 1.13, 16.12, 15.88, 21.69 and 10.91 mg l−1, respectively. The resulting therapeutic indices for sanguinarine, cryptopine, β-allocryptopine, protopine and 6-methoxyl-dihydro-chelerythrine were 3.03, 4.82, 3.40, 2.66 and 2.99 correspondingly. Correlations analysis between the log P and EC50, LC50 of the five alkaloids revealed that the activity of the five alkaloids was well correlated with their hydrophobicity and r2 = 0.45 is for anthelmintic activity while r2 = 0.47 is for acute toxicity for goldfish, respectively. These results provided evidence that the studied plant extract, as well as the isolated compounds, especially sanguinarine, might be potential plant-based medicines for the treatment of D. intermedius infection.