Antiparasitic efficacy and safety assessment of magnolol against Ichthyophthirius multifiliis in goldfish

作者：Song, Chenguang; Song, Kaige; Wu, Xiaohu; Tu, Xiao; Qi, Xiaozhou; Wang, Gaoxue; Ling, Fei^*

来源：Aquaculture, 2018, 486: 9-17.

DOI：10.1016/j.aquaculture.2017.12.002

• Ichthyophthirius multifiliis
• Antiparasitic efficacy
• Magnolol
• Goldfish
• Safety assessment

Ichthyophthirius multifiliis causes high mortality rate of freshwater fish. It is necessary to find the effective alternatives that may both be affordable and environmentally acceptable since malachite green is banned to use. In this work, magnolol exhibited great anti-parasitic activity against all stages of I. multifiliis. Magnolol at concentrations of 0.6 mg/L or more resulted in 100% mortality of I. multifiliis theronts within 4 h exposure; and terminated reproduction of I. multifiliis post 6 h exposure of protomonts and encysted tomonts to 0.8 and 1.0 mg/L, respectively. Moreover, some of tomonts presented morphological characteristic changes and a larger part of tomonts were unable to reproduce. Magnolol possibly had a directly effect on the cell membrane, and more importantly, it could permeate into an encysted tomont across the cyst wall and then impact on the tomont proliferation. In vivo trials showed that 5 h exposure of infected fish to 1.5 mg/L of magnolol significantly reduced the number of theronts released from tomonts. In addition to determination of anti-Ichthyophthirius activity, we also systematically evaluated the safety of magnolol against fish. First of all, the results of acute toxicity experiment showed that the 96 h median lethal concentration (LC50) of magnolol to goldfish was 6.02 mg/L. Furthermore, gene expression (cyp1a, hsp70, gst and sod) and enzyme activity (GSH, SOD and T-AOC) in liver, spleen and kidney could recover to the same level as the control group up to 48 h, though magnolol induced goldfish stress response during 6-24 h exposure. More than that, magnolol can be easily synthesized with low cost, and further embellished and modified for higher bioactivity and lower toxicity because of its simple and symmetry chemical structure. Therefore, magnolol has the potential to be a safe and effective therapeutant, and it also can be used as a probable leading compound for the development of commercial drug to control ichthyophthiriasis in aquaculture.

• 出版日期2018-2-3
• 单位西北农林科技大学