|LIANG, JING-HAN - Guangzhou University|
|FU, YAO-WU - Guangzhou University|
|ZHANG, QI-ZHONG - Guangzhou University|
|WANG, BIN - Guangzhou University|
|LIN, DE-JIE - Guangzhou University|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2015
Publication Date: 1/21/2015
Publication URL: http://handle.nal.usda.gov/10113/60497
Citation: Liang, J., Fu, Y., Zhang, Q., Xu, D., Wang, B., Lin, D. 2015. Identification and effect of two flavonoids from root bark of Morus alba against Ichthyophthirius multifiliis in grass carp. Journal of Agricultural and Food Chemistry. 63:1452-1459.
Interpretive Summary: “White spot” disease, caused by a ciliated protozoan Ichthyophthirius multifiliis (Ich), is one of the major parasitic diseases in freshwater fishes, which causes high mortalities of fish worldwide and results in a huge economic loss in the aquaculture industry. Chemotherapeutants that can be used to treat parasites in fish are limited and there is an urgent need to find new parasiticides to treat Ich infections. This study aimed to (1) purify and identify the compounds responsible for the antiparasitic activity from root bark extracts of Morus alba using bioassay-guided fractionation, (2) evaluate compounds for their anti-Ich efficacy and (3) determine acute toxicity of the compounds to grass carp. Two flavonoids (kuwanons G and O) with antiparasitic activity were isolated from the root bark extracts and the chemical structures were determined. The antiparasitic assays revealed that kuwanons G and O could cause 100% mortality of Ichthyophthirius multifiliis theronts at the concentration of 2 mg/L in 30 min. In addition, kuwanons G and O could significantly reduce the infective ability of I. multifiliis theronts at 0.125 mg/L or higher concentrations. The acute toxicity of kuwanons G or O to grass carp was 50 and 35 times of the concentrations for killing the parasite, demonstrating their safety for fish. The study results are important to aquaculture and will help develop effective parasiticides against I. multifiliis.
Technical Abstract: Morus alba is an important plant for sericulture and has a high medicinal value. In this study, two flavonoids (kuwanons G and O) with antiparasitic activity were isolated from the root bark of M. alba by bioassay-guided fractionation. The chemical structures were determined by pectroscopic analyses. The antiparasitic assays revealed that kuwanons G and O could cause 100% mortality of Ichthyophthirius multifiliis theronts at the concentration of 2 mg/L in 30 min and possessed a median effective concentration (EC50) of 0.8 mg/L against the theronts. In addition, kuwanons G and O could significantly reduce the infective ability of I. multifiliis theronts at concentrations of = 0.125 mg/L. The acute toxicity of kuwanons G or O to grass carp was 37.98 mg/L and 26.87 mg/L, which were approximately 50 and 35 times that of the EC50 (0.8 mg/L for both compounds) for killing theronts.