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Antiparasitic efﬁcacy of dihydrosanguinarine and
dihydrochelerythrine from Macleaya microcarpa against
Ichthyophthirius multiﬁliis in richadsin (Squaliobarbus curriculus)
Jia-yun Yao a , Zhi-ming Zhou a , Xi-lian Li b , Wen-linYin a , Hong-shun Ru a , Xiao-yi Pan a ,
Gui-jie Hao a , Yang Xu a , Jin-yu Shen a,∗
Zhejiang Institute of Freshwater Fisheries, Huzhou, Zhejiang 313001, China
College of Animal Science and Technology, Northwest A&F University, Yangling 712100, China
Received 15 January 2011
Received in revised form 21 June 2011
Accepted 8 July 2011
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 purecompounds 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 anddihydrochelerythrine 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
(EC50 ) values of 5.18 and 9.43 mg/l, respectively. The acute toxicities (LC50 ) of dihydrosanguinarine anddihydrochelerythrine for richadsin were 13.3 and 18.2 mg/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.
© 2011 Elsevier B.V. All rights reserved.
The ciliate Ichthyophthirius multiﬁiis is one of the most
pathogenic parasites ofﬁsh, and it constitutes a major
disease problem in aquaculture (Bisharyan et al., 2003;
Dickerson and Dawe, 1995; McCallum, 1985, 1986). The
morbidity rate due to this disease may reach up to 100%,
causing great economic losses in aquaculture and ornamental ﬁsh breeding (Osman et al., 2009).
∗ Corresponding author. Tel.: +86 572 2045132; fax: +86 572 2041403.
E-mail addresses:firstname.lastname@example.org (J.-y. Yao),
email@example.com (J.-y. Shen).
0304-4017/$ – see front matter © 2011 Elsevier B.V. All rights reserved.
To cope with the parasitism and deleterious consequences, various parasiticides have been used in
aquaculture. Formerly, ichthyophthiriasis was treated
effectively with malachite green, a compound that has been
banned on ﬁsh farms due toits conﬁrmed carcinogenicity in most countries (Alderman, 1985; Wahli et al., 1993).
Since the ban, formalin (Stoskopf, 1993; Rowland et al.,
2009), copper sulfate (Straus et al., 2009; Rowland et al.,
2009), potassium permanganate (Straus and Grifﬁn, 2001;
Buchmann et al., 2003), hydrogen peroxide (Lahnsteiner
and Weismann, 2007), sodium percarbonate (Heinecke and
Buchmann, 2009) have beenused with varying levels of
success. Strategic treatments using sodium percarbonate in
combination with continuous ﬁltration of the pond water
J.-y. Yao et al. / Veterinary Parasitology 183 (2011) 8–13
are suggested to provide a powerful and more environmentally friendly method to minimize and control infections
with I. multiﬁliis. In terms of current strategies for controlling...