Tohoku J. Exp. Med., 2004, 202(1)

Short Report

Transmission Electron Microscopy of Schistosoma mansoni Cercariae Treated with Hinokitiol (β-thujaplicin), a Compound for Potential Skin Application against Cercarial Penetration

MOHAMMOD MOINUDDIN CHISTY, MAHFUZA NARGIS, TAKASHI INABA,¹ KUNIO ISHITA,² ARIHIRO OSANAI and HARUO KAMIYA

Department of Parasitology, Hirosaki University School of Medicine, Hirosaki 036-8562,
¹Department of Medical Technology, Hirosaki University School of HealthSciences, Hirosaki 036-8564, and
²Institute for Animal Experiments, Hirosaki University School of Medicine,Hirosaki 036-8562

Since skin is the only route of entry of the parasite in schistosomiasis patients, intervention at the level of skin penetration should control the infection. Several compounds were screened for their ability to protect against cercarial penetration. Hinokitiol (β-thujaplicin) was found to have a significant cercaricidal effect in vitro, although there is no information on its cercaricidal mechanisms. To study the kinetics of morphological changes in Schistosoma mansoni associated with exposure to hinokitiol in vitro, cercariae were incubated in media containing hinokitiol at different concentrations and examined by transmission electron microscopy (TEM). TEM revealed that ultrastructural changes occurred by 15 minutes post exposure, at a concentration of 25 μg/ml. Degenerative changes involving both tegument and deeper parenchymal structures were progressive with duration of exposure at the concentration of 50mg/ml. These structural changes may account for the inability of hinokitiol-treated cercariae to infect the host.

keywords —— hinokitiol; Schistosoma mansoni; cercariae; transmission electron microscopy

© 2004 Tohoku University Medical Press

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Address for reprints: Haruo Kamiya, Department of Parasitology, Hirosaki University School of Medicine, Hirosaki 036-8562, Japan.

e-mail: hkamiya@cc.hirosaki-u.ac.jp