**Peridinin from the Marine Symbiotic Dinoflagellate,**  *Symbiodinium* **sp., Regulates Eosinophilia in Mice**

**Ken-ichi Onodera 1,\*, Yuko Konishi 2, Takahiro Taguchi 3, Sumio Kiyoto 1 and Akira Tominaga 3**

	- E-Mail: jm-konishiy@kochi-u.ac.jp

*Received: 10 December 2013; in revised form: 25 February 2014 / Accepted: 28 February 2014 /* 

*Published: 25 March 2014* 

> **Abstract:** Peridinin and fucoxanthin, which are natural carotenoids isolated from a symbiotic dinoflagellate, *Symbiodinium* sp., and a brown alga, *Petalonia fascia*, respectively, were compared for inhibitory effects on delayed-type hypersensitivity in mice. The number of eosinophils at the site of inflammation and in peripheral blood was compared for the administration of peridinin and fucoxanthin applied by painting and intraperitoneally. Peridinin, but not the structurally-related fucoxanthin, significantly suppressed the number of eosinophils in both the ear lobe and peripheral blood. Furthermore, peridinin applied topically, but not administered intraperitoneally, suppressed the level of eotaxin in the ears of sensitized mice. Fucoxanthin weakly suppressed the concentration of eotaxin in ears only by intraperitoneal administration. Although both carotenoids inhibited the migration of eosinophils toward eotaxin, the inhibitory effect of peridinin was higher than that of fucoxanthin. Peridinin may be a potential agent for suppressing allergic inflammatory

responses, such as atopic dermatitis, in which eosinophils play a major role in the increase of inflammation. 

**Keywords:** peridinin; fucoxanthin; delayed-type hypersensitivity; eosinophils; eotaxin; *Symbiodinium*; dinoflagellate 
