**Protective E** ff**ect of a Fucose-Rich Fucoidan Isolated from** *Saccharina japonica* **against Ultraviolet B-Induced Photodamage In Vitro in Human Keratinocytes and In Vivo in Zebrafish**

#### **Wanchun Su 1, Lei Wang 2,3, Xiaoting Fu 1,\*, Liying Ni 1, Delin Duan 4,5, Jiachao Xu 1 and Xin Gao 1**


Received: 14 May 2020; Accepted: 8 June 2020; Published: 15 June 2020

**Abstract:** A fucose-rich fucoidan was purified from brown seaweed *Saccharina japonica*, of which the UVB protective e ffect was investigated in vitro in keratinocytes of HaCaT cells and in vivo in zebrafish. The intracellular reactive oxygen species levels and the viability of UVB-irradiated HaCaT cells were determined. The results indicate that the purified fucoidan significantly reduced the intracellular reactive oxygen species levels and improved the viability of UVB-irradiated HaCaT cells. Furthermore, the purified fucoidan remarkably decreased the apoptosis by regulating the expressions of Bax/Bcl-xL and cleaved caspase-3 in UVB-irradiated HaCaT cells in a dose-dependent manner. In addition, the in vivo UV protective e ffect of the purified fucoidan was investigated using a zebrafish model. It significantly reduced the intracellular reactive oxygen species level, the cell death, the NO production, and the lipid peroxidation in UVB-irradiated zebrafish in a dose-dependent manner. These results sugges<sup>t</sup> that purified fucoidan has a grea<sup>t</sup> potential to be developed as a natural anti-UVB agen<sup>t</sup> applied in the cosmetic industry.

**Keywords:** ROS; Phaeophyta; carbohydrate; UVB irradiation; HaCaT cells; zebrafish
