Protective effect of Ecklonia cava on UVB-induced oxidative stress: in vitro and in vivo zebrafish model

Chronic exposure of the skin to ultraviolet B (UVB) radiation induces oxidative stress, which plays a crucial role in the induction of skin aging. In this study, potential protective effect of extracts of six species of brown seaweeds on UVB radiation-induced cell damage was assessed via cell viability in HaCaT cells. The Ecklonia cava extract showed a profound protective effect against UVB radiation-induced cell damage, compared to that exhibited by other brown seaweed extracts. Thus, E. cava was selected for use in further experiments and was extracted with different solvents. The protection effect was evaluated via DCFH-DA, MTT, and morphological changes in HaCaT cells. Profound protective effect against UVB radiation-induced cell damage was detected in the 100% methanol extract. Partitioning of the 100% methanol extract with different organic solvents revealed a pronounced protective effect in the ethyl acetate fraction. The isolated active compounds were phlorotannins, especially dieckol, as identified using ultra-performance liquid chromatography-tandem mass spectrometry. Among the phlorotannins, dieckol showed a higher protective effect on UVB-induced cell damage in HaCaT cells than the other phlorotannins. Therefore, UVB protection of dieckol was evaluated via DCFH-DA, DAF-FM DA, acridine orange, and morphological changes in zebrafish model. Reactive oxygen species, nitric oxide, and cell death in live zebrafish induced by UVB radiation were reduced by the addition of dieckol. These results indicated that dieckol has potential protective effects on UVB-induced skin damage, which might be useful in pharmaceutical and cosmetic formulations.