Protective effects of fucoidan purified from Undaria pinnatifida against UV-irradiated skin photoaging

Exposure to ultraviolet (UV) radiation (UVB and UVA) is the most well-known extrinsic factor that induces skin aging. Fucoidan has been shown to possess antiphotoaging effects against UV irradiation and can be used as an ingredient in the pharmaceutical industry. The present study evaluated the photoprotective effect of fucoidan purified from Undaria pinnatifida (UPF) on UV-induced skin photoaging and explored its potential molecular mechanism.To evaluate the effect of UPF on UV-induced skin aging, HaCaT cells and HFF-1 cells were pretreated with or without UPF and then exposed to UVB and UVA radiation, respectively, and the levels of cellular senescence, reactive oxygen species (ROS) production and mitochondrial dysfunction were evaluated. The mitochondrial ROS (mROS) was stained through MitoSOX, and the confocal microscope was used to capture the images. For further exploration of AMPK/SIRT-1/PGC-1α signaling, western blot was employed.The results demonstrated that pretreatment of HaCaT and HFF-1 cells with UPF ameliorated cellular senescence, ROS and mROS overproduction, and mitochondrial dysfunction caused by UV exposure. This research also revealed that UPF could activate the AMPK/SIRT-1/PGC-1α signaling pathway to promote mitochondrial biogenesis.UPF can ameliorate UV-induced skin photoaging through inhibition of ROS production via the alleviation of mitochondrial dysfunction by regulating the SIRT-1/PGC-1α signaling pathway.