Polysaccharide precipitation enhances the preventive effects of ultrasonicated Undaria pinnatifida (Laminariales, Phaeophyta) sporophyll extract against acute skin damage and oxidative stress

Abstract

Although Undaria pinnatifida sporophyll is rich in beneficial components such as polysaccharides, proteins, and phytochemicals,its inaccessible structure limits its usability. To overcome this limitation, we ultrasonically extracted U. pinnatifidasporophyll extract (UPE) under optimized conditions (20 kHz, 1,080 W, 30¡ÆC) for 8 h and used gradient ethanolprecipitation to isolate the UPE fractions (UEF). The yield, composition, and molecular weight of the UEFs changed asfractionation progressed, and the galactose and fucose content increased. Interestingly, the sulfate polysaccharide contentswere not related to the fractionation process: UEF3 showed the highest content among the fractions (33.89 ¡¾ 0.05%). UEFs had no cytotoxic effects on HaCaT, RAW 264.7, or BEAS-2B cells, and UEF3 prevented ultraviolet B (UVB)-inducedcyclooxygenase-2 (COX-2) expression by regulating the ERK kinase pathway. The oral administration of UEF3 preventedepidermal thickening and COX-2 overexpression in UVB-exposed mice. UEF3 also alleviated oxidative stress by reducingreactive oxygen species levels via the activation of the HO-1 / NRF2 signaling pathway. This indicates that polysaccharideprecipitation fractionation enhances efficacy by isolating the functional components. In conclusion, fractional processingusing ultrasonic-assisted extr