Protective effect of MAAs extracted from Porphyra tenera against UV irradiation-induced photoaging in mouse skin

The objective of this study was to investigate the effect of Mycosporine-like amino acids (MAAs) extracted from Porphyra tenera skin against UV irradiation-induced photoaging using an ICR mouse model of skin photoaging and to explore the curative effects of the compounds in MAAs. The skin damage and collagenous tissue impairments induced by ultraviolet radiation were observed by histopathological analysis, and the effects of MAAs on protecting against skin damage and maintaining an intact structure of collagenous tissue were studied. The expression of NF-κB and the MAPK signaling pathway and nuclear transcription factors MMP-1, MMP-3 and TNF-α was analyzed used quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and ELISA assays. The results showed that the MAAs extracted from Porphyra tenera contained Porphyra-334 and shinorine, which could prevent skin photoaging induced by ultraviolet irradiation and reduce the damage to collagen and elastin. Meanwhile, MAAs significantly inhibited the decrease in hydroxyproline and collagen content and protected against pathological damage to collagen fibers in photoaging skin. MAAs resulted in a reduction in the expression of interstitial collagenase (MMP-1), matrix metalloproteinases (MMP-3) and tumor necrosis factor-α (TNF-α) and a reduction in the content of tissue matrix metalloproteinase (MMPs). Furthermore, MAAs may promote procollagen synthesis by downregulating the expression of TNF-α and downregulating the levels of MMPs, which demonstrates that MAAs are involved in matrix collagen synthesis by activating the NF-kB pathway in photoaging skin. Based on these results, we concluded that MAAs protect skin from UV irradiation-induced photodamage, and therefore, MAAs may be a potentially effective agent for the prevention of photoaging.