The significant increase in life expectancy is closely related to the growing interest in the impact of aging on the function and appearance of the skin. Skin aging is influenced by several factors, and solar ultraviolet (UV) irradiation is considered one of the most important causes of skin photoaging. The aim of this study was to examine the anti-photoaging role of porphyra-334 from Porphyra (P.) yezoensis, a mycosporine-like amino acid (MAA), using high-performance liquid chromatography (HPLC), and electrospray ionization‑mass spectrometry (ESI-MS). In the present study, extracted UV‑absorbing compounds from P. yezoensis included palythine, asterina-330 and porphyra-334. Porphyra-334 was the most abundant MAA in P. yezoensis, and it was therefore used for conducting antiphotoaging experiments. The effect of porphyra-334 on the prevention of photoaging was investigated by measuring reactive oxygen species (ROS) production and matrix metalloproteinase (MMP) levels, as well as extracellular matrix (ECM) components and protein expression in UVA‑irradiated human skin fibroblasts. Porphyra-334 suppressed ROS production and the expression of MMPs following UVA irradiation, while increasing levels of ECM components, such as procollagen, type I collagen, elastin. These results suggest that porphyra-334 has various applications in cosmetics and toiletries because of its anti‑photoaging activities and may serve as a novel anti-aging agent.

Laminarin, found in marine brown algae, is used as a carbohydrate reserve for phytoplankton; however, it is also used in traditional Chinese medicine, and has been shown to have several biological activities, including anticancer activities. In this study, we examined the mechanisms through which laminarin from Laminaria digitata induces apoptosis in HT-29 colon cancer cells, as well as the involvement of the ErbB signaling pathway. Cell viability assay revealed that laminarin induced cell death in a dose-dependent manner. Cell cycle analysis revealed that laminarin increased the percentage of cells in the sub-G1 and G2-M phase. Western blot analysis demonstrated that laminarin inhibited the heregulin-stimulated phosphorylation of ErbB2. A decrease in cellular proliferation was also observed; this was found to be dependent on ErbB, which activates c-Jun N-terminal kinase. These findings demonstrate the important role of the epidermal growth factor receptor in colon cancer tumorigenesis, and suggest the potential of laminarin as a bio-functional food with anticancer effects on human colon cancer.

Phycoerythrin is a major light-harvesting pigment of red algae and cyanobacteria that is widely used as a fluorescent probe or as a colorant in the food and cosmetic industries. In this study, phycoerythrin was extracted from the red algae Pyropia yezoensis and purified by ammonium sulfate precipitation and various chromatography methods. The purified phycoerythrin was analyzed by UV-visible and fluorescence spectroscopy. The isolated pigment had the typical spectrum of R-phycoerythrin, with a trimmer state with absorbance maxima at 497, 536, and 565 nm. It was further purified and identified by LC-MS/MS and Mascot search. It showed a 100% sequence similarity with the R-phycoerythrin alpha subunit of Pyropia yezoensis. The molecular mass was 17.97 kDa. The antioxidant activity of the purified R-phycoerythrin alpha subunit was analyzed. It showed significant antioxidant activity in ABTS and FRAP assays and had significant cytotoxicity against HepG2 cells.

Pyropia yezoensis (P. yezoensis) is a marine algae that exhibits antioxidant, anti-inflammatory, antitumor and anti-aging activities. In this study, we investigated the effects of the P. yezoensis peptide, PYP1‑5, on collagen synthesis in the human dermal fibroblast cell line Hs27. Skin aging is related to reduced collagen production and the activities of multiple enzymes, including matrix metalloproteinases (MMPs), which degrade collagen structure in the dermis, and tissue inhibitor of tissue inhibitor of metalloproteinases (TIMPs), which inhibit the action of MMPs. While collagen synthesis is associated with a number of signaling pathways, we examined the increased collagen synthesis via the upregulation of the transforming growth factor-β (TGF-β)/Smad signaling pathway. Using MTS assay, we found that PYP1‑5 did not affect cell viability. Moreover, we confirmed that PYP1‑5 increased type 1 collagen expression using enzyme-linked immunosorbent assay (ELISA), western blot analysis and quantitative PCR. In addition, we identified changes in various enzymes, as well as the mechanisms behind the PYP1‑5-induced collagen synthesis. PYP1‑5 decreased the MMP-1 protein and mRNA levels, and increased the TIMP-1 and TIMP-2 protein and mRNA levels. In addition, PYP1‑5 activated the TGF-β/Smad signaling pathway, which increased TGF-β1, p-Smad2 and p-Smad3 expression, while inhibiting Smad7, an inhibitor of the TGF-β/Smad pathway. Furthermore, PYP1‑5 upregulated transcription factor specificity protein 1 (Sp1) expression, which is reportedly involved in type 1 collagen expression. These findings indicate that PYP1‑5 activates the TGF-β/Smad signaling pathway, which subsequently induces collagen synthesis in Hs27 cells.

In recent years, algae have been highlighted as potential sources of anticancer agents. Laminarin is a molecule found in marine brown algae that has potentially beneficial biological activities. However, these activities have not been investigated. In the present study, we examined the effects of laminarin on HT-29 cells and analyzed its effect on the insulin-like growth factor (IGF-IR) signaling pathway. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays revealed that laminarin induced cell death in a dose-dependent manner. Western blotting showed that laminarin decreased mitogen-activated protein kinases (MAPK) and ERK phosphorylation. Decreased proliferation depended on IGF-IR, which was associated with the downregulation of MAPK/ERK. These results are important for understanding the roles of IGF-IR in colon cancer cell tumorigenesis, and suggest that laminarin shows activity against human colon cancer.

Fucosterol from edible brown seaweeds has various biological activities, including anti-inflammatory, anti-adipogenic, antiphotoaging, anti-acetylcholinesterase, and anti-beta-secretase 1 activities. However, little is known about its effects on soluble amyloid beta peptide (sAβ)-induced endoplasmic reticulum (ER) stress and cognitive impairment. Fucosterol was isolated from the edible brown seaweed Ecklonia stolonifera, and its neuroprotective effects were analyzed in primary hippocampal neurons and in aging rats. Fucosterol attenuated sAβ_1-42-induced decrease in the viability of hippocampal neurons and downregulated sAβ_1-42-induced increase in glucose-regulated protein 78 (GRP78) expression in hippocampal neurons via activation of tyrosine receptor kinase B-mediated ERK1/2 signaling. Fucosterol co-infusion attenuated sAβ_1-42-induced cognitive impairment in aging rats via downregulation of GRP78 expression and upregulation of mature brain-derived neurotrophic factor expression in the dentate gyrus. Fucosterol might be beneficial for the management of cognitive dysfunction via suppression of aging-induced ER stress.