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Skin is the outmost layer of human and sustains most of the external UVB irradiation, which possibly causes the skin photoaging. As a natural antioxidant, marine natural products have been paid more and more attention to their positive effects on photoaging. 6,6'-bieckol is a phlorotanin isolated from Ecklonia cava, while its antiphotoaging bioactivity and mechanism have not been clear yet. This study proves that 6,6'-bieckol enhances cells viability and decreases the level of ROS in UVB-induced human immortalized keratinocytes (HaCaT) cells. It also resulted in significant downregulation of matrix metalloproteinases (MMPs), p-c-Fos, phosphorylated JNK, p38, IκB and p65. In addition, molecular docking also showed that 6,6'-bieckol could bind to MMP-1, MMP-3 and MMP-9. Finally, it was proved that 6,6'-bieckol acts on MMPs through the MAPK/AP-1 and NF-κB pathways to reduce UVB-induced oxidative stress damage in HaCaT cells. Therefore, 6,6'-bieckol is a functional food and skin care ingredient with great potential in preventing photoaging.

Laurencia undulata, as one of the most biologically active species in the genus Laurencia, is an edible folk herb red algae. Among them, d-isofloridoside (DIF, 940.68 Da) is isolated from Laurencia undulata, which has antioxidant and matrix metalloproteinases (MMP) inhibitory activities. However, its mechanism of action on tumor angiogenesis has not yet been reported. In this study, we have studied the mechanism of DIF on tumor metastasis and angiogenesis in HT1080 cell and human vascular endothelial cell (HUVEC). The results show that DIF can reduce the activity of MMP-2/9, and can inhibit the expression of hypoxia-inducible factor-1α (HIF-1α) by regulating the downstream PI3K/AKT and mitogen-activated protein kinases (MAPK) pathways, thereby down-regulating the production of vascular endothelial growth factor (VEGF) in CoCl2-induced HT1080 cell. In addition, DIF can inhibit the activation of VEGF receptor (VEGFR-2), regulate downstream PI3K/AKT, MAPK, nuclear factor-kappa B (NF-κB) signal pathways, activate apoptosis, and thus down-regulate the production of platelet-derived growth factor (PDGF) in VEGF-induced HUVEC. In conclusion, our research shows that DIF has the potential to develop into a tumor-preventing functional food and tumor angiogenesis inhibitor, and it can provide theoretical guidance for the high-value comprehensive utilization of edible red algae Laurencia undulata.

Triabin, a lipocalin-like thrombin inhibitor from the saliva of the blood-sucking triatomine bug Triatoma pallidipennis, exhibits effective inhibition comparable to hirudin despite binding exclusively at exosite I. Interestingly, it was reported that higher triabin doses would not inhibit thrombin completely, which makes it a promising antithrombotic candidate agent with a larger therapeutic window. However, few structural and functional studies about triabin have been reported in the past three decades, mostly due to the lack of a reliable and practicable recombinant expression technology for this seemingly small protein. In this work, we have adopted the SUMO fusion technology for the expression of triabin in E. coli cells-with facile refolding and purification procedures-and the bioactive triabin was produced in ∼12 mg/L culture medium. Subsequently, the structure-function studies through extensive site-directed mutagenesis reveal that triabin's Phe-106 involved in the hydrophobic contacts plays a surprisingly important role in the thrombin inhibition, in contrast to the negatively charged residues Asp-135 or Glu-128 involved in the salt-bridge interaction. As such, this study complements our understanding of the interaction mechanism of natural thrombin inhibitors, which should facilitate the development of anticoagulant drugs with a novel mode of action against thrombin.

Marine microalgae can be used as sustainable protein sources in many fields with positive effects on human and animal health. DAPTMGY is a heptapeptide isolated from Isochrysis zhanjiangensis which is a microalga. In this study, we evaluated its anti-photoaging properties and mechanism of action in human immortalized keratinocytes cells (HaCaT). The results showed that DAPTMGY scavenged reactive oxygen species (ROS) and increase the level of endogenous antioxidants. In addition, through the exploration of its mechanism, it was determined that DAPIMGY exerted anti-photoaging effects. Specifically, the heptapeptide inhibits UVB-induced apoptosis through down-regulation of p53, caspase-8, caspase-3 and Bax and up-regulation of Bcl-2. Thus, DAPTMGY, isolated from I. zhanjiangensis, exhibits protective effects against UVB-induced damage.

Introduction A previous study has shown that Ala-Thr-Pro-Gly-Asp-Glu-Gly (ATPGDEG) peptide identified from boiled abalone by-products has high antioxidant activities and antihypertensive effect. Objective In this study, we further investigated its antiphotoaging activities by ultraviolet B (UVB)-induced HaCaT cells. Result UVB irradiation significantly increased the content of intercellular reactive oxygen species (ROS) and the production of matrix metalloproteinases (MMPs) in HaCaT cells and decreased its content of collagen. First, the generation of intercellular ROS was reduced by abalone peptide in UVB-induced HaCaT cells. And activities of MMP-1 and MMP-9 were reduced by abalone peptide in a dose-dependent manner. Furthermore, western blot analysis demonstrated that abalone peptide downregulated the expression of p38, c-Jun N-terminal kinases, and extracellular signal-regulated kinases via mitogen-activated protein kinases (MAPKs) and NF-κB signaling to protect type I pro collagen and DNA damage. Molecular docking simulation confirms that abalone peptide inhibited activities of MMP-1 and MMP-9 by docking their active site, among them N-terminal Ala, C-terminal Gly, and Pro at the third position of N-terminal made a great contribution. Conclusion and recommendation Abalone peptide could protect type I procollagen synthesis in UVB-irradiated HaCaT cells, and it is a potential peptide for the treatment of skin photoaging in the future.

In this study, we investigated the protective effects of a peptide (YGDEY, Tyr-Gly-Asp-Glu-Tyr) isolated from tilapia skin gelatin hydrolysates (TGHs), against UVB-induced photoaging in human keratinocytes (HaCaT) cells. Results showed that YGDEY significantly decreased levels of intracellular reactive oxygen species (ROS), increased antioxidant factors (Superoxide Dismutase, SOD and Glutathione, GSH) expression and maintained balance between GSH and GSSG in HaCaT cells. Comet assay shows that YGDEY can protect DNA from oxidative damage. Furthermore, it significantly inhibited MMP-1 (collagenase) and MMP-9 (gelatinase) expression and increased Type I procollagen production. In addition, the molecular docking study showed that YGDEY may form active sites with MMP-1 and MMP-9. Moreover, Western blot analysis was utilized to measure the protein levels of UVB-induced mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. Therefore, these results suggested that YGDEY has a therapeutic effectiveness in prevention of UVB-induced cellular damage, and it is a candidate worthy of being developed as a potential natural antioxidant and food additive.

Ultraviolet radiation B cause photoaging of the skin by enhancing the high expression of matrix metalloproteinases (MMPs) to degrade collagen and inhibit the synthesis of procollagen. Trehalose (TRE), a widely occurring natural disaccharide, has been shown to play a cytoprotective role in many pathological processes. However, few studies have evaluated whether it has anti-photoaging potential. In this study, we investigated the anti-photoaging and mechanism of action of TRE using Human immortalized keratinocytes (HaCaT) cells. The results indicated that TRE pretreatment effectively scavenges reactive oxygen species (ROS) accumulation induced by UVB and increases the content of certain endogenous antioxidant factors in HaCaT cells. TRE suppressed UVB-induced MMP expression by blocking mitogen-activated protein kinases (MAPKs), activator protein 1 (AP-1) and NF-κB signaling. TRE treatment increased procollagen I synthesis via activating transforming growth factor-β (TGF-β)/Smad pathway and demonstrated that TRE may be a potential natural disaccharide for photoaging therapy in the future.

Alcoholic liver disease (ALD) threatens human health, so it is imperative that we find ways to prevent or treat it. In recent years, the study of polysaccharides has shown that they have different kinds of bioactivities. Among them are many biological effects that have been attributed to polysaccharide precursors. D-Isofloridoside (DIF) is one of the polysaccharide precursors from the marine red alga Laurencia undulata. This study evaluated the effect of DIF on alcohol-induced oxidative stress in human hepatoma cells (HepG2). As a result, DIF attenuated alcohol-induced cytotoxicity, reduced the amount of intracellular reactive oxygen species (ROS), and effectively reduced alcohol-induced DNA damage in HepG2 cells. In addition, a western blot showed that, after DIF treatment, the expression levels of glutathione (GSH), superoxide dismutase (SOD), and B-cell lymphoma-2 (bcl-2) increased, while the expression levels of &gamma, glutamyl transferase (GGT), BCL2-associated X (bax), cleaved caspase-3, and mitogen-activated protein kinase (p38 and c-Jun N-terminal kinase ) signal transduction proteins reduced. This showed that DIF may protect cells by reducing the amount of intracellular ROS and inhibiting intracellular oxidative stress and apoptotic processes. Finally, molecular docking demonstrated that DIF can bind to SOD, GGT, B-cell lymphoma-2, and bax proteins. These results indicated that DIF can protect HepG2 cells from alcohol-induced oxidative stress damage, making it an effective potential ingredient in functional foods.

Background Excessive exposure to Ultraviolet (UV) rays can cause premature skin aging. Ishigoside (IGS) is a new glyceroglycolipid compound isolated from brown algal Ishige okamurae, However, whether it can protect the skin from (Ultraviolet-B) UVB damage has not been illuminated. Methods The in vitro anti-photoaging effect of IGS was conducted in UVB-induced HaCaT. The HaCaT cells were divided into the following five groups: (1) cells didn't suffer from UVB irradiation or IGS treatment. (2–5) Cells were treated with various concentrations of IGS (0, 10, 50, and 100 μM) and irradiated by 40 mJ/cm2 UVB. The Matrix metalloproteinase (MMP) of photoaging process was determined by ELISA kits and the latent interaction between IGS and MMP was further performed by molecular docking. The crucial signaling pathway proteins involved in the collagen synthesis and degradation were subsequently evaluated by Western blotting, immunofluorescence and EMSA. Results IGS effectively suppresses the high expressions and secretions of matrix metalloproteinases (MMPs) and photo-inflammation by blocking MAPKs, AP-1 and NF-κB. Meanwhile, increasing antioxidant enzyme expression. Molecular docking results suggest that inhibition of IGS on MMPs may be attributed to its hydrogen supply and hydrophobic capacity. In addition, IGS enhanced procollagen production by upregulating the TGF-β/Smad pathways. Conclusions IGS exhibited anti-photoaging activity in UVB-damage HaCaT. These effects might be a contribution by its suppression of MMPs expression via MAPKs, AP-1 and NF-κB pathway and have anti-oxidative and anti-inflammatory effects. Therefore, IGS has the great potential to become skin-care products or functional foods for preventing skin photoaging.

In this study, we investigated the protective effects of a peptide (YGDEY, Tyr-Gly-Asp-Glu-Tyr) isolated from tilapia skin gelatin hydrolysates (TGHs), against UVB-induced photoaging in human keratinocytes (HaCaT) cells. Results showed that YGDEY significantly decreased levels of intracellular reactive oxygen species (ROS), increased antioxidant factors (Superoxide Dismutase, SOD and Glutathione, GSH) expression and maintained balance between GSH and GSSG in HaCaT cells. Comet assay shows that YGDEY can protect DNA from oxidative damage. Furthermore, it significantly inhibited MMP-1 (collagenase) and MMP-9 (gelatinase) expression and increased Type I procollagen production. In addition, the molecular docking study showed that YGDEY may form active sites with MMP-1 and MMP-9. Moreover, Western blot analysis was utilized to measure the protein levels of UVB-induced mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B (NF-κB) signaling pathways. Therefore, these results suggested that YGDEY has a therapeutic effectiveness in prevention of UVB-induced cellular damage, and it is a candidate worthy of being developed as a potential natural antioxidant and food additive.

The liver is vulnerable to oxidative stress-induced damage, which leads to many diseases, including alcoholic liver disease (ALD). Liver disease endanger people’s health, and the incidence of ALD is increasing, therefore, prevention is very important. 7-phloro-eckol (7PE) is a seaweed polyphenol, which was isolated from Ecklonia cava in a previous study. In this study, the antioxidative stress effect of 7PE on HepG2/CYP2E1 cells was evaluated by alcohol-induced cytotoxicity, DNA damage, and expression of related inflammation and apoptosis proteins. The results showed that 7PE caused alcohol-induced cytotoxicity to abate, reduced the amount of reactive oxygen species (ROS) and nitric oxide (NO), and effectively inhibited DNA damage in HepG2/CYP2E1 cells. Additionally, the expression levels of glutathione (GSH), superoxide dismutase (SOD), B cell lymphoma 2 (Bcl-2), and Akt increased, while γ-glutamyltransferase (GGT), Bcl-2 related x (Bax), cleaved caspase-3, cleaved caspase-9, nuclear factor-κB (NF-κB), and JNK decreased. Finally, molecular docking proved that 7PE could bind to BCL-2 and GSH protein. These results indicate that 7PE can alleviate the alcohol-induced oxidative stress injury of HepG2 cells and that 7PE may have a potential application prospect in the future development of antioxidants.