Ishophloroglucin A, derived from Ishige okamurae, regulates high-fat-diet-induced fat accumulation via the leptin signaling pathway, associated with peripheral metabolism

Structure-Based In Silico Screening of Marine Phlorotannins for Potential Walrus Calicivirus Inhibitor

A new calicivirus isolated from a walrus was reported in 2004. Since unknown marine mammalian zoonotic viruses could pose great risks to human health, this study aimed to develop therapeutic countermeasures to quell any potential outbreak of a pandemic caused by this virus. We first generated a 3D model of the walrus calicivirus capsid protein and identified compounds from marine natural products, especially phlorotannins, as potential walrus calicivirus inhibitors. A 3D model of the target protein was generated using homology modeling based on two publicly available template sequences. The sequence of the capsid protein exhibited 31.3% identity and 42.7% similarity with the reference templates. The accuracy and reliability of the predicted residues were validated via Ramachandran plotting. Molecular docking simulations were performed between the capsid protein 3D model and 17 phlorotannins. Among them, five phlorotannins demonstrated markedly stable docking profiles; in particular, 2,7-phloroglucinol-6,6-bieckol showed favorable structural integrity and stability during molecular dynamics simulations. The results indicate that the phlorotannins are promising walrus calicivirus inhibitors. Overall, the study findings showcase the rapid turnaround of in silico-based drug discovery approaches, providing useful insights for developing potential therapies against novel pathogenic viruses, especially when the 3D structures of the viruses remain experimentally unknown.

Cosmeceutical Effects of Ishige okamurae Celluclast Extract

Sulfated polysaccharides extracted from brown algae are unique algal polysaccharides and potential ingredients in the cosmeceutical, functional food, and pharmaceutical industries. Therefore, the present study evaluated the cosmeceutical effects, including antioxidant, anti-wrinkle, anti-inflammation, and photoprotective activities, of Ishige okamurae Celluclast extract (IOC). The IOC was abundant in sulfated polysaccharides (48.47%), polysaccharides (44.33%), and fucose (43.50%). Moreover, the IOC effectively scavenged free radicals, and its anti-inflammatory properties were confirmed in lipopolysaccharide-induced RAW 264.7 macrophages; therefore, the IOC may produce auxiliary effects by inhibiting reactive oxygen species (ROS). In vitro (Vero cells) and in vivo (zebrafish) studies further confirmed that the IOC produced a protective effect against hydrogen-peroxide-induced oxidative stress in a dose-dependent manner. In addition, the IOC suppressed intracellular ROS and apoptosis and enhanced HO-1 and SOD-1 expression through transcriptional activation of Nrf2 and downregulation of Keap1 in HaCaT cells. Furthermore, the IOC exhibited a potent protective effect against ultraviolet-B-induced skin damage and photoaging. In conclusion, the IOC possesses antioxidant, anti-inflammatory, and photoprotective activities, and can, therefore, be utilized in the cosmeceutical and functional food industries.

Ishophloroglucin A, a potent PTP1B inhibitor isolated from brown alga Ishige okamurae inhibits adipogenesis in 3T3-L1 adipocytes

Ishophloroglucin A (IPA) is one of the most abundant and active compounds in Ishige okamurae and is known to be a potential therapeutic candidate for the improvement of metabolic diseases. However, IPA on the inhibitory effects of protein tyrosine phosphatase 1B (PTP1B) and adipogenesis have not been determined. In this study, we investigated the effects of IPA on the inhibition of PTP1B, the effects on adipogenesis, and its mechanisms of action in 3 T3-L1 adipocytes. The IC50 value of IPA against PTP1B was 0.43 μM, which evidenced the higher inhibition activity than that of ursolic acid, a known PTP1B inhibitor. For further insight, we predicted the 3D structure of PTP1B and used a docking algorithm to simulate the binding between PTP1B and IPA. Molecular docking studies revealed a high and stable binding affinity between IPA and PTP1B and indicated that the IPA could interacts with the amino acid residues located in a region to the active site of PTP1B. Further studies showed that IPA concentrations between 6.25 μM and 25 μM dose-dependently attenuated adipogenesis, which was accompanied by a reduction in adipogenesis-related factors, including PPARγ, C/EBPα, SREBP-1c, and FABP4. Our findings suggested that IPA may be a promising natural compound for the treatment of obesity and related diseases.

A novel glyceroglycolipid from brown algae Ishige okamurae improve photoaging and counteract inflammation in UVB-induced HaCaT cells

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.

Diphlorethohydroxycarmalol (DPHC) Isolated from the Brown Alga Ishige okamurae Acts on Inflammatory Myopathy as an Inhibitory Agent of TNF-α

Inflammation affects various organs of the human body, including skeletal muscle. Phlorotannins are natural biologically active substances found in marine brown algae and exhibit anti-inflammatory activities. In this study, we focused on the effects of phlorotannins on anti-inflammatory activity and skeletal muscle cell proliferation activity to identify the protective effects on the inflammatory myopathy. First, the five species of marine brown algal extracts dramatically inhibited nitric oxide (NO) production in lipopolysaccharide (LPS)-induced RAW 264.7 cells without toxicity at all the concentrations tested. Moreover, the extracts collected from Ishige okamurae (I. okamurae) significantly increased cell proliferation of C2C12 myoblasts compared to the non-treated cells with non-toxicity. In addition, as a result of finding a potential tumor necrosis factor (TNF)-α inhibitor that regulates the signaling pathway of muscle degradation in I. okamurae-derived natural bioactive compounds, Diphlorethohydroxycarmalol (DPHC) is favorably docked to the TNF-α with the lowest binding energy and docking interaction energy value. Moreover, DPHC down-regulated the mRNA expression level of pro-inflammatory cytokines and suppressed the muscle RING-finger protein (MuRF)-1 and Muscle Atrophy F-box (MAFbx)/Atrgoin-1, which are the key protein muscle atrophy via nuclear factor-κB (NF-κB), and mitogen-activated protein kinase (MAPKs) signaling pathways in TNF-α-stimulated C2C12 myotubes. Therefore, it is expected that DPHC isolated from IO would be developed as a TNF-α inhibitor against inflammatory myopathy.