Eckol

Planta . 2015 Jun;241(6):1313-1324.

Physiological role of phenolic biostimulants isolated from brown seaweed Ecklonia maxima on plant growth and development[Pubmed: 25672504]

Eckol, a major phenolic compound isolated from brown seaweed significantly enhanced the bulb size and bioactive compounds in greenhouse-grown Eucomis autumnalis. We investigated the effect of Eckol and phloroglucinol (PG) (phenolic compounds) isolated from the brown seaweed, Ecklonia maxima (Osbeck) Papenfuss on the growth, phytochemical and auxin content in Eucomis autumnalis (Mill.) Chitt. The model plant is a popular medicinal species with increasing conservation concern. Eckol and PG were tested at 10(-5), 10(-6) and 10(-7) M using soil drench applications. After 4 months, growth parameters, phytochemical and auxin content were recorded. When compared to the control, Eckol (10(-6) M) significantly improved bulb size, fresh weight and root production while the application of PG (10(-6) M) significantly increased the bulb numbers. However, both compounds had no significant stimulatory effect on aerial organs. Bioactive phytochemicals such as p-hydroxybenzoic and ferulic acids were significantly increased in Eckol (10(-5) M) and PG (10(-6) M) treatments, compared to the control. Aerial (1,357 pmol/g DW) and underground (1,474 pmol/g DW) parts of Eckol-treated (10(-5) M) plants yielded the highest concentration of indole-3-acetic acid. Overall, Eckol and PG elicited a significant influence on the growth and physiological response in E. autumnalis. Considering the medicinal importance of E. autumnalis and the increasing strains on its wild populations, these compounds are potential tools to enhance their cultivation and growth.

Biol Pharm Bull . 2012;35(6):873-880.

Eckol inhibits ultraviolet B-induced cell damage in human keratinocytes via a decrease in oxidative stress[Pubmed: 22687478]

In previous reports, the antioxidant effects of Eckol were shown to protect cells against hydrogen peroxide- and gamma ray-induced oxidative stress. In this study, the role of Eckol in protecting human skin keratinocytes (HaCaT) against UVB-induced oxidative cell damage was investigated. Also, triphlorethol-A, one of the chemical components in Ecklonia cava, and quercetin a well known antioxidant, were compared with Eckol in terms of antioxidant activity based on chemical structure. Eckol decreased UVB-induced intracellular reactive oxygen species (ROS), decreased injury to cellular components resulting from UVB-induced oxidative stress, and restored cell viability. In addition, Eckol reduced UVB-induced apoptosis by inhibiting the disruption of mitochondrial membranes. These results suggest that Eckol protects human keratinocytes against UVB-induced oxidative stress by scavenging ROS, thereby lessening injury to cellular components.

Int Immunopharmacol . 2020 Feb 20;82:106146.

Eckol from Ecklonia cava ameliorates TNF-α/IFN-γ-induced inflammatory responses via regulating MAPKs and NF-κB signaling pathway in HaCaT cells[Pubmed: 32088638]

We investigated the protective effect of the bioactive compound Eckol on inflammatory-related skin lesions in vitro. HaCaT cells were stimulated with tumor necrosis factor-alpha (TNF-α) and interferon-gamma (IFN-γ) mixture, and treated with various concentration of Eckol (25, 50, and 100 μg/ml). The expression of pro-inflammatory cytokines and chemokines were analyzed by enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR), respectively. Mitogen-activated protein kinase (MAPKs) and nuclear factor-kappa B (NF-κB) signaling pathways regulate immune and inflammation responses. Phosphorylation of MAPKs and NF-κB, indicating activation of respective signaling pathways, was examined by western blot analysis. Treatment of TNF-α and IFN-γ promoted the mRNA expression and production of pro-inflammatory cytokines and chemokines in HaCaT cells. However, Eckol significantly suppressed the these mediators. Furthermore, activation of TNF-α/IFN-γ-induced MAPKs and NF-κB signaling pathway was inhibited by Eckol treatment. Eckol also hampered the TNF-α/IFN-γ-mediated nuclear translocation of NF-κB p65 in HaCaT cells. Taken together, our findings demonstrate that Eckol shows effective protective activity against TNF-α/IFN-γ-induced skin inflammation.

Nutrients . 2020 May 9;12(5):1361

Eckol from Ecklonia cava Suppresses Immunoglobulin E-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis in Mice[Pubmed: 32397556]

Eckol, a precursor compound belonging to the dibenzo-1,4-dioxin class of phlorotannins, is a phloroglucinol derivative that exerts various activities. In the present study, we investigated the antiallergic effects of Eckol isolated from the marine brown algae, Ecklonia cava using immunoglobulin E (IgE)/bovine serum albumin (BSA)-stimulated mouse bone marrow-derived cultured mast cells (BMCMC) and a mouse model of anaphylaxis. Eckol inhibited IgE/BSA-induced BMCMC degranulation by reducing β-hexosaminidase release. A flow cytometric analysis revealed that Eckol decreases FcεRI expression on cell surface and IgE binding to the FcεRI in BMCMC. Moreover, Eckol suppressed the production of the cytokines, interleukin (IL)-4, IL-5, IL-6, and IL-13 and the chemokine, thymus activation-regulated chemokine (TARC) by downregulating, IκB-α degradation and NF-κB nuclear translocation. Furthermore, it attenuated the passive cutaneous anaphylactic reaction induced by IgE/BSA-stimulation in the ear of BALB/c mice. These results suggest that Eckol is a potential therapeutic candidate for the prevention and treatment of allergic disorders.

Phytother Res . 2008 Feb;22(2):238-242

Protective effect of phlorotannin components phloroglucinol and eckol on radiation-induced intestinal injury in mice[Pubmed: 17886227]

Components of phlorotannin, which were extracted from Ecklonia species, have been reported to have in vitro radioprotective and antioxidative effects. The radioprotective effects of two of the components of phlorotannin, phloroglucinol and Eckol, in intestinal stem cells were examined by evaluating their effects on jejunal crypt survival and apoptosis in gamma-irradiated mice. Pretreating the mice (i.p. 20 mg/kg of body weight at 12 and 36 h before irradiation) prior to irradiation with either phloroglucinol or Eckol significantly improved the survival of the jejunal crypt (p < 0.001 and p < 0.01 vs irradiation controls at 3.5 days after 8 Gy irradiation, respectively). The administration of phloroglucinol and Eckol prior to irradiation protected the intestinal crypts from radiation-induced apoptosis (p < 0.05 vs irradiation controls at 12 h after 1 Gy irradiation). Although the mechanism for this inhibitory effect remains unknown, these results showed that phloroglucinol and Eckol might be useful radioprotectors that can defend intestinal stem cells against the oxidative damage caused by gamma-irradiation.

Bioorg Med Chem Lett . 2012 Jun 1;22(11):3710-3712

Vascular barrier protective effects of eckol and its derivatives[Pubmed: 22543027]

In this Letter, we first investigated the barrier protective effects of Eckol and its derivatives against pro-inflammatory responses in human umbilical vein endothelial cells (HUVECs) and in mice. Data showed that Eckol (1) and diEckol (2) inhibited lipopolysaccharide (LPS)-mediated barrier disruption and transendothelial migration of leukocytes to human endothelial cells. Eckol (1) also suppressed acetic acid induced-hyperpermeability and carboxymethylcellulose-induced leukocytes migration in vivo. Interestingly, the barrier protective effects of diEckol (2) were better than those of Eckol (1) and hydroxyl groups in diEckol (2) positively regulate protective effects.

Nutrients . 2020 May 9;12(5):1361

Eckol from Ecklonia cava Suppresses Immunoglobulin E-mediated Mast Cell Activation and Passive Cutaneous Anaphylaxis in Mice[Pubmed: 32397556]

Eckol, a precursor compound belonging to the dibenzo-1,4-dioxin class of phlorotannins, is a phloroglucinol derivative that exerts various activities. In the present study, we investigated the antiallergic effects of Eckol isolated from the marine brown algae, Ecklonia cava using immunoglobulin E (IgE)/bovine serum albumin (BSA)-stimulated mouse bone marrow-derived cultured mast cells (BMCMC) and a mouse model of anaphylaxis. Eckol inhibited IgE/BSA-induced BMCMC degranulation by reducing β-hexosaminidase release. A flow cytometric analysis revealed that Eckol decreases FcεRI expression on cell surface and IgE binding to the FcεRI in BMCMC. Moreover, Eckol suppressed the production of the cytokines, interleukin (IL)-4, IL-5, IL-6, and IL-13 and the chemokine, thymus activation-regulated chemokine (TARC) by downregulating, IκB-α degradation and NF-κB nuclear translocation. Furthermore, it attenuated the passive cutaneous anaphylactic reaction induced by IgE/BSA-stimulation in the ear of BALB/c mice. These results suggest that Eckol is a potential therapeutic candidate for the prevention and treatment of allergic disorders.

Exp Ther Med . 2019 Oct;18(4):2825-2832

Eckol inhibits Reg3A-induced proliferation of human SW1990 pancreatic cancer cells[Pubmed: 31572529]

Pancreatic cancer (PaC) is characterized by a highly inflammatory tumor microenvironment, and inflammatory mediators are implicated in the progression of this cancer. Regenerating gene protein (Reg) 3A is significantly upregulated during pancreatic inflammation, and has been demonstrated to serve an important role during PaC progression, based on its increased expression levels in PaC and potent cell proliferation-promoting activity. The aim of the present study was to investigate the effect of Eckol, a phlorotannin compound with a variety of biological activities including anti-inflammatory, anti-tumor and cytoprotective effects, on Reg3A-induced proliferation of human SW1990 PaC cells. SW1990 cells were pre-treated with Eckol for 48 h at concentrations of 5, 10 and 20 μg/ml. Subsequently, Reg3A protein was added to the culture media at a final concentration of 50 ng/ml in the presence or absence of Eckol for 24 h. The cytotoxicity and proliferative capacity of the SW1990 cells was determined using an MTT and flow cytometry analysis. Cell colony formation was also used to determine the effect of Eckol on the anchorage-independent growth and colony-forming capacity of Reg3A-treated PaC cells. The expression levels of cyclin D1, STAT3, JAK2, and NF-κB p65 were measured with reverse transcription-quantitative PCR and western blotting. Eckol reduced Reg3A-promoted cell survival, inhibited Reg3A-induced cell cycle progression and inhibited colony growth of SW1990 cells in soft agar in a concentration-dependent manner. Additionally, the Reg3A-mediated upregulation of expression of JAK2, STAT3, NF-κBp65 and cyclin D1 was reduced when treated with Eckol. Reg3A is upregulated during pancreatic inflammation and exhibits a pro-growth function and may thus serve a critical role during inflammation-driven PaC malignancies. Eckol may be a potential protective agent against progression of PaC accompanied by pancreatic inflammation.

Int J Mol Sci . 2020 Jul 3;21(13):4755.

Eckol Alleviates Intestinal Dysfunction during Suckling-to-Weaning Transition via Modulation of PDX1 and HBEGF[Pubmed: 32635412]

Maintaining intestinal health in livestock is critical during the weaning period. The precise mechanisms of intestinal dysfunction during this period are not fully understood, although these can be alleviated by phlorotannins, including Eckol. This question was addressed by evaluating the changes in gene expression and intestinal function after Eckol treatment during suckling-to-weaning transition. The biological roles of differentially expressed genes (DEGs) in intestinal development were investigated by assessing intestinal wound healing and barrier functions, as well as the associated signaling pathways and oxidative stress levels. We identified 890 DEGs in the intestine, whose expression was altered by Eckol treatment, including pancreatic and duodenal homeobox (PDX)1, which directly regulate heparin-binding epidermal growth factor-like growth factor (HBEGF) expression in order to preserve intestinal barrier functions and promote wound healing through phosphoinositide 3-kinase (PI3K)/AKT and P38 signaling. Additionally, Eckol alleviated H2O2-induced oxidative stress through PI3K/AKT, P38, and 5'-AMP-activated protein kinase (AMPK) signaling, improved growth, and reduced oxidative stress and intestinal permeability in pigs during the weaning period. Eckol modulates intestinal barrier functions, wound healing, and oxidative stress through PDX/HBEGF, and improves growth during the suckling-to-weaning transition. These findings suggest that Eckol can be used as a feed supplement in order to preserve the intestinal functions in pigs and other livestock during this process.