Asian Pacific Journal of Tropical Biomedicine

: 2022  |  Volume : 12  |  Issue : 6  |  Page : 262--269

Dieckol isolated from Eisenia bicyclis extract suppresses RANKL-induced osteoclastogenesis in murine RAW 264.7 cells

Su-Hyeon Cho1, Tae-Hyung Kwon2, Hoibin Jeong3, Jin Sook Kim3, Song-Rae Kim3, Myeong Seon Jeong3, SeonJu Park3, Miri Choi3, Jung-Hee Woo4, Juhee Ahn5, Kil-Nam Kim6,  
1 Chuncheon Center, Korea Basic Science Institute; Department of Medical Biomaterials Engineering, College of Biomedical Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea
2 Department of Research and Development, Chuncheon Bio-industry Foundation, Chuncheon, Republic of Korea
3 Chuncheon Center, Korea Basic Science Institute, Chuncheon 24341, Republic of Korea
4 Marine Industry Research Institute for East se rim, Uljin-gun, Gyeongsangbuk-do, Republic of Korea
5 Department of Medical Biomaterials Engineering, College of Biomedical Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea
6 Chuncheon Center, Korea Basic Science Institute, Chuncheon 24341; Department of Bio-analysis Science, University of Science & Technology, Daejeon, 34113, Republic of Korea

Correspondence Address:
Juhee Ahn
Department of Medical Biomaterials Engineering, College of Biomedical Sciences, Kangwon National University, Chuncheon 24341
Republic of Korea
Kil-Nam Kim
Chuncheon Center, Korea Basic Science Institute, Chuncheon 24341; Department of Bio-analysis Science, University of Science & Technology, Daejeon, 34113
Republic of Korea


Objective: To demonstrate the effect of dieckol from Eisenia bicyclis on osteoclastogenesis using RAW 264.7 cells. Methods: Murine macrophage RAW 264.7 cells were subjected to dieckol treatment, followed by treatment with receptor activator of nuclear factor kappa-B ligand (RANKL) to induce osteoclastogenesis. Tartrate-resistant acid phosphatase (TRAP) activity was examined using a TRAP activity kit. Western blotting analysis was conducted to examine the level of osteoclast- related factors, including TRAP and calcitonin receptor (CTR), transcriptional factors, including c-Fos, c-Jun, and nuclear factor of activated T cells cytoplasmic 1 (NFATc1), nuclear factor kappa-B (NF-κB), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK). Immunofluorescence staining was conducted to examine the expression of c-Fos, c-Jun, and NFATc1. Results: Among the four phlorotannin compounds present in Eisenia bicyclis, dieckol significantly hindered osteoclast differentiation and expression of RANKL-induced TRAP and CTR. In addition, dieckol downregulated the expression levels of c-Fos, c-Jun, NFATc1, ERK, and JNK, and suppressed NF-κB signaling. Conclusions: Dieckol can suppress RANKL-induced osteoclastogenesis. Therefore, it has therapeutic potential in treating osteoclastogenesis- associated diseases.

How to cite this article:
Cho SH, Kwon TH, Jeong H, Kim JS, Kim SR, Jeong MS, Park S, Choi M, Woo JH, Ahn J, Kim KN. Dieckol isolated from Eisenia bicyclis extract suppresses RANKL-induced osteoclastogenesis in murine RAW 264.7 cells.Asian Pac J Trop Biomed 2022;12:262-269

How to cite this URL:
Cho SH, Kwon TH, Jeong H, Kim JS, Kim SR, Jeong MS, Park S, Choi M, Woo JH, Ahn J, Kim KN. Dieckol isolated from Eisenia bicyclis extract suppresses RANKL-induced osteoclastogenesis in murine RAW 264.7 cells. Asian Pac J Trop Biomed [serial online] 2022 [cited 2022 Jul 3 ];12:262-269
Available from:

Full Text

Significance Dieckol from Eisenia bicyclis was shown to be an effective osteoclastogenesis inhibitor via blocking NF-?B, JNK, and ERK pathways in RANKL-stimulated RAW 264.7 cells. Dieckol could be a promising agent for treating osteoporosis.

 1. Introduction

Osteoporosis is a skeletal disease that induces bone loss and damages bone quality, which increases the risk of fractures and decreases quality of life[1],[2]. Normal bone undergoes modeling and remodeling through osteoclasts and osteoblasts[1],[3]. However, an imbalance between bone resorption and formation results in the generation of bone disorders[4]. Increased osteoclast differentiation plays a crucial role in bone disorders, such as osteoporosis[1],[5]. Therefore, blocking osteoclast differentiation and function is essential to treat osteoporosis. Osteoclasts are multinucleated cells derived from monocyte/macrophage precursor cells that resorb the bone[6]. The receptor activator of nuclear factor-κB ligand (RANKL) plays a pivotal role in osteoclastogenesis process[7]. RAW 264.7 cells, a mouse monocytic cell line, have been widely used as they express receptor activator of nuclear factor-κB (RANK) and differentiate into functional osteoclasts upon stimulation with RANKL[8],[9]. RANKL is an important cytokine of the tumor necrosis factor (TNF) family[9]. The binding of RANKL to RANK begins the TNF receptor-associated factor 6 (TRAF6) recruitment[9],[10]. TRAF6 recruitment facilitates the activation of downstream pathways, including mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B (NF-κB), thereby inducing osteoclastogenesis- related factors, including tartrate-resistant acid phosphatase (TRAP), matrix metallopeptidase-9, calcitonin receptor (CTR), and cathepsin K, through the activation of nuclear factor of activated T cells cytoplasmic 1 (NFATC1)[11],[12].

Bisphosphonates have been used to reduce osteoporotic fracture risk by suppressing bone resorption[13]. However, they have been reported to cause several adverse effects, such as osteonecrosis of the jaw, suppression of bone turnover, and unusual fractures in the femur (thigh bone) and the shaft (diaphysis or sub-trochanteric region) of bone[14],[15]. Natural products have been demonstrated to have specific biological activities and low side effects[16]. Therefore, natural products serve as important sources for new drug discovery.

Marine seaweeds are an abundant source of bioactive compounds with biomedical, pharmaceutical, and nutraceutical potential[17],[18]. Eisenia bicyclis (E. bicyclis), a phlorotannin-rich brown alga, is a common kelp inhabiting the middle Pacific coast around Korea and Japan[19],[20]. In a previous study, Kim et al. demonstrated that E. bicyclis extracts inhibit osteoclast activity and promote osteoblast activity in vitro[21]. Moreover, it has been demonstrated that E. bicyclis hampers the depletion of bone in ovariectomized rats[22]. In a previous study, we obtained four phlorotannin compounds (6,6′-bieckol, 6,8′-bieckol, 8,8′-bieckol, and dieckol) from E. bicyclis and demonstrated their effects on adipogenesis and lipogenesis[23]. Dieckol, one of the most potent bioactive compounds, is abundant in brown algae including Ecklonia cava (E. cava), E. bicyclis, Ecklonia stolonifera, and Ecklonia kurome[24],[25],[26],[27]. Dieckol has been proven to have different biological activities, including anti-diabetic, antioxidant, and anti-inflammatory activities[25],[28],[29]. Previous studies have found that high concentrations of dieckol are non-toxic to several cell lines based on cell viability assays[25]. Therefore, this study aimed to evaluate the effect of dieckol isolated from E. bicyclis on RANKL-promoted osteoclast differentiation in RAW 264.7 cells.

 2. Materials and methods

2.1. Cell culture

Murine macrophage RAW 264.7 cells were purchased from the Korean Cell Line Bank (KCLB, Korea). Cells were cultured in Dulbecco’s Modified Eagle Media (Welgene, Korea) containing 10% fetal bovine serum (Welgene, Korea) and 1% antibiotics (Gibco/ BRL, CA) at 37 °C in a humidified incubator with 5% CO2.

2.2. Measurement of cell viability

The four compounds (6,6′-bieckol, 6,8′-bieckol, 8,8′-bieckol, and dieckol; [Supplementary Figure 1])[SUPPORTING:1] had been isolated in previous studies, and their separation methods have been described in detail[23]. The cells were seeded (2 × 104 cells/mL) and treated with 12.5, 25, and 50 μM of the four compounds for 5 d at 37 °C. The medium was changed to fresh media every 2 d. Cell viability was measured according to the method described by Lee et al. with some modifications[30]. Absorbance at 540 nm was measured using a spectrophotometer (Molecular Devices, USA).

2.3. Measurement of TRAP activity

The cells were seeded (2 × 104 cells/mL), pre-treated with 25 μM of the four compounds for 2 h, and incubated for an additional 5 days at 37 °C in medium containing RANKL derived from mouse (100 ng/mL; Sigma-Aldrich, USA). The medium was changed to fresh media every 2 d. TRAP activity was analyzed using a TRAP staining kit (Cosmo Bio Co., Ltd., Japan) according to the manufacturer’s protocols. TRAP-positive cells were observed and counted under a light microscope (Carl Zeiss, Germany).

2.4. Western blotting analysis

The cells were seeded (2 × 104 cells/mL), pre-treated with various concentrations of dieckol for 2 h, and added with 100 ng/mL RANKL for the indicated times at 37 °C. Protein expression was examined according to the method described by Ko et al. with some modifications[31]. Membranes were left to react overnight using the following primary antibodies: anti-TRAP (ab96372, 1:1 000; Abcam, USA), anti-CTR (ab11042, 1:1 000; Abcam, USA), anti- NFATc1 (556602, 1:1 000; BD Pharmingen™, USA), anti-c-Fos (2250S, 1:1 000; Cell Signaling Technology, USA), anti-c-Jun (9165S, 1:1 000; Cell Signaling Technology, USA), anti-phospho- ERK (9101S, 1:1 000; Cell Signaling Technology, USA), anti- ERK (9102S, 1:1 000; Cell Signaling Technology, USA), anti- phospho-JNK (9251S, 1:1 000; Cell Signaling Technology, USA), anti-JNK (9252S, 1:1 000; Cell Signaling Technology, USA), anti- phospho-lκB (2859S, 1:1 000; Cell Signaling Technology, USA), anti-phospho-p65 (3033S, 1:1 000; Cell Signaling Technology, USA), anti-phospho-p105 (4806S, 1:1 000; Cell Signaling Technology, USA), and anti-β-actin (SC-47778, 1:1 000; Santa Cruz Biotechnology, USA). The membranes were reacted for 2 h using the following secondary antibodies: anti-rabbit and anti- mouse IgG, HRP-linked antibody (7074S, 1:3 000; 7076S, 1:3 000; Cell Signaling Technology). Protein bands were visualized using a SuperSignal West Femto Trial kit (Thermo Fisher Scientific, USA). Protein band density was measured using ImageJ (NIH, USA).

2.5. Immunofluorescence staining

The cells were seeded (5 × 104 cells/mL), pre-treated with 25 μM dieckol for 2 h, and added with 100 ng/mL RANKL for various time points (NFATc1, c-Fos, and c-Jun: 9 h; p65: 5 min) based on the individual experiment. Immunofluorescence staining was conducted according to the method of Ko et al. with some modifications[31]. The cells were incubated overnight at 4 °C with the following primary antibodies: anti-NFATc1 (556602, 1:100; BD Pharmingen™, USA), anti-c-Fos (2250S, 1:100; Cell Signaling Technology, USA), anti-c-Jun (9165S, 1:100; Cell Signaling Technology, USA), and anti-p65 (8242S, 1:100; Cell Signaling Technology, USA). After another washing three times with PBS, cells were incubated with the following secondary antibodies: Alexa fluor488-labeled goat anti-rabbit IgG (H+L) cross-adsorbed secondary antibody (A11008, 1:800; Thermo Fisher Scientific, USA) and Alexa fluor488-labeled goat anti-mouse IgG (H+L) cross-adsorbed secondary antibody (A11001, 1:800; Thermo Fisher Scientific, USA). Nuclei were stained using 40 μg/mL Hoechst 33342 (Sigma Aldrich, USA) for 10 min at room temperature and mounted with ProLong™ Gold antifade mountant (Thermo Fisher Scientific, USA). Fluorescence was visualized using an LSM 700 Zeiss confocal laser scanning microscope (400× magnification; Carl Zeiss, Germany).

2.6. Statistical analysis

Data were expressed as mean ± standard deviation (SD) and analyzed by one-way ANOVA with Tukey’s post hoc test. P<0.05 was considered a statistical significance. All statistical tests were performed using GraphPad PRISM software version 8.0 (GraphPad Software, USA).

 3. Results

3.1. Effect of dieckol on the viability of RAW 264.7 cells and RANKL-promoted TRAP activity

As shown in [Figure 1], 6,6′-bieckol, 6,8′-bieckol, 8,8′-bieckol, and dieckol were non-toxic to RAW 264.7 cells at the concentrations up to 25 μM. Next, to demonstrate the effect of these compounds on RANKL-promoted osteoclast differentiation, TRAP, an osteoclast- related factor, was determined. As shown in [Figure 2], RANKL significantly promoted osteoclast differentiation, as evidenced by TRAP-positive cells compared with the control group (P<0.001). However, dieckol markedly reduced TRAP-positive cells (P<0.001). In contrast, other compounds did not affect RANK-induced osteoclast differentiation and TRAP activity. Therefore, dieckol at different concentrations (6.25, 12.5, and 25 μM) was used for further experiment. The results showed that dieckol at 12.5 and 25 μM markedly inhibited RANKL-induced TRAP activity (P<0.05) [Figure 3]A, [Figure 3]B.{Figure 1}{Figure 2}{Figure 3}

3.2. Effect of dieckol on RANKL-stimulated expression of osteoclastogenesis-related factors in RAW 264.7 cells

RANKL markedly induced CTR and TRAP expression compared with the control group (P<0.001) [Figure 3]C. However, dieckol at all tested concentrations markedly suppressed CTR and TRAP expression levels (P<0.001). Moreover, RANKL promoted the expression of the transcriptional factors including c-Fos, c-Jun, and NFATc1 [Figure 4]. In contrast, treatment with dieckol significantly suppressed the induction of these factors (P<0.001).{Figure 4}

3.3. Effect of dieckol on RANK-activated NF-κB, ERK, and JNK signaling pathways in RAW 264.7 cells

We further evaluated the effect of dieckol on the activation of NF-κB, ERK, and JNK signaling pathways. Dieckol markedly suppressed RANKL-induced IκB, p65, and p105 activation and p65 nuclear translocation (P<0.001) [Figure 5]A, [Figure 5]B. Moreover, RANKL activated both ERK and JNK signaling pathways, which were prominently blocked by dieckol (P<0.001) [Figure 6].{Figure 5}{Figure 6}

 4. Discussion

Polyphenolic compounds, such as bromophenol, phenolic terpenoids, and phlorotannins, are abundant in seaweeds and exhibit several biological activities[26],[29]. Previous studies have reported the osteoclastogenesis-inhibitory activities of polyphenolic compounds. Ha et al. demonstrated that fucoxanthin isolated from E. cava inhibits osteoclastogenesis by blocking MAPK and Nrf2 signaling pathways in RAW 264.7 cells[32]. Further, Bang et al. proved that fucosterol isolated from Undaria pinnatifida suppresses RANKL-activated osteoclast differentiation in bone marrow- derived macrophages (BMMs)[33]. Phlorotannins are polyphenolic compounds found in brown seaweeds[34]. Their inhibitory effects on osteoporosis have been reported in literature. Ihn et al. demonstrated that diphlorethohydroxycarmalol from Ishige okamurae inhibits osteoclastogenesis by hindering NF-κB activation in vitro[35]. In a previous study, Oh et al. revealed that phlorofucofuroeckol A from E. cava enhances osteoblastogenesis in vitro[36]. Moreover, an extract from the brown alga E. cava containing dieckol inhibits RANKL-promoted osteoclast differentiation by downregulating MAPK and NF-κB activation and activating heme oxygenase-1 in vitro[37]. Therefore, this study demonstrated the effect of dieckol on RANKL-stimulated osteoclast differentiation using RAW 264.7 cells.

Many studies have been conducted on the inhibition of osteoclastogenesis using RANKL-treated RAW 264.7 cells[38],[39]. Osteoclastogenesis-related factors were generated via RANKL treatment in RAW 264.7 cells. In the present study, the effect of phlorotannin compounds (6,6′-bieckol, 6,8′-bieckol, 8,8′-bieckol, and dieckol) was evaluated at a non-cytotoxic concentration. The results showed that among four compounds, only dieckol significantly inhibited RANKL-promoted TRAP activity. Furthermore, dieckol reduced the expression of TRAP and CTR protein at 6.25-25 μM.

Osteoclasts require RANKL for their proliferation, survival, differentiation, and activation[40]. The binding of RANKL to RANK causes the recruitment of TRAF6, thereby activating downstream signaling cascades including MAPK and NF-κB[38],[40]. Among the MAPK family members, ERK and JNK promote the activation of c-Fos and c-Jun, respectively [41],[42]. c-Jun produces the activator protein-1 complex with c-Fos, an important transcription factor for osteoclastogenesis[42]. Moreover, TRAF6 mediates inhibitor of κB (IκB) kinase (IKK) activation and subsequently IκB phosphorylation[43]. Phosphorylated IκB is degraded via the ubiquitin/proteasome pathway, and NF-κB is translocated from the cytoplasm to the nucleus[44]. NFATc1, induced by activator protein-1 and NF-κB, plays an essential role in osteoclastogenesis-related gene expressions, such as TRAP and CTR; hence, it controls osteoclast differentiation[13],[14]. Our study showed that dieckol suppressed RANKL-induced TRAP and CTR generation in cells. Additionally, dieckol significantly inhibited RANKL-generated expression of the nuclear transcriptional factors c-Fos, c-Jun, and NFATc1. Dieckol also significantly inhibited the phosphorylation of ERK, and JNK and NF-κB signaling.

Other phlorotannins, such as diphlorethohydroxycarmalol (25, 50, and 75 μg/mL), also inhibit the TRAP-positive cells and osteoclast differentiation in bone marrow-derived macrophages[35]. In addition, they significantly inhibit osteoclastogenesis-related genes including TRAP (Acp5) and NFAFc1 (Nfatc1)[35]. The effective inhibitory activity of phlorotannins is controlled by NF-κB and MAPK signaling pathways. The effect of dieckol observed in this study was similar to that in a previous study, indicating that dieckol may inhibit osteoclastogenesis in bone marrow-derived macrophages. However, further studies are required to prove this effect.

The main limitations of this study are that we are not yet able to perform additional experiments using human osteoclast precursor cells and an ovariectomized mouse model. These experiments are essential to demonstrate the effect of osteoporosis. Therefore, further studies are also needed to prove the effect of dieckol on human osteoclast precursor cells and in an ovariectomized mouse model.

In conclusion, our study proved that dieckol suppresses RANKL- induced osteoclastogenesis-related factors including TRAP and CTR, by inhibiting c-Fos, c-Jun, and NFATc1 and by downregulating the ERK, JNK, and NF-κB signaling pathways. Therefore, dieckol may be useful for inhibition of osteoclastogenesis.

Conflict of interest statement

The authors declare that there is no conflict of interest.


This work was supported by a National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT; No. NRF-2020R1A2C1008527).

Authors’ contributions

JA and KNK supervised and designed the study. SHC, THK, HJ, JSK, SRK, MSJ, SP, MC, and JHW performed experimental analysis. THK provided the resources. SHC, THK, JA, and KNK wrote the manuscript.


1Lee KY, Kim JH, Kim EY, Yeom M, Jung JS, Sohn Y. Water extract of Cnidii Rhizoma suppresses RANKL-induced osteoclastogenisis in RAW 264.7 cell by inhibiting NFATc1/c-Fos signaling and prevents ovariectomized bone loss in SD-rat. BMC Complement Altern Med 2019; 19(1): 207.
2Yang K, Kim JH, Kim M, Ryu GH, Moon JH, Lee HI, et al. Gentianae macrophylla Radix water extract inhibits RANKL-induced osteoclastogenesis and osteoclast specific genes. Korean J Acupunct 2020; 37(2): 63-75.
3Katsimbri P. The biology of normal bone remodeling. Eur J Cancer Care 2017; 26(6): e12740.
4Arjmand B, Sarvari M, Alavi-Moghadam S, Payab M, Goodarzi P, Gilany K, et al. Prospect of stem cell therapy and regenerative medicine in osteoporosis. Front Endocrinol (Lausanne) 2020; 11: 430.
5de Villiers TJ. Bone health and osteoporosis in postmenopausal women. Best Pract Res Clin Obstet Gynaecol 2009; 23(1): 73-85.
6Levaot N, Ottolenghi A, Mann M, Guterman-Ram C, Kam Z, Geiger B. Osteoclast fusion is initiated by a small subset of RNAKL-stimulated monocyte progenitors, which can fuse to RANKL-unstimulated progenitors. Bone 2015; 79: 21-28.
7Nagy V, Penninger KJM. The RANKL-RANK story. Gerontology 2015; 61(6): 534-542.
8Chen H, Fang C, Zhi X, Song S, Gu Y, Chen X, et al. Neobavaisoflavone inhibits osteoclastogenesis through blocking RANKL signaling-mediated TRAP6 and c-Src recruitment and NF-κB, MAPK and Akt pathways. J Cell Mol Med 2020; 24(16): 9067-9084.
9Xu H, Chen F, Liu T, Xu J, Li J, Jiang L, et al. Ellagic acid blocks RANKL-RANK interaction and suppresses RANKL-induced osteoclastogenesis by inhibiting RANK signaling pathways. Chem Biol Interact 2020; 331: 109235.
10Chen X, Zhi X, Yin Z, Li X, Qin L, Qiu Z, et al. 18β-Glycyrrhetinic acid inhibits osteoclastogenesis in vivo and in vitro by blocking RANKL-Mediated RANK-TRAF6 interactions and NF-κB and MAPK signaling pathways. Front Pharmacol 2018; 9: 647.
11Thummuri D, Jeengar MK, Shrivastava S, Nemani J, Ramavat RN, Chaudhari R, et al. Thymoquinone prevents RANKL-induced osteoclastogenesis activation and osteolysis in an in vivo model of inflammation by suppressing NF-κB and MAPK signaling pathway. Pharmacol Res 2015; 99: 63-73.
12Zhi X, Chen Q, Song S, Gu Z, Wei W, Chen H, et al. Myostatin promotes osteoclastogenesis by regulating ccdc50 gene expression and RANKL- induced NF-κB and MAPK pathways. Front Pharmacol 2020; 11: 565163.
13Imam B, Aziz K, Khan M, Zubair T, Iqbal A. Role of bisphosphonate in postmenopausal women with osteoporosis prevent future fractures: A literature review. Cureus 2019; 11(8): e5328.
14Kennel KA, Drack MT. Adverse effects of bisphosphonates: Implications for osteoporosis management. Mayo Clin Proc 2009; 84(7): 632-638.
15Shan E. Evolving data about subtrochanteric fractures and bisphosphonates. N Engl J Med 2010; 362(19): 1825-1827.
16Mushtag S, Abbasi BH, Uzair B, Abbasi R. Natural products as reservoirs of novel therapeutic agents. EXCLI J 2018; 17: 420-451.
17Kiuru P, D’Auria MV, Muller CD, Tammela P, Vuorela H, Yli- Kauhaluoma J. Exploring marine resources for bioactive compounds. Planta Med 2014; 80(14): 1234-1246.
18Holdt SL, Kraan S. Bioactive compounds in seaweed: Functional food applications and legislation. J Appl Phycol 2011; 23: 543-597.
19Bangoura I, Chowdhury MTH, Cetachew P, Cho JY, Hong YK. Feeding the abalone Haliotis discus hannai with the seaweed Eisenia bicyclis allows the accumulation of phlorotannins. Fish Aquat Sci 2015; 18(2): 165-171.
20Eom SJ, Lee MS, Lee EW, Kim YM, Kim TH. Pancreatic lipase inhibitory activity of phlorotannins isolated from Eisenia bicyclis. Phytothr Res 2013; 27(1): 148-151.
21Kim SY, Jeon MJ, Cheon J, Lee SH, Kong C, Kim YY, et al. Effects of Eisenia bicyclis extracts on the proliferation and activity of osteoblasts and osteoclast. J Life Sci 2014; 24(3): 297-303.
22Park YS, Kang MS, Kim BK, Kim M. The effect of Eisenia bicyclis extract on bone tissue in ovariectomized rats. Korean J Food Nutr 2013; 42(1): 33-39.
23Kwon TH, Wu YX, Kim JS, Woo JH, Park KT, Kwon OJ, et al. 6,6’-Bieckol inhibits adipocyte differentiation through downregulation of adipogenesis and lipogenesis in 3T3-L1 cells. J Sci Food Agric 2015; 95(9): 1830-1837.
24Sanjeewa KKA, Fernando IPS, Kim HS, Jayawardena TU, Ryu B, Yang HW, et al. Dieckol: An algal polyphenol attenuates urban fine dust- induced inflammation in RAW 264.7 cells via the activation of anti-inflammatory and antioxidant signaling pathways. J Appl Phycol 2020; 32: 2387-2396.
25Rajan DK, Mohan K, Zhang S, Ganesan AR. Dieckol: A brown algal phlorotannin with biological potential. Biomed Pharmacother 2021; 142: 111988.
26Cotas J, Leandro A, Monteiro P, Pacheco D, Figueirinha A, Goncalves AMM, et al. Seaweed phenolics: From extraction to appilcations. Mar Drugs 2020; 18(8): 384.
27Gómez-Guzmán M, Rodriguez-Nogales A, Algieri F, Gálvezm J. Potential role of seaweed polyphenols in cardiovascular-associated disorders. Mar Drugs 2018; 16(8): 250.
28Lee SH, Park MH, Kang SM, Ko SC, Kang MC, Cho S, et al. Dieckol isolated from Ecklonia cava protects against high glucose induced damage to rat insulinoma cells by reducing oxidative stress and apoptosis. Biosci Biotechnol Biochem 2012; 76(8): 1445-1451.
29Lee MS, Lee B, Park KE, Utsuki T, Shin T, Oh CW, et al. Dieckol enhances the expression of antioxidant and detoxifying enzymes by the activation of Nrf2-MAPK signaling pathway in HepG2 cells. Food Chem 2015; 174: 538-546.
30Lee SH, Kim JK, Jang HD. Genistein inhibitors osteoclastic differentiation of RAW 264.7 cells via ROS production and scavenging. Int J Mol Sci 2020; 15(6): 10605-10621.
31Ko EY, Cho SH, Kang K, Kim G, Lee JH, Jeon YJ, et al. Anti-inflammatory activity of hydrosols from Tetragonia tetragonoides in LPS- induced RAW 264.7 cells. EXCLI J 2017; 16: 521-530.
32Ha YJ, Choi YS, Oh YR, Kang EH, Khang G, Park YB, et al. Fucoxanthin suppresses osteoclasogenesis via modulation of MAP kinase and Nrf2 signaling pathway. Mar Drugs 2021; 19(3): 132.
33Bang MH, Kim HH, Lee DY, Han MW, Baek YS, Chung DK, et al. Anti-osteoporotic activities of fucosterol from sea mustard (Undaria pinnatifida). Food Sci Biotechnol 2011; 20(2): 343-347.
34Erpel R, Mateos R, Pérez-Jiménez J, Ricardo Pérez-Correa J. Phlorotannins: From isolation and structural characterization, to the evaluation of the evaluation of their antidiabetic and anticancer potential. Food Res Int 2020; 137: 109589.
35Ihn HJ, Kim JA, Cho HS, Shin HI, Kim GY, Choi YH, et al. Diphlorethohydroxycarmalol from Ishige okamurae suppresses osteoclast differentiation by downregulating the NF-κB signaling pathway. Int J Mol Sci 2017; 18(12): 2635.
36Oh JH, Ahn BN, Karadeniz R, Kim JA, Lee JI, Seo Y, et al. Phlorofucofuroeckol A from edible brown algae Ecklonia cava enhances osteoblastogenesis in bone marrow-derived human mesenchymal stem cells. Mar Drugs 2019; 17(10): 543.
37Kim S, Kang SS, Choi SI, Kim GH, Imm JY. Ecklonia cava extract containing dieckol suppresses RANKL-induced osteoclastogenesis via MAP kinase/NF-κB pathway inhibition and heme oxygenase-1 induction. J Microbiol Biotechnol 2019; 29(1): 11-20.
38He X, Andersson G, Lindgren U, Li Y. Resveratrol prevents RANKL- induced osteoclast differentiation of murine osteoclast progenitor RAW 264.7 cells through inhibition ROS production. Biochem Biophys Res Commun 2010; 401(3): 356-362.
39Kim B, Lee KY, Park B. Icariin abrogates osteoclast formation through the regulation of the RANKL-mediated TRAF6/NF-κB/ERK signaling pathway in RAW 264.7 cells. Phytomedicine 2018; 51: 181-190.
40Park JH, Lee NK, Lee SY. Current understanding of RANK signaling in osteoclast differentiation and maturation. Mol Cells 2017; 40(10): 706-713.
41Lee K, Seo I, Choi MH, Jeong D. Roles of mitogen-activated protein kinase in osteoclast biology. Int J Mol Sci 2018; 19(10): 3004.
42Ikeda F, Nishimura R, Matsubara T, Tanaka S, Inoue JI, Reddy SV, et al. Critical roles of c-Jun signaling in regulation of NFAT family and RANKL-regulated osteoclast differentiation. J Clin Invest 2004; 114(4): 475-484.
43Deng L, Wang C, Spencer E, Yang L, Braun A, You J, et al. Activation of the IκB kinase complex by TRAF6 requires a dimeric ubiquitin- conjugating enzyme complex and a unique polyubiquitin chain. Cell 2000; 103(2): 351-361.
44Chiou WF, Huang YL, Liu YW. (+)-Vitisin A inhibits osteoclast differentiation by preventing TRAF6 ubiquitination and TRAF6-TAK1 formation to suppress NFATc1 activation. PLoS One 2014; 9(2): e89159.