Inhibitory effect of sulphated polysaccharide porphyran (isolated from Porphyra yezoensis) on RANKL-induced differentiation of RAW264.7 cells into osteoclasts

Extraction, structural features, and pharmacological effects of the polysaccharides from Porphyra yezoensis: A review

Porphyra yezoensis, an important medicinal seaweed extensively cultivated and consumed in China, Japan, and South Korea, is traditionally considered a precious healthy food and food additive. Published studies showed that the polysaccharides are major bioactive macromolecules from P. yezoensis with great potential for the development of nutraceuticals and functional foods. As an important component of P. yezoensis, P. yezoensis polysaccharide (PYP) is mainly extracted by hot water extraction, ultrasonic-assisted extraction, and microwave-assisted extraction methods. Subsequently obtained by decolorization, deproteinization, removal of other small molecules, and separation on various chromatographic columns. The main structural components of PYP were (1 → 3)-linked β-D-galactose and (1 → 4)-linked 3,6-anhydro-α-L-galactose. Accumulating evidence has revealed that PYP has diverse biological activities, such as antioxidant, suppressing kidney stones, immunomodulatory, etc. This review systematically summarizes the recent preparation progress, chemical structures, bioactivities, and the underlying mechanisms of PYP. Information from this review provides insights into the further development of PYP as therapeutic agents and functional foods. Although there have been extensive studies on PYP, there are gaps in establishing quality standard, toxicological research, clinical application and other aspects. To enhance the utility of P. yezoensis, it is necessary to strengthen the research on these aspects.

Sulfated Galactans from Agarophytes: Review of Extraction Methods, Structural Features, and Biological Activities

Agarophytes are important seaweeds of the Rhodophyta type, which have been highly exploited for industrial use as sources of a widely consumed polysaccharide of agar. In addition to that, sulfated galactans (SGs) from agarophytes, which consist of various functional sulfate groups, have attracted the attention of scientists in current studies. SGs possess various biological activities, such as anti-tumor, anticoagulant, anti-inflammatory, antioxidant, anti-obesity, anti-diabetic, anti-microbial, anti-diarrhea, and gut microbiota regulation properties. Meanwhile, the taxonomy, ecological factors, i.e., environmental factors, and harvest period, as well as preparation methods, i.e., the pretreatment, extraction, and purification conditions, have been found to influence the chemical compositions and fine structures of SGs, which have, further, been shown to have an impact on their biological activities. However, the gaps in the knowledge of the properties of SGs due to the above complex factors have hindered their industrial application. The aim of this paper is to collect and systematically review the scientific evidence about SGs and, thus, to pave the way for broader and otherwise valuable industrial applications of agarophytes for human enterprise. In the future, this harvested biomass could be sustainably used not only as a source of agar production but also as natural materials in functional food and pharmaceutical industries.

Glycobiology in osteoclast differentiation and function

Glycans, either alone or in complex with glycan-binding proteins, are essential structures that can regulate cell biology by mediating protein stability or receptor dimerization under physiological and pathological conditions. Certain glycans are ligands for lectins, which are carbohydrate-specific receptors. Bone is a complex tissue that provides mechanical support for muscles and joints, and the regulation of bone mass in mammals is governed by complex interplay between bone-forming cells, called osteoblasts, and bone-resorbing cells, called osteoclasts. Bone erosion occurs when bone resorption notably exceeds bone formation. Osteoclasts may be activated during cancer, leading to a range of symptoms, including bone pain, fracture, and spinal cord compression. Our understanding of the role of protein glycosylation in cells and tissues involved in osteoclastogenesis suggests that glycosylation-based treatments can be used in the management of diseases. The aims of this review are to clarify the process of bone resorption and investigate the signaling pathways mediated by glycosylation and their roles in osteoclast biology. Moreover, we aim to outline how the lessons learned about these approaches are paving the way for future glycobiology-focused therapeutics.

Sulfated Glucuronorhamnoxylan from Capsosiphon fulvescens Ameliorates Osteoporotic Bone Resorption via Inhibition of Osteoclastic Cell Differentiation and Function In Vitro and In Vivo

Excessive osteoclast differentiation and/or bone resorptive function causes a gradual loss of bone, leading to the pathogenesis of bone diseases such as osteoporosis (OP). In this study, a sulfated glucuronorhamnoxylan polysaccharide (designated SPS-CF) of the green alga Capsosiphon fulvescens was evaluated for anti-osteoporotic activity using osteoclastic cells differentiated from RAW264.7 macrophages by receptor activator of NF-κB ligand (RANKL) treatment and ovariectomized (OVX) female mice as a postmenopausal OP model. With negligible cytotoxicity, SPS-CF (50 μg/mL) significantly suppressed tartrate-resistant acid phosphatase (TRAP) activity, actin ring formation, and expression of matrix metalloproteinase 9 (MMP-9), cathepsin K, TRAF6, p-Pyk2, c-Cbl, c-Src, gelsolin, carbonic anhydrase II (CA II), and integrin β3, indicating that SPS-CF inhibits the differentiation and bone resorptive function of osteoclasts. Removal of sulfate groups from SPS-CF abolished its anti-osteoclastogenic activities, demonstrating that sulfate groups are critical for its activity. Oral administration of SPS-CF (400 mg/kg/day) to OVX mice significantly augmented the bone mineral density (BMD) and serum osteoprotegerin (OPG)/RANKL ratio. These results demonstrated that SPS-CF exerts significant anti-osteoporotic activity by dampening osteoclastogenesis and bone resorption via downregulation of TRAF6-c-Src-Pyk2-c-Cbl-gelsolin signaling and augmentation of serum OPG/RANKL ratios in OVX mice, suggesting that SPS-CF can be a novel anti-osteoporotic compound for treating postmenopausal OP.

Immunomodulatory effects of polysaccharides from marine algae for treating cancer, infectious disease, and inflammation

A significant rise in the occurrence and severity of adverse reactions to several synthetic drugs has fueled considerable interest in natural product-based therapeutics. In humans and animals, polysaccharides from marine microalgae and seaweeds have immunomodulatory effects. In addition, these polysaccharides may possess antiviral, anticancer, hypoglycemic, anticoagulant, and antioxidant properties. During inflammatory diseases, such as autoimmune diseases and sepsis, immunosuppressive molecules can serve as therapeutic agents. Similarly, molecules that participate in immune activation can induce immune responses against cancer and infectious diseases. We aim to discuss the chemical composition of the algal polysaccharides, namely alginate, fucoidan, ascophyllan, and porphyran. We also summarize their applications in the treatment of cancer, infectious disease, and inflammation. Recent applications of nanoparticles that are based on algal polysaccharides for the treatment of cancer and inflammatory diseases have also been addressed. In conclusion, these applications of marine algal polysaccharides could provide novel therapeutic alternatives for several diseases.

Isolation, Identification, and Anti-Inflammatory Activity of Polysaccharides of Typha angustifolia

The present study aimed to purify, structurally characterize, and evaluate the anti-inflammatory activity of the polysaccharide extracted from Typha angustifolia. Two purified polysaccharides (PTA-1 and PTA-2) were obtained via DEAE-52 cellulose chromatography. Their structural characterizations and antioxidant activity were in vitro analyzed. To evaluate the anti-inflammatory activity of PTA-2, the levels of inflammatory cytokines, intracellular ROS production, and the inhibitory effects of the transcriptional activation of the nuclear factor kappa B (NF-κB) signaling pathway were determined. PTA-1 comprises glucose (100%) with α-(1 → 3) glycosidic bonds, and PTA-2 comprises glucose (66.7%) and rhamnose (33.3%) formed by β-(1 → 3) glycosidic bonds. PTA-1 and PTA-2 showed strong antioxidant activity in vitro. Moreover, PTA-2 intervention (50, 100, and 200 μg/mL) suppressed the production of inflammatory cytokines, the activation of NF-κB signaling, and reactive oxygen species production significantly. The results identified PTA-2 as a natural product that could be applied in anti-inflammatory drugs.

Antidepressant-like Effects of Degraded Porphyran Isolated from Porphyra haitanensis

INTRODUCTION

Degraded porphyran is a bioactive polysaccharide extracted from Porphyra haitanensis (P. haitanensis). According to the previous studies, it produced anti-inflammatory activity, but little is known about its effects on depression.

METHODS AND RESULTS

As inflammation is one of the critical factors involved in the development of depression, this study aims to elucidate the potential antidepressant-like effects of degraded porphyran. The results show that acute porphyran treatment decreased the immobility time in despair tests. In addition, subchronic porphyran administration reverses depressive-like behaviors in lipopolysaccharide (LPS)-treated mice. Meanwhile, porphyran inhibits NF-κB/NLRP3 signaling, proinflammatory cytokine release, and microglial activation in the hippocampus. Moreover, chronic porphyran treatment activates hippocampal brain derived neurotrophic factor (BDNF)/TrkB/ERK/CREB signaling pathway in chronic unpredictable mild stress (CUMS) in mice. As a result, neurogenesis and spinogenesis are maintained.

CONCLUSIONS

The findings of the present study indicate that degraded porphyran intake provides a potential strategy for depression treatment, which is mediated by the inhibition of neuroinflammation and the enhancement of neurogenesis and spinogenesis in the central nervous systems.

Porphyran and oligo-porphyran originating from red algae Porphyra: Preparation, biological activities, and potential applications

Porphyra is one of the most economically important red algae in the world. The functional components extracted from Porphyra such as porphyrans, proteins, lipids, and minerals have strong physiological activities. Porphyran, a sulfated galactan, is composed of alternating 1,4-linked α-l-galactopyranose-6-sulfate (L6S) and 1,3-linked β-d-galactopyranose (G). Porphyran and oligo-porphyran have a series of pharmacological and biological functions, such as antioxidation, anticancer, antiaging, antiallergic, immunomodulatory, hypoglycaemic, and hypolipidemic effects. Thus, red algae Porphyra-derived porphyran and oligo-porphyran have various potential applications in food, medicine, and cosmetic fields. For better application, this review introduces and summarizes the structure and source of porphyran as well as the preparation methods, biological activities, and potential applications of porphyran and oligo-porphyran. Moreover, the future research directions and emphasis of porphyran and oligo-porphyran preparation as well as their functional activities and applications are highlighted and prospected.

ASP2-1, a polysaccharide from Acorus tatarinowii Schott, inhibits osteoclastogenesis via modulation of NFATc1 and attenuates LPS-induced bone loss in mice

Spectroscopic analysis of HPLC-purified 7.3-kD Acorus tatarinowii Schott root polysaccharide ASP2-1 (FT-IR, NMR) revealed respective monosaccharide proportions of glucose: galactose: arabinose: xylose: galacturonic acid: mannose: rhamnose: glucuronic acid:fucose of 49.1:16.0:11.6:10.2:5.3:2.9:2.2:1.7:0.8. In vitro, ASP2-1 inhibited osteoclastogenesis-associated bone resorption, RANKL-induced osteoclastogenesis and F-actin ring formation and suppressed osteoclastogenesis-associated gene expression (e.g., TRAP, OSCAR, Atp6v0d2, αV, β3, MMP9 and CtsK) as shown via RT-PCR. ASP2-1-treated RANKL-stimulated bone marrow-derived macrophages exhibited decreased levels of NFATc1 and c-Fos mRNAs and corresponding transcription factor proteins, elevated expression of negative NFATc1 regulators (Mafb, IRF8, Bcl6) and reduced their upstream negative regulator (Blimp1) expression. ASP2-1 inhibition of NFATc1 expression involved PLCγ2-Ca²⁺ oscillation-calcineurin axis suppression, reflecting suppression of RANKL-induced PLCγ2 activation (and associated Ca²⁺ oscillation) and calcineurin catalytic subunit PP2BAα expression without inhibiting NF-κB and MAPKs activation or phosphorylation. Staining (H&E, TRAP) and micro-CT assays revealed ASP2-1 attenuated bone destruction and osteoclast over-activation and improved tibia micro-architecture in a murine LPS-induced bone loss model. Thus, ASP2-1 may alleviate inflammatory bone loss-associated diseases.

Inhibitory effects of Porphyra dentata extract on 3T3-L1 adipocyte differentiation

This study was aimed to investigate the inhibitory effects of Porphyra dentata (P. dentata) extract on the adipogenesis of 3T3-L1 cells and evaluate its anti-obesity effect. The proliferation of 3T3-L1 cells and differentiation of adipocytes under treatment of P. dentata extract was examined by measuring the cell viability using alamarBlue assay and lipid droplets by Oil Red O staining. Results showed that P. dentata extract has no cytotoxicity effect and lipid droplets formation decreased in a concentration-dependent manner in 3T3-L1 cells. It has been confirmed that transcription factors affecting lipid accumulation and anti-adipogenic effects during cell differentiation are linked to P. dentata extract. We observed that P. dentata shows lowering the mRNA expression of peroxisome proliferator-activated receptor γ2 (PPARγ2), CCAAT/enhancer binding protein α (C/EBPα) that adipogenesis-associated key transcription factors and inhibiting adipogenesis in the early stages of differentiation. Treating the cells with P. dentata did not only suppressed PPARγ2 and C/EBPα but also significantly decreased the mRNA expression of adiponectin, Leptin, fatty acid synthase, adipocyte protein 2, and Acetyl-coA carboxylase 1. Overall, the P. dentata extract demonstrated inhibitory property in adipogenesis, which has a potential effect in anti-obesity in 3T3-L1 cells.

The Evolution Road of Seaweed Aquaculture: Cultivation Technologies and the Industry 4.0

Seaweeds (marine macroalgae) are autotrophic organisms capable of producing many compounds of interest. For a long time, seaweeds have been seen as a great nutritional resource, primarily in Asian countries to later gain importance in Europe and South America, as well as in North America and Australia. It has been reported that edible seaweeds are rich in proteins, lipids and dietary fibers. Moreover, they have plenty of bioactive molecules that can be applied in nutraceutical, pharmaceutical and cosmetic areas. There are historical registers of harvest and cultivation of seaweeds but with the increment of the studies of seaweeds and their valuable compounds, their aquaculture has increased. The methodology of cultivation varies from onshore to offshore. Seaweeds can also be part of integrated multi-trophic aquaculture (IMTA), which has great opportunities but is also very challenging to the farmers. This multidisciplinary field applied to the seaweed aquaculture is very promising to improve the methods and techniques; this area is developed under the denominated industry 4.0.

Structure and Bioactivities of Porphyrans and Oligoporphyrans

BACKGROUND

Pyropia (Porphyra), commonly known as nori or laver, is an important food source in many parts of the world. Edible dried Pyropia contains numerous nutrients and biofunctional components, including proteins, vitamins, eicosapentaenoic acid, minerals, carotenoids, mycosporine-like amino acids, and carbohydrate, and one of the compounds which we are interested in is porphyran, a sulfated polysaccharide comprising the hot-water-soluble portion of Pyropia cell walls. Researchers have performed a large number of in-depth studies on the biological activity and potential therapeutic applications of porphyrans and oligoporphyrans.

METHODS

This mini review aims to provide comprehensive and update overview on the source, extraction, structure, biological activities and structure-activity relationships of porphyrans and oligoporphyrans based on the studies in the past 30 years which were included in Web of Science.

RESULTS

The structure of porphyran has been basically determined given that its straight chain is relatively simple, and the skeleton structure has been described. The extraction methods were simplified continuously, but different extraction methods and post- processing methods still had great influence on the structure and composition of porphyran, so there was no standardized extraction process which can achieve quality control until now. In order to obtain oligoporphyrans, there are a variety of degradation methods, including chemical method, physical method and enzymatic method, but it is worth mentioning that specific degradation enzyme is still unavailable. Studies on the biological and pharmacology properties include antioxidant, anti-tumor, anti-inflammatory, immunomodulation, anti-cardiovascular and cerebrovascular diseases and drug delivery.

CONCLUSION

Owing to the therapeutic potential and drug delivery applications, porphyran and oligoporphyrans are expected to be further developed as a medicine against human diseases, as well as a supplement in cosmetics and health products.

Health Functionality and Quality Control of Laver (Porphyra, Pyropia): Current Issues and Future Perspectives as an Edible Seaweed

The growing interest in laver as a food product and as a source of substances beneficial to health has led to global consumer demand for laver produced in a limited area of northeastern Asia. Here we review research into the benefits of laver consumption and discuss future perspectives on the improvement of laver product quality. Variation in nutritional/functional values among product types (raw and processed (dried, roasted, or seasoned) laver) makes product-specific nutritional analysis a prerequisite for accurate prediction of health benefits. The effects of drying, roasting, and seasoning on the contents of both beneficial and harmful substances highlight the importance of managing laver processing conditions. Most research into health benefits has focused on substances present at high concentrations in laver (porphyran, Vitamin B12, taurine), with assessment of the expected effects of laver consumption. Mitigation of chemical/microbiological risks and the adoption of novel technologies to exploit under-reported biochemical characteristics of lavers are suggested as key strategies for the further improvement of laver product quality. Comprehensive analysis of the literature regarding laver as a food product and as a source of biomedical compounds highlights the possibilities and challenges for application of laver products.

PYP1-4 peptide from Pyropia yezoensis protects against acetaminophen-induced hepatotoxicity in HepG2 cells

Acetaminophen (APAP) is a widely used analgesic and antipyretic. It is safe at normal treatment doses; however, APAP overdose is a major cause of acute liver and kidney failure. A variety of methods to reduce the damage caused by APAP overdose have previously been evaluated. The protein-rich seaweed Pyropia yezoensis has antioxidant, antitumor and anti-inflammatory activities, and protects against cytotoxicity. However, little is known regarding the protective effects of P. yezoensis peptide against APAP-induced hepatotoxicity. The present study investigated the ability of P. yezoensis peptide (PYP1-4) to ameliorate the damage caused by APAP-induced hepatotoxicity using HepG2 as the model cell line in addition to the signaling pathways involved. Briefly, cell viability, nitric oxide, reactive oxygen species and apoptosis assays were performed in conjunction with western blot analysis and reverse transcription-quantitative PCR. First, the present study revealed the minimum toxic concentration of APAP (15 mM) and the resting concentration of PYP1-4 (0–500 ng/ml). Administration of PYP1-4 to APAP-induced cells decreased the nitric oxide and reactive oxygen species levels, and restored the levels of antioxidant-associated proteins (catalase, heme oxygenase 1, superoxide dismutase 2 and quinone oxidoreductase 1). PYP1-4 increased the translocation of nuclear factor, erythroid 2 like 2 to the nucleus and the activities of glycogen synthase kinase-3β, Akt and AMP-activated protein kinase. In addition, APAP induced apoptosis; however, PYP1-4 inhibited apoptosis by modulating the levels of pro-apoptotic markers (Bad), anti-apoptotic markers (Bcl-2 and BH3 interacting domain death agonist), caspases and poly (ADP-ribose) polymerase 1. Subsequently, the insulin-like growth factor 1 receptor signaling pathway was investigated to determine whether PYP1-4 treatment restored the levels of cell growth-associated factors during APAP-induced hepatotoxicity. PYP1-4 treatment impacted the levels of components of the insulin receptor substrate 1/PI3K/Akt and Ras/Raf/ERK signaling pathways, and promoted cell survival. Therefore, the P. yezoensis peptide PYP1-4 may be useful for preventing APAP-induced hepatotoxicity.

Physicochemical characterization and antioxidant activity of sulphated polysaccharides derived from Porphyra haitanensis

This study was designed to fully characterize Porphyra haitanensis polysaccharides, and to evaluate their antioxidant activity. The polysaccharides primarily contained galactose and 3,6-anhydrogalactose in a molar ratio of 1.2:1.0, respectively and sulfate content about 3.8%. The molecular weight of polysaccharides is 2.5 × 10⁵ Da. Scanning electron microscopy and atomic force microscopy of the polysaccharides pointed towards an irregular network with more or less hexagonal and a few rectangular pores. The chemical structure was confirmed through Fourier transform infrared spectroscopy, and 1D and 2D nuclear magnetic resonance structural characterization wherein → 4-3,6-anhydro-α-L-galactopyranose-(1 → 3)-β-D-galactopyranose segments. The extracted polysaccharides revealed relatively high 2, 2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid radical scavenging activity (53.16% at 2 mg/mL), moderate 2,2-diphenyl-1-picrylhydrazyl radical scavenging efficacy (34.63% at 2 mg/mL), and low hydroxyl radical scavenging potential (23.80% at 2 mg/mL). Further purification of these polysaccharides, hence, is advised for their potential role as antioxidants in the food, pharmaceutical and cosmeceutical industry.

6,7,4'-Trihydroxyflavone inhibits osteoclast formation and bone resorption in vitro and in vivo

The balance between the osteoblasts and the osteoclasts is important for the maintenance of the skeleton of the human body. The osteoclasts absorb bone after differentiated into polymorphonuclear cells by the fusion of monocytes/macrophages. We have found that 6,7,4'-Trihydroxyflavone (THF), a compound from the heartwood of Dalbergia Odorifera inhibits receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation, actin ring formation, and bone resorption in RAW 264.7 cells and bone marrow macrophage. THF significantly inhibited the c-Jun-N-terminal kinase signaling pathway without affecting extracellular signal-regulated kinase, p38, and AKT signaling. Moreover, THF inhibited the expression of c-Fos, nuclear factor-activated T cells cytoplasm 1, cathepsin K, and c-src by RANKL. We used a lipopolysaccharide (LPS)-induced bone loss model in mice. Consequently, bone volume per tissue volume, trabecular number's reduction was recovered in THF-treated mice, and trabecular separation's augmentation was also attenuated by THF administration. In summary, THF inhibits RANKL-induced osteoclast differentiation by MAPK signaling pathway and inhibits bone resorption by destroying the actin ring in mature osteoclasts. THF also prevented LPS-induced bone loss in a mice model. Thus, THF may be useful in the treatment of bone diseases associated with excessive osteoclast differentiation and bone resorption.

Magnolol prevents ovariectomy‑induced bone loss by suppressing osteoclastogenesis via inhibition of the nuclear factor‑κB and mitogen‑activated protein kinase pathways

Magnolol is the active component of the traditional Chinese medicine Magnolia officinalis, and has antioxidant, anti-inflammatory and anticancer activities, as well as an effect on bone metabolism in vitro. In the present study, it is reported that magnolol suppresses osteoclastogenesis in vivo and in vitro. Magnolol prevented ovariectomy-induced bone loss and osteoclastogenesis in vivo, and decreased the serum levels of C-terminal telopeptide of type 1 collagen, interleukin-6, tumor necrosis factor (TNF)-α and tartrate-resistant acid phosphatase 5B. In vitro, magnolol inhibited the osteoclastogenesis induced by the receptor activator for nuclear factor-κB ligand, and impaired the osteoclast function in bone marrow monocytes and RAW264.7 cells in a dose-dependent manner. Furthermore, magnolol suppressed the expression levels of the osteoclastogenesis markers cathepsin K, calcitonin receptor, matrix metalloproteinase 9, TNF receptor-associated factor 6 and tartrate-resistant acid phosphatase by inhibiting the nuclear factor-κB and mitogen-activated protein kinase pathways. Therefore, magnolol is a promising agent for the treatment of osteoporosis and associated disorders.

Acidic polysaccharides isolated from marine algae inhibit the early step of viral infection

We examined the effects of various acidic polysaccharides isolated from marine algae on the infection and replication of human immunodeficiency virus type-1 (HIV-1), hepatitis B virus (HBV), hepatitis C virus (HCV), and human T-cell leukemia virus type-1 (HTLV-1). It was found that sulfated fucan polysaccharides, ascophyllan, and two fucoidans derived from different sources significantly inhibited the early step of HIV-1 (R9 and JR-FL) infection, while they did not affect the late step. The alginate oligomer consisted of uronic acids and sulfated-galactan porphyran showed no significant inhibitory effects. In addition, ascophyllan and two fucoidans inhibited the early step of HBV infection in a dose-dependent manner. Furthermore, these polysaccharides inhibited the early step of HCV infection but had no inhibitory effects on HTLV-1 replication. To further examine the specificity of these polysaccharides in viral infections, we used vesicular stomatitis virus (VSV)-G-pseudotyped HIV-1 infection. Ascophyllan, the two fucoidans, and alginate oligomer also potently inhibited VSV-G-pseudotyped HIV-1 infection in HeLa cells. Taken together, these results suggest that the acidic polysaccharides used in this study are capable of inhibiting the early step of viral infections depending on the polysaccharides but not in a strict species-specific manner.

Sargassum serratifolium attenuates RANKL-induced osteoclast differentiation and oxidative stress through inhibition of NF-κB and activation of the Nrf2/HO-1 signaling pathway

Sargassum serratifolium C. Agardh is a marine brown alga that has long been used as an ingredient for food and medicine by many people living along Asian coastlines. Recently, various beneficial effects of extracts or compounds isolated from S. serratifolium have been reported, but their efficacies against bone destruction are unclear. Therefore, in this study, we investigated the inhibitory property of an ethanol extract of S. serratifolium (EESS) on osteoclast differentiation by focusing on the receptor activator of nuclear factor-κB ligand (RANKL)-stimulated osteoclastogenesis model using RAW 264.7 macrophages. Our results demonstrated that EESS reduced RANKL-induced osteoclast differentiation in RAW 264.7 cells, by inhibiting tartrate-resistant acid phosphatase (TRAP) activity and destroying the F-actin ring formation. EESS also attenuated RANKL-induced expressions of key osteoclast-specific genes, such as nuclear factor of activated T cells cytoplasmic 1 (NFATC1), TRAP, cathepsin K and matrix metalloproteinase-9. These effects were mediated by impaired nuclear translocation of nuclear factor (NF)-κB and suppression of IκB-α degradation. In addition, EESS effectively inhibited the production of reactive oxygen species (ROS) by RANKL, which was associated with enhanced expression of nuclear translocation of nuclear factor-erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). Overall, our findings provide evidence that EESS suppresses RANKL-induced osteoclastogenesis and oxidative stress through suppression of NF-κB and activation of Nrf2/HO-1 signaling pathway, indicating that S. serratifolium has a potential application the prevention and treatment of osteoclastogenic bone disease.