Sanguinarine inhibits osteoclast formation and bone resorption via suppressing RANKL-induced activation of NF-κB and ERK signaling pathways

Attenuation of cisplatin-induced acute kidney injury by sanguinarine: modulation of oxidative stress, inflammation, and cellular damage

Introduction

Cisplatin (CP)-induced acute kidney injury (AKI) is a significant side effect of CP chemotherapy, driven by oxidative stress and inflammation. Sanguinarine (SANG), an alkaloid from the rhizomes of Sanguinaria canadensis and poppy-fumaria species, exhibits antioxidant and anti-inflammatory properties. This study examined SANG's effect on CP-induced AKI in mice and its underlying mechanisms.

Methods

Mice were orally administered 5 mg/kg SANG for 10 days. On the seventh day, they received a single intraperitoneal CP injection (20 mg/kg) and were sacrificed on the 11th day.

Results

SANG significantly improved CP-induced decreases in body weight, water intake, urine volume, relative kidney weight, creatinine clearance, albumin-to-creatinine ratio, and plasma urea and creatinine levels. It also reduced elevated plasma neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, cystatin C, and adiponectin levels, as well as renal markers of inflammation and oxidative stress induced by CP administration. SANG normalized kidney mitochondrial dysfunction, DNA damage, and apoptosis caused by CP. It also inhibited the CP-induced increase in the expression of phosphorylated nuclear factor-κB and autophagy markers in the kidney. Histological analysis showed that SANG reduced acute tubular necrosis and intraluminal protein accumulation due to CP.

Discussion

In conclusion, SANG mitigated CP-induced AKI by reducing inflammation, oxidative stress, DNA damage, apoptosis, and autophagy. Pending more comprehensive pharmacological and toxicological assessments, SANG may be regarded as a potential therapeutic agent for mitigating CP-induced AKI.

Exploring the Mechanisms of Sanguinarine in the Treatment of Osteoporosis by Integrating Network Pharmacology Analysis and Deep Learning Technology

BACKGROUND

Sanguinarine (SAN) has been reported to have antioxidant, antiinflammatory, and antimicrobial activities with potential for the treatment of osteoporosis (OP).

OBJECTIVE

This work purposed to unravel the molecular mechanisms of SAN in the treatment of OP.

METHODS

OP-related genes and SAN-related targets were predicted from public databases. Differential expression analysis and VennDiagram were adopted to detect SAN-related targets against OP. Protein-protein interaction (PPI) network was served for core target identification. Molecular docking and DeepPurpose algorithm were further adopted to investigate the binding ability between core targets and SAN. Gene pathway scoring of these targets was calculated utilizing gene set variation analysis (GSVA). Finally, we explored the effect of SAN on the expressions of core targets in preosteoblastic MC3T3-E1 cells.

RESULTS

A total of 21 candidate targets of SAN against OP were acquired. Furthermore, six core targets were identified, among which CASP3, CTNNB1, and ERBB2 were remarkably differentially expressed in OP and healthy individuals. The binding energies of SAN with CASP3, CTNNB1, and ERBB2 were -6, -6.731, and -7.162 kcal/mol, respectively. Moreover, the GSVA scores of the Wnt/calcium signaling pathway were significantly lower in OP cases than in healthy individuals. In addition, the expression of CASP3 was positively associated with Wnt/calcium signaling pathway. CASP3 and ERBB2 were significantly lower expressed in SAN group than in DMSO group, whereas the expression of CTNNB1 was in contrast.

CONCLUSION

CASP3, CTNNB1, and ERBB2 emerge as potential targets of SAN in OP prevention and treatment.

One arrow two eagles: Multifunctional nano-system for macrophage reprogramming and osteoclastogenesis inhibition against inflammatory osteolysis

Inflammatory osteolysis poses a significant worldwide threat to public health. However, current monotherapies, which target either the prevention of the inflammatory response or the attenuation of osteoclast (OC) formation, have limited efficacy due to the complexity of the bone immune system being overlooked. Herein, by means of modifying salmon calcitonin (sCT), a multifunctional nano-system (AuNDs-sCT) was designed to synergistically inhibit OC differentiation and reverse the inflammatory microenvironment against inflammatory osteolysis. On the one hand, AuNDs-sCT effectively restrained OC differentiation by binding to the calcitonin receptors on the surface of OC precursors, resulting in the down-regulation of OC-specific genes and proteins. The targeted capacity of AuNDs-sCT provided a more durable and precise therapeutic effect. On the other hand, AuNDs-sCT exhibited antioxidant and anti-inflammatory effects, which regulated the polarization "switch" from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype in macrophages by the inhibition of NF-κB p65 phosphorylation, thereby effectively reversed the local inflammatory microenvironment. Additionally, AuNDs-sCT served as a promising fluorescent probe, enabling real-time visualization of the therapeutic process. This capability is expected to optimize drug administration and evaluate therapeutic effects. In summary, by inhibiting OC differentiation and reprogramming macrophages, AuNDs-sCT successfully realized drug repurposing and achieved the "one arrow two eagles" therapeutic strategy, which offers a synergistic and effective treatment option for the clinical management of inflammatory osteolysis.

Artemisinic acid attenuates osteoclast formation and titanium particle-induced osteolysis via inhibition of RANKL-induced ROS accumulation and MAPK and NF-κB signaling pathways

Periprosthetic osteolysis (PPO) is the most common cause of joint arthroplasty failure. Its progression involves both biological and mechanical factors. Osteoclastogenesis induced by wear from debris-cell interactions, ultimately leading to excessive bone erosion, is considered the primary cause of PPO; therefore, targeting osteoclasts is a promising treatment approach. Currently available drugs have various side effects and limitations. Artemisinic acid (ArA) is a sesquiterpene isolated from the traditional herb Artemisia annua L. that has various pharmacological effects, such as antimalarial, anti-inflammatory, and antioxidant activities. Therefore, this study was aimed at investigating the effect of ArA on osteoclast formation and bone resorption function in vitro, as well as wear particle-induced osteolysis in vivo, and to explore its molecular mechanism of action. Here, we report that ArA inhibits RANKL-stimulated osteoclast formation and function. Mechanistically, ArA suppresses intracellular reactive oxygen species levels by activating the antioxidant response via nuclear factor erythroid-2-related factor 2 (Nrf2) pathway upregulation. It also inhibits the mitogen-activated kinases (MAPK) and nuclear factor-κB (NF-κB) pathways, as well as the transcription and expression of NFATc1 and c-Fos. In vivo experiments demonstrated that ArA reduces osteoclast formation and alleviates titanium particle-induced calvarial osteolysis. Collectively, our study highlights that ArA, with its osteoprotective and antioxidant effects, is a promising therapeutic agent for preventing and treating PPO and other osteoclast-mediated osteolytic diseases.

Synthesis, DPPH Radical Scavenging, Cytotoxic Activity, and Apoptosis Induction Efficacy of Novel Thiazoles and Bis-thiazoles

BACKGROUND

Heterocyclic materials-containing thiazoles exhibited incredible importance in pharmaceutical chemistry and drug design due to their extensive biological properties.

METHODS

Synthesis of thiazoles and bis-thiazoles from the reaction of 2-((6-Nitrobenzo[ d][1,3]dioxol-5-yl)methylene)hydrazine-1-carbothioamide with hydrazonoyl chlorides in dioxane and in the existence of triethylamine as basic catalyst. The antioxidant, in vitro antiproliferative, and cytotoxicity efficacy of thiazoles and bis-thiazoles were measured.

RESULTS

In this work, novel series of 5-methyl-2-(2-(-(6-nitrobenzo[d][1,3]dioxol-5-yl)methylene) hydrazinyl)-4-(aryldiazenyl)thiazoles (4a-f) were prepared via the reaction of hydrazonoyl chlorides 2a-f with 2-((6-nitrobenzo[d][1,3]dioxol-5-yl)methylene)hydrazine-1-carbothioamide (1) in dioxane and employing triethylamine as basic catalyst. Following the same procedure, bisthiazoles (6, 8, and 10) have been synthesized by utilizing bis-hydrazonoyl chlorides (5, 7, and 9) and carbothioamide 1 in a molar ratio (1:2), respectively. The distinctive features in the structure of isolated products were elucidated by spectroscopic tools and elemental analyses. The antioxidant, in vitro anti-proliferative, cytotoxicity, and anti-cancer efficacy of thiazoles and bis-thiazoles were evaluated. Compounds 4d and 4f were the most potent antioxidant agents. Gene expression of apoptosis markers and fragmentation assay of DNA were assessed to explore the biochemical mechanism of synthesized products. Thiazoles significantly inhibited cell growth and proliferation more than bis-thiazoles. They induced apoptosis through induction of apoptotic gene expression P53 and downregulation of antiapoptotic gene expression Bcl-2. Moreover, they induced fragmentation of DNA in cancer cells, indicating that they could be employed as anticancer agents by inhibiting tumor growth and progression and can be considered effective compounds in the strategy of anti-cancer agents' discovery.

CONCLUSION

Synthesis, DPPH Radical Scavenging, Cytotoxic activity, and Apoptosis Induction Efficacy based on Novel Thiazoles and Bis-thiazoles.

Transient receptor potential ankyrin 1 (TRPA1) modulators: Recent update and future perspective

The transient receptor potential ankyrin 1 (TRPA1) channel is a non-selective cation channel that senses irritant chemicals. Its activation is closely associated with pain, inflammation, and pruritus. TRPA1 antagonists are promising treatments for these diseases, and there has been a recent upsurge in their application to new areas such as cancer, asthma, and Alzheimer's disease. However, due to the generally disappointing performance of TRPA1 antagonists in clinical studies, scientists must pursue the development of antagonists with higher selectivity, metabolic stability, and solubility. Moreover, TRPA1 agonists provide a deeper understanding of activation mechanisms and aid in antagonist screening. Therefore, we summarize the TRPA1 antagonists and agonists developed in recent years, with a particular focus on structure-activity relationships (SARs) and pharmacological activity. In this perspective, we endeavor to keep abreast of cutting-edge ideas and provide inspiration for the development of more effective TRPA1-modulating drugs.

Zingerone attenuates Ti particle-induced inflammatory osteolysis by suppressing the NF-κB signaling pathway in osteoclasts

Aseptic loosening caused by inflammatory osteolysis is one of the most frequent and serious long-term complications after total joint arthroplasty (TJA). Development of a new therapeutic drug is required due to the lack of effective therapy and serious adverse effects. This study aimed to explore the pharmacological properties of zingerone (ZO) in attenuating osteoclast-mediated periprosthetic osteolysis and how ZO modulates osteoclastogenesis. The nontoxic concentration of ZO was clarified by the CCK-8 method. Then, we explored the efficacy of ZO on suppressing osteoclast differentiation, F-actin ring formation, bone resorption, and NF-κB luciferase activity in vitro as well as osteoprotection in vivo. Polymerase chain reaction and western blotting were applied to detect the underlying mechanisms involved in osteoclastogenesis. ZO showed an obvious inhibitory effect on osteoclastogenesis and bone resorption in a dose-dependent manner by mainly suppressing the activation of NF-κB signaling pathways. Furthermore, ZO administration successfully attenuated titanium (Ti) particle-stimulated periprosthetic osteolysis and osteoporosis by regulating osteoclast formation. Our findings demonstrated the pharmacological properties of ZO in inhibiting osteoclast formation and function by downregulation of NF-κB signaling activation. As a result, these findings could be expected to provide a novel reagent for regulating inflammatory osteolysis caused by prosthetic loosening.

The Ethanol Extracts of Osmanthus fragrans Leaves Ameliorate the Bone Loss via the Inhibition of Osteoclastogenesis in Osteoporosis

The aim of this study was to evaluate the anti-osteoporosis effects of Osmanthus fragrans leaf ethanol extract (OFLEE) in bone marrow-derived macrophages (BMM) and animals with osteoporosis. OFLEE not only suppressed tartrate-resistant acid phosphatase (TRAP)-positive cells with multiple nuclei but also decreased TRAP activity in BMM treated with macrophage colony stimulating factor (M-CSF) and receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL). The formation of F-actin rings and the expression and activation of matrix metalloproteinases were decreased by OFLEE in BMM treated with M-CSF and RANKL. OFLEE suppressed M-CSF- and RANKL-induced osteoclastogenesis by inhibiting NF-κB phosphorylation, tumor necrosis factor receptor-associated factor 6, c-fos, the nuclear factor of activated T-cells, cytoplasmic 1, and cathepsin K in BMM. OFLEE downregulated reactive oxygen species, cyclooxygenase-2, inducible nitric oxide synthase, prostaglandin E₂, tumor necrosis factor α, interleukin (IL)-1β, IL-6, IL-17, and RANKL in BMM treated with M-CSF and RANKL. Oral administration of OFLEE suppressed osteoporotic bone loss without hepatotoxicity in ovariectomy-induced osteoporosis animals. Our findings suggest that OFLEE, with anti-inflammatory effects, prevents osteoporotic bone loss through the suppression of osteoclastic differentiation in BMM and animals with osteoporosis.

Molecular Mechanisms of Sanguinarine in Cancer Prevention and Treatment

Historically, natural plant-derived drugs received a great impact of consideration in the treatment of several human-associated disorders. Cancer is a devastating disease and the second most cause of mortality. Sanguinarine (SANG), a naturally isolated plant alkaloidal agent, possesses chemo-preventive effects. Several studies have revealed that SANG impedes tumor metastasis and development by disrupting a wide range of cell signaling pathways and its molecular targets, such as BCL-2, MAPKs, Akt, NF-κB, ROS, and microRNAs (miRNAs). However, its low chemical stability and poor oral bioavailability remain key issues in its use as a medicinal molecule. A novel method (e.g., liposomes, nanoparticles, and micelles) and alternative analogs provide an exciting approach to alleviate these problems and broaden its pharmacokinetic profile. Cancer-specific miRNA expression is synchronized by SANG, which has also been uncertain. In this critical study, we review the utilization of SANG mimics and nano-technologies to improve its support in cancer. We focus on recently disclosed studies on SANG anti-cancer properties.

Carboxymethyl Cellulose/Zn-Organic Framework Down-Regulates Proliferation and Up-Regulates Apoptosis and DNA Damage in Colon and Lung Cancer Cell Lines

A solvothermal technique was used to prepare a Zn-benzenetricarboxylic acid (Zn@BTC) organic framework covered with a carboxymethyl cellulose (CMC/Zn@BTC). Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FESEM), and Brunauer, Emmett, and Teller (BET) surface area were applied to characterize CMC/Zn@BTC. Moreover, the anticancer, anti-migrative, anti-invasive, and anti-proliferative action of CMC/Zn@BTC nanoparticles were assessed on cancer cell lines. Apoptotic markers and DNA damage were assessed to explore the cellular and biological changes induced by CMC/Zn@BTC nanoparticles. The microscopic observation revealed that CMC controls the surface morphology and surface characteristics of the Zn@BTC. The obtained BET data revealed that the Zn@BTC nanocomposite surface area lowers from 1061 m2/g to 740 m2/g, and the pore volume decreases from 0.50 cm3/g to 0.37 cm3/g when CMC is applied to Zn@BTC nanocomposites. The cellular growth of DLD1 and A549 was suppressed by CMC/Zn@BTC, with IC50 values of 19.1 and 23.1 μg/mL, respectively. P53 expression was upregulated, and Bcl-2 expression was downregulated by CMC/Zn@BTC, which promoted the apoptotic process. Furthermore, CMC/Zn@BTC caused DNA damage in both cancer cell lines with diverse impact, 66 percent (A549) and 20 percent (DLD1) compared to cisplatin's 52 percent reduction. CMC/Zn@BTC has anti-invasive properties and significantly reduced cellular migration. Moreover, CMC/Zn@BTC aims key proteins associated with metastasis, proliferation and programmed cellular death.

Chitosan Containing Nano Zn-Organic Framework: Synthesis, Characterization and Biological Activity

A biologically active agent based on a Zn-1,3,5-benzen tricarboxylic acid (Zn-BTC) framework incorporated into a chitosan (CS) biopolymer (Zn-BTC@CS) was successfully synthesized using a microwave irradiation technique. The synthesized Zn-BTC@CS was characterized using a scanning electron microscope (SEM) and the obtained data indicated a highly smooth surface morphology of the synthesized Zn-BTC and no morphological changes when the Zn-BTC covered the CS. In addition, the particle size diameter varied from 20 to 40 nm. XRD displayed a well-maintained Zn-BTC structure, and the crystal structure of Zn-BTC was not distorted by the composition of Zn-BTC and chitosan in the nanocomposite. Data from BET analysis revealed that the specific surface area of the Zn-BTC was reduced from 995.15 m2/g to 15.16 m2/g after coating with chitosan. The pore size distribution and pore volume of the Zn-BTC, Zn-BTC@CS were centered at 37.26 nm and at 22.5 nm, respectively. Zn-BTC@CS exhibited anticancer efficacy against lung and colon cancer cell lines. Zn-BTC@CS inhibited the proliferation of A549 and DLD-1 cancer cell lines in a dose-dependent manner with IC50 values of 13.2 and 19.8 µg/mL for the colon and lung cancer cell lines, respectively. Zn-BTC@CS stimulated the apoptotic process through up-regulating P53 expression and down-regulating Bcl-2 expression. Moreover, Zn-BTC@CS induced in vitro DNA fragmentation in both cancer cell lines with significantly different affinity by 66% (A549) and 20% (DLD-1) versus 52% reduction by Cisplatin. Zn-BTC@CS (IC50) exhibited anti-invasive activity and dramatically inhibited the migration of lung and colon cancer cell lines. This study provides evidence that Zn-BTC@CS targets the essential proteins involved in proliferation, metastasis, and apoptosis. Thus, Zn-BTC@CS has chemotherapeutic potential for inhibiting lung and colon cancer viability and growth.

Anti-fatigue effect of hypericin in a chronic forced exercise mouse model

ETHNOPHARMACOLOGICAL RELEVANCE

Hypericum perforatum L. is a traditional Chinese medicine used to sooth the liver, relieve depression, reduce body temperature, reduce sweating, and stimulate lactation. HP was extracted from Hypericum perforatum L.

AIM OF STUDY

The antifatigue effects of hypericin were assessed in a series of experiments.

MATERIALS AND METHODS

Six-to eight-week-old male ICR mice were raised in our lab. Mice were subjected to swimming training for 2 h, 6 days/week for 6 weeks. One hour prior to each swimming session, intraperitoneal injection of saline or HP (2 or 4 mg/kg) was performed.

RESULTS

Compared with the fatigue model control group, HP was found to significantly increase the swimming time in forced swimming tests. The molecular mechanisms underlying the antifatigue effects were further revealed by analysing energy metabolism, the oxidant-antioxidant system and the inflammatory response. HP normalized changes in BLA, LDH, BUN, and CK, LG in the liver. In addition, multiple assays have confirmed that HP improved the MDA, T-AOC, GSH-PX and SOD activity, and the relevant signalling pathways involved in the antifatigue effects were clarified. Furthermore, HP improves the expression of pro- and anti-inflammatory cytokines in skeletal muscle.

CONCLUSION

These results suggested that the anti-chronic fatigue effects of HP are likely achieved by normalizing energy metabolism and attenuating oxidative and inflammatory responses. Consequently, this study supports HP use in the clinic to alleviate chronic fatigue.

Effects and mechanisms of natural plant active compounds for the treatment of osteoclast-mediated bone destructive diseases

Bone-destructive diseases, caused by overdifferentiation of osteoclasts, reduce bone mass and quality, and disrupt bone microstructure, thereby causes osteoporosis, Paget's disease, osteolytic bone metastases, and rheumatoid arthritis. Osteoclasts, the only multinucleated cells with bone resorption function, are derived from haematopoietic progenitors of the monocyte/macrophage lineage. The regulation of osteoclast differentiation is considered an effective target for the treatment of bone-destructive diseases. Natural plant-derived products have received increasing attention in recent years due to their good safety profile, the preference of natural compounds over synthetic drugs, and their potential therapeutic and preventive activity against osteoclast-mediated bone-destructive diseases. In this study, we reviewed the research progress of the potential antiosteoclast active compounds extracted from medicinal plants and their molecular mechanisms. Active compounds from natural plants that inhibit osteoclast differentiation and functions include flavonoids, terpenoids, quinones, glucosides, polyphenols, alkaloids, coumarins, lignans, and limonoids. They inhibit bone destruction by downregulating the expression of osteoclast-specific marker genes (CTSK, MMP-9, TRAP, OSCAR, DC-STAMP, V-ATPase d2, and integrin av3) and transcription factors (c-Fos, NFATc1, and c-Src), prevent the effects of local factors (ROS, LPS, and NO), and suppress the activation of various signalling pathways (MAPK, NF-κB, Akt, and Ca²⁺). Therefore, osteoclast-targeting natural products are of great value in the prevention and treatment of bone destructive diseases.

Bisphosphonate-enoxacin inhibit osteoclast formation and function by abrogating RANKL-induced JNK signalling pathways during osteoporosis treatment

Osteoporosis is an age‐related disease characterized by low mineral density, compromised bone strength and increased risk of fragility fracture. Most agents for treating osteoporosis focus primarily on anti‐resorption by inhibiting osteoclast activity. Bisphosphonate (BP) is a potent anti‐resorptive agent that has been used clinically for decades and is proven to be effective. However, BP has a variety of side effects and is far from being an ideal anti‐osteoporosis agent. BP selectively binds to calcium crystals, which are subsequently taken up or released by osteoclasts. Based on the action of BP, we previously demonstrated the inhibitory effect of a novel bone‐targeting BP derivative, bisphosphonate‐enoxacin (BE). In the current study, we used bone marrow‐derived osteoclast cultures to further assess the inhibitory effect of BE on osteoclastogenesis and employed reverse transcription PCR and real‐time PCR to examine expression of osteoclast‐specific genes. Additionally, we used bone resorption and F‐actin immunofluorescence assays to evaluate the effect of BE on osteoclast function and investigated the potential mechanisms affecting osteoclast differentiation and function in vitro. Furthermore, an ovariectomized (OVX) rat model was established to evaluate the therapeutic effects of BE on preventing bone loss. Results showed that BE exerted potent inhibitory effects on osteoclast formation and bone resorption by specifically abrogating RANKL‐induced JNK signalling, and that it preserved OVX rat bone mass in vivo without any notable side effects. Collectively, these results indicated that the BP derivative BE may have significant potential as a treatment for osteoporosis and other osteolytic diseases.

The Antiangiogenic Effect of Sanguinarine Chloride on Experimental Choroidal Neovacularization in Mice via Inhibiting Vascular Endothelial Growth Factor

Background: The purpose of this study is to investigate the antiangiogenic effect of Sanguinarine chloride (SC) on models of age-related macular degeneration (AMD) both in vivo and in vitro.

Methods: Choroidal neovascularization (CNV) was conducted by laser photocoagulation in C57BL6/J mice. SC (2.5 μM, 2 μl/eye) was intravitreally injected immediately after laser injury. The control group received an equal amount of PBS. 7 days after laser injury, CNV severity was evaluated using fundus fluorescein angiography, hematoxylin and eosin (H&E) staining, and choroid flat-mount staining. Vascular endothelial growth factor (VEGF) expression in the retina/choroid complex was measured by western blot analysis and ELISA kit. In vitro, human retinal microvascular endothelial cells (HRMECs) were used to investigate the effects of SC on cell tube formation, migration, and cytotoxicity. The expression of VEGF-induced expression of extracellular signal-regulated kinase (ERK)1/2, protein kinase B (AKT), mitogen-activated protein kinases (p38-MAPK) in vitro and laser induced VEGF expression in vivo were also analyzed.

Results: SC (≤2.5 μM) was safe both in vitro and in vivo. Intravitreal injection of SC restrained the formation of laser induced CNV in mice and decreased VEGF expression in the laser site of the retina/choroid complex. In vitro, SC inhibited VEGF-induced tube formation and endothelial cell migration by decreasing the phosphorylation of AKT, ERK1/2, and p38-MAPK in HRMECs.

Conclusions: SC could inhibit laser-induced CNV formation via down-regulating VEGF expression and restrain the VEGF-induced tube formation and endothelial migration. Therefore, SC could be a potential candidate for the treatment of wet AMD.

PIP5k1β controls bone homeostasis through modulating both osteoclast and osteoblast differentiation

PIP5k1β is crucial to the generation of phosphotidylinosotol (4, 5)P2. PIP5k1β participates in numerous cellular activities, such as B cell and platelet activation, cell phagocytosis and endocytosis, cell apoptosis, and cytoskeletal organization. In the present work, we aimed to examine the function of PIP5k1β in osteoclastogenesis and osteogenesis to provide promising strategies for osteoporosis prevention and treatment. We discovered that PIP5k1β deletion in mice resulted in obvious bone loss and that PIP5k1β was highly expressed during both osteoclast and osteoblast differentiation. Deletion of the gene was found to enhance the proliferation and migration of bone marrow-derived macrophage-like cells to promote osteoclast differentiation. PIP5k1β-/- osteoclasts exhibited normal cytoskeleton architecture but stronger resorption activity. PIP5k1β deficiency also promoted activation of mitogen-activated kinase and Akt signaling, enhanced TRAF6 and c-Fos expression, facilitated the expression and nuclear translocation of NFATC1, and upregulated Grb2 expression, thereby accelerating osteoclast differentiation and function. Finally, PIP5k1β enhanced osteoblast differentiation by upregulating master gene expression through triggering smad1/5/8 signaling. Therefore, PIP5k1β modulates bone homeostasis and remodeling.

Sanguinarine is an agonist of TRPA1 channel

Sanguinarine, a benzyl isoquinoline alkaloid extracted from the root of Papaveraceae plants, shows extensive pharmacological activities including anti-microbial, anti-trypanosoma, anti-tumor, anti-platelet, anti-hypertensive effects, as well as inhibition of osteoclast formation. Here we demonstrate that TRPA1 channel (Transient receptor potential cation channel, member A1) is a potential target for sanguinarine. Electrophysiological recordings show that sanguinarine activates TRPA1 channel potently with an EC50 0.09 (0.04-0.13) μM, but has no effects on other examined TRP channels. Sanguinarine increases the intracellular calcium levels and upregulates the excitability of mouse dorsal root ganglion (DRG) neurons in vitro significantly. Plantar injection of sanguinarine evokes nociceptive behaviors similar to that elicited by allyl isothiocyanate (AITC), a classic agonist of TRPA1. Both the enhancement of excitability of DRG neurons and the nociceptive behaviors can be attenuated by treatment of TRPA1 channel antagonist HC030031 or knockout of trpa1 gene. Taken together, our data demonstrate that sanguinarine is a potent and relatively selective agonist of TRPA1 channel.

Aaptodines A-D, Spiro Naphthyridine-Furooxazoloquinoline Hybrid Alkaloids from the Sponge Aaptos suberitoides

LC-MS-oriented fractionation of the sponge Aaptos suberitoides resulted in the isolation of four heptacyclic alkaloids, aaptodines A-D (1-4), which contain 9,10-dihydrofuro[2,3-f][1,3]oxazolo[5,4-h]quinolone and 7,8-dihydrocyclopenta[de][1,6]naphthyridine subunits with a spiro carbon atom. The structures were determined on the basis of NMR spectroscopic and single-crystal X-ray diffraction data analysis aided by electronic circular dichroism calculations and Mosher's method. A biosynthetic pathway for the formation of aaptodines A-D is postulated. Aaptodine D exhibits potent inhibition against osteoclast formation.

CircRNA_28313/miR-195a/CSF1 axis modulates osteoclast differentiation to affect OVX-induced bone absorption in mice

Osteoblastic bone formation and osteoclastic bone resorption dynamically maintain the bone homeostasis; in the present study, we attempt to investigate the mechanism of the excessive activation of osteoclasts inducing the deregulation of bone homeostasis from the perspective of non-coding RNA regulation. Differentially expressed patterns of circRNAs were examined in non-treated and RANKL + CSF1-treated bone marrow monocyte/macrophage (BMM) cells and differentially-expressed miRNAs during osteoclast differentiation were analyzed and identified. We found that circRNA_28313 was significantly induced by RANKL + CSF1 treatment. circRNA_28313 knockdown significantly inhibited RANKL + CSF1-induced differentiation of osteoclasts within BMM cells in vitro, while suppressed ovariectomized (OVX)-induced bone resorption in mice in vivo. Via bioinformatics analyses, it has been demonstrated that miR-195a might bind to circRNA_28313 and CSF1 and together form a circRNA-miRNA-mRNA network. circRNA_28313 relieves miR-195a-mediated suppression on CSF1 via acting as a ceRNA, therefore modulating the osteoclast differentiation in BMM cells. In conclusion, circRNA_28313, miR-195a, and CSF1 form a ceRNA network to function in RANKL + CSF1-induced osteoclast differentiation, thus affecting OVX-induced bone absorption in mice.

Leukemia growth is inhibited by benzoxime without causing any harmful effect in rats bearing RBL-1 ×enotransplants

The present study aimed to investigate the effect of benzoxime on leukemia RBL-1 cell proliferation and a leukemic Sprague-Dawley rat model. Proliferation of RBL-1 cells was determined using an MTT assay. Sprague-Dawley rats were assigned randomly into three groups of 10 animals each, where the positive control group was administered an intravenous injection of normal saline, the negative control group was administered 1×10⁶ RBL-1 cells and the treatment group was administered with 1×10⁶ RBL-1 cells and then benzoxime (50 mg/kg/day) for 1 week. Increased dosage of benzoxime reduced RBL-1 cell viability from 92 at 2 µM to ٢١٪ at ١٢ µM after ٢٤ h. Benzoxime treatment prevented the loss of body weight in the rats with leukemia. Compared with the negative control rats, the body weight was determined to be significantly reduced (P<0.05) in the positive control rats. The weight of the spleen and liver was determined to be significantly increased (P<0.02) in the positive control rats and the benzoxime-treated rats compared with that in the negative control group on day 35 of RBL-1 cell implantation. Analysis of leukocytes in rats on day 35 demonstrated a significant reduction (P<0.05) in the cluster of differentiation (CD)11b and CD45 level in the positive control group compared with that in the negative control group. The level of CD11b and CD45 was determined to be similar in the rats in the benzoxime treatment and negative control groups. Analysis of the level of serum glutamic pyruvic transaminase, serum glutamic oxaloacetic transaminase and blood urea nitrogen indicated that all three components exhibited no significant changes in the rats following treatment with benzoxime compared with the component levels in the negative control group. The levels of these three components were in the normal range in rats treated with benzoxime on day 35 of cell implantation. These data demonstrated that the liver and kidneys are not influenced by benzoxime in rats with leukemia. In summary, the present study demonstrated that benzoxime efficiently prevents leukemia growth without inducing any harmful effects in rat models through targeting CD11b and CD45 level; thus, benzoxime should be evaluated further regarding its use in the treatment of leukemia.

The Beneficial Effect of Praeruptorin C on Osteoporotic Bone in Ovariectomized Mice via Suppression of Osteoclast Formation and Bone Resorption

Being a highly prevalent disease, osteoporosis causes metabolism defects. Low bone density, compromised bone strength, and an increased danger of fragility fracture are its main characteristics. Natural compounds have been considered as potential alternative therapeutic agents for treating osteoporosis. In this study, we demonstrated that a natural compound, praeruptorin C (Pra-C), derived from the dried roots of Peucedanum praeruptorum, has beneficial effects in suppressing osteoclast formation and resorption function via attenuating the activation of nuclear factor kappa B as well as c-Jun N-terminal kinase/mitogen-activated protein kinase signaling pathways. Moreover, Pra-C was tested in the ovariectomized (OVX) mice, a well-established model of post-menopausal bone loss, and the results indicated Pra-C exerted beneficial effects on inhibiting excessive osteoclast activity and increasing bone mass of OVX mice. Therefore, the protective effects of Pra-C on OVX mice bone are related to its inhibition of osteoclast formation and bone resorption, suggesting that Pra-C is a good potential candidate for osteoporosis treatment.

Modulation of platelet-derived microparticles to adhesion and motility of human rheumatoid arthritis fibroblast-like synoviocytes

Platelet-derived microparticles (PMPs) are closely associated with disease activity in rheumatoid arthritis (RA) and contribute to the inflammatory process. Rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) play important roles in the progression of joint destruction. The aim of this study is to demonstrate whether PMPs affect the adhesion and motility of RA-FLSs. Our data indicated that PMPs promoted migration, invasion and adhesion to extracellular matrix (ECM) of RA-FLSs. Further study showed that PMPs up-regulated the expression of matrix metalloproteinase-1 (MMP1) and increased the level of phosphorylation of NF-κB (p-NF-κB) and Erk (p-Erk) in RA-FLSs. These results suggest that PMPs promote RA-FLSs adhesion and motility presumably by increasing MMP1 via activating Erk-mediated NF-κB pathway.

Sanguinarine protects against ovariectomy‑induced osteoporosis in mice

Natural compounds are alternative agents that have therapeutic potential for preventing and treating osteoporosis. Traditionally, sanguinarine has been used clinically due to its diverse biological properties, including antimicrobial, anti-inflammatory and anticancer effects. Recently, for the first time, it was reported that sanguinarine inhibits osteoclast differentiation and bone resorption by suppressing the tumor necrosis factor ligand superfamily member 11-induced nuclear factor-κB and extracellular signal-regulated kinase signaling pathways in vitro. Therefore, the present study further investigated the pharmacological effect of sanguinarine on osteoporosis in vivo. Micro-computed tomography and histomorphometry analysis demonstrated that sanguinarine, at low and high concentrations, prevents ovariectomy (OVX)-induced bone loss. In addition, further investigation of the cellular response in vivo revealed that sanguinarine inhibited osteoclastic bone resorption and promoted osteoblastic bone formation in a dose-dependent manner. Therefore, the present study demonstrated that sanguinarine protected mice from OVX-induced osteoporosis by modulating bone remodeling, indicating that sanguinarine may have potential in the treatment of osteoporosis.

Sanguinarine protects against osteoarthritis by suppressing the expression of catabolic proteases

Inflammatory cytokines play critical roles in the pathogenesis of osteoarthritis. Recent studies have demonstrated that natural active substances can serve as alternative therapeutic agents for the prevention and treatment of osteoarthritis. Sanguinarine, an alkaloid isolated from the roots of Sanguinaria canadensis, is known to have anti-inflammatory properties. The aim of the present study was to investigate the therapeutic effect of Sanguinarine against osteoarthritis. Sanguinarine inhibited interleukin-1β-induced expression of matrix metalloproteinase 1, 3, and 13, and A disintegrin and metalloproteinase with thrombospondin motifs-5 in chondrocytes, which involved the nuclear factor-κB and c-Jun N-terminal kinase signalling pathways. Furthermore, the study of interleukin-1β-induced cartilage matrix degradation in an anterior cruciate ligament transection-induced osteoarthritis model revealed that Sanguinarine ameliorated osteoarthritis by inhibiting the expression of matrix metalloproteinase 1, 3, and 13, and A disintegrin and metalloproteinase with thrombospondin motifs-5. In conclusion, we demonstrated for the first time that Sanguinarine suppressed the expression of matrix metalloproteinase 1, 3, and 13, and A disintegrin and metalloproteinase with thrombospondin motifs-5 in vitro, ex vivo, and in vivo, indicating its potential usefulness in treating osteoarthritis.

Anti-inflammatory and neuroprotective effects of sanguinarine following cerebral ischemia in rats

Stroke is one of the leading causes of mortality worldwide. Protective agents that can diminish injuries caused by cerebral ischemia-reperfusion (I/R) are important in alleviating the harmful outcomes of stroke. The aim of the present study was to investigate the protective role of sanguinarine in cerebral I/R injury. A rat middle cerebral artery occlusion model was used to assess the clinical effect of sanguinarine, and inflammatory cytokines in the serum were detected by ELISA. Western blotting was performed to examine the change in levels of apoptosis-associated proteins in the injured brains. The results suggested that sanguinarine, an anti-inflammatory agent derived from the roots of Sanguinaria canadensis, improved the state of cerebral ischemia in a rat model. The data demonstrated that when rats were treated with sanguinarine prior to middle cerebral artery occlusion, the infarct volume was reduced significantly. The inflammatory factors tumor necrosis factor-α, interleukin (IL)-6 and IL-1β were measured in sanguinarine and vehicle-treated groups using an enzyme-linked immunosorbent assay, and the expression levels of the three factors were significantly reduced following treatment with sanguinarine (P<0.05). In addition, western blot analysis demonstrated that the ratio of B-cell lymphoma 2/Bcl-2-associated X protein was significantly increased following treatment with sanguinarine (P<0.05). The study demonstrated that sanguinarine exerts a protective effect in cerebral ischemia, and that this effect is associated with the anti-inflammatory and anti-apoptotic properties of sanguinarine.

Scutellarin inhibits RANKL-mediated osteoclastogenesis and titanium particle-induced osteolysis via suppression of NF-κB and MAPK signaling pathway

Aseptic prosthetic loosening is a major complication after hip joint replacement. Wear particle-induced periprosthetic osteolysis plays a key role in aseptic prosthetic loosening. Attempting to modulate receptor activator of nuclear factor-κB (RANKL) mediated signaling pathways is a promising strategy to prevent aseptic prosthetic loosening. In the present study, we determined the effect of scutellarin (SCU) on titanium (Ti) particle-induced osteolysis in a mouse calvarial model and RANKL-mediated osteoclastogenesis. We determined that SCU, the major effective constituent of breviscapine isolated from a Chinese herb, has potential effects on preventing Ti particle-caused osteolysis in calvarial model of mouse. In vitro, SCU could suppress RANKL-mediated osteoclastogenesis, the function of osteoclast bone resorption, and the expression levels of osteoclast-specific genes (tartrate-resistant acid phosphatase (TRAP), cathepsin K, c-Fos, NFATc1). Further investigation indicated that SCU could inhibit RANKL-mediated MAPK and NF-κB signaling pathway, including JNK1/2, p38, ERK1/2, and IκBα phosphorylation. Taken together, these results indicate that SCU could inhibit osteoclastogenesis and prevent Ti particle-induced osteolysis by suppressing RANKL-mediated MAPK and NF-κB signaling pathway. These results suggest that SCU is a promising therapeutic agent for preventing wear particle-induced periprosthetic osteolysis.

Natural products for treatment of bone erosive diseases: The effects and mechanisms on inhibiting osteoclastogenesis and bone resorption

Excessive bone resorption plays a central role on the development of bone erosive diseases, including osteoporosis, rheumatoid arthritis, and periodontitis. Osteoclasts, bone-resorbing multinucleated cells, are differentiated from hemopoietic progenitors of the monocyte/macrophage lineage. Regulation of osteoclast differentiation is considered an effective therapeutic target to the treatment of pathological bone loss. Natural plant-derived products, with potential therapeutic and preventive activities against bone-lytic diseases, have received increasing attention in recent years because of their whole regulative effects and specific pharmacological activities, which are more suitable for long-term use than chemically synthesized medicines. In this review, we summarized the detailed research progress on the active compounds derived from medical plants with potential anti-resorptive effects and their molecular mechanisms on inhibiting osteoclast formation and function. The active ingredients derived from natural plants that are efficacious in suppressing osteoclastogenesis and bone resorption include flavonoids, terpenoids (sesquiterpenoids, diterpenoids, triterpenoids), glycosides, lignans, coumarins, alkaloids, polyphenols, limonoids, quinones and others (steroid, oxoxishhone, fatty acid). Studies have shown that above natural products exert the inhibitory effects via regulating many factors involved in the process of osteoclast differentiation and bone resorption, including the essential cytokines (RANKL, M-CSF), transcription factors (NFATc1, c-Fos), signaling pathways (NF-κB, MAPKs, Src/PI3K/Akt, the calcium ion signaling), osteoclast-specific genes (TRAP, CTSK, MMP-9, integrin β3, OSCAR, DC-STAMP, Atp6v0d2) and local factors (ROS, LPS, NO). The development of osteoclast-targeting natural products is of great value for the prevention or treatment of bone diseases and for bone regenerative medicine.

Validation of downregulated microRNAs during osteoclast formation and osteoporosis progression

Enhanced osteoclast formation and function have essential roles during post‑menopausal osteoporosis. A number of cytokines have been reported to regulate osteoclastogenesis and to be involved during the pathogenesis of osteoporosis. However, the regulation of osteolysis by microRNAs (miRNAs) has remained to be fully elucidated. The present study used a microarray analysis to identify a variety of miRNAs that are differentially expressed during osteoclast formation. Six down‑regulated miRNAs, miR‑21a‑5p, miR‑27a‑3p, let‑7i‑5p, miR‑22‑3p, miR‑340‑5p and miR‑23a‑5p, whose molecular mechanisms during osteoclast differentiation have not been reported previously, were further assessed. Using an osteoclast formation assay and a mouse model of progressive osteoporosis, the downregulation of these miRNAs was validated in vitro and in vivo. Of note, the expression patterns of these six miRNAs were associated with the progression of osteoporosis. Therefore, these miRNAs are of potential diagnostic and therapeutic value for osteolytic diseases.

Metformin Improves Diabetic Bone Health by Re-Balancing Catabolism and Nitrogen Disposal

Objective

Metformin, a leading drug used to treat diabetic patients, is reported to benefit bone homeostasis under hyperglycemia in animal models. However, both the molecular targets and the biological pathways affected by metformin in bone are not well identified or characterized. The objective of this study is to investigate the bioengergeric pathways affected by metformin in bone marrow cells of mice.

Materials and Methods

Metabolite levels were examined in bone marrow samples extracted from metformin or PBS -treated healthy (Wild type) and hyperglycemic (diabetic) mice using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. We applied an untargeted high performance LC-MS approach which combined multimode chromatography (ion exchange, reversed phase and hydrophilic interaction (HILIC)) and Orbitrap-based ultra-high accuracy mass spectrometry to achieve a wide coverage. A multivariate clustering was applied to reveal the global trends and major metabolite players.

Results

A total of 346 unique metabolites were identified, and they are grouped into distinctive clusters that reflected general and diabetes-specific responses to metformin. As evidenced by changes in the TCA and urea cycles, increased catabolism and nitrogen waste that are commonly associated with diabetes were rebalanced upon treatment with metformin. In particular, we found glutamate and succinate whose levels were drastically elevated in diabetic animals were brought back to normal levels by metformin. These two metabolites were further validated as the major targets of metformin in bone marrow stromal cells.

Conclusion

Overall using limited sample size, our study revealed the metabolic pathways modulated by metformin in bones which have broad implication in our understanding of bone remodeling under hyperglycemia and in finding therapeutic interventions in mammals.

In silico target fishing and pharmacological profiling for the isoquinoline alkaloids of Macleaya cordata (Bo Luo Hui)

Background

Some isoquinoline alkaloids from Macleaya cordata (Willd). R. Br. (Bo Luo Hui) exhibited antibacterial, antiparasitic, antitumor, and analgesic effects. The targets of these isoquinoline alkaloids are undefined. This study aims to investigate the compound–target interaction network and potential pharmacological actions of isoquinoline alkaloids of M. cordata by reverse pharmacophore database screening.

Methods

The targets of 26 isoquinoline alkaloids identified from M. cordata were predicted by a pharmacophore-based target fishing approach. Discovery Studio 3.5 and two pharmacophore databases (PharmaDB and HypoDB) were employed for the target profiling. A compound–target interaction network of M. cordata was constructed and analyzed by Cytoscape 3.0.

Results

Thirteen of the 65 predicted targets identified by PharmaDB were confirmed as targets by HypoDB screening. The targets in the interaction network of M. cordata were involved in cancer (31 targets), microorganisms (12 targets), neurodegeneration (10 targets), inflammation and autoimmunity (8 targets), parasitosis (5 targets), injury (4 targets), and pain (3 targets). Dihydrochelerythrine (C6) was found to hit 23 fitting targets. Macrophage migration inhibitory factor (MIF) hits 15 alkaloids (C1–2, C11–16, C19–25) was the most promising target related to cancer.

Conclusion

Through in silico target fishing, the anticancer, anti-inflammatory, and analgesic effects of M. cordata were the most significant among many possible activities. The possible anticancer effects were mainly contributed by the isoquinoline alkaloids as active components.

Gambogic acid inhibits osteoclast formation and ovariectomy-induced osteoporosis by suppressing the JNK, p38 and Akt signalling pathways

Excessive osteoclast formation and bone resorption are key causes of osteoporosis. Natural compounds can serve as alternative therapeutic agents for the prevention and treatment of osteoporosis, and some natural compounds may have advantages over traditional drugs. In the present paper, we report that the natural compound GBA (gambogic acid), which is bioavailable, effective and less toxic, inhibits osteoclast formation, thereby attenuating osteoclastic bone resorption in vitro. Further in vivo studies demonstrated that GBA prevented ovariectomy-induced bone loss in a dose-dependent manner. Moreover, we demonstrated that GBA suppressed RANKL (receptor activator of nuclear factor κB ligand)-induced JNK (c-Jun N-terminal kinase), p38 and Akt phosphorylation. Taken together, our results demonstrate that GBA inhibits osteoclast formation in vitro and in vivo, suggesting that it is of potential value in the treatment of osteoclast-related diseases.

Breaking a pathogen's iron will: Inhibiting siderophore production as an antimicrobial strategy

The rise of antibiotic resistance is a growing public health crisis. Novel antimicrobials are sought, preferably developing nontraditional chemical scaffolds that do not inhibit standard targets such as cell wall synthesis or the ribosome. Iron scavenging has been proposed as a viable target, because bacterial and fungal pathogens must overcome the nutritional immunity of the host to be virulent. This review highlights the recent work toward exploiting the biosynthetic enzymes of siderophore production for the design of next generation antimicrobials.

Inhibition of MDA-MB-231 breast cancer cell migration and invasion activity by andrographolide via suppression of nuclear factor-κB-dependent matrix metalloproteinase-9 expression

Breast cancer is one of the most common types of cancer worldwide. The majority of patients with cancer succumb to the disease as a result of distant metastases (for example, in the bones), which cause severe complications. Despite advancements in breast cancer treatment, chemotherapeutic outcomes remain far from satisfactory, prompting a search for effective natural agents with few side‑effects. Andrographolide (AP), a natural diterpenoid lactone isolated from Andrographis paniculata, inhibits cancer cell growth. The current study aimed to examine the effect of AP on breast cancer cell proliferation, survival and progression in vitro and also its inhibitory activity on breast cancer bone metastasis in vivo. To achieve this, CCK8, flow cytometry, migration, invasion, western blot, PCR and luciferase reporter assay analyses were performed in vitro as well as establishing intratibial xenograft model of breast cancer bone metastasis in vivo. The results demonstrated that AP inhibits the migration and invasion of the MBA‑MD‑231 aggressive breast cancer cell line at non‑lethal concentrations, in addition to suppressing proliferation and inducing apoptosis at high concentrations in vitro. In vivo, AP significantly inhibited the growth of tumors planted in bone and attenuated cancer‑induced osteolysis. Tartrate‑resistant acid phosphatase staining revealed osteoclast activation in tumor‑bearing mice and AP was observed to attenuate this activation. The anti‑tumor activity of AP in vitro and in vivo correlates with the downregulation of the nuclear factor κB signaling pathway and the inhibition of matrix metalloproteinase‑9 expression levels. These results indicate that AP may be an effective anti‑tumor agent for the treatment of breast cancer bone metastasis.

Macrophage migration inhibitory factor is essential for osteoclastogenic mechanisms in vitro and in vivo mouse model of arthritis

Macrophage migration inhibitory factor (MIF) enhances activation of leukocytes, endothelial cells and fibroblast-like synoviocytes (FLS), thereby contributing to the pathogenesis of rheumatoid arthritis (RA). A MIF promoter polymorphism in RA patients resulted in higher serum MIF concentration and worsens bone erosion; controversially current literature reported an inhibitory role of MIF in osteoclast formation. The controversial suggested that the precise role of MIF and its putative receptor CD74 in osteoclastogenesis and RA bone erosion, mediated by locally formed osteoclasts in response to receptor activator of NF-κB ligand (RANKL), is unclear. We reported that in an in vivo K/BxN serum transfer arthritis, reduced clinical and histological arthritis in MIF(-/-) and CD74(-/-) mice were accompanied by a virtual absence of osteoclasts at the synovium-bone interface and reduced osteoclast-related gene expression. Furthermore, in vitro osteoclast formation and osteoclast-related gene expression were significantly reduced in MIF(-/-) cells via decreasing RANKL-induced phosphorylation of NF-κB-p65 and ERK1/2. This was supported by a similar reduction of osteoclastogenesis observed in CD74(-/-) cells. Furthermore, a MIF blockade reduced RANKL-induced osteoclastogenesis via deregulating RANKL-mediated NF-κB and NFATc1 transcription factor activation. These data indicate that MIF and CD74 facilitate RANKL-induced osteoclastogenesis, and suggest that MIF contributes directly to bone erosion, as well as inflammation, in RA.

Hypericin suppresses osteoclast formation and wear particle-induced osteolysis via modulating ERK signalling pathway

Osteoclast-induced bone resorption and wear-particle-induced osteolysis leads to prosthetic loosening, one of the most common causes of joint implant failure, resulting in revision surgery. Thus, inhibition of osteoclastic bone resorption, which further prevents wear particle-induced osteolysis, is a potential treatment strategy for prosthetic loosening. Here, we examined the therapeutic effect of hypericin (HP), which was photosensitive, on osteoclastogenesis and wear particle-induced osteolysis in the absence of visible light. HP inhibited RANKL-induced osteoclast differentiation in bone marrow macrophages (BMMs) and RAW264.7 cell line without any evidence of cytotoxicity. The bone-resorbing activity of mature osteoclasts was significantly inhibited by HP. As HP has been previously reported to inhibit signalling pathway such as ERK and NF-κB in other cells, which is also important in osteoclast differentiation. We thus examined the molecular mechanism and showed that HP significantly inhibited the ERK/mitogen-activated protein kinase (MAPK) signalling pathway without affecting nuclear factor kappaB (NF-κB), c-Jun N-terminal kinase (JNK) and p38 signalling in RANKL-stimulated BMMs. Further in vivo studies revealed HP attenuated osteoclast formation and subsequently prevented wear particle-induced bone erosion. Taken together, the results suggest that HP inhibits RANKL-mediated osteoclastogenesis via affecting ERK signalling in vitro and suppresses wear particle-induced osteolysis in vivo. We therefore conclude that HP may be an innovative and safe alternative treatment for osteoclast-related prosthetic loosening.