Differential effects of formononetin and cladrin on osteoblast function, peak bone mass achievement and bioavailability in rats

Elucidating the immunomodulatory effects of phytoestrogens and their groundbreaking applications in transplantation medicine

Phytoestrogens are natural compounds found in plants and plant-based foods. When ingested, they can affect the human body in the same way as estrogen produced by the body. Phytoestrogens affect the regulation, differentiation, and production of immune cells. People who consume polyphenol and flavonoid-rich foods have lower incidences of inflammation, autoimmune diseases, and cancer. In organ transplantation, immune rejection is a lifelong problem for patients. In clinical practice, acute rejection is treated with hormonal shock or immunosuppressive drugs. However, effective reversal measures for chronic rejection, specifically for prevention, are still lacking. Recipients are also prone to post-transplant complications such as new tumors, diabetes, hyperlipidemia, hyperuricemia, and cardiovascular and cerebrovascular diseases, owing to the long-term use of immunosuppressive drugs. Phytoestrogens play a promising role in immune regulation and exert curative effects on cardiovascular diseases and cancer. In this study, we reviewed the use of phytoestrogens in the fields of immune regulation and organ transplantation.

Formononetin Derivative for Osteoporosis by Simultaneous Regulating Osteoblast and Osteoclast

Seven new formononetin derivatives (1-7) were designed and prepared from formononetin (phase II phytoestrogen). The derivatives 9-butyl-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (2) and 9-(furan-3-ylmethyl)-3-(4-methoxyphenyl)-9,10-dihydro-4H,8H-chromeno[8,7-e][1,3]oxazin-4-one (7) promoted significant osteoblast formation by modulating the BMP/Smad pathway. Compound 7 exhibited potent antiosteoclastogenesis activity in RANKL-induced RAW264.7 cells and ovariectomy (OVX)-induced osteoporosis in mice by regulation of the RANK/RANKL/OPG pathway. Compound 7 regulated osteoblast and osteoclast simultaneously and showed better effect than the well-known drug ipriflavone in vivo, suggesting 7 as a patented antiosteoporosis candidate.

Design, synthesis and biological evaluation of novel pyrimidine derivatives as bone anabolic agents promoting osteogenesis via the BMP2/SMAD1 signaling pathway

Anti-resorptive inhibitors such as bisphosphonates are widely used but they have limited efficacy and serious side effects. Though subcutaneous injection of teriparatide [PTH (1-34)] is an effective anabolic therapy, long-term repeated subcutaneous administration is not recommended. Henceforth, orally bio-available small-molecule-based novel therapeutics are unmet medical needs to improve the treatment. In this study, we designed, synthesized, and carried out a biological evaluation of 31 pyrimidine derivatives as potent bone anabolic agents. A series of in vitro experiments confirmed N-(5-bromo-4-(4-bromophenyl)-6-(2,4,5-trimethoxyphenyl)pyrimidin-2-yl)hexanamide (18a) as the most efficacious anabolic agent at 1 pM. It promoted osteogenesis by upregulating the expression of osteogenic genes (RUNX2 and type 1 col) via activation of the BMP2/SMAD1 signaling pathway. In vitro osteogenic potential was further validated using an in vivo fracture defect model where compound 18a promoted the bone formation rate at 5 mg kg-1. We also established the structure-activity relationship and pharmacokinetic studies of 18a.

Neuroprotective potential of formononetin, a naturally occurring isoflavone phytoestrogen

The increased prevalence of neurological illnesses is a burgeoning challenge to the public healthcare system and presents greater financial pressure. Formononetin, an O-methylated isoflavone, has gained a lot of attention due to its neuroprotective potential explored in several investigations. Formononetin is widely found in legumes and several types of clovers including Trifolium pratense L., Astragalus membranaceus, Sophora tomentosa, etc. Formononetin modulates various endogenous mediators to confer neuroprotection. It prevents RAGE activation that results in the inhibition of neuronal damage via downregulating the level of ROS and proinflammatory cytokines. Furthermore, formononetin also increases the expression of ADAM-10, which affects the pathology of neurodegenerative disease by lowering tau phosphorylation, maintaining synaptic plasticity, and boosting hippocampus neurogenesis. Besides these, formononetin also increases the expression of antioxidants, Nrf-2, PI3K, ApoJ, and LRP1. Whereas, reduces the expression of p65-NF-κB and proinflammatory cytokines. It also inhibits the deposition of Aβ and MAO-B activity. An inhibition of Aβ/RAGE-induced activation of MAPK and NOX governs the protection elicited by formononetin against inflammatory and oxidative stress-induced neuronal damage. Besides this, PI3K/Akt and ER-α-mediated activation of ADAM10, ApoJ/LRP1-mediated clearance of Aβ, and MAO-B inhibition-mediated preservation of dopaminergic neurons integrity are the major modulations produced by formononetin. This review covers the biosynthesis of formononetin and key molecular pathways modulated by formononetin to confer neuroprotection.

The potential pharmacological mechanism of prunetin against osteoporosis: transcriptome analysis, molecular docking, and experimental approaches

BACKGROUND

Prunetin is an O-methylated isoflavone, known for its beneficial properties. However, its specific pharmacological effects in the treatment of osteoporosis (OP) remain poorly understood. This study aims to elucidate the mechanisms underlying the antiosteoporotic effects of prunetin through a combination of bioinformatics analysis and cell experiments.

METHODS

We gathered predicted targets of prunetin from various online platforms. Differential expression analysis of mRNAs in patients with OP was conducted using the Limma package, based on the GSE35959 dataset. A PPI network diagram was visualized and analyzed using Cytoscape 3.7.2 software. Molecular docking was employed to assess the binding affinity between ligands and receptors, and selected key genes were further validated through cell experiments.

RESULTS

A total of 4062 differentially expressed genes (DEGs) were identified from the GSE35959 dataset. Among these, 58 genes were found to overlap with the targets of prunetin, indicating their potential as therapeutic targets. The enrichment analysis indicated these targets were mainly enriched in MAPK, FoxO, and mTOR signaling pathways. The molecular docking analysis demonstrated that prunetin exhibited strong binding activity with the core targets. Furthermore, cell experiments revealed that prunetin effectively reversed the expression levels of ALB, ESR1, PTGS2, and FGFR1 mRNA in MC3T3-E1 cells treated with dexamethasone (DEX).

CONCLUSION

Our research revealed the multi-pathway and multi-target features of prunetin in treating OP, shedding light on the potential mechanisms underlying the effectiveness of prunetin against OP. These findings serve as a theoretical foundation for future drug development in this field.

Mechanism of action of gut microbiota and probiotic Lactobacillus rhamnosus GG on skeletal remodeling in mice

INTRODUCTION

Gut microbiota (GM) is the collection of small organisms such as bacteria, fungi, bacteriophages and protozoans living in the intestine in symbiotics relation within their host. GM regulates host metabolism by various mechanisms.

METHODS

This review aims to consolidate current information for physicians on the effect of GM on bone health. For this, an online search of the literature was conducted using the keywords gut microbiota, bone mass, osteoporosis, Lactobacillus and sex steroid.

RESULTS AND CONCLUSIONS

There is a considerable degree of variation in bone mineral density (BMD) within populations, and it is estimated that a significant component of BMD variability is due to genetics. However, the remaining causes of bone mass variance within populations remain largely unknown. A well-recognized cause of phenotypic variation in bone mass is the composition of the microbiome. Studies have shown that germ-free (GF) mice have higher bone mass compared to conventionally raised (CR) mice. Furthermore, GM dysbiosis, also called dysbacteriosis, is defined as any alteration in the composition of the microbial community that has been colonized in the host intestine and associated with the development of bone diseases. For instance, postmenopausal osteoporosis (PMO) and diabetes. GM can be modulated by several factors such as genetics, age, drugs, food habits and probiotics. Probiotics are defined as viable bacteria that confer health benefits by modulating GM when administered in adequate quantity. Lactobacillus rhamnosus GG (LGG) is a great example of such a probiotic. LGG has been shown to regulate bone mass in healthy mice as well as ovariectomized (OVX) mice via two different mechanisms. This review will focus on the literature regarding the mechanism by which GM and probiotic LGG regulate bone mass in healthy mice as well as in OVX mice, a model of PMO.

Formononetin improves the inflammatory response and bone destruction in knee joint lesions by regulating the NF-kB and MAPK signaling pathways

Formononetin (FMN) is a phytoestrogen that belongs to the isoflavone family. It has antioxidant and anti-inflammatory effects, as well as, many other biological activities. Existing evidence has aroused interest in its ability to protect against osteoarthritis (OA) and promote bone remodeling. To date, research on this topic has not been thorough and many issues remain controversial. Therefore, the purpose of our study was to explore the protective effect of FMN against knee injury and clarify the possible molecular mechanisms. We found that FMN inhibited osteoclast formation induced by receptor activator of NF-κB ligand (RANKL). Inhibition of the phosphorylation and nuclear translocation of p65 in the NF-κB signaling pathway plays a role in this effect. Similarly, during the inflammatory response of primary knee cartilage cells activated by IL-1β, FMN inhibited the NF-κB signaling pathway and the phosphorylation of the ERK and JNK proteins in the MAPK signaling pathway to suppress the inflammatory response. In addition, in vivo experiments showed that both low- and high-dose FMN had a clear protective effect against knee injury in the DMM (destabilization of the medial meniscus) model, and the therapeutic effect of high-dose FMN was stronger. In conclusion, these studies provide evidence of the protective effect of FMN against knee injury.

Estrogenic flavonoids and their molecular mechanisms of action

Flavonoids are a major group of phytoestrogens associated with physiological effects, and ecological and social impacts. Although the estrogenic activity of flavonoids was reported by researchers in the fields of medical, environmental and food studies, their molecular mechanisms of action have not been comprehensively reviewed. The estrogenic activity of the respective classes of flavonoids, anthocyanidins/anthocyanins, 2-arylbenzofurans/3-arylcoumarins/α-methyldeoxybenzoins, aurones/chalcones/dihydrochalcones, coumaronochromones, coumestans, flavans/flavan-3-ols/flavan-4-ols, flavanones/dihydroflavonols, flavones/flavonols, homoisoflavonoids, isoflavans, isoflavanones, isoflavenes, isoflavones, neoflavonoids, oligoflavonoids, pterocarpans/pterocarpenes, and rotenone/rotenoids, was summarized through a comprehensive literature search, and their structure-activity relationship, biological activities, signaling pathways, and applications were discussed. Although the respective classes of flavonoids contained at least one chemical mimicking estrogen, the mechanisms varied, such as those with estrogenic, anti-estrogenic, non-estrogenic, and biphasic activities, and additional activities through crosstalk/bypassing, which exert biological activities through cell signaling pathways. Such mechanistic variations of estrogen action are not limited to flavonoids and are observed among other broad categories of chemicals, thus this group of chemicals can be termed as the "estrogenome". This review article focuses on the connection of estrogen action mainly between the outer and the inner environments, which represent variations of chemicals and biological activities/signaling pathways, respectively, and form the basis to understand their applications. The applications of chemicals will markedly progress due to emerging technologies, such as artificial intelligence for precision medicine, which is also true of the study of the estrogenome including estrogenic flavonoids.

Inhibitory effects of Formononetin on CoCrMo particle-induced osteoclast activation and bone loss through downregulating NF-κB and MAPK signaling

Wear particle-induced osteoclast over-activation is a major contributor to periprosthetic osteolysis and aseptic loosening, which can cause pathological bone loss and destruction. Hence, inhibiting excessive osteoclast-resorbing activity is an important strategy for preventing periprosthetic osteolysis. Formononetin (FMN) has been shown to have protective effects against osteoporosis, but no previous study has evaluated the effects of FMN on wear particle-induced osteolysis. In this study, we found that FMN alleviated CoCrMo alloy particles (CoPs)-induced bone loss in vivo and inhibited the formation and bone-resorptive function of osteoclasts in vitro. Moreover, we revealed that FMN exerted inhibitory effects on the expression of osteoclast-specific genes via the classical NF-κB and MAPK signaling pathways in vitro. Collectively, FMN is a potential therapeutic agent for the prevention and treatment of periprosthetic osteolysis and other osteolytic bone diseases.

Development of an indirect competitive enzyme-linked immunosorbent assay for formononetin and its application in a cell-based assay using MC3T3-E1 cells

Formononetin (FMN) is a methoxy isoflavone found abundantly in leguminous plants and associated foods. Several analytical methods have been developed to detect FMN. However, they are costly, complicated, and time-consuming. This study describes an indirect competitive enzyme-linked immunosorbent assay (icELISA) to determine FMN content in food samples using a monoclonal antibody (mAb) against FMN produced by a newly established hybridoma cell line. Validation studies were conducted, and this assay was found to be sufficiently reliable, with an analytical measurement range of 19.53-1250 ng/mL and a detection limit of 17.42 ng/mL. Furthermore, icELISA was successfully applied for a cell-based assay in which the amount of FMN and ononin uptake was quantified in MC3T3-E1 cells. Hence, icELISA is a simple and reliable method for the detection and quantification of FMN, as well as elucidation of its functions and underlying mechanisms of action.

Cladrin alleviates dexamethasone-induced apoptosis of osteoblasts and promotes bone formation through autophagy induction via AMPK/mTOR signaling

Glucocorticoid-induced osteoporosis (GIOP) is a common clinical consequence that arises due to the extensive usage of glucocorticoids. Cladrin (Clad), a methoxylated isoflavone has been reported to have a bone protecting effect by enhancing osteoblast proliferation and differentiation. However, its consequences on GIOP are not reported yet. This study investigates whether Clad protects against the deleterious effects of Dexamethasone (Dex) on osteoblast and bone. Mice calvarial osteoblasts were treated with Clad and then exposed to Dex to study the effect on osteoblast differentiation, proliferation, and survival. Further, GIOP mice were treated with Clad (5 and 10 mg/kg) doses along with reference standard alendronate (ALN 3 mg/kg) for evaluation of bone protecting effect of Clad. We analyzed bone and vertebral microarchitecture, mechanical strength, and biochemical parameters. We observed that Clad at 10 nM concentration mitigated Dex-induced cytotoxicity and defend osteoblasts against apoptosis. Subsequent results demonstrate that Clad suppressed apoptosis of osteoblast in the presence of Dex by enhancing autophagy in a way that was reliant on the AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway. Furthermore, micro-CT scanning, eco MRI results, and serum CTX levels revealed that 12 weeks of Clad treatment prevented bone loss and preserved trabecular bone mass in GIOP animals. We also observed that Clad treated osteoblasts had a lower rate of apoptosis and a greater LC3-II/LC3-I ratio than the Dex group. Our findings show that Clad can protect osteoblasts against glucocorticoids by inducing autophagy via the AMPK/mTOR pathway.

The effectiveness of synthetic methoxylated isoflavones in delivering to the skin and alleviating psoriasiform lesions via topical absorption

This study was conducted to appraise the possible potential of synthetic isoflavones (SIFs) on psoriasis treatment. A practical and easy-to-operate approach was employed in synthesizing a series of SIFs, considering that acquiring flavonoids from natural resources is usually expensive, time-consuming, and non-eco-friendly. Seven SIFs derived from daidzein were produced with differences in the location of the hydroxyl groups and degree of methoxylation. The in vitro and in vivo skin absorption of topically applied SIFs was estimated. Further, keratinocytes (HaCaT) were employed as the model to investigate the anti-inflammatory activity of the isoflavones. The lipophilicity was increased from SIF-1 to -7. Noteworthily, there was a parabolic relationship between lipophilicity and skin absorption, with SIF-5 (4',7-dihydroxyisoflavone, daidzein) and SIF-6 (7-hydroxy-3',4'-dimethoxyisoflavone, cladrin) demonstrating the highest retention in pig skin. The methoxylated isoflavone SIF-5 showed the greatest permeation into barrier-deficient skin among the compounds tested, with a 6- and 8-fold increase after lipid and protein removal. The cell-based study exhibited the capability of SIFs to restrain the overexpressed IL-6, IL-8, and CXCL1 in stimulated HaCaT. The therapeutic index (TI) predicted the potential candidates of SIF-5 and SIF-6 for topical application to treat psoriatic inflammation. The imiquimod (IMQ)-driven psoriasiform murine model manifested the inhibition of hyperplasia and immune cell infiltration by topically administered SIF-5 and SIF-6. The epidermal thickness of IMQ-treated skin was decreased from 172 to 40 μm by both isoflavones. This effect was comparable with that of betamethasone, the positive control. The topical treatment of SIF-6 significantly reduced cytokine/chemokine upregulation by IMQ. The methoxylated isoflavone with dramatic anti-inflammatory activity is promising for the development of an antipsoriatic agent.

Extract and fraction of Musa paradisiaca flower have osteogenic effect and prevent ovariectomy induced osteopenia

BACKGROUND

Osteoporosis is an asymptomatic bone disorder leading to altered bone microarchitecture, mineralization and strength. Musa paradisiaca has been reported to have antioxidant and anti-inflammatory effects in various diseases. Its impact on postmenopausal osteoporosis has not been investigated yet.

PURPOSE

The intention of the current study was to evaluate the bone regeneration and osteoprotective potential of extract and fraction of M. paradisiaca flower in ovariectomized (Ovx) Sprague Dawley (SD) rats, a model of post-menopausal bone loss. The study also aims to identify osteogenic compounds from active fraction.

METHODS

Ethanolic extract (MFE) and butanolic fraction (MFE-Bu) from flower of M. paradisiaca were prepared and their efficacy was tested in rat femur osteotomy model at different doses. Effective dose from both extract (250 mg/kg) and fraction (50 mg/kg) were taken for study in osteopenic bone loss model. PTH was taken as reference standard (20 µg/kg/twice a week). Bones were harvested at autopsy for dynamic and static histomorphometry. Serum was collected for ELISA. Pure compounds were isolated from butanolic fraction (MFE-Bu), and were assessed for their osteogenic effect.

RESULTS

MFE and MFE-Bu were observed for their potential in bone healing and prevention of bone loss. Both MFE and MFE-Bu promoted new bone regeneration at injury site as assessed by microCT and calcein dye labeling studies. These also led to restoration of bone microarchitecture deteriorated as a result of osteopenia and improved bone biomechanical properties. Extract as well as the fraction exhibited dual bone anabolic and anti-resorptive properties where they elevated serum procollagen type I N-terminal propeptide (P1NP), a bone formation marker and suppressed serum C-telopeptide of type I collagen (CTX-1), a bone resorption marker. As many as four osteogenic compounds were isolated from MFE-Bu. Oleracein-E was found to be the most potent osteogenic agent based on osteoblast differentiation, mineralization assays, qPCR and protein expression studies.

CONCLUSION

Our studies demonstrates that ethanolic extract from the flower of M. paradisiaca and its butanolic fraction exhibit dual osteogenic and anti-resorptive potential, and have an advantage over PTH which though promotes bone formation but is also bone catabolic in nature.

Probiotics and Isoflavones as a Promising Therapeutic for Calcium Status and Bone Health: A Narrative Review

Probiotics have potential clinical effects for treating and preventing osteoporosis. Meanwhile, isoflavones have attracted much attention due to their ability to prevent postmenopausal symptoms. Research has established that probiotics and isoflavones can regulate hormones, immune cells, and the gastrointestinal system, acting as links in the gut-bone axis. However, combining the effects of probiotics and isoflavones on calcium status and bone health is a more novel and a still-evolving research area. Lactobacillus and Bifidobacterium are the foremost strains that influence bone health to a significant extent. Among the isoflavones, daidzein, genistein, and the metabolites of genistein (such as equol) stimulate bone formation. It can be concluded that probiotics and isoflavones promote bone health by regulating calcium uptake, gut microbiota, and various metabolic pathways that are associated with osteoblast activity and bone formation. Nevertheless, further experiments of probiotics and isoflavones are still necessary to confirm the association between calcium bioavailability and bone health.

The Osteogenic Function of Danggui Buxue Tang, a Herbal Decoction Containing Astragali Radix and Angelicae Sinensis Radix, Is Optimized by Boiling the Two Herbs Together: Signaling Analyses Revealed by Systems Biology

The therapeutic efficacy of a herbal mixture, being multi-target, multi-function and multi-pathway, is the niche of traditional Chinese medicine (TCM). Systems biology can dissect the network of signaling mechanisms in a complex biological system. In preparing TCM decoctions, the boiling of herbs together in water is a common practice; however, the rationale of this specific preparation has not been fully revealed. An approach of mass-spectrometry-based multi-omics was employed to examine the profiles of the cellular pathways, so as to understand the pharmacological efficacy of Danggui Buxue Tang (DBT), a Chinese herbal mixture containing Astragali Radix and Angelicae Sinensis Radix, in cultured rat osteoblasts and mesenchymal stem cells. The results, generated from omics analyses, were compared from DBT-treated osteoblasts to those of treating the herbal extract by simple mixing of extracts from Astragali Radix and Angelicae Sinensis Radix, i.e., herbal mixture without boiling together. The signaling pathways responsible for energy metabolism and amino acid metabolism showed distinct activation, as triggered by DBT, in contrast to simple mixing of two herbal extracts. The result supports that boiling the herbs together is designed to maximize the osteoblastic function of DBT, such as in energy and lipid metabolism. This harmony of TCM formulation, by having interactive functions of two herbs during preparation, is being illustrated. The systems biology approach provides new and essential insights into the synergy of herbal preparation. Well-defined multiple targets and multiple pathways in different levels of omics are the key to modernizing TCM.

Bisphenol A exposure prenatally delays bone development and bone mass accumulation in female rat offspring via the ERβ/HDAC5/TGFβ signaling pathway

Previous studies have suggested that bisphenol A (BPA) has a toxic effect on bone development; however, its pathological mechanism has not been fully elucidated. In the present study, pregnant Wistar rats were intragastrically administered BPA (10 μg/kg per day) during gestational days 14-21. Then, bone tissues were obtained from neonatal rats on postnatal day 1 for histological analysis, and the bone mass of adult rat offspring was analyzed by micro-CT at postnatal week 10. Furthermore, osteoprogenitors from neonatal rats were obtained and treated with various concentrations of BPA in vitro to clarify the associated mechanism. In vivo, we found that prenatal BPA exposure reduced body weight and body length in female neonatal rats but not in male neonatal rats. Meanwhile, BPA exposure during pregnancy delayed bone development and reduced bone mass only in female rat offspring. Moreover, BPA exposure during pregnancy inhibited osteogenic function and downregulated the transforming growth factor β (TGF β) signaling pathway in the bone tissue of female neonatal rats. Our in vitro findings further indicated that various concentrations of BPA suppressed the osteogenic function of osteoprogenitors by downregulating the TGFβ signaling pathway. Meanwhile, BPA downregulated H3K9ac and expression levels of TGFβ via the ERβ/HDAC5 signaling pathway. Collectively, this research revealed that prenatal BPA exposure impairs bone development and bone mass accumulation in female rat offspring, which was attributed to inhibitory osteogenic function via the ERβ/HDAC5/TGFβ signaling pathway.

Formononetin: Biological effects and uses - A review

Formononetin (FORM) is an isoflavone from the group of phytoestrogens that exhibits a broad spectrum of physiological effects beneficial to health through dependent and independent mechanisms of estrogen. This article aimed to present FORM main functions and future prospects for applications in different areas. Scientific publications and patents dated between 1998 and 2019 were analyzed. FORM has potential as an active compound of interest to product development for the industries of food, medicine, and cosmetics, among others. Moreover, in the medical area, this active compound has shown potential in the prevention and treatment of several diseases, including chronic ones, such as cancer, obesity, and neurodegenerative diseases.

Effects of Jixueteng on Experimental Periodontitis During Orthodontic Tooth Movement in Rats

Recently, natural ingredients have focused on the inhibition of bacteria-induced alveolar bone resorption in orthodontic treatment. Jixueteng (Jix), a Chinese traditional medicine, contains several kinds of flavonoids given their biological properties. We evaluated the effects of Jix on experimental periodontitis during orthodontic tooth movement (OTM) in rats. To this end, 9-week-old male Wistar rats, which were equipped with orthodontic appliance, were orally infected with Porphyromonas gingivalis (Pg), while Jix was administered in their drinking water. A total of 28 days after the beginning of OTM, alveolar bone resorption on the right side of the upper jaws was scanned with micro-computed tomography. These were also used as histological specimens and underwent tartrate-resistant acid phosphatase (TRAP) staining. TRAP-positive multinucleated cells were counted as osteoclasts. As a result, the distance of tooth movement in the OTM and Pg infection with Jix administration (OTM + Pg + Jix) group was the same as that of the sham-infected group. The amount of bone resorption and number of osteoclasts in the OTM + Pg + Jix group was more significantly decreased than that in the OTM and Pg-infected group ( P < 0.05). Hence, Jix had little effect on OTM and inhibited Pg-induced alveolar bone destruction. We suggested that the administration of Jix can support tooth movement and contribute to the prevention of periodontitis during orthodontic treatment.

Flavonoids in Bone Erosive Diseases: Perspectives in Osteoporosis Treatment

Imbalance of bone homeostasis, with excessive bone resorption compared with bone formation, leads to the development of progressive osteopenia leading to lower bone resistance to load, with consequent pain and functional limitations. Phytochemicals with therapeutic and preventive effects against bone resorption have recently received increasing attention since they are potentially more suitable for long-term use than traditional therapeutic chemical compounds. In this systematic review of the literature of the past 5 years, comprehensive information is provided on flavonoids with potential antiresorption and pro-osteogenic effects. It aims to highlight the molecular mechanisms of these molecules, often epigenetic, and their possible pharmacological use, which is of great importance for the prevention and treatment of osteoporosis (OP).

Applicability of the OECD 455 in-vitro assay for determination of hERa agonistic activity of isoflavonoids

The Organisation for Economic Co-operation and Development (OECD)-validated transactivation assay using the human estrogen receptor alpha (hERα) Hela9903 cell line is used for activity evaluation of hERα agonists and antagonists. Due to many advantages, this assay is broadly used as an initial screening process. However, response significantly higher from that of 17-β estradiol (E2) was observed with phytoestrogens for concentrations commonly above 1 μM in previous studies. The main aim of this study was thus to ascertain the applicability of OECD protocol 455 for evaluation of estrogenic activity of natural flavonoids, including known phytoestrogens. The estrogenic activities of aglycones as well as of O-methylated and glycosylated flavonoids were evaluated. Supra-maximal luciferase activity was seen for most of the flavonoids tested at concentrations even below 1 μM. hERα-mediated luciferase expression was confirmed with the competition assay specified in OECD protocol 455. However, at concentrations above 1 μM, non-specific interactions were also observed. Instead of EC₅₀ values, which could not be determined for most of the isoflavonoids tested, the concentrations corresponding to 10% (PC₁₀) and 50% (PC₅₀) of the maximum activity of the positive control, E2, were used for quantitative determination of estrogenic activities. Appropriate evaluation of the data obtained with the current OECD protocol 455 validated assay represents a valuable tool for initial screening of natural flavonoids for estrogenic activity.

Nicotine exposure during pregnancy programs osteopenia in male offspring rats via α4β2-nAChR-p300-ACE pathway

Prenatal nicotine exposure (PNE) induces developmental toxicity in offspring. However, the long-term harmful effects on bone development and the intrauterine programming mechanism attributed to PNE remain unclear. In the present research, pregnant Wistar rats were injected subcutaneously with nicotine (2 mg/kg/d) to obtain and analyze bone samples from the fetal and adult offspring. Bone marrow mesenchymal stem cells (BMSCs) were treated with nicotine during osteogenic differentiation to clarify the related molecular mechanisms. The results indicated that PNE led to bone dysplasia in the fetuses and reduced bone mass in the adult offspring, which was mediated by the sustained activation of the local bone renin angiotensin system (RAS) and suppressed osteogenic differentiation before and after birth. In vitro, nicotine suppressed BMSCs' osteogenic function through promoting angiotensin-converting enzyme (ACE) expression and activating RAS. Furthermore, nicotine induced histone acetylase p300 into the nuclei of the BMSCs by acting on the α4β2-nicotinic acetylcholine receptor (α4β2-nAChR), leading to the increased histone 3 lysine 9 acetylation level of ACE and RAS activation. Taken together, the sustained activation of local bone RAS mediated prenatal nicotine-induced osteopenia in adult offspring via the α4β2-nAChR-p300-ACE pathway.-Xiao, H., Wen, Y., Pan, Z., Shangguan, Y., Magdalou, J., Wang, H., Chen, L. Nicotine exposure during pregnancy programs osteopenia in male offspring rats via α4β2-nAChR-p300-ACE pathway.

Sinusoidal Electromagnetic Fields Increase Peak Bone Mass in Rats by Activating Wnt10b/β-Catenin in Primary Cilia of Osteoblasts

Extremely low-frequency electromagnetic fields have been considered a potential candidate for the prevention and treatment of osteoporosis; however, their action mechanism and optimal magnetic flux density (intensity) parameter are still elusive. The present study found that 50-Hz sinusoidal electromagnetic fields (SEMFs) at 1.8 mT increased the peak bone mass of young rats by increasing bone formation. Gene array expression studies with femoral bone samples showed that SEMFs increased the expression levels of collagen-1α1 and Wnt10b, a critical ligand of the osteogenic Wnt/β-catenin pathway. Consistently, SEMFs promoted osteogenic differentiation and maturation of rat calvarial osteoblasts (ROBs) in vitro through activating the Wnt10b/β-catenin pathway. This osteogenesis-promoting effect of SEMFs via Wnt10b/β-catenin signaling was found to depend on the functional integrity of primary cilia in osteoblasts. When the primary cilia were abrogated by small interfering RNA (siRNA) targeting IFT88, the ability of SEMFs to promote the osteogenic differentiation of ROBs through activating Wnt10b/β-catenin signaling was blocked. Although the knockdown of Wnt10b expression with RNA interference had no effect on primary cilia, it significantly suppressed the promoting effect of SEMFs on osteoblastic differentiation/maturation. Wnt10b was normally localized at the bases of primary cilia, but it disappeared (or was released) from the cilia upon SEMF treatment. Interestingly, primary cilia were elongated to different degrees by different intensities of 50-Hz SEMFs, with the window effect observed at 1.8 mT, and the expression level of Wnt10b increased in accord with the lengths of primary cilia. These results indicate that 50-Hz 1.8-mT SEMFs increase the peak bone mass of growing rats by promoting osteogenic differentiation/maturation of osteoblasts, which is mediated, at least in part, by Wnt10b at the primary cilia and the subsequent activation of Wnt/β-catenin signaling. © 2019 American Society for Bone and Mineral Research.

Total flavonoid extract of Epimedium herb increases the peak bone mass of young rats involving enhanced activation of the AC10/cAMP/PKA/CREB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Epimedium sagittatum brevicornum Maxim. is an important traditional Chinese herb that has long been used to promote bone fracture healing and treat osteoporosis.

AIM OF THE STUDY

Achieving peak bone mass by adolescence has now been accepted to be fundamental for preventing osteoporosis in adulthood life. This study investigated the possibility of increasing peak bone mass in young rats using the total flavonoid extract of Epimedium herb (TFE).

MATERIALS AND METHODS

TFE was intragastrically administered to one-month-old Wistar rats at a low (100 mg/kg), middle (200 mg/kg) or high dose (400 mg/kg). Whole body bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry every two weeks. When BMD of any one of TFE groups was found to be significantly higher than that of the control, all rats were sacrificed, serum samples were collected for bone turnover biochemical assays, and femurs, tibiae and vertebrae were isolated and used in BMD, mechanical, micro-structural, histomorphometric and mechanistic studies.

RESULTS

Administration of TFE at middle and high doses for two months significantly increased the whole body, femoral and vertebral BMDs, and improved the bone mechanical and micro-architectural properties. The serum turnover biochemical results and the enhanced expression levels of bone-formation regulatory genes (Runx-2, OSX, and BMP-2) demonstrated that TFE administration increased bone formation but had no effect on bone resorption. The increased phosphorylation levels in femurs of PKA and CREB and expression of AC10 (the only soluble form of adenylyl cyclase) and the increased serum cAMP level after 4 h of TFE administration indicated that TFE promoted bone formation by activating the AC10/cAMP/PKA/CREB pathway in vivo.

CONCLUSIONS

Oral administration of TFE at 200 mg/kg for two months can increase the peak bone mass of growing rats, suggesting the possibility of using total flavonoid extract of Epimedium herb to increase the peak bone mass in adolescence which is important for preventing osteoporosis in adult life.

Exposure Duration Is a Determinant of the Effect of Sinusoidal Electromagnetic Fields on Peak Bone Mass of Young Rats

We proposed a three-step strategy to obtain the optimal therapeutic parameters, which is composed of large-scale screening at cellular level, verification in animal experiments, and confirmation by a clinical trial. The objective of the current study was to test the feasibility of our strategy. Newborn rat calvarial osteoblasts were treated by 50 Hz 1.8 mT sinusoidal electromagnetic fields (SEMFs) with 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 h/days, respectively. The osteogenic differentiation and maturation of the osteoblast were assayed and compared to obtain the optimal duration. One-month-old growing rats were then treated by the same SEMFs with 0.5, 1.5, and 2.5 h/days, respectively, and the peak bone mass was analyzed after 2 months. It was found that the optimal exposure duration to promote the osteogenic differentiation and maturation of osteoblasts was 1.5 h/days, judging by the increasing degrees of ALP activity, calcified nodules formed, the gene and protein expression levels of Runx-2, BMP-2, and Col-I, as well as the expression levels of signaling proteins of the BMP-2/Smad1/5/8 pathway. The highest increase of peak bone mass after 2 months was also obtained by 1.5 h/days, judging by the results of X-ray dual-energy absorptiometry, mechanical property analysis, micro-CT scanning, and serum bone turnover marker examinations. The above results indicated that exposure duration is a determinant for the therapeutic effect of EMFs, and the optimal therapeutic effects only can be obtained by the optimal exposure duration.

Increased H3K27ac level of ACE mediates the intergenerational effect of low peak bone mass induced by prenatal dexamethasone exposure in male offspring rats

Prenatal dexamethasone exposure (PDE) induces developmental toxicities of multiple organs in offspring. Here, we verified the intergenerational effect of low peak bone mass induced by PDE and investigated its intrauterine programming mechanism. Pregnant rats were injected subcutaneously with 0.2 mg/kg/d dexamethasone from gestation day (GD) 9 to 20. Some pregnant rats were killed for the fetuses on GD20, and the rest went on to spontaneous labor to produce the first-generation (F1) offspring. The adult F1 male offspring were mated with normal females to produce the F2 offspring. In vivo, PDE leads to low peak bone mass in F1 male offspring rats at postnatal week (PW) 28. Furthermore, PDE reduced the bone mass in F1 male offspring from GD20 to PW12. Meanwhile, the osteogenic differentiation was suppressed and the local renin–angiotensin system (RAS) was activated continuously by PDE. Moreover, the histone 3 lysine 27 acetylation (H3K27ac) level in angiotensin-converting enzyme (ACE) promoter region was increased by PDE from GD20 to PW12. Likewise, PDE induced the low peak bone mass and the activated local RAS in F2 male offspring. Meaningfully, the H3K27ac level of ACE was increased by PDE in the F2 offspring. In vitro, dexamethasone inhibited bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation and promoted RAS activation. Furthermore, dexamethasone recruited CCAAT/enhancer-binding protein α and p300 into the BMSCs nucleus by activating glucocorticoid receptor, which cooperatively increased the H3K27ac level in the ACE promoter region. In conclusion, PDE induced the low peak bone mass and its intergenerational effect, which was mediated by sustained activation of RAS via increasing H3K27ac level of ACE.

Identification of novel microRNA inhibiting actin cytoskeletal rearrangement thereby suppressing osteoblast differentiation

We report the role of miR-1187 in regulation of osteoblast functions. Over-expression of miR-1187 inhibited osteoblast differentiation. Target prediction analysis tools and experimental validation by luciferase 3' UTR reporter assay identified BMPR-II and ArhGEF-9 as direct targets of miR-1187. ArhGEF-9 activates Cdc42 which has a major role in actin reorganization. BMP-2 also induces actin polymerization. Role of miR-1187 in actin reorganization was determined by western blotting, immunofluorescence, and in vivo gene silencing studies. Reduced protein levels of BMPR-II, activated Cdc42, and downstream signaling molecules were observed in miR-1187-transfected osteoblasts. miR-1187 over-expression resulted in decreased actin polymerization. Additionally, P-cofilin, which does not bind F-actin, was decreased in miR-1187-transfected cells. These results were corroborated by administration of BMPR-II exogenously in miR-1187-transfected osteoblasts. Silencing of miR-1187 in neonatal mice mitigated all the inhibitory effects of miR-1187 on actin cytoskeletal rearrangement. Importantly, in vivo treatment of miR-1187 inhibitor to ovariectomized BALB/c mice led to significant improvement in trabecular bone microarchitecture. Overall, miR-1187 functions as a negative regulator of osteogenesis by repressing BMPR-II and ArhGEF-9 expression thus suppressing non-Smad BMP2/Cdc42 signaling pathway and inhibiting actin reorganization. miR-1187 functions as a negative regulator of osteogenesis by repressing BMPR-II expression, which in turn, suppresses non-Smad BMP2/Cdc42 signaling pathway, thus inhibiting actin cytoskeletal rearrangement. Silencing of miR-1187 significantly improves trabecular bone microarchitecture. As miR-1187 exerts a negative regulatory role in osteoblasts function, hence, we propose that therapeutic approaches targeting miR-1187 could be useful in enhancing the bone formation and treatment of pathological conditions of bone loss.

MicroRNA-495 Inhibits New Bone Regeneration via Targeting High Mobility Group AT-Hook 2 (HMGA2)

Background

MicroRNAs play critical roles in post-translational gene expression. In this study, we explored the role of miR-495 in new bone regeneration.

Material/Methods

Murine calvarial osteoblasts were isolated and cultured. Microarray was performed to identify differential miRNAs in medicarpin-induced osteoblasts differentiation. Luciferase reporter assay was performed to identify the target gene of miRNA. Murine osteoblast cells were transfected with miC, miR-495, or anti-miR-495. CCK-8 and flow cytometry were performed to detect osteoblasts proliferation and apoptosis. Western blot was used to analyze apoptosis-related proteins. qRT-PCR analysis was performed to detect gene expression. ALP activity and mineralized nodule formation test were used to evaluate bone formation. Dill-hole injury model was constructed and micro CT was utilized to measuring bone healing.

Results

Microarray analysis identified miR-495 as our miRNA of interest and luciferase reporter assay identified HMGA2 as its target gene. Over-expression of miR-495 significantly inhibited ALP activity and mineralized nodule formation as well as the expression of RUNX-2, BMP-2, and Osterix. Also, miR-495 over-expression inhibited osteoblasts proliferation and promoted apoptosis obviously. In this in vivo study, the downregulation of miR-495 promoted murine femur healing.

Conclusions

MiR-495 inhibits new bone regeneration via targeting high mobility group AT-Hook 2 (HMGA2). We propose that targeting miR-495 may be a promising therapeutic approach for bone regeneration.

Combined bioavailable isoflavones and probiotics improve bone status and estrogen metabolism in postmenopausal osteopenic women: a randomized controlled trial

Background: Female age-related estrogen deficiency increases the risk of osteoporosis, which can be effectively treated with the use of hormone replacement therapy. However, hormone replacement therapy is demonstrated to increase cancer risk. Bioavailable isoflavones with selective estrogen receptor affinity show potential to prevent and treat osteoporosis while minimizing or eliminating carcinogenic side effects.Objective: In this study, we sought to determine the beneficial effects of a bioavailable isoflavone and probiotic treatment against postmenopausal osteopenia.Design: We used a novel red clover extract (RCE) rich in isoflavone aglycones and probiotics to concomitantly promote uptake and a favorable intestinal bacterial profile to enhance isoflavone bioavailability. This was a 12-mo, double-blind, parallel design, placebo-controlled, randomized controlled trial of 78 postmenopausal osteopenic women supplemented with calcium (1200 mg/d), magnesium (550 mg/d), and calcitriol (25 μg/d) given either RCE (60 mg isoflavone aglycones/d and probiotics) or a masked placebo [control (CON)].Results: RCE significantly attenuated bone mineral density (BMD) loss at the L2-L4 lumbar spine vertebra (P < 0.05), femoral neck (P < 0.01), and trochanter (P < 0.01) compared with CON (-0.99% and -2.2%; -1.04% and -3.05%; and -0.67% and -2.79, respectively). Plasma concentrations of collagen type 1 cross-linked C-telopeptide was significantly decreased in the RCE group (P < 0.05) compared with CON (-9.40% and -6.76%, respectively). RCE significantly elevated the plasma isoflavone concentration (P < 0.05), the urinary 2-hydroxyestrone (2-OH) to 16α-hydroxyestrone (16α-OH) ratio (P < 0.05), and equol-producer status (P < 0.05) compared with CON. RCE had no significant effect on other bone turnover biomarkers. Self-reported diet and physical activity were consistent and differences were nonsignificant between groups throughout the study. RCE was well tolerated with no adverse events.Conclusions: Twice daily RCE intake over 1 y potently attenuated BMD loss caused by estrogen deficiency, improved bone turnover, promoted a favorable estrogen metabolite profile (2-OH:16α-OH), and stimulated equol production in postmenopausal women with osteopenia. RCE intake combined with supplementation (calcium, magnesium, and calcitriol) was more effective than supplementation alone. This trial was registered at clinicaltrials.gov as NCT02174666.

Formononetin, a methoxy isoflavone, enhances bone regeneration in a mouse model of cortical bone defect

The bone regeneration and healing effect of formononetin was evaluated in a cortical bone defect model that predominantly heals by intramembranous ossification. For this study, female Balb/c mice were ovariectomised (OVx) and a drill-hole injury was generated in the midfemoral bones of all animals. Treatment with formononetin commenced the day after and continued for 21 d. Parathyroid hormone (PTH1-34) was used as a reference standard. Animals were killed at days 10 and 21. Femur bones were collected at the injury site for histomorphometry studies using microcomputed tomography (μCT) and confocal microscopy. RNA and protein were harvested from the region surrounding the drill-hole injury. For immunohistochemistry, 5 µm sections of decalcified femur bone adjoining the drill-hole site were cut. μCT analysis showed that formononetin promoted bone healing at days 10 and 21 and the healing effect observed was significantly better than in Ovx mice and equal to PTH treatment in many aspects. Formononetin also significantly enhanced bone regeneration as assessed by calcein-labelling studies. In addition, formononetin enhanced the expression of osteogenic markers at the injury site in a manner similar to PTH. Formononetin treatment also led to predominant runt-related transcription factor 2 and osteocalcin localisation at the injury site. These results support the potential of formononetin to be a bone-healing agent and are suggestive of its promising role in the fracture-repair process.

3-Piperidylethoxypterocarpan: A potential bone anabolic agent that improves bone quality and restores trabecular micro-architecture in ovariectomized osteopenic rats

A series of new 6H-benzofuro[3, 2-c]chromenes (BFC, pterocarpans) with structure-activity relationships were investigated for their potential use in osteoporosis treatment. One of the BFCs 3-piperidylethoxypterocarpan 20 promotes osteoblast differentiation and mineralization at a dose as low as 1 pM via activation of ER/P38MAPK/BMP-2 pathway. When evaluated for in-vivo osteogenic activity in female Sprague-Dawley rats, BFC 20 increased bone mineral density and new bone formation, compared with control at 1.0 and 10.0 mg/kg/body weight by oral gavage for 30 days. The compound was devoid of any uterotrophic effect and led to the new bone formation in adult ovariectomized osteopenic rats. BFC 20 compound also inhibited bone resorption by reducing Ovx induced increase in urinary CTx, thus exhibiting both bone anabolic and anti-catabolic action. Finally, BFC 20 treatment to Ovx rats led to improved trabecular microarchitectural restoration and exhibited therapeutic potential as a dual acting anti-osteoporotic agent for the management of osteoporosis.

Formononetin, an isoflavone, activates AMP-activated protein kinase/β-catenin signalling to inhibit adipogenesis and rescues C57BL/6 mice from high-fat diet-induced obesity and bone loss

Balance between adipocyte and osteoblast differentiation is the key link of disease progression in obesity and osteoporosis. We have previously reported that formononetin (FNT), an isoflavone extracted from Butea monosperma, stimulates osteoblast formation and protects against postmenopausal bone loss. The inverse relationship between osteoblasts and adipocytes prompted us to analyse the effect of FNT on adipogenesis and in vivo bone loss, triggered by high-fat diet (HFD)-induced obesity. The anti-obesity effect and mechanism of action of FNT was determined in 3T3-L1 cells and HFD-induced obese male mice. Our findings show that FNT suppresses the adipogenic differentiation of 3T3-L1 fibroblasts, through down-regulation of key adipogenic markers such as PPARγ, CCAAT/enhancer-binding protein alpha (C/EBPα) and sterol regulatory element-binding protein (SREBP) and inhibits intracellular TAG accumulation. Increased intracellular reactive oxygen species levels and AMP-activated protein kinase (AMPK) activation accompanied by stabilisation of β-catenin were attributed to the anti-adipogenic action of FNT. In vivo, 12 weeks of FNT treatment inhibited the development of obesity in mice by attenuating HFD-induced body weight gain and visceral fat accumulation. The anti-obesity effect of FNT results from increased energy expenditure. FNT also protects against HFD-induced dyslipidaemia and rescues deterioration of trabecular bone volume by increasing bone formation and decreasing bone resorbtion caused by HFD. FNT's rescuing action against obesity-induced osteoporosis commenced at the level of progenitors, as bone marrow progenitor cells, obtained from the HFD mice group supplemented with FNT, showed increased osteogenic and decreased adipogenic potentials. Our findings suggest that FNT inhibits adipogenesis through AMPK/β-catenin signal transduction pathways and protects against HFD-induced obesity and bone loss.

MicroRNA-467g inhibits new bone regeneration by targeting Ihh/Runx-2 signaling

MicroRNAs are important post transcriptional regulators of gene expression and play critical role in osteoblast differentiation. In this study we report miR-467g, an uncharacterized novel miRNA, in regulation of osteoblast functions. Over-expression of miR-467g inhibited osteoblast differentiation. Target prediction analysis tools and experimental validation by luciferase 3' UTR reporter assay identified Runx-2 as a direct target of miR-467g. Over expression of miR-467g in osteoblasts down regulated Runx-2 and Ihh signaling components. Furthermore, silencing of miR-467g was done to see its role in Ihh and Runx-2 mediated bone healing and regeneration in a drill hole injury model in BALB/c mice. Silencing of miR-467g led to significant increase in new bone regeneration and Ihh and Runx-2 localization at injury site in a day dependent manner. In conclusion, miR-467g negatively regulates osteogenesis by targeting Ihh/Runx-2 signaling. We, thus, propose that therapeutic approaches targeting miR-467g could be useful in enhancing the new bone formation.

An isoflavone cladrin prevents high-fat diet-induced bone loss and inhibits the expression of adipogenic gene regulators in 3T3-L1 adipocyte

Objective

This study evaluates the effect of isoflavone cladrin on high-fat diet (HFD)-induced bone loss and adipogenesis.

Methods

Thirty-two 4-week-old male C57BL/6J mice were divided into four groups: a standard diet group, a HFD group and HFD group with cladrin (5 and 10 mg/kg per day orally) for 12 weeks. The effect of cladrin on bone micro-architecture, bone marrow cell lineages and hyperlipidaemia were assessed. For assessing anti-adipogenic activity of cladrin, 3T3-L1 cells were used.

Key findings

Cladrin attenuated HFD-induced hyperlipidaemia and bone loss by preserving bone micro-architecture and strength. Effect of cladrin was found at the level of bone marrow progenitor cells. Gene expression profile of cladrin-treated mice bone showed upregulation of osteoblast and downregulation of adipogenic transcription factors and increased OPG/RANKL ratio. Cladrin inhibited cellular lipid accumulation through downregulation of transcription factors such as PPAR-γ and C/EBP-α and modulated the expression of major adipokines involved behind obesity stimulation without eliciting cell cytotoxicity in 3T3-L1 adipocytes.

Conclusion

We conclude that cladrin may improve obesity-induced bone loss and hyperlipidaemia in mice fed HFD and adipogenesis in 3T3-L1 cells by modifying adipokines and could offer clinical benefits as a supplement to treat obesity-induced disorders.

Natural Products from Chinese Medicines with Potential Benefits to Bone Health

Osteoporosis is a progressive, systemic bone disorder characterized by loss of bone mass and microstructure, leading to reduced bone strength and increased risk of fracture. It is often associated with reduced quality of life and other medical complications. The disease is common in the aging population, particularly among postmenopausal women and patients who receive long-term steroidal therapy. Given the rapid growth of the aging population, increasing life expectancy, the prevalence of bone loss, and financial burden to the healthcare system and individuals, demand for new therapeutic agents and nutritional supplements for the management and promotion of bone health is pressing. With the advent of global interest in complementary and alternative medicine and natural products, Chinese medicine serves as a viable source to offer benefits for the improvement and maintenance of bone health. This review summarizes the scientific information obtained from recent literatures on the chemical ingredients of Chinese medicinal plants that have been reported to possess osteoprotective and related properties in cell-based and/or animal models. Some of these natural products (or their derivatives) may become promising leads for development into dietary supplements or therapeutic drugs.

9-Demethoxy-medicarpin promotes peak bone mass achievement and has bone conserving effect in ovariectomized mice: Positively regulates osteoblast functions and suppresses osteoclastogenesis

We report a new bone anabolic and anti-catabolic pterocarpan 9-demethoxy-medicarpin (DMM) for the management of postmenopausal osteoporosis. DMM promoted osteoblast functions via activation of P38MAPK/BMP-2 pathway and suppressed osteoclastogenesis in bone marrow cells (BMCs). In calvarial osteoblasts, DMM blocked nuclear factor kappaB (NFκB) signaling and inhibited the mRNA levels of pro-inflammatory cytokines. DMM treatment led to increased OPG (osteoprotegrin) and decreased transcript levels of TRAP (tartarate resistant acid phosphatase), RANK (receptor activator of NFκB) and RANKL (RANK ligand) in osteoblast-osteoclast co-cultures. Immature female SD rats administered with DMM exhibited increased bone mineral density, bone biomechanical strength, new bone formation and cortical bone parameters. Ovx mice administered with DMM led to significant restoration of trabecular microarchitecture and had reduced formation of osteoclasts and increased formation of osteoprogenitor cells in BMCs. DMM exhibited no uterine estrogenicity. Overall, these results demonstrate the therapeutic potential of DMM for the management of postmenopausal osteoporosis.

Prunetin signals via G-protein-coupled receptor, GPR30(GPER1): Stimulation of adenylyl cyclase and cAMP-mediated activation of MAPK signaling induces Runx2 expression in osteoblasts to promote bone regeneration

Prunetin is found in red clover and fruit of Prunus avium (red cherry). The effect of prunetin on osteoblast function, its mode of action and bone regeneration in vivo were investigated. Cultures of primary osteoblasts, osteoblastic cell line and HEK293T cells were used for various in vitro studies. Adult female rats received drill-hole injury at the femur diaphysis to assess the bone regenerative effect of prunetin. Prunetin at 10nM significantly (a) increased proliferation and differentiation of primary cultures of osteoblasts harvested from rats and (b) promoted formation of mineralized nodules by bone marrow stromal/osteoprogenitor cells. At this concentration, prunetin did not activate any of the two nuclear estrogen receptors (α and β). However, prunetin triggered signaling via a G-protein-coupled receptor, GPR30/GPER1, and enhanced cAMP levels in osteoblasts. G15, a selective GPR30 antagonist, abolished prunetin-induced increases in osteoblast proliferation, differentiation and intracellular cAMP. In osteoblasts, prunetin up-regulated runt-related transcription factor 2 (Runx2) protein through cAMP-dependent Erk/MAP kinase activation that ultimately resulted in the up-regulation of GPR30. Administration of prunetin at 0.25mg/kg given to rats stimulated bone regeneration at the site of drill hole and up-regulated Runx2 expression in the fractured callus and the effect was comparable to human parathyroid hormone, the only clinically used osteogenic therapy. We conclude that prunetin promotes osteoinduction in vivo and the mechanism is defined by signaling through GPR30 resulting in the up-regulation of the key osteogenic gene Runx2 that in turn up-regulates GPR30.

Potential osteogenic activity of ethanolic extract and oxoflavidin isolated from Pholidota articulata Lindley

ETHNOPHARMACOLOGICAL RELEVANCE

Pholidota articulata Lindley (PA) locally known as Hadjojen (bone jointer) belongs to family Orchidaceae is used for healing fractures in folklore tradition of Kumaon region of Uttarakhand, Himalaya, India. Bone is a dynamic organ and is constantly being remodeled in order to facilitate growth and repair. This process requires the involvement of bone forming osteoblast and bone resorbing osteoclast cells, which function in generating and mineralizing bone, giving strength and rigidity to the skeletal system. Present study was aimed to determine the therapeutic potential of ethanolic extract of PA and its isolated compound oxoflavidin, by characterizing their fracture healing properties.

MATERIALS AND METHODS

Ovariectomized (Ovx) estrogen deficient adult female Balb/c mice were used for in vivo evaluation of osteogenic or bone healing potential of ethanolic extract of PA. Further, its isolated compounds were tested for their osteogenic efficacy using alkaline phosphatase assay and mineralization assay in vitro in mice calvarial osteoblasts.

RESULTS

The ethanolic extract of PA exhibited significant restoration of trabecular micro-architecture in both femoral and tibial bones. Additionally, treatment with PA extract led to better bone quality and devoid of any uterine estrogenicity in ovariectomized estrogen deficient mice. One of the isolated compound, oxoflavidin enhanced ALP activity (a marker of osteoblast differentiation), mineral nodule formation and mRNA levels of osteogenic markers like BMP-2, Type 1 Collagen, RUNX-2 and osteocalcin.

CONCLUSION

These results warrant that ethanolic extract of PA and it's pure compound oxoflavidin have fracture healing properties. The extract and oxoflavidin exhibit a strong threapeutical potential for the treatment and management of postmenopausal osteoporosis.

Pathophysiological Mechanism of Bone Loss in Type 2 Diabetes Involves Inverse Regulation of Osteoblast Function by PGC-1α and Skeletal Muscle Atrogenes: AdipoR1 as a Potential Target for Reversing Diabetes-Induced Osteopenia

Type 2 diabetes is associated with increased fracture risk and delayed fracture healing; the underlying mechanism, however, remains poorly understood. We systematically investigated skeletal pathology in leptin receptor-deficient diabetic mice on a C57BLKS background (db). Compared with wild type (wt), db mice displayed reduced peak bone mass and age-related trabecular and cortical bone loss. Poor skeletal outcome in db mice contributed high-glucose- and nonesterified fatty acid-induced osteoblast apoptosis that was associated with peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) downregulation and upregulation of skeletal muscle atrogenes in osteoblasts. Osteoblast depletion of the atrogene muscle ring finger protein-1 (MuRF1) protected against gluco- and lipotoxicity-induced apoptosis. Osteoblast-specific PGC-1α upregulation by 6-C-β-d-glucopyranosyl-(2S,3S)-(+)-5,7,3',4'-tetrahydroxydihydroflavonol (GTDF), an adiponectin receptor 1 (AdipoR1) agonist, as well as metformin in db mice that lacked AdipoR1 expression in muscle but not bone restored osteopenia to wt levels without improving diabetes. Both GTDF and metformin protected against gluco- and lipotoxicity-induced osteoblast apoptosis, and depletion of PGC-1α abolished this protection. Although AdipoR1 but not AdipoR2 depletion abolished protection by GTDF, metformin action was not blocked by AdipoR depletion. We conclude that PGC-1α upregulation in osteoblasts could reverse type 2 diabetes-associated deterioration in skeletal health.

Pomegranate and its derivatives can improve bone health through decreased inflammation and oxidative stress in an animal model of postmenopausal osteoporosis

PURPOSE

Recently, nutritional and pharmaceutical benefits of pomegranate (PG) have raised a growing scientific interest. Since PG is endowed with anti-inflammatory and antioxidant activities, we hypothesized that it may have beneficial effects on osteoporosis.

METHODS

We used ovariectomized (OVX) mice as a well-described model of postmenopausal osteoporosis to study the influence of PG consumption on bone health. Mice were divided into five groups as following: two control groups sham-operated and ovariectomized (OVX CT) mice fed a standard diet, versus three treated groups OVX mice given a modified diet from the AIN-93G diet, containing 5.7% of PG lyophilized mashed totum (OVX PGt), or 9.6% of PG fresh juice (OVX PGj) or 2.9% of PG lyophilized mashed peel (OVX PGp).

RESULTS

As expected, ovariectomy was associated with a decreased femoral bone mineral density (BMD) and impaired bone micro-architecture parameters. Consumption of PGj, PGp, or PGt induced bone-sparing effects in those OVX mice, both on femoral BMD and bone micro-architecture parameters. In addition, PG (whatever the part) up-regulated osteoblast activity and decreased the expression of osteoclast markers, when compared to what was observed in OVX CT animals. Consistent with the data related to bone parameters, PG consumption elicited a lower expression of pro-inflammatory makers and of enzymes involved in ROS generation, whereas the expression of anti-inflammatory markers and anti-oxidant actors was enhanced.

CONCLUSION

These results indicate that all PG parts are effective in preventing the development of bone loss induced by ovariectomy in mice. Such an effect could be partially explained by an improved inflammatory and oxidative status.

Osteogenic activity of natural diterpenoids isolated from Cupressus sempervirens fruits in calvarial derived osteoblast cells via differentiation and mineralization

The aim of the present study was to investigate the antiosteoporotic activity of four structurally related diterpenoids: sugiol (1), trans-communic acid (2), 15-acetoxy imbricatolic acid (3) and imbricatolic acid (4). Their osteogenic effect was evaluated by using validated models including alkaline phosphatase (ALP) assay, mineralization assay and expression of osteogenic genes-bone morphogenetic protein-2 (BMP-2) and osteoblast transcription factor (RUNX2) - in primary calvarial cultures harvested from neonatal mice. Among them, compound 1 at a dose of 1.0 mg/kg body weight exhibited significant osteoprotective effects and did not show uterine estrogenicity at the same dose. Additionally, compound 1 treatment led to improved biomechanical properties as exhibited by increased power, energy and stiffness in femoral bones compared to untreated Ovx animals. Since osteoporotic compression fracture correlates with the mechanical characteristics of trabecular bone, so that it could effectively reduce the risk of this type of fracture by improving trabecular micro architecture in postmenopausal women. Therefore, our findings proposed that diterpenoids may be useful new chemical agents in the treatment of diseases associated with bone loss.

Red clover isoflavones enriched with formononetin lower serum LDL cholesterol-a randomized, double-blind, placebo-controlled study

BACKGROUND

Although postmenopausal combined hormone replacement therapy reduces the risk of hip fracture, long-term use may be associated with an increased risk of breast cancer, and in women more than 10 years after menopause it is associated with an increased risk of cardiovascular disease. Isoflavones, because of preferential binding to estrogen receptor beta, may retain the beneficial effects on bone but lessen the adverse effects on the breast.

OBJECTIVE

The objective of this study was to study the effects of an isoflavone obtained from red clover (Rimostil) on bone mineral density, and on low-density lipoprotein (LDL) cholesterol.

DESIGN

In a double-blind, randomized, placebo-controlled trial, 50 mg of Rimostil was given to women who were menopausal for at least 1 year. Bone mineral density of the spine, femoral neck and forearm and serum LDL cholesterol were measured at baseline and at 6-month intervals. The duration of follow-up was 2 years.

RESULTS

There was no beneficial effect of Rimostil on bone density at any site. There was a 12% fall in serum LDL cholesterol in the Rimostil-treated arm, which was significantly greater than the 2% drop seen in the control arm (P=0.005).

Ethanolic extract of Coelogyne cristata Lindley (Orchidaceae) and its compound coelogin promote osteoprotective activity in ovariectomized estrogen deficient mice

Coelogyne cristata Lindley (CC) family Orchidaceae is an Indian medicinal plant used for the treatment of fractured bones in folk-tradition of Kumaon region, Uttarakhand, India. In continuation of our drug discovery program, feeding of ethanolic extract to ovariectomized estrogen deficient mice led to significant restoration of trabecular micro architecture in both femoral and tibial bones, better bone quality and also devoid of any uterine estrogenicity. Subsequently, coelogin, a pure compound was isolated from ethyl acetate fraction of C. cristata and evaluated in in vitro osteoblast cell cultures. Treatment of coelogin to osteoblasts led to enhanced ALP activity (a marker of osteoblast differentiation), mineral nodule formation and mRNA levels of osteogenic markers like BMP-2, Type 1 Collagen and RUNX-2. Based on these results, we propose that ethanolic extract of C. cristata and its pure compound coelogin have potential in the management of post menopausal osteoporosis.

miR-542-3p suppresses osteoblast cell proliferation and differentiation, targets BMP-7 signaling and inhibits bone formation

MicroRNAs (miRNAs) are short non-coding RNAs that interfere with translation of specific target mRNAs and thereby regulate diverse biological processes. Recent studies have suggested that miRNAs might have a role in osteoblast differentiation and bone formation. Here, we show that miR-542-3p, a well-characterized tumor suppressor whose downregulation is tightly associated with tumor progression via C-src-related oncogenic pathways, inhibits osteoblast proliferation and differentiation. miRNA array profiling in Medicarpin (a pterocarpan with proven bone-forming effects) induced mice calvarial osteoblast cells and further validation by quantitative real-time PCR revealed that miR-542-3p was downregulated during osteoblast differentiation. Over-expression of miR-542-3p inhibited osteoblast differentiation, whereas inhibition of miR-542-3p function by anti-miR-542-3p promoted expression of osteoblast-specific genes, alkaline phosphatase activity and matrix mineralization. Target prediction analysis tools and experimental validation by luciferase 3′ UTR reporter assay identified BMP-7 (bone morphogenetic protein 7) as a direct target of miR-542-3p. It was seen that over-expression of miR-542-3p leads to repression of BMP-7 and inhibition of BMP-7/PI3K- survivin signaling. This strongly suggests that miR-542-3p suppresses osteogenic differentiation and promotes osteoblast apoptosis by repressing BMP-7 and its downstream signaling. Furthermore, silencing of miR-542-3p led to increased bone formation, bone strength and improved trabecular microarchitecture in sham and ovariectomized (Ovx) mice. Although miR-542-3p is known to be a tumor repressor, we have identified second complementary function of miR-542-3p where it inhibits BMP-7-mediated osteogenesis. Our findings suggest that pharmacological inhibition of miR-542-3p by anti-miR-542-3p could represent a therapeutic strategy for enhancing bone formation in vivo.

A novel flavonoid C-glucoside from Ulmus wallichiana preserves bone mineral density, microarchitecture and biomechanical properties in the presence of glucocorticoid by promoting osteoblast survival: a comparative study with human parathyroid hormone

PURPOSE

6-C-β-D-glucopyranosyl-(2S,3S)-(+)-5,7,3',4'-tetrahydroxydihydroflavonol (GTDF) is a novel compound isolated from Ulmus wallichiana, reported to have bone anabolic action in ovariectomized rats. Here, we studied the effect of GTDF in glucocorticoid (GC)-induced bone loss and its mode of action.

METHODS

Osteoblasts were cultured from rat calvaria or bone marrow to study apoptosis and differentiation by dexamethasone (Dex), methylprednisolone (MP), GTDF, quercetin and rutin. Female Sprague Dawley rats were treated with Dex or MP with or without GTDF or PTH. Efficacy was evaluated by bone microarchitecture using microcomputed tomography, determination of new bone formation by fluorescent labeling of bone and osteoblast apoptosis by co-labeling bone sections with Runx-2 and TUNEL. Serum osteocalcin was determined by ELISA.

RESULTS

GTDF preserved trabecular and cortical bones in the presence of Dex and MP and mitigated the MP-mediated suppression of serum osteocalcin. Co-administration of GTDF to MP rats increased mineral apposition, bone formation rates, bone biomechanical strength, reduced osteoblast apoptosis and increased osteogenic differentiation of bone marrow stromal cells compared to MP group, suggesting in vivo osteogenic effect of GTDF. These effects of GTDF were to a great extent comparable to PTH. GTDF prevented GC-induced osteoblast apoptosis by inhibiting p53 expression and acetylation, and activation of AKT but did not influence transactivation of GC receptor (GR).

CONCLUSIONS

GTDF protects against GC-induced bone loss by promoting osteoblast survival through p53 inhibition and activation of AKT pathways but not as a GR antagonist. GTDF has the potential in the management of GC-induced osteopenia.

Effect of formononetin on mechanical properties and chemical composition of bones in rats with ovariectomy-induced osteoporosis

Formononetin is a naturally occurring isoflavone, which can be found in low concentrations in many dietary products, but the greatest sources of this substance are Astragalus membranaceus, Trifolium pratense, Glycyrrhiza glabra, and Pueraria lobata, which all belong to Fabaceae family. Due to its structural similarity to 17β-estradiol, it can mimic estradiol's effect and therefore is considered as a “phytoestrogen.” The aim of this study was to examine the effect of formononetin on mechanical properties and chemical composition of bones in rats with ovariectomy-induced osteoporosis. 12-week-old female rats were divided into 4 groups: sham-operated, ovariectomized, ovariectomized treated with estradiol (0.2 mg/kg) and ovariectomized treated with formononetin (10 mg/kg). Analyzed substances were administered orally for 4 weeks. Ovariectomy caused osteoporotic changes, which can be observed in bone biomechanical features (decrease of maximum load and fracture load and increase of displacements for maximum and fracture loads) and bone chemical composition (increase of water and organic fraction content, while a decrease of minerals takes place). Supplementation with formononetin resulted in slightly enhanced bone mechanical properties and bone chemistry improvement (significantly lower water content and insignificantly higher mineral fraction content). To summarize, administration of formononetin to ovariectomized rats shows beneficial effect on bone biomechanical features and chemistry; thus, it can prevent osteoporosis development.