Quercitrin attenuates osteoporosis in ovariectomized rats by regulating mitogen-activated protein kinase (MAPK) signaling pathways

Quercetin ameliorates bone loss in OVX rats by modulating the intestinal flora-SCFAs-inflammatory signaling axis

BACKGROUND

Osteoporosis (OP) is a common systemic skeletal disorder characterized by an imbalance in bone homeostasis, involving increased osteoclastic bone formation and decreased osteoblastic bone resorption. Quercetin is a plant polyphenol that has been found to exhibit various biological activities, including antioxidant, anti-inflammatory, and antimicrobial effects. Previous studies have demonstrated its potential to improve postmenopausal OP, although the exact mechanism remains unclear. This study aims to investigate the anti-osteoporotic mechanism of quercetin based on the "intestinal flora - short-chain fatty acids (SCFAs) - inflammatory" signaling axis.

METHODS

In this study, we established an ovariectomized (OVX)-induced rat model, quercetin intervention and evaluated the effects on rats following antibiotic (ABX) treatment and fecal microbiota transplantation (FMT). After 6 weeks of intervention, the rats were euthanized, and samples from their femur, tibia, lumbar spine, serum, colon and feces were collected, and bone strength, intestinal flora structure, SCFAs levels and cytokine levels were assessed.

RESULTS

Quercetin modulates the intestinal flora by increasing potentially probiotic bacteria (i.e., Lactobacillales, Prevotellaceae, and Blautia) and decreasing potentially pathogenic bacteria (Desulfobacterota, Erysipelotrichales, Romboutsia, and Butyricoccaceae). It also increases SCFAs content and reduces colonic permeability by enhancing tight junction proteins (ZO-1, Occludin). Furthermore, quercetin lowers proinflammatory cytokine levels (LPS, IL-1β, and TNF-α), which enhances bone strength and prevents OVX-induced bone loss.

CONCLUSIONS

Quercetin may effectively reduce bone loss in OVX rats via the "intestinal flora - SCFAs - inflammatory" signaling pathway.

Effect of sheep bone protein hydrolysate on promoting calcium absorption and enhancing bone quality in low-calcium diet fed rats

Calcium deficiency is prone to fractures, osteoporosis and other symptoms. In this study, sheep bone protein hydrolysates (SBPHs) were obtained by protease hydrolysis. A low-calcium-diet-induced calcium-deficiency rat model was established to investigate the effects of SBPHs on calcium absorption and intestinal flora composition. The results showed that an SBPHs + CaCl2 treatment significantly increased the bone calcium content, bone mineral density, trabecular bone volume, and trabecular thickness, and reduced trabecular separation, and changed the level of bone turnover markers (P < 0.05). Supplementation of SBPHs + CaCl2 can remarkably enhance the bone mechanical strength, and the microstructure of bone was improved, and the trabecular network was more continuous, complete, and thicker. Additionally, SBPHs + CaCl2 dietary increased the abundance of Firmicutes and reduced the abundance of Proteobacteria and Verrucomicrobiota, and promoted the production of short chain fatty acids. This study indicated that SBPHs promoted calcium absorption and could be applied to alleviate osteoporosis.

Quercetin in Osteoporosis Treatment: A Comprehensive Review of Its Mechanisms and Therapeutic Potential

PURPOSE OF REVIEW

This review aims to provide a theoretical basis and insights for quercetin's clinical application in the prevention and treatment of osteoporosis (OP), analyzing its roles in bone formation promotion, bone resorption inhibition, anti-inflammation, antioxidant effects, and potential mechanisms.

RECENT FINDINGS

OP, a prevalent bone disorder, is marked by reduced bone mineral density and impaired bone architecture, elevating the risk of fractures in patients. The primary approach to OP management is pharmacotherapy, with quercetin, a phytochemical compound, emerging as a focus of recent interest. This natural flavonoid exerts regulatory effects on bone marrow mesenchymal stem cells, osteoblasts, and osteoclasts and promotes bone health and metabolic equilibrium via anti-inflammatory and antioxidative pathways. Although quercetin has demonstrated significant potential in regulating bone metabolism, there is a need for further high-quality clinical studies focused on medicinal quercetin.

Sea Buckthorn Flavonoid Extracted by High Hydrostatic Pressure Inhibited IgE-Stimulated Mast Cell Activation through the Mitogen-Activated Protein Kinase Signaling Pathway

Sea buckthorn (Hippophaë rhamnoides L.), as one of the Elaeagnaceae family, has the significant function of anti-tumor, anti-inflammation, anti-oxidation, and other physiological activities. High hydrostatic pressure (HHP) extraction has the advantages of being easy and efficient, while maintaining biological activity. In this study, sea buckthorn flavonoid (SBF) was extracted with HHP and purified sea buckthorn flavonoid (PSBF) was isolated by AB-8 macroporous resin column. HPLC analysis was used to quantified them. In addition, the effect of anti-allergy in RBL-2H3 cells by SBF, PSBF, and their flavonoid compounds was evaluated. The results demonstrate the conditions for obtaining the maximum flavonoid amount of SBF: 415 MPa for 10 min, 72% ethanol concentration, and a liquid to solid ratio of 40 mL/g, which increased the purity from 1.46% to 13.26%. Both SBF and PSBF included rutin, quercitrin, quercetin, isorhamnetin, and kaempferol. In addition, quercitrin, kaempferol, and SBF could regulate Th1/Th2 cytokine balance. Moreover, extracellular Ca2+ influx was reduced by quercitrin and PSBF. Furthermore, rutin, quercetin, iso-rhamnetin, and SBF could also inhibit P-p38 and P-JNK expression, thereby suppressing the phosphorylation of the MAPK signaling pathways. Overall, SBF is effective for relieving food allergy and might be a promising anti-allergic therapeutic agent.

Pharmacological and mechanistic aspects of quercetin in osteoporosis

Osteoporosis (OP) is a bone disease associated with increasing age. Currently, the most common medications used to treat OP are anabolic agents, anti-resorptive agents, and medications with other mechanisms of action. However, many of these medications have unfavorable adverse effects or are not intended for long-term use, potentially exerting a severe negative impact on a patient's life and career and placing a heavy burden on families and society. There is an urgent need to find new drugs that can replace these and have fewer adverse effects. Quercetin (Que) is a common flavonol in nature. Numerous studies have examined the therapeutic applications of Que. However, a comprehensive review of the anti-osteoporotic effects of Que has not yet been conducted. This review aimed to describe the recent studies on the anti-osteoporotic effects of Que, including its biological, pharmacological, pharmacokinetic, and toxicological properties. The outcomes demonstrated that Que could enhance OP by increasing osteoblast differentiation and activity and reducing osteoclast differentiation and activity via the pathways of Wnt/β-catenin, BMP/SMAD/RUNX2, OPG/RANKL/RANK, ERK/JNK, oxidative stress, apoptosis, and transcription factors. Thus, Que is a promising novel drug for the treatment of OP.

Integrating network analysis and pharmacokinetics to investigate the mechanisms of Danzhi Tiaozhi Decoction in metabolic-associated fatty liver disease (MAFLD)

ETHNOPHARMACOLOGICAL RELEVANCE

Based on ancient classics, Danzhi Tiaozhi Decoction has been successfully used to treat nonalcoholic fatty liver disease for decades. However, its therapeutic mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to investigate the effects of Danzhi Tiaozhi Decoction (DZTZD) on metabolic-associated fatty liver disease (MAFLD).

MATERIALS AND METHODS

First, we identified the active ingredients of DZTZD and their potential targets in the Traditional Chinese Medicine System Pharmacology database. Using the overlapped genes, we selected the key MAFLD-associated genes, then conducted GO and KEGG pathway enrichment analyses. Furthermore, DZTZD was administered orally to rats, and their serum and liver tissues were examined for absorbed compounds using pharmacochemistry. UPLC-Q-Exactive Orbitrap/MS was used to determine the main compounds. Then, we validated the binding association of the key targets with their active compounds with AutoDock Tools and other software. Finally, the predicted hub targets were experimentally validated.

RESULTS

We found 254 active compounds in DZTZD corresponding to 208 targets. Sixteen key genes were identified, and the enrichment analysis revealed multiple signaling pathways, including the AGE-RAGE pathway in diabetic complications and the lipid and atherosclerosis signaling pathway. Next, 160 absorbed components and metabolites were characterized in vivo, and 53 absorbed components and metabolites were characterized in liver tissue. Thirteen parent compounds were identified, including coptisine, quercetin, luteolin, and aloe-emodin. The molecular docking data demonstrated the strongest binding between the active compounds and the core proteins. Moreover, the animal experiments showed that DZTZD decreased body weight, liver weight, lipid accumulation, and ALT, AST, CRP, FFA, IL-6, PEPCK, G6P, TG, TC, and LDL-c serum levels, and increased serum HDL-c levels compared to high-fat induced rats. Besides, the RT-PCR and Western blot showed that DZTZD inhibited the SREBP1c and FAS and increased hyperlipidemia-induced CPT-1A levels. In the high-fat group, JNK phosphorylation increased, and AKT protein phosphorylation decreased, while DZTZD reversed these effects.

CONCLUSION

Based on the pharmacological network analysis, pharmacochemistry, and experimental validation, DZTZD can potentially improve MAFLD via the JNK/AKT pathway.

Quercetin suppresses ovariectomy-induced osteoporosis in rat mandibles by regulating autophagy and the NLRP3 pathway

With the aging population and the popularity of implant prostheses, an increasing number of postmenopausal osteoporosis (PMOP) patients require implant restorations; however, poor bone condition affects the long-term stability of implant prostheses. This study aimed to investigate the therapeutic effect of quercetin (QR) compared with alendronate (ALN), the primary treatment for PMOP, on mandibular osteoporosis (OP) induced by ovariectomy (OVX) in female rats. Adult female rats were treated with QR (50 mg/kg/day), ALN (6.25 mg/kg/week) by gavage for 8 weeks, chloroquine (CQ, 10 mg/kg/twice a week), and cytokine release inhibitory drug 3 (MCC950, 10 mg/kg/three times a week) by intraperitoneal injection for 8 weeks after bilateral OVX. Blood samples were collected prior to euthanasia; the mandibles were harvested and subjected to micro-computed tomography (micro-CT) and pathological analysis. QR administration controlled weight gain and significantly improved the bone microstructure in OVX rats, increasing bone mass, and bone mineral density (BMD), reducing bone trabecular spacing, and decreasing osteoclast numbers. Western blotting, real-time quantitative PCR (RT-qPCR), and serum markers confirmed that QR inhibited interleukin- 1β (IL-1β) and interleukin-18 (IL-18) on the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) protein 3 (NLRP3) pathway thereby inhibiting osteoclast differentiation, immunofluorescence and western blotting also confirmed that QR inhibited autophagy in OVX rats and suppressed the number of tartrate-resistant acid phosphatase (TRAP)-stained positive osteoclasts. The findings suggest that QR may protect the bone structure and prevent bone loss in osteoporotic rats by inhibiting the NLRP3 pathway and autophagy in osteoclasts with comparable effects to ALN, thus QR may have the potential to be a promising alternative supplement for the preventive and therapeutic treatment of PMOP.

Euonymus alatus (Thunb.) Siebold Prevents Osteoclast Differentiation and Osteoporosis

Euonymus alatus (Thunb.) Siebold, a traditional medicinal plant, has been used in China and several other Asian countries to address a variety of health concerns. The extensive research conducted on E. alatus is driven by its diverse pharmacological applications. However, its biological effects on osteoclastogenesis and osteoporosis have not been previously studied. In this research, we investigated the impact of an ethanolic extract of E. alatus (EEEA) on osteoclast differentiation and function as well as estrogen deficiency-induced bone loss. We found that EEEA inhibits osteoclast differentiation by downregulating the expression of the receptor activator of nuclear factor-κB ligand (RANKL) in osteoclast-supporting cells and by directly impeding RANKL-mediated signaling pathways for osteoclastogenesis in precursor cells. In addition, EEEA inhibited the bone-resorptive function of mature osteoclasts in vitro. Furthermore, oral administration of EEEA significantly alleviated bone loss in an ovariectomy-induced osteoporosis mouse model. Additionally, we identified phytochemicals in EEEA that have suppressive effects on osteoclast differentiation and bone loss. Collectively, these results suggest that EEEA holds potential as a biotherapeutic candidate for anti-postmenopausal osteoporosis.

Bioactivity, Molecular Mechanism, and Targeted Delivery of Flavonoids for Bone Loss

Skeletal disabilities are a prominent burden on the present population with an increasing life span. Advances in osteopathy have provided various medical support for bone-related diseases, including pharmacological and prosthesis interventions. However, therapeutics and post-surgery complications are often reported due to side effects associated with modern-day therapies. Thus, therapies utilizing natural means with fewer toxic or other side effects are the key to acceptable interventions. Flavonoids constitute a class of bioactive compounds found in dietary supplements, and their pharmacological attributes have been well appreciated. Recently, flavonoids' role is gaining renowned interest for its effect on bone remodeling. A wide range of flavonoids has been found to play a pivotal role in the major bone signaling pathways, such as wingless-related integration site (Wnt)/β-catenin, bone morphogenetic protein (BMP)/transforming growth factor (TGF)-β, mitogen-activated protein kinase (MAPK), etc. However, the reduced bioavailability and the absorption of flavonoids are the major limitations inhibiting their use against bone-related complications. Recent utilization of nanotechnological approaches and other delivery methods (biomaterial scaffolds, micelles) to target and control release can enhance the absorption and bioavailability of flavonoids. Thus, we have tried to recapitulate the understanding of the role of flavonoids in regulating signaling mechanisms affecting bone remodeling and various delivery methods utilized to enhance their therapeutical potential in treating bone loss.

Using network pharmacology and molecular docking verification to explore the mechanism of ursolic acid in the treatment of osteoporosis

Whether ursolic acid is an effective drug in treatment of osteoporosis (OP) and how it exhibit activity effect on OP is unclear. To investigated the potential molecular mechanism of ursolic acid in the treatment of OP and figured out its possible mechanism is necessary. The target genes of ursolic acid were screened by using the database of traditional chinese medicine systems pharmacology, PubMed database and UniProt database. OP-related target genes were searched by GeneCards database, and utilized online mapping tool to obtain common target genes of component-disease. String database was used to construct a protein-protein interaction (PPI) network of component-disease common target genes and perform topological analysis to screen core target genes. DAVID database was performed gene ontology (GO) functional annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis for component-disease shared target genes. Using the core target protein as the receptor and ursolic acid as the ligand, the molecular docking was performed using AutoDockVina 1.1.2 software. A total of 52 ursolic acid-related target genes and 4657 OP-related target genes were excavated, with a total of collective 43 target genes. The above-mentioned PPI network with shared target genes contains 43 nodes and 510 edges, with an average node degree value of 23.32. A total of 24 core target genes were obtained, mainly including tumor protein p53 (TP53), vascular endothelial growth factor A (VEGFA), interleukin-6 (IL6), tumor necrosis factor (TNF), caspase3 (CASP3), matrix metallo protein (MMP9), transcription factor AP-1 (JUN), activator of transcription 3 (STAT3), mitogen-activated protein kinase 8 (MAPK8), and prostaglandin endoperoxidase 2 (PTGS2), respectively. According to KEGG enrichment analysis, there are 126 treatment of OP signaling pathway were enriched. GO enrichment analysis revealed that 313 biological processes were identified. The molecular docking result showed that the binding energies were all lower than -5 kcal/mol, indicating strong binding activity to the protein by the 6 core target gene. The therapeutic effect of ursolic acid on OP may be achieved by regulating TP53, JUN, IL6, VEGFA, CASP3, and MAPK8 genes, respectively. It exhibits possible biological function in the treatment of OP mainly involve positive regulation of apoptotic process, response to drug, incytoplasm, cytosol, protein binding, identical protein binding. Its mechanism may related to multiple therapeutic targets and signaling pathways such as cancer pathway, hepatitis B, and TNF signaling pathway.

Overexpression of dihydroflavonol 4-reductase (CoDFR) boosts flavonoid production involved in the anthracnose resistance

The outbreak of anthracnose caused by Colletotrichum spp. represents a devastating epidemic that severely affects oil tea (Camellia oleifera) production in China. However, the unknown resistance mechanism to anthracnose in C. oleifera has impeded the progress of breeding disease-resistant varieties. In this study, we investigated the physiological responses of resistant and susceptible lines during C. gloeosporioides infection. Our results showed that the accumulation of malondialdehyde (MDA), catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD) in both disease-resistant and susceptible lines increased by C. gloeosporioides infection. Also, disease-resistant lines exhibited lower MDA, but higher POD, SOD, and CAT activities compared to susceptible lines. The accumulation of flavonoids in both resistant and susceptible C. oleifera leaves increased following C. gloeosporioides infection, and the increase was greater in resistant lines. Further, we identified and functionally characterized the dihydroflavonol 4-reductase (CoDFR) from the resistant C. oleifera line. We showed that the full-length coding sequence (CDS) of CoDFR is 1044 bp encoding 347 amino acids. The overexpression of CoDFR in tobacco altered the expression of flavonoid biosynthetic genes, resulting in an increased flavonoid content in leaves. CoDFR transgenic tobacco plants exhibited increased anthracnose resistance. Furthermore, the transgenic plants had higher salicylic acid content. These findings offer potential insights into the pivotal role of CoDFR involved in flavonoid-mediated defense mechanisms during anthracnose invasion in resistant C. oleifera.

A mechanistic review of chinese medicine polyphenols on bone formation and resorption

Bone reconstruction includes a steady state system of bone formation and bone absorption. This tight coupling requires subtle coordination between osteoblasts and osteoclasts. If this balance is broken, it will lead to bone mass loss, bone density reduction, and bone metabolic diseases, such as osteoporosis. Polyphenols in Chinese herbal medicines are active ingredients in plant extracts with high safety and few side effects, and they can play a role in affecting bone formation and bone resorption. Some of these have estrogen-like effects and can better target bone health in postmenopausal women. The purpose of this review is to provide comprehensive information on the mechanisms underlying the relationship between traditional Chinese medicine polyphenols and bone formation or bone resorption.

Research on the Mechanism of Liuwei Dihuang Decoction for Osteoporosis Based on Systematic Biological Strategies

Background

Osteoporosis is an important health problem worldwide. Liuwei Dihuang Decoction (LDD) and its main ingredients may have a good clinical effect on osteoporosis. Meanwhile, its mechanism for treating osteoporosis needs to be further revealed in order to provide a basis for future drug development.

Methods

A systematic biological methodology was utilized to construct and analyze the LDD-osteoporosis network. After that, the human transcription data of LDD intervention in patients with osteoporosis and protein arrays data of LDD intervention in osteoporosis rats were collected. The human transcription data analysis, protein arrays data analysis, and molecular docking were performed to validate the findings of the prediction network (LDD-osteoporosis PPI network). Finally, animal experiments were conducted to verify the prediction results of systematic pharmacology.

Results

(1) LDD-osteoporosis PPI network shows the potential compounds, potential targets (such as ALB, IGF1, SRC, and ESR1), clusters, biological processes (such as positive regulation of calmodulin 1-monooxygenase activity, estrogen metabolism, and endothelial cell proliferation), and signaling and Reactome pathways (such as JAK-STAT signaling pathway, osteoclast differentiation, and degradation of the extracellular matrix) of LDD intervention in osteoporosis. (2) Human transcriptomics data and protein arrays data validated the findings of the LDD-osteoporosis PPI network. (3) The animal experiments showed that LDD can improve bone mineral density (BMD), increase serum estradiol (E2) and alkaline phosphatase (ALP) levels, and upregulate Wnt3a and β-catenin mRNA expression (P < 0.05). (4) Molecular docking results showed that alisol A, dioscin, loganin, oleanolic acid, pachymic acid, and ursolic acid may stably bind to JAK2, ESR1, and CTNNB1.

Conclusion

LDD may have a therapeutic effect on osteoporosis through regulating the targets (such as ALB, IGF1, SRC, and ESR1), biological processes (such as positive regulation of calmodulin 1-monooxygenase activity, estrogen metabolism, and endothelial cell proliferation), and pathways (such as JAK-STAT signaling pathway, osteoclast differentiation, and degradation of the extracellular matrix) found in this research.

Therapeutic application of quercetin in aging-related diseases: SIRT1 as a potential mechanism

Quercetin, a naturally non-toxic flavonoid within the safe dose range with antioxidant, anti-apoptotic and anti-inflammatory properties, plays an important role in the treatment of aging-related diseases. Sirtuin 1 (SIRT1), a member of NAD+-dependent deacetylase enzyme family, is extensively explored as a potential therapeutic target for attenuating aging-induced disorders. SIRT1 possess beneficial effects against aging-related diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), Depression, Osteoporosis, Myocardial ischemia (M/I) and reperfusion (MI/R), Atherosclerosis (AS), and Diabetes. Previous studies have reported that aging increases tissue susceptibility, whereas, SIRT1 regulates cellular senescence and multiple aging-related cellular processes, including SIRT1/Keap1/Nrf2/HO-1 and SIRTI/PI3K/Akt/GSK-3β mediated oxidative stress, SIRT1/NF-κB and SIRT1/NLRP3 regulated inflammatory response, SIRT1/PGC1α/eIF2α/ATF4/CHOP and SIRT1/PKD1/CREB controlled phosphorylation, SIRT1-PINK1-Parkin mediated mitochondrial damage, SIRT1/FoxO mediated autophagy, and SIRT1/FoxG1/CREB/BDNF/Trkβ-catenin mediated neuroprotective effects. In this review, we summarized the role of SIRT1 in the improvement of the attenuation effect of quercetin on aging-related diseases and the relationship between relevant signaling pathways regulated by SIRT1. Moreover, the functional regulation of quercetin in aging-related markers such as oxidative stress, inflammatory response, mitochondrial function, autophagy and apoptosis through SIRT1 was discussed. Finally, the prospects of an extracellular vesicles (EVs) as quercetin loading and delivery, and SIRT1-mediated EVs as signal carriers for treating aging-related diseases, as well as discussed the ferroptosis alleviation effects of quercetin to protect against aging-related disease via activating SIRT1. Generally, SIRT1 may serve as a promising therapeutic target in the treatment of aging-related diseases via inhibiting oxidative stress, reducing inflammatory responses, and restoring mitochondrial dysfunction.

N,N-Dimethylformamide inhibits high glucose-induced osteoporosis via attenuating MAPK and NF-κB signalling

Aims

The role of N,N-dimethylformamide (DMF) in diabetes-induced osteoporosis (DM-OS) progression remains unclear. Here, we aimed to explore the effect of DMF on DM-OS development.

Methods

Diabetic models of mice, RAW 264.7 cells, and bone marrow macrophages (BMMs) were established by streptozotocin stimulation, high glucose treatment, and receptor activator of nuclear factor-κB ligand (RANKL) treatment, respectively. The effects of DMF on DM-OS development in these models were examined by micro-CT analysis, haematoxylin and eosin (H&E) staining, osteoclast differentiation of RAW 264.7 cells and BMMs, H&E and tartrate-resistant acid phosphatase (TRAP) staining, enzyme-linked immunosorbent assay (ELISA) of TRAP5b and c-terminal telopeptides of type 1 (CTX1) analyses, reactive oxygen species (ROS) analysis, quantitative reverse transcription polymerase chain reaction (qRT-PCR), Cell Counting Kit-8 (CCK-8) assay, and Western blot.

Results

The established diabetic mice were more sensitive to ovariectomy (OVX)-induced osteoporosis, and DMF treatment inhibited the sensitivity. OVX-treated diabetic mice exhibited higher TRAP5b and c-terminal telopeptides of type 1 (CTX1) levels, and DMF treatment inhibited the enhancement. DMF reduced RAW 264.7 cell viability. Glucose treatment enhanced the levels of TRAP5b, cathepsin K, Atp6v0d2, and H⁺-ATPase, ROS, while DMF reversed this phenotype. The glucose-increased protein levels were inhibited by DMF in cells treated with RANKL. The expression levels of antioxidant enzymes Gclc, Gclm, Ho-1, and Nqo1 were upregulated by DMF. DMF attenuated high glucose-caused osteoclast differentiation by targeting mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signalling in BMMs.

Conclusion

DMF inhibits high glucose-induced osteoporosis by targeting MAPK and NF-κB signalling.

Cite this article: Bone Joint Res 2022;11(4):200–209.

Chemistry, pharmacokinetics, pharmacological activities, and toxicity of Quercitrin

Quercitrin is a naturally available type of flavonoid that commonly functions as the dietary ingredient and supplement. So far, a wide spectrum of bioactivities of quercitrin have been revealed, including antioxidative stress, antiinflammation, anti-microorganisms, immunomodulation, analgesia, wound healing, and vasodilation. Based on these various pharmacological activities, increasing studies have focused on the potency of quercitrin in diverse diseases in recent years, such as bone metabolic diseases, gastrointestinal diseases, cardiovascular and cerebrovascular diseases, and others. In this paper, by collecting and summarizing publications from the recent years, the natural sources, pharmacological activities and roles in various diseases, pharmacokinetics, structure-activity relationship, as well as the toxicity of quercitrin were systematically reviewed. In addition, the underlying molecular mechanisms of quercitrin in treating related diseases, the dose-effect relationships, and the novel preparations were discussed on the purpose of broadening the application prospect of quercitrin as functional food and providing reference for its clinical application. Notably, clinical studies of quercitrin are insufficient at present, further high-quality studies are needed to firmly establish the clinical efficacy of quercitrin.

Quercitrin protects human bronchial epithelial cells from oxidative damage

Chronic obstructive pulmonary disease (COPD) is mainly caused by cigarette smoking (CS), with oxidative stress being one key component during its pathogenesis. This study aimed to investigate the effects of quercitrin (QE) on cigarette smoke extract (CSE)-induced cell apoptosis and oxidative stress in human bronchial epithelial cells (HBECs) and its underlying mechanism. HBECs were treated with 2% CSE for 24 h to establish in vitro COPD cellular models. CCK-8 assay and flow cytometry analysis were performed to evaluate cell viability and apoptosis, respectively. Western blotting was applied to examine protein levels and ELISA kits were used to examine contents of the indicated oxidant/antioxidant markers. The results demonstrated that CSE promoted apoptosis and suppressed viability of HBECs and QE reversed these effects. CSE caused increase in T-AOC, superoxide dismutase, and glutathione (GSH) peroxidase contents and decrease in MDA, reactive oxygen species , and GSH contents in HBECs, which were rescued by QE treatment. The CSE-induced Nrf2 nuclear translocation and elevation of NAD(P)H: quinone oxidoreductase 1 (NQO1) and heme oxygenase-1 (HO-1) expression were also reversed by QE in HBECs. The mitogen-activated protein kinase (MAPK) signaling was activated by CSE and further suppressed by QE in HBECs. Collectively, QE exerts a protective role in HBECs against cell apoptosis and oxidative damage via inactivation of the Nrf2/HO-1/NQO1 pathway and the MAPK/ERK pathway.

Role of Polyphenols in the Metabolism of the Skeletal System in Humans and Animals – A Review

Polyphenols are a group of compounds arousing enormous interest due to their multiple effects on both human and animal health and omnipresence in plants. A number of in vitro and animal model studies have shown that all polyphenols exhibit anti-inflammatory and antioxidant activities, and play a significant role against oxidative stress-related pathologies. They also exert gut promotory effects and prevent chronic degenerative diseases. However, less attention has been paid to the potential influence of polyphenols on bone properties and metabolism. It is well known that proper growth and functioning of the organism depend largely on bone growth and health. Therefore, understanding the action of substances (including polyphenols) that may improve the health and functioning of the skeletal system and bone metabolism is extremely important for the health of the present and future generations of both humans and farm animals. This review provides a comprehensive summary of literature related to causes of bone loss during ageing of the organism (in both humans and animals) and possible effects of dietary polyphenols preventing bone loss and diseases. In particular, the underlying cellular and molecular mechanisms that can modulate skeletal homeostasis and influence the bone modeling and remodeling processes are presented.

Potential mechanism of Ziyin Tongluo Formula in the treatment of postmenopausal osteoporosis: based on network pharmacology and ovariectomized rat model

Background

Amending from ancient classic, Ziyin Tongluo Formula (ZYTLF) has been prescribed to treat postmenopausal osteoporosis (PMOP) for decades with good curative effect. However, the possible mechanisms of it are still unknown.

Methods

Ovariectomized rat model was established to validate the therapeutic effect of ZYTLF on PMOP by Micro-CT bone analysis and pathological observation. Subsequently, active ingredients of ZYTLF and corresponding putative targets were identified by online databases. Overlapping genes were first obtained from mining genes associated with PMOP and then overlapped them with the putative targets. Key genes were selected from the multiple constructed and analyzed networks. GO and KEGG pathway enrichment analysis were performed by importing the key genes to the DAVID database. Moreover, validation of the binding association between key targets and their corresponding active compounds were accomplished by AutoDock Tools and other software. Lastly, Enzyme linked immunosorbent assay (Elisa) detection and Western blot analysis were utilized to further explore the possible mechanism of ZYTLF on PMOP.

Results

With 129 target genes interacting with PMOP, 92 active compounds of ZYTLF corresponded to 243 targets, and 50 key genes were chosen. Network analysis revealed the top 10 active ingredients, such as quercetin and kaempferol and the top 50 key genes, such as ERα, p38 MAPK, p-AKT and TGF-β1. Enrichment analysis uncovered multiple signaling pathways, including estrogen signaling pathway, TNF signaling pathway, PI3K-Akt signaling pathway and MAPK signaling pathway. Furthermore, our finding of the foremost active compounds was tightly bound to the core proteins, which were verified by molecular docking analysis. Through experimental studies, we confirmed that the prescription of ZYTLF could ameliorate the OVX-induced bone loss, suppress the osteoclast activity and boost osteoblast ability through experimental studies.

Conclusion

The potential mechanisms and therapeutic effects of ZYTLF against PMOP may be ascribed to inhibition of osteoclast activity, boost of osteoblast activity and enhancement of the expression of ERα.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00503-5.

The mechanism of Epimedin B in treating osteoporosis as revealed by RNA sequencing-based analysis

With the ageing of populations, the management of osteoporosis is a priority of society in general. Epimedin B, a major ingredient of Herba Epimedii, which has the advantages of high content and hypotoxicity has been proved to be effective in preventing osteoporosis in vitro. However, the efficacy and mechanism of Epimedin B on osteoporosis in vivo have not been well elucidated yet. This study aimed to investigate the effects and the potential mechanisms of 8-week repeated oral administration of Epimedin B (10 and 20 mg/kg/day) on a mouse osteoporosis model. Effects of Epimedin B were evaluated by examinations of serum bone turnover markers, bone mineral density, bone microstructure parameters and histopathological section. Epimedin B significantly rose N-terminal propeptide of type I procollagen (P1NP) and dropped C-telopeptide of type I collagen (CTX1). Connectivity density (Conn.D) increased significantly while structure model index (DA) decreased significantly after treated by Epimedin B. Meanwhile, Epimedin B administration significantly increased the number of trabecular bones while significantly decreased the gap between them. Overall, Epimedin B showed beneficial effects on osteoporosis. Furthermore, RNA sequencing-based analysis revealed 5 significantly down-regulated transcripts and 107 significantly up-regulated transcripts between the Epimedin B administration group and the model group. These transcripts were mapped to 15 pathways by KEGG enrichment analysis, of which PI3K-Akt signalling pathway, MAPK signalling pathway and PPAR signalling pathway were most connected to osteoporosis. To conclude, Epimedin B is effective in treating osteoporosis in mice via regulating PI3K-Akt, MAPK and PPAR signalling pathway.

Coating Polyelectrolyte Multilayers Loaded with Quercetin on Titanium Surfaces by Layer-By-Layer Assembly Technique to Improve Surface Osteogenesis Under Osteoporotic Condition

Titanium (Ti) and its alloy implants are widely used in the field of orthopedics, and osteoporosis is an important reason for implantation failure. This study aimed to establish a quercetin (QTN) controlled release system on the surface of titanium implants and to study its effects on osteogenesis and osseointegration on the surface of implants. Polyethylenimine (PEI) was first immobilized on a titanium substrate as the base layer, and then, hyaluronic acid/chitosan-quercetin (HA/CS-QTN) multilayer films were assembled on the PEI layer by a self-assembly technique. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and contact angle measurements were used to characterize and analyze the samples. The release characteristics of QTN were studied by release assays. The osteogenic ability of the samples was evaluated by experiments on an osteoporosis rat model and MC3T3-E1 cells. The FTIR, SEM, and contact angle measurements all showed that the PEI substrate layer and HA/CS-QTN multilayer film were successfully immobilized on the titanium matrix. The drug release test showed the successful establishment of a QTN controlled release system. The in vitro results showed that osteoblasts exhibited higher adhesion, proliferation and differentiation ability on the coated titanium matrix than on the pure titanium surface. In addition, the in vivo results showed that the HA/CS-QTN coating significantly increased the new bone mass around the implant. By depositing a PEI matrix layer and HA/CS-QTN multilayer films on titanium implants, a controlled release system of QTN was established, which improved implant surface osseointegration under osteoporotic conditions. This study proposes a new implant therapy strategy for patients with osteoporosis.

Developments for Collagen Hydrolysate in Biological, Biochemical, and Biomedical Domains: A Comprehensive Review

The collagen hydrolysate, a proteinic biopeptide, is used for various key functionalities in humans and animals. Numerous reviews explained either individually or a few of following aspects: types, processes, properties, and applications. In the recent developments, various biological, biochemical, and biomedical functionalities are achieved in five aspects: process, type, species, disease, receptors. The receptors are rarely addressed in the past which are an essential stimulus to activate various biomedical and biological activities in the metabolic system of humans and animals. Furthermore, a systematic segregation of the recent developments regarding the five main aspects is not yet reported. This review presents various biological, biochemical, and biomedical functionalities achieved for each of the beforementioned five aspects using a systematic approach. The review proposes a novel three-level hierarchy that aims to associate a specific functionality to a particular aspect and its subcategory. The hierarchy also highlights various key research novelties in a categorical manner that will contribute to future research.

Quantitative Determination of Quercitrin Levels in Rat Plasma Using UHPLC-MS/MS and its Application in a Pharmacokinetic Study after the Oral Administration of Polygoni Cuspidati Folium Capsules

BACKGROUND

Quercitrin is widely found in herbal medicines, and it is particularly important in the design of new therapeutic agents. Because of its wide range of biological activities, methods for detecting quercitrin and its pharmacokinetics in biological samples must be investigated.

OBJECTIVE

To develop and validate a sensitive and reliable ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the quantitative determination of quercitrin levels in rat plasma and test its application in a pharmacokinetic investigation after the oral administration of Polygoni cuspidati folium capsules (HC).

METHODS

First, a rapid analytical method implementing UHPLC-MS/MS for the quantification of quercitrin levels in rat plasma was developed and validated. The analyte and internal standard (IS) tinidazole were extracted from rat plasma via protein precipitation with 800 μL of methanol and 50 μL of 1% formic acid solution. Chromatographic separation was performed using an Agilent ZORBAX C18 column within 4 min. Mass spectrometry was performed for quantification using a triple-quadrupole mass spectrometer employing electrospray ionization in the negative ion mode. The MRM transitions for quercitrin and IS were m/z 447.2→229.9 and m/z 246.0→125.8, respectively. The UHPLC-MS/MS method for the quantitative determination of quercitrin levels in rat plasma was then applied to investigate its pharmacokinetics after the oral administration of HC in rats.

RESULTS

The developed UHPLC-MS/MS method for detecting quercitrin in rat plasma was linear over the range of 0.1-160 ng/mL. The linear regression equation was Y = (0.7373 ± 0.0023)X - (0.0087 ± 0.0021) (r2 = 0.9978). The intra- and interday precision values were within 7.8%, and the recoveries of quercitrin and IS exceeding 67.3%. The UHPLC-MS/MS method was successfully applied to characterize the pharmacokinetic profile of quercitrin in eight rats after the oral administration of HC. The experimentally obtained values were fit to a one-compartment, first-order pharmacokinetic model, and they appeared to fit the concentration-time curve.

CONCLUSION

Quercitrin was proven to be stable during sample storage, preparation, and analytical procedures. The pharmacokinetic parameters suggested that quercitrin may be present in the peripheral tissues of rats.

Stevia Genus: Phytochemistry and Biological Activities Update

The Stevia genus (Asteraceae) comprises around 230 species, distributed from the southern United States to the South American Andean region. Stevia rebaudiana, a Paraguayan herb that produces an intensely sweet diterpene glycoside called stevioside, is the most relevant member of this genus. Apart from S. rebaudiana, many other species belonging to the Stevia genus are considered medicinal and have been popularly used to treat different ailments. The members from this genus produce sesquiterpene lactones, diterpenes, longipinanes, and flavonoids as the main types of phytochemicals. Many pharmacological activities have been described for Stevia extracts and isolated compounds, antioxidant, antiparasitic, antiviral, anti-inflammatory, and antiproliferative activities being the most frequently mentioned. This review aims to present an update of the Stevia genus covering ethnobotanical aspects and traditional uses, phytochemistry, and biological activities of the extracts and isolated compounds.

Predicting and Exploring the Mechanisms of Erzhi Pill in Prevention and Treatment of Osteoporosis Based on Network Pharmacology and Zebrafish Experiments

Background

Erzhi Pill (EZP), a traditional Chinese medicine (TCM) prescription, has been widely applied to improve bone metabolism and treat osteoporosis (OP) in China. However, its effective constituents and mechanisms remain unclear.

Methods

By combining network pharmacology and zebrafish experiments, an integrative method was employed to address this problem. Firstly, the disease targets of OP were collected from two public gene databases. Secondly, the active compounds and drug targets of EZP were obtained from the traditional Chinese medicine systems pharmacology database and analysis platform (TCMSP). Thirdly, a drug-target-disease interaction network was constructed, and the key active components were identified by analyzing the topological characteristics of the network. Finally, these predicted results were tested by zebrafish experiments and compared with those from the literature. Specifically, quercetin as an important representative active component of EZP was applied to wild type and transgenic zebrafish larvae to assess its effects on skull mineralization and osteoplastic differentiation.

Results

Our study identified 72 active compounds, 220 targets and 166 signaling pathways probably involved in the prevention and treatment of OP by EZP, wherein quercetin, apigenin, daidzein, luteolin, ursolic acid and kaempferol could be the key compounds, while PI3K-Akt signaling pathway, TNF signaling pathway and IL-17 signaling pathway could be the key signaling pathways. The experiments indicated that quercetin attenuated both the decrease of skull mineralization and the inhibition of skull osteoplastic differentiation in zebrafish larvae trigged by dexamethasone.

Conclusion

Our study not only investigated potentially effective constituents and mechanisms of EZP in the prevention and treatment of OP, but also provided a reference for the in-depth research, development and application of TCM.

Quercitrin alleviates cartilage extracellular matrix degradation and delays ACLT rat osteoarthritis development: An in vivo and in vitro study

Introduction: Disruptions of extracellular matrix (ECM) degradation homeostasis play a significant role in the pathogenesis of osteoarthritis (OA). Matrix metalloproteinase 13 (MMP13) and collagen Ⅱ are important components of ECM. Earlier we found that quercitrin could significantly decrease MMP13 gene expression and increase collagen Ⅱ gene expression in IL-1β-induced rat chondrocytes and human chondrosarcoma (SW1353) cells. Objectives: The effects and mechanism of quercitrin on OA were explored. Methods: Molecular mechanisms of quercitrin on OA were studied in vitro in primary chondrocytes and SW1353 cells. An anterior cruciate ligament transection (ACLT) rat model of OA was used to investigate the effect of quercitrin in vivo. Micro-CT analysis and Safranin O-Fast Green Staining of knee joint samples were performed to observe the damage degree of tibial subchondral bone. Immunohistochemistry of knee joint samples were conducted to observe the protein level of MMP13, collagen Ⅱ and p110α in articular cartilage. Results: In vitro, quercitrin promoted cell proliferation and delayed ECM degradation by regulating MMP13 and collagen II gene and protein expressions. Moreover, quercitrin activated the Phosphatidylinositol 3-kinase p110α (p110α)/AKT/mTOR signaling pathway by targeting p110α. We also firstly showed that the gene expression level of p110α was remarkably decreased in cartilage of OA patients. The results showed that intra-articular injection of quercitrin increased bone volume/tissue volume of tibial subchondral bone and cartilage thickness and reduced the Osteoarthritis Research Society International scores in OA rats. Meanwhile, immunohistochemical results showed that quercitrin exerted anti-OA effect by delaying ECM degradation. Conclusion: These findings suggested that quercitrin may be a prospective disease-modifying OA drug for prevention and treatment of early stage OA.

Genome-wide identification of lncRNAs and mRNAs differentially expressed in human vascular smooth muscle cells stimulated by high phosphorus

Background: Cardiovascular events are the primary cause of death for chronic kidney disease patients, which occurred via vascular calcification evolving pathogenically. Although a high level of phosphorus contributes to the induction of osteogenic differentiation of vascular smooth muscle cells (VSMCs), the role of lncRNA in this process awaits further study.Methods: In this study, we systematically investigated the variation of gene expression in human VSMCs induced by high phosphorus. LncRNAs and mRNAs expression were revealed by microarray analyses of the control group and high-phosphorus (HP) group. LncRNA-mRNA co-expression network was established based on the specific lncRNA-mRNA relationships. Hierarchical clustering was used to identify a common set of regulated genes. In addition, Gene Ontology enrichment, Kyoto Gene-Encyclopedia and genomic analyses were conducted for the mRNAs differentially expressed under high phosphorus.Result: RT-qPCR results confirmed that the expression of RUNX2, BMP2 and osteocalcin in HP group exhibited significant increases than in control group (p < .05). VSMC in HP group also showed higher intracellular calcium content. Volcano plots results show that 379 mRNAs and 728 lncRNAs different expressed in HP group. LncRNA-mRNA co-expression networks analysis revealed that 8 lncRNAs were the most highly connected lncRNAs. Quantitative analysis indicated that two lncRNAs were confirmed to increase significantly in the HP group. The mRNA expression of NT5E and ICAM1 were higher in group HP, while MAP3K7CL was lower than CON group (p < .05).Conclusion: This study provided a working list of lncRNAs that may be relevant to osteogenic differentiation, which presents a new insights into the mechanism of vascular calcification induced by high phosphorus in VSMCs.

Zanthoxylum piperitum alleviates the bone loss in osteoporosis via inhibition of RANKL-induced c-fos/NFATc1/NF-κB pathway

BACKGROUND

The fruit of Zanthoxylum piperitum (ZP) is an herbal medicine as well as a spice agent in Asia to treat carminative, stomachic, anthelmintic and degenerative diseases. Z. piperitum was reported to have anti-oxidant, anti-inflammatory, anti-osteoarthritic and osteosarcoma proliferation-control effects.

PURPOSE AND STUDY DESIGN

This study was conducted to determine the anti-osteoporotic effects and mechanisms of action of ZP.

METHODS

Female ICR mice underwent ovariectomies (OVX) and were orally administered ZP at 1, 10 and 100 mg/kg for 6 weeks. The femoral and tibial bones were assessed by dual-energy X-ray absorptiometry and histology to analyze the bone mineral density (BMD) and the number of osteoclasts. Raw 264.7 cells were stimulated by 100 ng/ml receptor activator of nuclear factor-κB ligand (RANKL) for 7 days in the presence of ZP. RANKL-induced signaling molecules were analyzed in osteoclasts.

RESULTS

The levels of femoral and tibial BMD were significantly increased by ZP administration. Serum biomarkers such as osteocalcin, calcium, alkaline phosphatase and bone-specific alkaline phosphatase concentrations were markedly recovered to normal levels in ZP-treated osteoporotic mice. In addition, the number of osteoclasts in the head, trochanter and body of the femur was obviously decreased in the ZP treatment groups. Moreover, ZP treated-cells showed a reduction in the number of TRAP-positive multinuclear cells in RANKL-stimulated Raw 264.7 cells. ZP decreased the RANKL-activated NFATc1 and c-fos, transcription factors of osteoclast formation. The nuclear translocation of NF-κB and phosphorylation of ERK42/44 were inhibited by the ZP treatment in RANKL-induced osteoclasts.

CONCLUSION

Collectively, ZP exerts its inhibitory effect against bone resorption by regulating RANKL-mediated c-fos/NFATc1/NF-κB in osteoclast. ZP may prove to be a therapeutic agent for osteoporosis.

Recent Research on Flavonoids and their Biomedical Applications

Flavonoids, commonly found in various plants, are a class of polyphenolic compounds having a basic structural unit of 2-phenylchromone. Flavonoid compounds have attracted much attention due to their wide biological applications. In order to facilitate further research on the biomedical application of flavonoids, we surveyed the literature published on the use of flavonoids in medicine during the past decade, documented the commonly found structures in natural flavonoids, and summarized their pharmacological activities as well as associated mechanisms of action against a variety of health disorders including chronic inflammation, cancer, cardiovascular complications and hypoglycemia. In this mini-review, we provide suggestions for further research on the biomedical applications of flavonoids.

Metabolomics strategy reveals the osteogenic mechanism of yak (Bos grunniens) bone collagen peptides on ovariectomy-induced osteoporosis in rats

Our previous work demonstrated that yak bone collagen peptides (YBP) possessed excellent osteogenic activity in vitro. However, associations between YBP and osteoporosis were less established, and the positive effect and underlying mechanism of YBP in the treatment of osteoporotic rats in vivo remained unclear. Herein, ovariectomized rats were intragastrically administered with YBP or 17β-estradiol for 12 weeks. Bone turnover markers, bone biomechanical parameters and bone microarchitecture were investigated to identify the specific changes of potential antagonistic effects of YBP on ovariectomized rats. Then, serum samples were analyzed by UPLC/Q-TOF-MS to identify metabolites. The results showed that YBP treatment remarkably altered the content of serum bone turnover markers and prevented the ovariectomy-induced deterioration of bone mechanical and microarchitecture characteristics. A total of forty-one biomarkers for which levels changed markedly upon treatment have been identified based on non-targeted metabolomics. Among them, twenty-one metabolites displayed a downward expression level, while twenty metabolites showed an upward expression level in the YBP group and finally were selected as potential biomarkers. The levels of these biomarkers displayed significant alterations and a tendency to be restored to normal values in YBP treated osteoporotic rats. A systematic network analysis of their corresponding pathways delineated that the protective or recovery effect of YBP on osteoporosis occurred primarily by regulating the amino acid metabolism and lipid metabolism (especially unsaturated fatty acid). Collectively, these findings highlight that such peptides hold promise in further advancement as a natural alternative for functional and health-promoting foods, which could be potentially used in mediated treatment of osteoporosis.

Mesenchymal Stem Cell in Mice Uterine and Its Therapeutic Effect on Osteoporosis

Osteoporosis is a silent disease caused by low bone mineral density and is complicated by fractures. This study was designed to examine the differentiation of uterine stem cell-derived osteoprogenitor cells (UOPCs) both in vitro and in vivo, assessing their effectiveness in treating osteoporosis. CD271⁺/CD45^- UOPCs were isolated from the endometrial tissue of inbred Balb/c mice through magnetic activated cell sorting. Stem cell differentiation assays were used for CD271⁺/CD45^- UOPCs in vitro. In vivo, the UOPCs were implanted into mouse osteoporosis models through tail-vein injection for 8 weeks. Osteogenic differentiation was examined by X-rays and computed tomography (CT) scans. Enhanced green fluorescent protein (EGFP)-labeled UOPCs, obtained from C57BL/6-Tg (ACTb-EGFP) 1Osb/J mice, were used to assess cell survival in the osteoporosis model. The levels of osteogenic markers were assessed by enzyme-linked immunosorbent assay. In vitro, UOPCs were able to form into typical spheres and various differentiations. In vivo, implantation of UOPCs into osteoporosis model significantly increased bone mineral densities and bone microstructure parameters. The levels of a biochemical marker of bone metabolism, Semaphorin-3A, increased significantly. However, levels of receptor activator of nuclear factor kappa-B ligand decreased. Immunofluorescence staining of osteoporosis mice injected with green fluorescent protein+ UOPCs showed their survival for up to 7 days. In conclusion, stem cells with osteogenic differentiation potential can be isolated from uterine or endometrial tissue. These UOPCs can stably proliferate and differentiate in vitro or in vivo, which can inhibit bone resorption and osteoclast marker expression. In vivo, UOPCs significantly improved reduction in bone density caused by reduced estrogen levels. Such cell transplantation approach is potentially useful in the treatment of osteoporosis.

Oral Administration of Quercetin or Its Derivatives Inhibit Bone Loss in Animal Model of Osteoporosis

Objectives. Quercetin (Q) and its derivatives are the major members of the naturally occurring flavonoid family, which possess beneficial effects on disease prevention including osteoporosis. The present study is aimed at further investigating the efficacy of the Q and its derivatives on bone pathology, bone-related parameters under imageology, bone maximum load, and serum bone metabolism indexes in animal model of osteoporosis. Potential mechanisms of Q and its derivatives in the treatment of osteoporosis as well as the existing problems regarding the modeling method and limitations of researches in this area were also summarized. Eight databases were searched from their inception dates to February 2020. Nineteen eligible studies containing 21 comparisons were identified ultimately. The risk of bias and data on outcome measures were analyzed by the CAMARADES 10-item checklist and Rev-Man 5.3 software separately. The results displayed the number of criteria met varied from 3/10 to 7/10 with an average of 5.05. The present study provided the preliminary preclinical evidence that oral administration of Q or its derivatives was capable of improving bone pathology, bone-related parameters under imageology and bone maximum load, increasing serum osteocalcin, alkaline phosphatase, and estradiol, and reducing serum c-terminal cross-linked telopeptide of type I collagen (P < 0.05). No statistical difference was seen in survival rate, index of liver, or kidney function (P > 0.05). Q and its derivatives partially reverse osteopenia probably via antioxidant, anti-inflammatory, promoting osteogenesis, inhibiting osteoclasts, and its estrogen-like effect. The findings reveal the possibility of developing Q or its derivatives as a drug or an ingredient in diet for clinical treatment of osteoporosis.

Quercetin as an Agent for Protecting the Bone: A Review of the Current Evidence

Quercetin is a flavonoid abundantly found in fruits and vegetables. It possesses a wide spectrum of biological activities, thus suggesting a role in disease prevention and health promotion. The present review aimed to uncover the bone-sparing effects of quercetin and its mechanism of action. Animal studies have found that the action of quercetin on bone is largely protective, with a small number of studies reporting negative outcomes. Quercetin was shown to inhibit RANKL-mediated osteoclastogenesis, osteoblast apoptosis, oxidative stress and inflammatory response while promoting osteogenesis, angiogenesis, antioxidant expression, adipocyte apoptosis and osteoclast apoptosis. The possible underlying mechanisms involved are regulation of Wnt, NF-κB, Nrf2, SMAD-dependent, and intrinsic and extrinsic apoptotic pathways. On the other hand, quercetin was shown to exert complex and competing actions on the MAPK signalling pathway to orchestrate bone metabolism, resulting in both stimulatory and inhibitory effects on bone in parallel. The overall interaction is believed to result in a positive effect on bone. Considering the important contributions of quercetin in regulating bone homeostasis, it may be considered an economical and promising agent for improving bone health. The documented preclinical findings await further validation from human clinical trials.

Quercetin for myocardial ischemia reperfusion injury: A protocol for systematic review and meta-analysis

BACKGROUND

At present, there is no effective therapy for preventing myocardial ischemia reperfusion injury (MIRI), and it is inevitable. The methods how to effectively decrease MIRI have attracted the attention of medical researches in recent years. Quercetin is a part of natural flavonoids in plant polyphenols. Many studies have found that quercetin has a positive effect on MIRI.

METHODS

In order to clarify the effectiveness and potential mechanisms of quercetin for MIRI animals, we searched for animal studies of quercetin for MIRI in Wanfang data Information, Chinese National Knowledge Infrastructure, VIP information database, China Biology Medicine disc, EMBASE, PubMed, and Web of Science. Participant intervention comparator outcomes of this study are as flowing: P, rats in MIRI; I, received quercetin treatment merely; C, received only vehicle or no treatment; O, Main outcomes are myocardial infarction size and markers of myocardial injury. Additional outcomes are serum indices or protein levels tied to the mechanisms of quercetin in myocardial l/R injury. Review Manager 5.2 software and Stata14.0 will be used for data analysis. SYRCLE's risk of bias tool will be used for risk of bias analysis of animal studies.

DISCUSSION

This preclinical systematic review and meta-analysis will evaluate the effects and mechanisms of quercetin for MIRI animals, and provide more evidence-based guidance for transforming basic research into clinical treatment.

TRIAL REGISTRATION

INPLASY202050067, registered on 16/5/2020.

MicroRNA-23 suppresses osteogenic differentiation of human bone marrow mesenchymal stem cells by targeting the MEF2C-mediated MAPK signaling pathway

BACKGROUND

The present study aimed to determine the role and mechanism of miR-23 with respect to regulating the osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs).

MATERIALS

The expression of miR-23 and MEF2C was measured in osteoporosis (OP) patients and healthy controls by a quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). The correlation between miR-23 and MEF2C was determined by the Pearson correlation coefficient. Moreover, bioinformatic analysis was performed using public databases. Target gene function and potential pathways were further examined. Then, we used a miR-23 mimic or inhibitor to further explore the potential mechanism of miR-23.

RESULTS

miR-23 is found to be up-regulated and MEF2C is down-regulated in OP patients compared to healthy controls. miR-23 had a negative correlation with MEF2C (r = -0.937, p = 0.001). Bioinformatic analysis revealed that a total of 664 overlapping target genes were found in the TargetScan (http://www.targetscan.org), miRDB (http://mirdb.org) and miRanda (http://www.microrna.org/microrna/home.do) databases. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis indicated that miR-23 may regulate the mitogan-activated protein kinase (MAPK) signaling pathway. miR-23 is down-regulated and MEF2C is significantly up-regulated in the osteogenic differentiation of hBMSCs. MEF2C was significantly up-regulated in the osteogenic differentiation of hBMSCs. Overexpression of miR-23 significantly down-regulated alkaline phosphatase (ALP) activity and calcium deposition, whereas the miR-23 inhibitor had the opposite effects. Moreover, overexpression of miR-23 significantly decreased osteoblast-related markers (Runx2, Osx, ALP and OCN). Further experiments confirmed that MEF2C is a direct target of miR-23. Moreover, the miR-23 mimic enhanced the expression of p-p38 but had no effect on p-JNK.

CONCLUSIONS

miR-23 decreases the osteogenic differentiation of hBMSCs through the MEF2C/MAPK signaling pathway.

Engineered human myocardium with local release of angiogenic proteins improves vascularization and cardiac function in injured rat hearts

Heart regeneration after myocardial infarction requires new cardiomyocytes and a supportive vascular network. Here, we evaluate the efficacy of localized delivery of angiogenic factors from biomaterials within the implanted muscle tissue to guide growth of a more dense, organized, and perfused vascular supply into implanted engineered human cardiac tissue on an ischemia/reperfusion injured rat heart. We use large, aligned 3-dimensional engineered tissue with cardiomyocytes derived from human induced pluripotent stem cells in a collagen matrix that contains dispersed alginate microspheres as local protein depots. Release of angiogenic growth factors VEGF and bFGF in combination with morphogen sonic hedgehog from the microspheres into the local microenvironment occurs from the epicardial implant site. Analysis of the 3D vascular network in the engineered tissue via Microfil® perfusion and microCT imaging at 30 days shows increased volumetric network density with a wider distribution of vessel diameters, proportionally increased branching and length, and reduced tortuosity. Global heart function is increased in the angiogenic factor-loaded cardiac implants versus sham. These findings demonstrate for the first time the efficacy of a combined remuscularization and revascularization therapy for heart regeneration after myocardial infarction.

Serum metabonomics analysis of quercetin against the toxicity induced by cadmium in rats

This study aimed to investigate the protective effect of quercetin against the toxicity induced by chronic exposure to low levels of cadmium in rats by an ultra performance liquid chromatography mass spectrometer. Rats were randomly divided into six groups as follows: control group (C), low dose of quercetin group (Q1: 10 mg/kg·bw), high dose of quercetin group (Q2: 50 mg/kg·bw), cadmium chloride group (D), low dose of quercetin plus cadmium chloride group (DQ1), and high dose of quercetin plus cadmium chloride group (DQ2). Cadmium chloride (CdCl₂ ) was administered to rats by drinking water ad libitum in a concentration of 40 mg/L. The final amount of CdCl₂ ingested was estimated from the water consumption data to be 4.85, 4.91, and 4.89 mg/kg·bw/day, for D, DQ1, and DQ2 groups, respectively. After a 12-week treatment, the serum samples of rats were collected for metabonomics analysis. Ten potential biomarkers were identified for which intensities were significantly increased or reduced as a result of the treatment. These metabolites included isorhamnetin 4'-O-glucuronide, 3-indolepropionic acid, tetracosahexaenoic acid, lysophosphatidylcholine (LysoPC) (20:5), lysoPC (18:3), lysophosphatidylethanolamine (LysoPE) (20:5/0:0), bicyclo-prostaglandin E2, sulpholithocholylglycine, lithocholyltaurine, and glycocholic acid. Results indicated that quercetin exerted a protective effect against cadmium-induced toxicity by regulating lipid and amino acid metabolism, enhancing the antioxidant defense system and protecting liver and kidney function.

A chitosan film containing quercetin-loaded transfersomes for treatment of secondary osteoporosis

Osteoporosis, due to its prevalence worldwide, is a serious health problem. Topical administration of quercetin, a phytoestrogen, in the form of deformable transfersomes, could be used to treat osteoporosis to overcome its low oral solubility and bioavailability. Formulation process of transfersomes was screened by fractional factorial design and further optimized using full factorial design. Transfersomes showed good characteristics such as entrapment efficiency, particle size, zeta potential, and polydispersity index (83.0 ± 2.2%, 75.95 ± 2 nm, - 13.6 ± 6 mv and 0.333, respectively). Transfersomes were further loaded into chitosan film and showed good permeation through rat skin. Further, glucocorticoid-induced osteoporosis rat model showed induction of osteoporosis after day 30. On day 45, treatment with chitosan film containing quercetin-loaded transfersomes showed remarkable rise in femur thickness, length, density as well as in serum biochemical parameters such as calcium, phosphorous, alkaline phosphatase, and tartrate-resistant alkaline phosphatase compared to positive control group. Tensile strength of osteoporotic femur bone was also found to be increased and was comparable with normal group. Histomicrographic analysis of femur bone exhibited less disruptive and lytic changes. Thus, all the above findings indicated the beneficial effects of quercetin-loaded transfersome chitosan film, due to decline in osteoclastogenesis and osteoblast apoptosis, which further favored increase in osteoblast numbers and mineralization of bones. Thus, chitosan film containing quercetin-loaded transfersomes was found to be good alternative to oral administration of quercetin to treat osteoporosis, while easy applicability of film in the form of wrist band anytime, anywhere, and even at work achieve patient compliance. Graphical abstract.

Extracellular regulated kinase 5 mediates osteoporosis through modulating viability and apoptosis of osteoblasts in ovariectomized rats

Postmenopausal osteoporosis is a common condition characterized by the increase and activation of osteoclasts. The present study aimed to investigate the effects of extracellular signal-regulated kinase (ERK) 5 (ERK-5) on postmenopausal osteoporosis by regulating the biological behaviors of osteoblasts. Sprague-Dawley (SD) rats were ovariectomized to develop an osteoporosis model. A lentivirus packaging system was employed to generate lentiviruses capable of up- or down-regulating the expression of ERK-5 in ovariectomized rats. The femoral biomechanical properties, bone mineral density (BMD), contents of calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) and bone turnover markers in rats, as well as viability, cycle and apoptosis of osteoblasts and ALP activity in osteoblasts were measured in the ovariectomized rats so as to explore the functional significance of ERK-5 in postmenopausal osteoporosis. The femoral mechanical strength of ovariectomized rats was enhanced by overexpression of ERK-5. Meanwhile femoral BMD, and bone metabolism were increased, and bone turnover normalized in the ovariectomized rats when ERK-5 was overexpressed. Lentivirus-mediated ERK-5 overexpression in osteoblasts was observed to inhibit osteoblast apoptosis, and promote viability, accompanied with increased ALP activity. Taken together, ERK-5 could decelerate osteoblast apoptosis and improve postmenopausal osteoporosis by increasing osteoblast viability. Thus, our study provides further understanding on a promising therapeutic target for postmenopausal osteoporosis.

Systems pharmacology dissection of action mechanisms of Dipsaci Radix for osteoporosis

AIMS

Osteoporosis (OP) is a systemic metabolic bone disease characterized by bone mass decrease and microstructural degradation, which may increase the risk of bone fracture and leading to high morbidity. Dipsaci Radix (DR), one typical traditional Chinese medicine (TCM), which has been applied in the treatment of OP with good therapeutic effects and few side effects. However, the underlying molecular mechanisms of DR to treat OP have not been fully elucidated. In this study, we aim to dissect the molecular mechanism of DR in the treatment of OP.

MATERIALS AND METHODS

A systems pharmacology approach was employed to comprehensively dissect the action mechanisms of DR for the treatment of OP.

KEY FINDINGS

10 compounds were screened out as the potential active ingredients with excellent biological activity based on in silico ADME (absorption, distribution, metabolism and excretion) prediction model. Then, 36 key protein targets of 6 compounds were identified by systems drug targeting model (SysDT) and they were involved in several biological processes, such as osteoclast differentiation, osteoblast differentiation and anti-inflammation. The target-pathway network indicated that targets are mainly mapped in multiple signaling pathways, i.e., MAPK, Tumor necrosis factor α (TNF-α), NF-κb and Toll-like receptor pathways. The in vitro results indicated that the compounds ursolic acid and beta-sitosterol effectively inhibited the osteoclast differentiation.

SIGNIFICANCE

These results systematically dissected that DR exhibits the therapeutic effects of OP by the regulation of immune system-related pathways, which provide novel perspective to drug development of OP.

The efficacy and potential mechanism of cnidium lactone to inhibit osteoclast differentiation

Cnidium lactone is effective in the maintenance of bone mass in various osteoporosis models; however, the precise molecular mechanisms are not understood. In this study, we investigated the effects and underlying mechanisms of action of cnidium lactone on receptor activator of NF-κB ligand (RANKL)-induced osteoclastogenesis. Cnidium lactone dose-dependently inhibited osteoclast differentiation and formation, decreased the bone-resorbing activity of osteoclasts, and downregulated the expression of osteoclast differentiation marker genes. Cnidium lactone treatment considerably reduced RANKL-induced p38 MAPK and PI3K-Akt signal activity in RAW264.7 cells. The cnidium lactone-induced osteoclastogenesis was significantly attenuated by inhibition of p38 and PI3K through pretreatment with SB203580 and LY294002, respectively. Furthermore, cnidium lactone inhibited the expression of c-Fos and NFATc-1 with dose-dependently and enhanced by SB203580 and LY294002. In conclusion, cnidium lactone inhibits osteoclast differentiation through p38 MAPK and PI3K-Akt signalling pathway/c-Fos/NFATc1 signalling pathway.

Bioinformatics Analysis Reveals the Altered Gene Expression of Patients with Postmenopausal Osteoporosis Using Liuweidihuang Pills Treatment

Postmenopausal osteoporosis (PMOP), as well as its associated increased risk for fragility fracture, is one of the most disabling consequences of aging in women. This present study aimed to identify candidate genes that involve pathogenesis of PMOP and the therapeutic mechanism of Liuweidihuang (LWDH) pills on PMOP. We integrated microarray datasets of PMOP derived from the Gene Expression Omnibus (GEO) to screen differentially expressed genes (DEGs) between PMOP and normal controls as well as patients with PMOP and patients after treatment of LWDH pills. GO and KEGG enrichment analysis for DEGs were performed. The shared DEGs, associated with both the pathogenesis of PMOP and the therapeutic mechanism of LWDH, were further analyzed by protein-protein interaction (PPI) network. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to verify the DEGs obtained by our integrated analysis. Compared with normal controls, 1732 DEGs in PMOP were obtained with p<0.05. According to the qRT-PCR results, expression of ATF2, FBXW7, RDX, and RBBP4 was consistent with that in our integrated analysis, generally. GO and KEGG enrichment analysis showed that those DEGs were significantly enriched in regulation of transcription, DNA-dependent, cytoplasm, protein binding, and MAPK signaling pathway. A total of 58 shared DEGs in PMOP versus normal control and in patients with PMOP versus patients after LWDH treatment were identified, which had opposite expression trend in these two comparisons. In the PPI network, CSNK2A1, ATF2, and FBXW7 were three hub proteins. Three genes including ATF2, FBXW7, and RDX were speculated to be therapeutic targets of LWDH for PMOP based on BATMAN-TCM database. We speculated that three genes of ATF2, FBXW7, and RDX may play crucial roles in both pathogenesis of PMOP and therapeutic mechanism of LWDH on PMOP. Our results may provide clues for the molecular pathogenesis of PMOP and offer new possibilities for treatment of PMOP.

Let-7a-5p inhibits BMSCs osteogenesis in postmenopausal osteoporosis mice

PURPOSE

The aim of this study was to investigate the mechanism of let-7a-5p in osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in postmenopausal osteoporosis (PMOP) mice.

METHODS

A mouse model of PMOP was established and osteoporosis model was identified by micro-CT scan. BMSCs in the sham group and PMOP group were cultured and osteogenic differentiation was induced. The expression of let-7a-5p in BMSCs was detected by qRT-PCR, and BMSCs was induced by osteogenic differentiation in sham and PMOP group. The BMSCs treated by let-7a-5p mimics, let-7a-5p inhibitor and negative control were named as let-7a-5p mimics group, mimics NC group, let-7a-5p inhibitor group and inhibitor NC group, respectively. ALP staining and alizarin red staining were used to detect osteogenic differentiation ability, qRT-PCR and western blot were used to detect the expression of Runt-related transcription factor 2 (Runx2) and Osterix. The targeting relationship between let-7a-5p and TGFBR1 were verificated by target scan and luciferase reporter gene assay.

RESULTS

The PMOP mouse model was successfully established. The expression of let-7a-5p in BMSCs of PMOP group was significantly higher than that in the sham group (P < 0.05). Let-7a-5p reduced the expression of ALP and the formation of calcified nodules, while also inhibited the expression of Runx2 and Osterix. TGFBR1 is the target gene of let-7a-5p.

CONCLUSION

Let-7a-5p might inhibit the osteogenic differentiation of BMSCs in PMOP mice by regulating TGFBR1.

Adenosine Attenuates LPS-Induced Cardiac Dysfunction by Inhibition of Mitochondrial Function via the ER Pathway

Sepsis is a life-threatening organ dysfunction syndrome with a high rate of mortality. It is caused by an abnormal immune response to infection, and the occurrence of sepsis-induced cardiomyopathy is the primary cause of death. The present study was designed to examine the effects of adenosine on lipopolysaccharide- (LPS-) induced cardiac anomalies and the underlying mechanisms involved. Adenosine (25, 50, and 100 mg/kg, i.g., 2 times/day) was administered for three days, followed by the induction of sepsis by intraperitoneal injection of LPS (10 mg/kg/2h). The effects of adenosine on inflammatory factors, LVEF, LVFS, and MAPK in septic rats (half male and half female) were observed. Subsequently, the effect of adenosine (10 μM) on the mitochondrial function of H9c2 cells stimulated with LPS (20 μg/mL, 24 h) was observed in the presence and absence of the estrogen receptor-specific antagonist ICI182,780. The results show that medium to high doses of adenosine can significantly promote cardiac function (LVEF and LVFS) and reduce the levels of inflammatory factors (TNF-α, IL-6, PCT, and cTnI) and p-JNK in septic rats, with a significant difference seen between male and female rats. The results of flow cytometry show that adenosine significantly inhibited increases in ROS levels, mitochondrial membrane potential, and the swelling degree of mitochondria in H9c2 cells stimulated with LPS, but this effect could be blocked by ICI182,780, indicating that adenosine attenuated LPS-induced cardiac dysfunction by inhibiting mitochondrial function via the ER pathway.

Decreased microRNA-182-5p helps alendronate promote osteoblast proliferation and differentiation in osteoporosis via the Rap1/MAPK pathway

Osteoporosis (OP) is a serious health problem that contributes to osteoporotic structural damage and bone fragility. MicroRNAs (miRNAs) can exert important functions over bone endocrinology. Therefore, it is of substantial significance to clarify the expression and function of miRNAs in bone endocrine physiology and pathology to improve the potential therapeutic value for metabolism-related bone diseases. We explored the effect of microRNA-182-5p (miR-182-5p) on osteoblast proliferation and differentiation in OP rats after alendronate (ALN) treatment by targeting adenylyl cyclase isoform 6 (ADCY6) through the Rap1/mitogen-activated protein kinase (MAPK) signaling pathway. Rat models of OP were established to observe the effect of ALN on OP, and the expression of miR-182-5p, ADCY6 and the Rap1/MAPK signaling pathway-related genes was determined. To determine the roles of miR-182-5p and ADCY6 in OP after ALN treatment, the relationship between miR-182 and ADCY6 was initially verified. Osteoblasts were subsequently extracted and transfected with a miR-182-5p inhibitor, miR-182-5p mimic, si-ADCY6 and the MAPK signaling pathway inhibitor U0126. Cell proliferation, apoptosis and differentiation were also determined. ALN treatment was able to ease the symptoms of OP. miR-182-5p negatively targeted ADCY6 to inhibit the Rap1/MAPK signaling pathway. Cells transfected with miR-182 inhibitor decreased the expression of ALP, BGP and COL I, which indicated that the down-regulation of miR-182-5p promoted cell differentiation and cell proliferation and inhibited cell apoptosis. In conclusion, the present study shows that down-regulated miR-182-5p promotes the proliferation and differentiation of osteoblasts in OP rats through Rap1/MAPK signaling pathway activation by up-regulating ADCY6, which may represent a novel target for OP treatment.

Contributions of Bioactive Molecules in Stem Cell-Based Periodontal Regeneration

Periodontal disease is a widespread disease, which without proper treatment, may lead to tooth loss in adults. Because stem cells from the inflammatory microenvironment created by periodontal disease exhibit impaired regeneration potential even under favorable conditions, it is difficult to obtain satisfactory therapeutic outcomes using traditional treatments, which only focus on the control of inflammation. Therefore, a new stem cell-based therapy known as cell aggregates/cell sheets technology has emerged. This approach provides sufficient numbers of stem cells with high viability for treating the defective site and offers new hope in the field of periodontal regeneration. However, it is not sufficient for regenerating periodontal tissues by delivering cell aggregates/cell sheets to the impaired microenvironment in order to suppress the function of resident cells. In the present review, we summarize some promising bioactive molecules that act as cellular signals, which recreate a favorable microenvironment for tissue regeneration, recruit endogenous cells into the defective site and enhance the viability of exogenous cells.