Protective Effects of Ligustroflavone, an Active Compound from Ligustrum lucidum, on Diabetes-Induced Osteoporosis in Mice: A Potential Candidate as Calcium-Sensing Receptor Antagonist

The screened compounds from Ligustri Lucidi Fructus using the immobilized calcium sensing receptor column exhibit osteogenic activity in vitro

Calcium sensing receptor (CaSR) has become the novel target of treating osteoporosis with herbal medicine Ligustri Lucidi Fructus (LLF), however, the bioactive compounds responsible for anti-osteoporosis are hard to clarify due to the complexity and diversity of chemical constituents in it. Herein, the immobilized CaSR column was packed with stationary phase materials, which were derived from integrating CLIP-tagged CaSR directly out of crude cell lysates onto the surface of silica gels (5.83 mg/g) in a site-specific covalent manner. The column had a great specificity of recognizing agonists and kept a good stability for at least 3 weeks. The two compounds from LLF extract were screened and identified as olenuezhenoside and ligustroflavone using the immobilized CaSR column in conjunction with mass spectrometry. Molecular docking predicted that both compounds were bound in venus flytrap (VFT) domain of CaSR by the formation of hydrogen bonds. Cellular results showed that both compounds exhibited the distinct osteogenic activity by enhancing the proliferation, differentiation and mineralization of osteoblastic cells. Our study demonstrated that, the immobilized protein column enables to screen the bioactive compounds rapidly from herbal extract, and the newly discovered natural product ligands towards CaSR, including olenuezhenoside and ligustroflavone, will be the candidates for the treatment of osteoporosis.

Mechanism of traditional Chinese medicine in elderly diabetes mellitus and a systematic review of its clinical application

Objective: Affected by aging, the elderly diabetes patients have many pathological characteristics different from the young people, including more complications, vascular aging, cognitive impairment, osteoporosis, and sarcopenia. This article will explore their pathogenesis and the mechanism of Traditional Chinese medicine (TCM) intervention, and use the method of systematic review to evaluate the clinical application of TCM in elderly diabetes. Method: Searching for randomized controlled trials (RCTs) published from January 2000 to November 2023 in the following databases: Web of Science, Pubmed, Embase, Cochrane Library, Sinomed, China National Knowledge Internet, Wanfang and VIP. They were evaluated by three subgroups of Traditional Chinese Prescription, Traditional Chinese patent medicines and Traditional Chinese medicine extracts for their common prescriptions, drugs, adverse reactions and the quality of them. Results and Conclusion: TCM has the advantages of multi-target and synergistic treatment in the treatment of elderly diabetes. However, current clinical researches have shortcomings including the inclusion of age criteria and diagnosis of subjects are unclear, imprecise research design, non-standard intervention measures, and its safety needs further exploration. In the future, the diagnosis of elderly people with diabetes needs to be further clarified. Traditional Chinese patent medicines included in the pharmacopoeia can be used to conduct more rigorous RCTs, and then gradually standardize the traditional Chinese medicine prescriptions and traditional Chinese medicine extracts, providing higher level evidence for the treatment of elderly diabetes with traditional Chinese medicine.

Mechanisms of action and synergetic formulas of plant-based natural compounds from traditional Chinese medicine for managing osteoporosis: a literature review

Osteoporosis (OP) is a systemic skeletal disease prevalent in older adults, characterized by substantial bone loss and deterioration of microstructure, resulting in heightened bone fragility and risk of fracture. Traditional Chinese Medicine (TCM) herbs have been widely employed in OP treatment owing to their advantages, such as good tolerance, low toxicity, high efficiency, and minimal adverse reactions. Increasing evidence also reveals that many plant-based compounds (or secondary metabolites) from these TCM formulas, such as resveratrol, naringin, and ginsenoside, have demonstrated beneficial effects in reducing the risk of OP. Nonetheless, the comprehensive roles of these natural products in OP have not been thoroughly clarified, impeding the development of synergistic formulas for optimal OP treatment. In this review, we sum up the pathological mechanisms of OP based on evidence from basic and clinical research; emphasis is placed on the in vitro and preclinical in vivo evidence-based anti-OP mechanisms of TCM formulas and their chemically active plant constituents, especially their effects on imbalanced bone homeostasis regulated by osteoblasts (responsible for bone formation), osteoclasts (responsible for bone resorption), bone marrow mesenchymal stem cells as well as bone microstructure, angiogenesis, and immune system. Furthermore, we prospectively discuss the combinatory ingredients from natural products from these TCM formulas. Our goal is to improve comprehension of the pharmacological mechanisms of TCM formulas and their chemically active constituents, which could inform the development of new strategies for managing OP.

The role of secreted osteoclastogenic factor of activated T cells in bone remodeling

The process of bone remodeling is connected with the regulated balance between bone cell populations (including bone-forming osteoblasts, bone-resorbing osteoclasts, and the osteocyte). And the mechanism of bone remodeling activity is related to the major pathway, receptor activator of nuclear factor kappaB (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) signaling axis. Recently, researchers have found a novel cytokine secreted by activated T cells, which is related to osteoclastogenesis in the absence of osteoblasts or RANKL, leading to bone destruction. They name it the secreted osteoclastogenic factor of activated T cells (SOFAT). SOFAT has been proven to play an essential role in bone remodeling, like mediating the bone resorption in rheumatoid arthritis (RA) and periodontitis. In this review, we outline the latest research concerning SOFAT and discuss the characteristics, location, and regulation of SOFAT. We also summarize the clinical progress of SOFAT and assume the future therapeutic target in some diseases related to bone remodeling.

A Review on the Molecular Mechanisms of Action of Natural Products in Preventing Bone Diseases

The drugs used for treating bone diseases (BDs), at present, elicit hazardous side effects that include certain types of cancers and strokes, hence the ongoing quest for the discovery of alternatives with little or no side effects. Natural products (NPs), mainly of plant origin, have shown compelling promise in the treatments of BDs, with little or no side effects. However, the paucity in knowledge of the mechanisms behind their activities on bone remodeling has remained a hindrance to NPs’ adoption. This review discusses the pathological development of some BDs, the NP-targeted components, and the actions exerted on bone remodeling signaling pathways (e.g., Receptor Activator of Nuclear Factor κ B-ligand (RANKL)/monocyte/macrophage colony-stimulating factor (M-CSF)/osteoprotegerin (OPG), mitogen-activated protein kinase (MAPK)s/c-Jun N-terminal kinase (JNK)/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), Kelch-like ECH-associated protein 1 (Keap-1)/nuclear factor erythroid 2–related factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1), Bone Morphogenetic Protein 2 (BMP2)-Wnt/β-catenin, PhosphatidylInositol 3-Kinase (PI3K)/protein kinase B (Akt)/Glycogen Synthase Kinase 3 Beta (GSK3β), and other signaling pathways). Although majority of the studies on the osteoprotective properties of NPs against BDs were conducted ex vivo and mostly on animals, the use of NPs for treating human BDs and the prospects for future development remain promising.

Fructus Ligustri Lucidi aqueous extract promotes calcium balance and short-chain fatty acids production in ovariectomized rats

ETHNOPHARMACOLOGICAL RELEVANCE

Fructus Ligustri Lucidi (FLL) is an edible herb with anti-osteoporotic activity, yet whether and how the aqueous extract of this herb affect calcium metabolism in preservation of bone quality remain unclear.

AIM OF THE STUDY

To investigate the effects of FLL aqueous extract on calcium balance and short-chain fatty acids (SCFAs) production in ovariectomized (OVX) rats.

MATERIALS AND METHODS

OVX rats were daily and orally administrated with FLL aqueous extract (3.5 g/kg) for 14 weeks. The levels of N-terminal propeptide of type I collagen (PINP) and C-terminal telopeptide of type I collagen (CTx-I) in rat serum were evaluated by ELISA assays. The concentration of calcium in serum, urine, and feces were determined by biochemical assays. Bone quality was determined by Micro-CT, a three-point bending assay, and Fourier Transform Infrared (FTIR) Spectrometry. The expressions of Calbindin D28K and Calcium-sensing receptor (CaSR) in kidney as well as the Vitamin D receptor (VDR), the transient receptor potential vanilloid receptor 6 (TRPV6), Calbindin D9k in the duodenum were measured by immunohistochemistry, western blotting, or real-time PCR. The short-chain fatty acids (SCFAs) levels in the feces of the cecum were tested by gas chromatograghy.

RESULTS

The administration of FLL to OVX rats resulted in a significant improvement in bone mineral density and biomechanical strength as well as in maintaining bone microstructures and material quality. Meanwhile, the decreased levels of PINP and increased levels of CTx-I in OVX rats were restored by FLL treatment. Additionally, FLL treatment increased calcium absorption, upregulated VDR, TRPV6, Calbindin D9k expressions in the duodenum, Calbindin D28K in kidney, and down-regulated CaSR expression in the kidney, as well as enhanced SCFAs levels in the feces of OVX rats.

CONCLUSIONS

FLL aqueous extract may preserve bone quality through regulation of the calcium balance and intestinal SCFAs production in OVX rats. This offers translational value of FLL into osteoporosis clinical trial.

Ligustroflavone ameliorates CCl4-induced liver fibrosis through down-regulating the TGF-β/Smad signaling pathway

Liver fibrosis is a pathological process characterized by excess deposition of extracellular matrix (ECM) that are mainly derived from activated hepatic stellate cells. Previous studies suggested that ligustroflavone (LF) was an ingredient of Ligustrum lucidum Ait. with activities of anti-inflammation and anti-oxidation. In this study, we investigated whether LF had any effect on liver fibrosis. In our study, we established a mouse model of carbon tetrachloride (CCl₄)-induced liver fibrosis and used TGF-β₁-stimulated human hepatic stellate cell line (LX-2) to explore the effect of LF and associated underlying mechanism. LF was used in vivo with low dose (L-LF, 5 mg·kg^-1, i.p., 3 times each week) and high dose (H-LF, 20 mg·kg^-1, i.p., 3 times each week) and in vitro (25 μmol·L^-1). Histopathological and biochemical assays investigations showed that LF delayed the formation of liver fibrosis; decreased AST, ALT activities and increased Alb activity in serum; decreased MDA level, Hyp content and increased GSH-Px concentration, SOD activity in liver tissues. Moreover, immunohistochemical, immunofluorescent and Western blot results showed that LF reduced the expressions of hepatic stellate cells specific marker proteins, including collagen I and α-SMA in vivo and in vitro. In addition, LF markedly suppressed TGF-β₁-upregulated protein expressions of TβR I, TβR II, P-Smad2, P-Smad3 and Smad4 in LX-2 cells. Taken together, these findings demonstrated LF could decrease histopathological lesions, ameliorate oxidative injury, attenuate CCl₄-induced liver fibrosis, which may be associated with down-regulating the TGF-β/Smad signaling pathway.

Flavonoids: structure-function and mechanisms of action and opportunities for drug development

Flavonoids are polyphenolic phytochemicals produced in fruits, nuts and vegetables and dietary consumption of these structurally diverse compounds is associated with multiple health benefits including increased lifespan, decreased cardiovascular problems and low rates of metabolic diseases. Preclinical studies with individual flavonoids demonstrate that these compounds exhibit anti-inflammatory and anticancer activities and they enhance the immune system. Their effectiveness in both chemoprevention and chemotherapy is associated with their targeting of multiple genes/pathways including nuclear receptors, the aryl hydrocarbon receptor (AhR), kinases, receptor tyrosine kinases and G protein-coupled receptors. However, despite the remarkable preclinical activities of flavonoids, their clinical applications have been limited and this is due, in part, to problems in drug delivery and poor bioavailability and these problems are being addressed. Further improvements that will expand clinical applications of flavonoids include mechanism-based precision medicine approaches which will identify critical mechanisms of action of individual flavonoids with optimal activities that can be used in combination therapies.

Phenol glycosides extract of Fructus Ligustri Lucidi attenuated depressive-like behaviors by suppressing neuroinflammation in hypothalamus of mice

Depression is partially caused by inflammation in central nervous system. This study investigated the ameliorative effects of phenol glycosides (PG) from Ligustrum lucidum Ait. (Oleaceae) on neuroinflammation and depressive-like behavior in mice hypothalamus as well as the molecular mechanism. Mice were administered with PG extract for 2 weeks prior to treatment with LPS. The mice treated with PG extract showed resistance to LPS-induced reduction in body weight and LPS-induced depressive-like behaviors shown by sucrose preference, tail suspension test, forced swimming test and open field test. LPS-induced activation of microglial cells and elevation in protein expression of inflammatory cytokines including IL-1β, RANTES and MCP-1 in hypothalamus of mice were abrogated by pre-treatment with PG extract. This extract down-regulated expression of TLR4, MyD88, NLRP3, renin and angiotensin II and decreased proportional area of Iba-1⁺ microglias in hypothalamus. Pre-treatment with PG extract inhibited LPS-triggered activation of CaSR/G_α11 signaling, stimulated 1-OHase expression in hypothalamus, and enhanced circulating 1,25(OH)₂ D₃ level. Overall, pre-treatment with PG extract ameliorated LPS-induced depressive-like behaviors by repressing neuroinflammation in mice hypothalamus which was attributed to its suppression on activation of microglia and production of inflammatory cytokines via acting on TLR4 pathway, CaSR and RAS cascade associated with improving vitamin D metabolism.

Perilipin2 inhibits diabetic nephropathy-induced podocyte apoptosis by activating the PPARγ signaling pathway

Podocyte apoptosis plays a pivotal role in the pathogenesis of diabetic nephropathy (DN). The main purpose of this study was to investigate the effects of perilipin2 on high glucose (HG)-induced podocyte apoptosis and associated mechanisms. Differentially expressed genes (DEGs) in BTBR ob/ob mice vs. nondiabetic mice kidneys were obtained from GSE106841 dataset and picked out using the 'limma' package. The protein-protein interaction (PPI) network was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) and was visualized by Cytoscape. Perilipin2 was a hub gene using the cytoHubba plug-in from Cytoscape. Gene ontology (GO) analysis revealed that the 126 overlapping DEGs were mainly enriched in 'oxidation reduction' [biological process, (BP)], metal ion binding' [molecular function, (MF)] and 'extracellular region' [cellular component, (CC)]. KEGG pathway analysis revealed that perilipin2 was mainly involved in 'PPAR signaling pathway'. DN inhibited perilipin2 expression and PPARγ expression, as by both in vitro and in vivo studies. In vitro experiments demonstrated that perilipin2 inhibition could not only reduced PPARγ expression in podocytes, it could also promote the apoptosis, and inhibit the viability in HG treated podocytes using western blot, CCK8 and flow cytometry assays. Perilipin2 overexpression reversed the effects of HG on inhibiting podocalyxin, nephrin, precursor (pro)-caspase-3/-9 and PPARγ protein expression and increasing cleaved caspase-3/-9 protein expression. Furthermore, the functions of perilipin2 overexpression reversing HG-induced podocyte apoptosis were inhibited by PPARγ inhibitor. In conclusion, the functions of DN-induced podocyte apoptosis were inhibited by activation of the PPARγ signaling pathway caused by perilipin2 overexpression.

Purification and characterization of positive allosteric regulatory peptides of calcium sensing receptor (CaSR) from desalted duck egg white

HPLC-ESI-MS/MS, molecular docking simulation and in situ single-pass intestinal perfusion (SPIP) study were used to identify, select, and confirm the binding affinities between peptides identified from desalted duck egg white peptides (DPs) and calcium sensing receptor (CaSR), respectively. F3 fraction from DPs possessed superior calcium binding activity (P < 0.05), and 16 peptides enriched aromatic amino acids and other 33 peptides were identified. FAE, FNE, INSW, FDPE and NFE presented well binding affinities with CaSR in molecular docking. Additionally, SPIP results showed that NFE and INSW significantly reduced the increased PTH levels by 45.8% and 48.8%, respectively (P < 0.05), and increased calcium percent absorption, calcium absorption rate constant (Ka) and calcium effective permeability (Peff) (P < 0.05), as well as up-regulated mRNA levels of CaSR (P < 0.05). Moreover, NFE and INSW could interact with the VFT domain of CaSR, which exhibited the potential activities in regulation of CaSR.

Shikonin mitigates ovariectomy-induced bone loss and RANKL-induced osteoclastogenesis via TRAF6-mediated signaling pathways

BACKGROUND

Postmenopausal osteoporosis results from estrogen withdrawal and is characterized mainly by bone resorption. Shikonin is a bioactive constitute of Chinese traditional herb which plays a role in antimicrobial and antitumor activities. The study was designed to investigate the role of shikonin on postmenopausal osteoporosis and explore its underlying mechanisms.

METHODS

Immunofluorescence staining was performed to evaluate the effects of shikonin on actin ring formation. The expression levels of the nuclear factor kappa-B (NF-κB) and mitogen-activated protein kinase (MAPK) pathway were determined by Western blot analysis. To determine whether shikonin influences the receptor activator of nuclear factor-κB ligand (RANKL)-induced association between receptor activator of NF-κB (RANK) and tumor necrosis factor receptor associated factor 6 (TRAF6), immunofluorescence staining and immunoprecipitation experiments were performed. During our validation model, histomorphometric examination and micro-computed tomography (CT) were conducted to assess the morphology of osteoporosis.

RESULTS

Shikonin prevented bone loss by inhibiting osteoclastogenesis in vitro and improving bone loss in ovariectomized mice in vivo. At the molecular level, Western blot analysis indicated that shikonin inhibited the phosphorylation of inhibitor of NF-κB (IκB), P50, P65, extracellular regulated protein kinases (ERK), c-Jun N-terminal kinase (JNK), and P38. Interaction of TRAF6 and RANK was prevented, and downstream MAPK and NF-κB signaling pathways were downregulated.

CONCLUSION

Osteoclastic bone resorption was reduced in the presence of shikonin in vitro and in vivo. Shikonin is a promising candidate for treatment of postmenopausal osteoporosis.

Oleanolic acid mitigates interleukin-1β-induced chondrocyte dysfunction by regulating miR-148-3p-modulated FGF2 expression

BACKGROUND

microRNA (miR)-mediated post-transcriptional repression has been reported in the process of chondrocyte dysfunction. The present study aimed to investigate the molecular mechanisms underlying in oleanolic acid (OLA)-prevented interleukin (IL)-1β-induced chondrocyte dysfunction via the miR-148-3p/fibroblast growth factor-2 (FGF-2) signaling pathway.

METHODS

Candidate miRs were filtrated using miR microarray assays in chondrocytes with or without IL-1β stimulation. Gene expression of candidate miRs and protein expression of FGF2 were analyzed using a quantitative reverse transcriptase-polymerase chain reaction and western blotting, respectively. Cell growth was evaluated using cell counting kit-8 assays. Cell apoptosis was detected using Annexin V-fluorescein isothiocyanate double staining.

RESULTS

Treatment with OLA counteracted IL-1β-evoked chondrocyte growth inhibition, apoptosis, caspase3 production, and release of malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine. Additionally, FGF2 protein expression levels elevated by IL-1β were down-regulated by OLA and transfection with miR-148-3p mimics. IL-1β-induced down-regulation of miR-148-3p in chondrocytes was evaluated by OLA administration. Bioinformatics algorithms and experimental measurements indicated that FGF2 might be a direct target of miR-148-3p. miR-148-3p mimics exhibited equal authenticity of OLA to protect against IL-1β-induced chondrocyte dysfunction.

CONCLUSIONS

Our present findings highlight a protective effect of OLA on IL-1β-induced chondrocyte dysfunction, and a novel signal cascade comprising the miR-148-3p/FGF2 signaling pathway might be a potential therapeutic target of OLA with respect to preventing the progression of osteoarthritis.