Catalpol attenuates osteoporosis in ovariectomized rats through promoting osteoclast apoptosis via the Sirt6-ERα-FasL axis

Iridoid glycosides in kidney-tonifying Chinese medicinal herbs: Mechanisms and implications for Alzheimer's disease therapy

ETHNOPHARMACOLOGICAL RELEVANCE

Alzheimer's disease (AD) is an incurable and irreversible type of dementia. Existing drugs cannot meet clinical needs; thus, developing new treatments is necessary. Traditional Chinese medicine (TCM) has been used in the prevention and treatment of AD. TCM holds the theory that "the kidney support brain function" and believes that dementia can be addressed from a kidney-based perspective. Kidney-tonifying herbs are a class of medicines that have the effect of tonifying the kidney and benefiting the brain. Some of these herbs have been shown to have anti-AD effects. Iridoid glycosides (IGs), which are important components of kidney-tonifying herbs, may have the potential to prevent and treat AD. However, their effects on AD have not yet been reviewed.

AIM OF THE REVIEW

This literature review provides a comprehensive summary of the potential of IGs in the prevention and treatment of AD. It also sets the foundation for future studies that will make the use of such drugs in clinical practice possible.

MATERIAL AND METHODS

Kidney-tonifying Chinese herbs were selected with reference to the Chinese Pharmacopoeia (2020 edition) and the textbook of Chinese Materia Medica (5th edition). Literature survey was conducted using PubMed, Web of Science, Google Scholar, and CNKI, with "Alzheimer's disease," "kidney-tonifying Chinese medicinal herbs," and "Iridoid Glycosides" as the primary keywords.

RESULTS

Kidney-tonifying herbal IGs include loganin, morroniside, verbenalin, cornuside, catalpol, rehmannioside A, geniposidic acid, and aucubin. These IGs have shown multiple pharmacological effects, including anti-AD effects. The effective mechanisms of IGs for AD treatment include anti-oxidative stress, inhibiting neuronal apoptosis, antagonizing amyloid neurotoxicity and tau protein hyperphosphorylation, regulating immune function, anti-inflammation, normalizing the function of the cholinergic nervous system, recuperating neurobiochemical, and regulating AD-related genes. Consequently, IGs can combat AD by modulating multiple targets and pathways.

CONCLUSION

Kidney-tonifying herbal IGs have great potential to combat AD.

New Perspectives on Postmenopausal Osteoporosis: Mechanisms and Potential Therapeutic Strategies of Sirtuins and Oxidative Stress

Estrogen levels are the core factor influencing postmenopausal osteoporosis (PMOP). Estrogen can affect the progression of PMOP by regulating bone metabolism, influencing major signaling pathways related to bone metabolism, and modulating immune responses. When estrogen levels decline, the activity of Sirtuins (SIRTs) is reduced. SIRTs are enzymes that function as NAD+-dependent deacetylases. SIRTs can modulate osteocyte function, sustain mitochondrial homeostasis, and modulate relevant signaling pathways, thereby improving bone metabolic imbalances, reducing bone resorption, and promoting bone formation. In PMOP, SIRT1, SIRT3, and SIRT6 are primarily affected. Oxidative stress (OS) is a crucial factor in PMOP, as it generates excessive reactive oxygen species (ROS) that exacerbate PMOP. There is a certain interplay between SIRTs and OS. The reduced activity of SIRTs leads to intensified OS and the excessive accumulation of ROS. In return, ROS suppresses the AMPK signaling pathway and the synthesis of NAD+, which consequently diminishes the function of SIRTs. Natural SIRT activators and natural antioxidants, which are characterized by high safety, convenience, and minimal side effects, represent a potential therapeutic strategy for PMOP. This study aims to investigate the mechanisms of SIRTs and OS in PMOP and summarize potential therapeutic strategies to assist in the improvement of PMOP.

Dual functional hydrogel of osteoclastic-inhibition and osteogenic-stimulation for osteoporotic bone defect regeneration

Osteoporotic bone regeneration poses significant challenges due to the complexity of the condition. Osteoporosis, a degenerative disorder, results from an imbalance in bone homeostasis driven by dysregulation of osteoblast and osteoclast activity. This complicates the treatment of osteoporosis and its related bone injuries in clinical practice. Despite the development of various polymer scaffolds for bone defect repair, achieving effective regeneration in osteoporotic bones-especially when combined with osteoporosis medications-remains difficult. In this study, we designed a drug delivery system composed of mesoporous bioactive glass (MBG) and photo-crosslinked hyaluronic acid methacrylate (HAMA). This system, loaded with the osteogenesis-promoting peptide DWIVA (D5) and the osteoclastogenesis-inhibiting drug alendronate (ALN), is gelled using a light initiator and 405 nm wavelength light. The MBG@D5-Gel complex enables the controlled spatiotemporal release of these agents, markedly enhancing bone regeneration in osteoporotic conditions within ovariectomized rats by inhibiting osteoclastogenesis and bone resorption while promoting osteogenic differentiation and mineralization. This dual-action system synergistically regulates osteoblast and osteoclast activity, optimizing the pathological microenvironment of osteoporosis and facilitating the repair of osteoporotic bone defects. MBG@D5-Gel holds great potential as an effective organic-inorganic hybrid biomimetic implant material for the treatment of osteoporotic bone defects.

Recent advances in the multifaceted mechanisms of catalpol in treating osteoporosis

Catalpol (CAT) is a landmark active ingredient in traditional Chinese medicine Rehmannia (TCT), also known as dehydroxybenzoate catalpone, which is a kind of iridoid terpene glycoside with strong antioxidant, anti-inflammatory, antitumor and other biological activities. It can exert its anti-disease effect in a variety of ways. For some patients with chronic diseases, the application of azalea alcohol in rehmannia may bring more comprehensive and long-lasting efficacy. Studies have shown that the anti-disease effect of catalpol in osteoporosis (OP) is mainly achieved through various pathways such as Wnt/β-catenin signaling pathways to promote osteogenic differentiation, and RANKL/RANK and other signaling pathways to inhibit osteoclastic differentiation. At present, there is a slight lack of analysis of the mechanism of action of catalpa alcohol in the treatment of osteoporosis, so this study comprehensively searched the literature on the mechanism of action of catalpa alcohol in the treatment of osteoporosis in various databases, and reviewed the research progress of its role and mechanism, to provide reference and theoretical basis for the further development and application of catalpol.

Multi-omics and bioinformatics for the investigation of therapeutic mechanism of roucongrong pill against postmenopausal osteoporosis

ETHNOPHARMACOLOGICAL RELEVANCE

The Roucongrong Pill (RCRP), originating from the historical General Medical Collection of Royal Benevolence, is frequently used to treat postmenopausal osteoporosis (PMOP). Despite its prevalent application, the specific anti-osteoporotic mechanisms of RCRP remain to be elucidated.

AIM OF THE STUDY

This study aims to elucidate the therapeutic mechanism of RCRP in the context of ovariectomy (OVX)-induced PMOP in rats. By employing an integrative approach, the research combines medicinal chemistry, gut microbiota (GM) profiling, metabolomics, MetOrigin traceability, network pharmacology, molecular docking, and molecular dynamics simulations to deliver a comprehensive analysis.

MATERIALS AND METHODS

Sprague-Dawley (SD) rats underwent bilateral OVX to establish a PMOP model. The therapeutic efficacy of RCRP was evaluated through bone metrics (BMD, bone strength, BV/TV, Tb.Sp), hematoxylin and eosin (H&E) histological assessment, and bone metabolism markers (OPG, BALP, TRACP-5b, β-CTX, RANKL). Fecal metabolomics and 16S rDNA sequencing were employed to assess the influence of RCRP on GM and metabolite profiles. Furthermore, MetOrigin facilitated the traceability analysis of relevant metabolites. Molecular docking identified potential RCRP compounds with anti-PMOP activity, while their stability and protein interactions were assessed through molecular dynamics simulations. Network pharmacology further confirms the targets of action.

RESULTS

RCRP alleviated PMOP in rats, enhancing bone strength, cortical and trabecular BMD, BV/TV, and serum OPG levels, while reducing Tb.Sp, serum BALP, TRACP-5b, β-CTX, and RANKL concentrations. A total of twenty-six distinct metabolites were identified, of which ten-tribufos, sulfoacetic acid, betamethasone dipropionate, 9-oxooctadeca-10,12,15-trienoic acid, menatetrenone, piperlongumine, maltopentaose, enol-phenylpyruvate, catechol, pentaacetate, and (+)-2-methylpropanoic acid-exhibited correlations with six GM species: Turicibacter, Roseburia, Colidextribacter, Helicobacter, Odoribacter, and Lachnoclostridium, as determined by Spearman's correlation analysis. Notably, MetOrigin revealed the microbial metabolism of taurine and hypotaurine, along with host-specific steroid hormone synthesis. Computational docking studies demonstrated robust interactions between five RCRP-derived steroids (hydroxyecdysone, corticosterone, trilostane, 5α-androstan-3,6,17-trione, and cortisol) and key enzymes (estradiol 17α-dehydrogenase and UDP-glucuronosyltransferase), suggesting a potential enhancement of therapeutic efficacy against PMOP. Furthermore, molecular dynamics simulations indicated stable interactions between hydroxyecdysone and two proteins, with binding free energies of -67.427 kJ/mol and -156.948 kJ/mol, respectively. Through network pharmacology and molecular docking approaches, potential targets of these metabolites were identified, including estrogen receptors ESR1 and ESR2, dual specificity phosphatase 6 (DUSP6), sex hormone-binding globulin (SHBG), prostaglandin E receptor 4 (PTGER4), cannabinoid receptor 2 (CNR2), cathepsin K (CTSK), and androgen receptor (AR).

CONCLUSIONS

RCRP effectively mitigates OVX-induced bone loss in PMOP rats by modulating GM and associated metabolites, along with their potential targets and key metabolic pathways, including taurine and hypotaurine metabolism, as well as steroid hormone biosynthesis. These findings offer new insights into the therapeutic mechanisms by which RCRP may alleviate PMOP.

Screening of ESR2-targeted anti-postmenopausal osteoporosis chemistry from Rehmanniae Radix Preparata based on affinity ultrafiltration with UPLC-QE-Orbitrap-MS

Rehmanniae Radix Preparata, a processed form of the traditional Chinese medicinal plant Rehmannia glutinosa Libosch, has long been valued for its medicinal properties and use as a food. It is notably effective in treating postmenopausal osteoporosis. This study utilized C18 to separate and purify different concentrations of its eluent streams. MC3T3-E1 cells were utilized to identify the optimal ESR2 activity fraction from various concentrations of Rehmanniae Radix Preparata, using osteoprotegerin (OPG) as an indicator. A single-target affinity ultrafiltration method was created, combining ESR2 affinity ultrafiltration with liquid chromatography-mass spectrometry (LC-MS). Molecular docking validated the interaction mechanism between small molecule ligands and ESR2 protein. These ligands were then tested in MC3T3-E1 cells to assess survival rate, OPG content, and alkaline phosphatase (ALP) activity, an osteogenic differentiation marker. The study showed that Radix Rehmanniae Praeparata effectively combats PMOP, and the combined method of single-target-affinity ultrafiltration-LC-MS with molecular docking offers a robust approach for identifying its anti-PMOP compounds.

Catalpol Enhances Osteogenic Differentiation of Human Periodontal Stem Cells and Modulates Periodontal Tissue Remodeling in an Orthodontic Tooth Movement Rat Model

Purpose

This study examines the effects and mechanisms of catalpol (CAT) on the proliferation and osteogenic differentiation of cultured human periodontal ligament stem cells (hPDLSCs) in vitro and assesses the impact of CAT on periodontal remodeling in vivo using an orthodontic tooth movement (OTM) model in rats.

Methods

hPDLSCs were cultured in a laboratory setting, and their proliferation and osteogenic differentiation were assessed using the Cell-counting Kit-8 (CCK-8), Alizarin Red Staining (ARS), quantitative calcium assay, alkaline phosphatase (ALP) staining and activity assay, and immunofluorescence assay. Additionally, the expression of collagen type 1 (COL-1), ALP, and runt-related transcription factor-2 (RUNX-2) was evaluated through qRT-PCR and Western blot analysis. To verify the function of the estrogen receptor-α (ER-α)-mediated phosphatidylinositol-3-kinase-protein kinase B (PI3K/AKT) pathway in this mechanism, LY294002 (a PI3K signaling pathway inhibitor) and the ER-α specific inhibitor methyl-piperidine-pyrazole (MPP) were used. The osteogenic markers ER-α, AKT, and p-AKT (phosphoprotein kinase B) were identified through Western blot analysis. Eighteen male Sprague-Dawley rats were assigned to two groups randomly: a CAT group receiving CAT and a control group receiving an equivalent volume of saline. Micro-computed tomography (micro-CT) analysis was employed to evaluate tooth movement and changes in alveolar bone structure. Morphological changes in the periodontal tissues between the roots were investigated using hematoxylin and eosin (HE) staining and tartaric-resistant acid phosphatase (TRAP) staining. The expression of COL-1, RUNX-2, and nuclear factor-κB (NF-κB) ligand (RANKL) was assessed through immunohistochemical staining (IHC) to evaluate periodontal tissue remodeling. Tests were analyzed using GraphPad Prism 8 software. Differences among more than two groups were analyzed by one-way or two-way analysis of variance (ANOVA) followed by the Tukey's test. Values of p < 0.05 were regarded as statistically significant.

Results

In vitro experiments demonstrated that 10 μM CAT significantly promoted the proliferation, ALP activity, and calcium nodule formation of hPDLSCs, with a notable increase in the expression of COL-1, ALP, RUNX-2, ER-α, and p-AKT. The PI3K/AKT pathway was inhibited by LY294002, and further analysis using MPP suggested that ER-α mediated this effect. In vivo, experiments indicated that CAT enhanced the expression of COL-1 and RUNX-2 on the tension side of rat tooth roots, reduced the number of osteoclasts on the compression side, inhibited RANKL expression, and suppressed OTM.

Conclusion

CAT can promote hPDLSCs proliferation and osteogenic differentiation in vitro through the ER-α/PI3K/AKT pathway and enhance periodontal tissue remodeling in vivo using OTM models. These findings suggest the potential for the clinical application of catalpol in preventing relapse following OTM.

Onion (Allium cepa L.) Flavonoid Extract Ameliorates Osteoporosis in Rats Facilitating Osteoblast Proliferation and Differentiation in MG-63 Cells and Inhibiting RANKL-Induced Osteoclastogenesis in RAW 264.7 Cells

Osteoporosis, a prevalent chronic health issue among the elderly, is a global bone metabolic disease. Flavonoids, natural active compounds widely present in vegetables, fruits, beans, and cereals, have been reported for their anti-osteoporotic properties. Onion is a commonly consumed vegetable rich in flavonoids with diverse pharmacological activities. In this study, the trabecular structure was enhanced and bone mineral density (BMD) exhibited a twofold increase following oral administration of onion flavonoid extract (OFE). The levels of estradiol (E2), calcium (Ca), and phosphorus (P) in serum were significantly increased in ovariectomized (OVX) rats, with effects equal to alendronate sodium (ALN). Alkaline phosphatase (ALP) and tartrate-resistant acid phosphatase (TRAP) levels in rat serum were reduced by 35.7% and 36.9%, respectively, compared to the OVX group. In addition, the effects of OFE on bone health were assessed using human osteoblast-like cells MG-63 and osteoclast precursor RAW 264.7 cells in vitro as well. Proliferation and mineralization of MG-63 cells were promoted by OFE treatment, along with increased ALP activity and mRNA expression of osteoprotegerin (OPG)/receptor activator of nuclear factor-kappaB ligand (RANKL). Additionally, RANKL-induced osteoclastogenesis and osteoclast activity were inhibited by OFE treatment through decreased TRAP activity and down-regulation of mRNA expression-related enzymes in RAW 264.7 cells. Overall findings suggest that OFE holds promise as a natural functional component for alleviating osteoporosis.

lncTIMP3 promotes osteogenic differentiation of bone marrow mesenchymal stem cells via miR-214/Smad4 axis to relieve postmenopausal osteoporosis

BACKGROUND

Promoting the balance between bone formation and bone resorption is the main therapeutic goal for postmenopausal osteoporosis (PMOP), and bone marrow mesenchymal stem cells (BMSCs) osteogenic differentiation plays an important regulatory role in this process. Recently, several long non-coding RNAs (lncRNAs) have been reported to play an important regulatory role in the occurrence and development of OP and participates in a variety of physiological and pathological processes. However, the role of lncRNA tissue inhibitor of metalloproteinases 3 (lncTIMP3) remains to be investigated.

METHODS

The characteristics of BMSCs isolated from the PMOP rat model were verified by flow cytometry assay, alkaline phosphatase (ALP), alizarin red and Oil Red O staining assays. Micro-CT and HE staining assays were performed to examine histological changes of the vertebral trabeculae of the rats. RT-qPCR and western blotting assays were carried out to measure the RNA and protein expression levels. The subcellular location of lncTIMP3 was analyzed by FISH assay. The targeting relationships were verified by luciferase reporter assay and RNA pull-down assay.

RESULTS

The trabecular spacing was increased in the PMOP rats, while ALP activity and the expression levels of Runx2, Col1a1 and Ocn were all markedly decreased. Among the RNA sequencing results of the clinical samples, lncTIMP3 was the most downregulated differentially expressed lncRNA, also its level was significantly reduced in the OVX rats. Knockdown of lncTIMP3 inhibited osteogenesis of BMSCs, whereas overexpression of lncTIMP3 exhibited the reverse results. Subsequently, lncTIMP3 was confirmed to be located in the cytoplasm of BMSCs, implying its potential as a competing endogenous RNA for miRNAs. Finally, the negative targeting correlations of miR-214 between lncTIMP3 and Smad4 were elucidated in vitro.

CONCLUSION

lncTIMP3 may delay the progress of PMOP by promoting the activity of BMSC, the level of osteogenic differentiation marker gene and the formation of calcium nodules by acting on the miR-214/Smad4 axis. This finding may offer valuable insights into the possible management of PMOP.