Effects and mechanisms of natural alkaloids for prevention and treatment of osteoporosis

Aucubin Promotes BMSCs Proliferation and Differentiation of Postmenopausal Osteoporosis Patients by Regulating Ferroptosis and BMP2 Signalling

Postmenopausal osteoporosis (PMOP) is a chronic systemic bone metabolism disorder. Promotion in the patterns of human bone marrow mesenchymal stem cells (hBMSCs) differentiation towards osteoblasts contributes to alleviating osteoporosis. Aucubin, a natural compound isolated from the well-known herbal medicine Eucommia, was previously shown to possess various pharmacological effects. However, its effects on hBMSCs of PMOP patients are unknown. The aim of this present research was to investigate the impact and underlying process of aucubin on cell proliferation and osteogenic differentiation in hBMSCs isolated from PMOP patients. The ability of aucubin to inhibit the ferroptosis induced by erastin in hBMSCs was detected; ROS production, ferrous ion levels, SOD, MDA, and GPX activities were tested by using commercial kits. Next, ALP staining, ARS staining, RT-qPCR, RNA-sequencing, and Western blot were applied for determining the mRNA and protein expression levels associated with the osteogenesis of hBMSCs. The study also explored the involvement of BMP2/Smads signalling in aucubin promoting the osteogenesis of hBMSCs and evaluated the effects of aucubin intervention on osteoporosis using an ovariectomised rat model. The results indicated that aucubin significantly inhibited ROS generation and oxidative stress induced by erastin and protected against ferroptosis in hBMSCs. Additionally, aucubin facilitated osteogenic differentiation of hBMSCs by activating the BMP2/SMADs pathway and attenuated the progression of osteoporosis in OVX rats, suggesting a potential therapeutic benefit for postmenopausal osteoporosis (PMOP).

Cyclic Imines and Their Salts as Universal Precursors in the Synthesis of Nitrogen-Containing Alkaloids

Alkaloids are predominantly nitrogen-containing heterocyclic compounds that are usually isolated from plants, and sometimes from insects or animals. Alkaloids are one of the most important types of natural products due to their diverse biological activities and potential applications in modern medicine. Cyclic imines were chosen as starting compounds for the synthesis of alkaloids due to their high synthetic potential. Thus, this review summarizes the achievements in the synthesis of various alkaloids from cyclic imines, paying special attention to stereoselective methods used for their preparation. Information on the biological activity of some alkaloids, their application and occurrence in natural objects is presented. Synthesis methods are classified based on the type of alkaloid obtained.

A Mechanistic Study of the Osteogenic Effect of Arecoline in an Osteoporosis Model: Inhibition of Iron Overload-Induced Osteogenesis by Promoting Heme Oxygenase-1 Expression

Iron overload-associated osteoporosis presents a significant challenge to bone health. This study examines the effects of arecoline (ACL), an alkaloid found in areca nut, on bone metabolism under iron overload conditions induced by ferric ammonium citrate (FAC) treatment. The results indicate that ACL mitigates the FAC-induced inhibition of osteogenesis in zebrafish larvae, as demonstrated by increased skeletal mineralization and upregulation of osteogenic genes. ACL attenuates FAC-mediated suppression of osteoblast differentiation and mineralization in MC3T3-E1 cells. RNA sequencing analysis suggests that the protective effects of ACL are related to the regulation of ferroptosis. We demonstrate that ACL inhibits ferroptosis, including oxidative stress, lipid peroxidation, mitochondrial damage, and cell death under FAC exposure. In this study, we have identified heme oxygenase-1 (HO-1) as a critical mediator of ACL inhibiting ferroptosis and promoting osteogenesis, which was validated by HO-1 knockdown and knockout experiments. The study links ACL to HO-1 activation and ferroptosis regulation in the context of bone metabolism. These findings provide new insights into the mechanisms underlying the modulation of osteogenesis by ACL. Targeting the HO-1/ferroptosis axis is a promising therapeutic approach for treating iron overload-induced bone diseases.

Phytochemicals and Their Usefulness in the Maintenance of Health

Inflammation is the immune system's first biological response to infection, injury, or irritation. Evidence suggests that the anti-inflammatory effect is mediated by the regulation of various inflammatory cytokines, such as nitric oxide, interleukins, tumor necrosis factor alpha-α, interferon gamma-γ, as well as the non-cytokine mediator, prostaglandin E2. Currently, the mechanism of action and clinical usefulness of phytochemicals is known; their action on the activity of cytokines, free radicals, and oxidative stress. The latter are of great relevance in the development of diseases, such that the evidence collected demonstrates the beneficial effects of phytochemicals in maintaining health. Epidemiological evidence indicates that regular consumption of fruits and vegetables is related to a low risk of developing cancer and other chronic diseases.

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.

The Therapeutic Potential of Two Egyptian Plant Extracts for Mitigating Dexamethasone-Induced Osteoporosis in Rats: Nrf2/HO-1 and RANK/RANKL/OPG Signals

The prolonged use of exogenous glucocorticoids, such as dexamethasone (Dex), is the most prevalent secondary cause of osteoporosis, known as glucocorticoid-induced osteoporosis (GIO). The current study examined the preventative and synergistic effect of aqueous chicory extract (ACE) and ethanolic purslane extract (EPE) on GIO compared with Alendronate (ALN). The phytochemical contents, elemental analysis, antioxidant scavenging activity, and ACE and EPE combination index were evaluated. Rats were randomly divided into control, ACE, EPE, and ACE/EPE MIX groups (100 mg/kg orally), Dex group (received 1.5 mg Dex/kg, Sc), and four treated groups received ACE, EPE, ACE/EPE MIX, and ALN with Dex. The bone mineral density and content, bone index, growth, turnover, and oxidative stress were measured. The molecular analysis of RANK/RANKL/OPG and Nrf2/HO-1 pathways were also evaluated. Dex causes osteoporosis by increasing oxidative stress, decreasing antioxidant markers, reducing bone growth markers (OPG and OCN), and increasing bone turnover and resorption markers (NFATc1, RANKL, ACP, ALP, IL-6, and TNF-α). In contrast, ACE, EPE, and ACE/EPE MIX showed a prophylactic effect against Dex-induced osteoporosis by modulating the measured parameters and the histopathological architecture. In conclusion, ACE/EPE MIX exerts a powerful synergistic effect against GIO by a mode of action different from ALN.

Nuciferine-loaded chitosan hydrogel-integrated 3D-printed polylactic acid scaffolds for bone tissue engineering: A combinatorial approach

Critical-sized bone defects resulting from severe trauma and open fractures cannot spontaneously heal and require surgical intervention. Limitations of traditional bone grafting include immune rejection and demand-over-supply issues leading to the development of novel tissue-engineered scaffolds. Nuciferine (NF), a plant-derived alkaloid, has excellent therapeutic properties, but its osteogenic potential is yet to be reported. Furthermore, the bioavailability of NF is obstructed due to its hydrophobicity, requiring an efficient drug delivery system, such as chitosan (CS) hydrogel. We designed and fabricated polylactic acid (PLA) scaffolds via 3D printing and integrated them with NF-containing CS hydrogel to obtain the porous biocomposite scaffolds (PLA/CS-NF). The fabricated scaffolds were subjected to in vitro physicochemical characterization, cytotoxicity assays, and osteogenic evaluation studies. Scanning electron microscopic studies revealed uniform pore size distribution on PLA/CS-NF scaffolds. An in vitro drug release study showed a sustained and prolonged release of NF. The cyto-friendly nature of NF in PLA/CS-NF scaffolds towards mouse mesenchymal stem cells (mMSCs) was observed. Also, cellular and molecular level studies signified the osteogenic potential of NF in PLA/CS-NF scaffolds on mMSCs. These results indicate that the PLA/CS-NF scaffolds could promote new bone formation and have potential applications in bone tissue engineering.

Transcriptome and Metabolome Analysis of Isoquinoline Alkaloid Biosynthesis of Coptis chinensis in Different Years

Coptis chinensis is a perennial herb of the Ranunculaceae family. The isoquinoline alkaloid is the main active component of C. chinensis, mainly exists in its rhizomes and has high clinical application potential. The in vitro synthesis of isoquinoline alkaloids is difficult because their structures are complex; hence, plants are still the main source of them. In this study, two-year and four-year rhizomes of C. chinensis were selected to investigate the effect of growth years on the accumulation of isoquinoline alkaloids. Two-year and four-year C. chinensis were selected for metabolomics detection and transcriptomic analysis. A total of 413 alkaloids were detected by metabolomics analysis, of which 92 were isoquinoline alkaloids. (S)-reticuline was a significantly different accumulated metabolite of the isoquinoline alkaloids biosynthetic pathway in C. chinensis between the two groups. The results of transcriptome analysis showed that a total of 464 differential genes were identified, 36 of which were associated with the isoquinoline alkaloid biosynthesis pathway of C. chinensis. Among them, 18 genes were correlated with the content of important isoquinoline alkaloids. Overall, this study provided a comprehensive metabolomic and transcriptomic analysis of the rapid growth stage of C. chinensis rhizome from the perspective of growth years. It brought new insights into the biosynthetic pathway of isoquinoline alkaloids and provided information for utilizing biotechnology to improve their contents in C. chinensis.

Natural products for the treatment of depression: Insights into signal pathways influencing the hypothalamic-pituitary-adrenal axis

Depression, a prevalent psychiatric malady, afflicts a substantial global demographic, engendering considerable disease burden due to its elevated morbidity and mortality rates. Contemporary therapeutic approaches for depression encompass the administration of serotonin reuptake inhibitors, monoamine oxidase inhibitors, and tricyclic antidepressants, albeit these pharmaceuticals potentially induce adverse neurological and gastrointestinal effects. Traditional Chinese Medicine (TCM) natural products proffer the benefits of multi-target, multi-level, and multi-channel depression treatment modalities. In this investigation, we conducted a comprehensive literature review of the past 5 years in PubMed and other databases utilizing the search terms "Depression," "Natural medicines," "Traditional Chinese Medicine," and "hypothalamic-pituitary-adrenal axis." We delineated the 5 most recent and pertinent signaling pathways associated with depression and hypothalamic-pituitary-adrenal (HPA) axis dysregulation: nuclear factor kappa light-chain-enhancer of activated B cell, brain-derived neurotrophic factor, mitogen-activated protein kinase, cyclic AMP/protein kinase A, and phosphoinositide 3-kinase/protein kinase B. Additionally, we deliberated the antidepressant mechanisms of natural medicines comprising alkaloids, flavonoids, polyphenols, saponins, and quinones via diverse pathways. This research endeavor endeavored to encapsulate and synthesize the progression of TCMs in modulating HPA axis-associated signaling pathways to mitigate depression, thereby furnishing robust evidence for ensuing research in this domain.

Therapeutic approach of natural products that treat osteoporosis by targeting epigenetic modulation

Osteoporosis (OP) is a metabolic disease that affects bone, resulting in a progressive decrease in bone mass, quality, and micro-architectural degeneration. Natural products have become popular for managing OP in recent years due to their minimal adverse side effects and suitability for prolonged use compared to chemically synthesized products. These natural products are known to modulate multiple OP-related gene expressions, making epigenetics an important tool for optimal therapeutic development. In this study, we investigated the role of epigenetics in OP and reviewed existing research on using natural products for OP management. Our analysis identified around twenty natural products involved in epigenetics-based OP modulation, and we discussed potential mechanisms. These findings highlight the clinical significance of natural products and their potential as novel anti-OP therapeutics.