Natural Products as Potential Bone Therapies

Metal-Drug Coordination Nanoparticles and Hydrogels for Enhanced Delivery

Drug delivery is a key component of nanomedicine, and conventional delivery relies on the adsorption or encapsulation of drug molecules to a nanomaterial. Many delivery vehicles contain metal ions, such as metal-organic frameworks, metal oxides, transition metal dichalcogenides, MXene, and noble metal nanoparticles. These materials have a high metal content and pose potential long-term toxicity concerns leading to difficulties for clinical approval. In this review, recent developments are summarized in the use of drug molecules as ligands for metal coordination forming various nanomaterials and soft materials. In these cases, the drug-to-metal ratio is much higher than conventional adsorption-based strategies. The drug molecules are divided into small-molecule drugs, nucleic acids, and proteins. The formed hybrid materials mainly include nanoparticles and hydrogels, upon which targeting ligands can be grafted to improve efficacy and further decrease toxicity. The application of these materials for addressing cancer, viral infection, bacterial infection inflammatory bowel disease, and bone diseases is reviewed. In the end, some future directions are discussed from fundamental research, materials science, and medicine.

Astaxanthin as a Potent Antioxidant for Promoting Bone Health: An Up-to-Date Review

In recent years, bone loss and its associated diseases have become a significant public health concern due to increased disability, morbidity, and mortality. Oxidative stress and bone loss are correlated, where oxidative stress suppresses osteoblast activity, resulting in compromised homeostasis between bone formation and resorption. This event causes upregulation of bone remodeling turnover rate with an increased risk of fractures and bone loss. Therefore, supplementation of antioxidants can be proposed to reduce oxidative stress, facilitate the bone remodeling process, suppress the initiation of bone diseases, and improve bone health. Astaxanthin (3,3'-dihydroxy-4-4'-diketo-β-β carotene), a potent antioxidant belonging to the xanthophylls family, is a potential ROS scavenger and could be a promising therapeutic nutraceutical possessing various pharmacological properties. In bone, astaxanthin enhances osteoblast differentiation, osteocytes numbers, and/or differentiation, inhibits osteoclast differentiation, cartilage degradation markers, and increases bone mineral density, expression of osteogenic markers, while reducing bone loss. In this review, we presented the up-to-date findings of the potential anabolic effects of astaxanthin on bone health in vitro, animal, and human studies by providing comprehensive evidence for its future clinical application, especially in treating bone diseases.

Qing`e Pill Inhibits Osteoblast Ferroptosis via ATM Serine/Threonine Kinase (ATM) and the PI3K/AKT Pathway in Primary Osteoporosis

Osteoporosis (OP) is an aging-related disease that is the main etiology of fragility fracture. Qing’e Pill (QEP) is a mixture of traditional Chinese medicine (TCM) consisting of Eucommia ulmoides Oliv., Psoralea corylifolia L., Juglans regia L., and Allium sativum L. QEP has an anti-osteoporosis function, but the underlying mechanism remains unclear. In this study, online databases were employed to determine the chemical compounds of QEP and potential target genes in osteoporosis. Potential pathways associated with genes were defined by Gene Ontology (GO) and Kyoto Encyclopaedia of Genes and Genomes (KEGG) databases. A compound–target–disease network was constructed. Hub genes screened through Cytoscape were intersected with the FerrDB database. The potential key genes were validated in HFOB 1.19 cells, and rat models were ovariectomized through Western blot, RT-qPCR, ELISA, HE staining, immunohistochemistry, and immunofluorescence analyses. The intersection targets of QEP and osteoporosis contained 121 proteins, whereas the target–pathway network included 156 pathways. We filtered five genes that stood out in the network analysis for experimental verification. The experiments validated that QEP exerted therapeutic effects on osteoporosis by inhibiting ferroptosis and promoting cell survival via the PI3K/AKT pathway and ATM. In conclusion, combining the application of network analysis and experimental verification may provide an efficient method to validate the molecular mechanism of QEP on osteoporosis.