Osteoarthritis (OA) is the most common degenerative joint disorder that causes disability in aged individuals, caused by functional and structural alterations of the knee joint. To investigate whether metabolic drivers might be harnessed to promote cartilage repair, a liquid chromatography–mass spectrometry (LC–MS) untargeted metabolomics approach was carried out to screen serum biomarkers in osteoarthritic rats. Based on the correlation analyses, α-ketoglutarate (α-KG) has been demonstrated to have antioxidant and anti-inflammatory properties in various diseases. These properties make α-KG a prime candidate for further investigation of OA. Experimental results indicate that α-KG significantly inhibited H₂O₂-induced cartilage cell matrix degradation and apoptosis, reduced levels of reactive oxygen species (ROS) and malondialdehyde (MDA), increased superoxide dismutase (SOD) and glutathione (GSH)/glutathione disulfide (GSSG) levels, and upregulated the expression of ETV4, SLC7A11 and GPX4. Further mechanistic studies observed that α-KG, like Ferrostatin-1 (Fer-1), effectively alleviated Erastin-induced apoptosis and ECM degradation. α-KG and Fer-1 upregulated ETV4, SLC7A11, and GPX4 at the mRNA and protein levels, decreased ferrous ion (Fe²⁺) accumulation, and preserved mitochondrial membrane potential (MMP) in ATDC5 cells. In vivo, α-KG treatment inhibited ferroptosis in OA rats by activating the ETV4/SLC7A11/GPX4 pathway. Thus, these findings indicate that α-KG inhibits ferroptosis via the ETV4/SLC7A11/GPX4 signaling pathway, thereby alleviating OA. These observations suggest that α-KG exhibits potential therapeutic properties for the treatment and prevention of OA, thereby having potential clinical applications in the future.

Streptococcus mutans (S. mutans) is the primary etiological agent of dental caries. The S. mutans enzyme sortase A (SrtA) is responsible for anchoring bacterial cell wall surface proteins involved in host cell attachment and biofilm formation. Thus, SrtA is an attractive target for inhibiting dental caries caused by S. mutans-associated acid fermentation. In this study, we observed that astilbin, a flavanone compound extracted from Rhizoma Smilacis Glabrae, has potent inhibitory activity against the S. mutans SrtA, with an IC₅₀ of 7.5 μg/mL. In addition, astilbin was proven to reduce the formation of biofilm while without affecting the growth of S. mutans. The results of a molecular dynamics simulation and a mutation analysis revealed that the Arg213, Leu111, and Leu116 of SrtA are important for the interaction between SrtA and astilbin. The results of this study demonstrate the potential of using astilbin as a nonbactericidal agent to modulate pathogenicity of S. mutans by inhibiting the activity of SrtA.

Ginseng has a long history of drug application in China, which can treat various diseases and achieve significant efficacy. Ginsenosides have always been deemed important ingredients for pharmacological activities. Based on the structural characteristics of steroidal saponins, ginsenosides are mainly divided into protopanaxadiol‐type saponins (PDS, mainly including Rb1, Rb2, Rd, Rc, Rh2, CK, and PPD) and protopanaxatriol‐type saponins (PTS, mainly including Re, R1, Rg1, Rh1, Rf, and PPT). The structure differences between PDS and PTS result in the differences of pharmacological activities. This paper provides an overview of PDS and PTS, mainly focusing on their chemical profile, pharmacokinetics, hydrolytic metabolism, and pharmacological activities including antioxidant, antifatigue, antiaging, immunodulation, antitumor, cardiovascular protection, neuroprotection, and antidiabetes. It is intended to contribute to an in‐depth study of the relationship between PDS and PTS.

Background: Knee osteoarthritis (KOA) is a persistent degenerative condition characterized by the deterioration of cartilage. The Chinese herbal formula Radix Rehmanniae Praeparata- Angelica Sinensis-Radix Achyranthis Bidentatae (RAR) has often been used in effective prescriptions for KOA as the main functional drug, but its underlying mechanism remains unclear. Therefore, network pharmacology and verification experiments were employed to investigate the impact and mode of action of RAR in the treatment of KOA. Methods: The destabilization of the medial meniscus model (DMM) was utilized to assess the anti-KOA effect of RAR by using gait analysis, micro-computed tomography (Micro-CT), and histology. Primary chondrocytes were extracted from the rib cartilage of a newborn mouse. The protective effects of RAR on OA cells were evaluated using a CCK‐8 assay. The antioxidative effect of RAR was determined by measuring reactive oxygen species (ROS), superoxide dismutase (SOD), and glutathione (GSH) production. Furthermore, network pharmacology and molecular docking were utilized to propose possible RAR targets for KOA, which were further verified through experiments. Results: In vivo, RAR significantly ameliorated DMM-induced KOA characteristics, such as subchondral bone sclerosis, cartilage deterioration, gait abnormalities, and the degree of knee swelling. In vitro, RAR stimulated chondrocyte proliferation and the expression of Col2a1, Comp, and Acan. Moreover, RAR treatment significantly reduced ROS accumulation in an OA cell model induced by IL-1β and increased the activity of antioxidant enzymes (SOD and GSH). Network pharmacology analysis combined with molecular docking showed that Mapk1 might be a key therapeutic target. Subsequent research showed that RAR could downregulate Mapk1 mRNA levels in IL-1β-induced chondrocytes and DMM-induced rats. Conclusion: RAR inhibited extracellular matrix (ECM) degradation and oxidative stress response via the MAPK signaling pathway in KOA, and Mapk1 may be a core target.

Aberrant changes in the hypoxic microenvironment are implicated in osteoarthritis (OA) development. Cuproptosis, a unique copper-dependent form of regulated cell death that depends on the activity of key enzymes in mitochondrial metabolism, is also linked to oxygen levels. However, the crosstalk among hypoxic environment, cuproptosis, and OA development remains unclear. This study confirmed that oxygen levels in the OA model gradually increased during OA progression, which suppressed the expression of anabolic genes for articular cartilage extracellular matrix, upregulated catabolic genes, and increased the cell death rate of primary chondrocytes. Mechanistically, oxygen elevation upregulated the expression of solute carrier family 31 member 1 (SCL31A1), a transmembrane pump facilitating copper uptake, whereas it downregulated the expression of ATPase copper transporting beta (ATP7B), a copper chaperone facilitating copper efflux, leading to aberrant copper accumulation in the cells. Ultimately, this accumulation efficiently induces oligomerization of dihydrolipoamide S-acetyltransferase (DLAT), triggering cell death, known as cuproptosis. Hypoxia-inducible factor-1α (HIF-1α), induced under hypoxic conditions, is negatively correlated with DLAT and the severity of OA, as confirmed in human and rat cartilage. Furthermore, siRNA-mediated HIF-1α silencing sensitized primary chondrocytes to cuproptosis, whereas HIF-1α stabilization had protective effects. In summary, increased oxygen levels in the cartilage induce cuproptosis, thereby accelerating OA progression, whereas HIF-1α stabilization mitigates this process. These findings may provide novel therapeutic targets for OA treatment in clinical practice.