Inhibition of osteoclastogenesis for periprosthetic osteolysis therapy through the suppression of p38 signaling by fraxetin

Fraxetin pretreatment alleviates cisplatin-induced kidney injury by antagonizing autophagy and apoptosis via mTORC1 activation

Cisplatin-induced kidney injury (CKI) is a common complication of chemotherapy. Fraxetin, derived from Fraxinus bungeana A. DC. bark, has antioxidant, anti-inflammatory, and anti-fibrotic effects. This study aims to investigate fraxetin's effects on CKI and its underlying mechanism in vivo and in vitro. Tubular epithelial cells (TECs) and mice were exposed to cisplatin with and without fraxetin preconditioning assess fraxetin's role in CKI. TECs autophagy was observed using transmission electron microscopy. Apoptosis levels in animal tissues were measured using TUNEL staining. The protective mechanism of fraxetin was explored through pharmacological and genetic regulation of mTORC1. Molecular docking was used to identify potential binding sites between fraxetin and mTORC1. The results indicated that fraxetin pretreatment reduced cisplatin-induced kidney injury in a time- and concentration-dependent way. Fraxetin also decreased autophagy in TECs, as observed through electron microscopy. Tissue staining confirmed that fraxetin pretreatment significantly reduced cisplatin-induced apoptosis. Inhibition of mTORC1 using rapamycin or siRNA reversed the protective effects of fraxetin on apoptosis and autophagy in cisplatin-treated TECs, while activation of mTORC1 enhanced fraxetin's protective effect. Molecular docking analysis revealed that fraxetin can bind to HEAT-repeats binding site on mTORC1 protein. In  summary, fraxetin pretreatment alleviates CKI by antagonizing autophagy and apoptosis via mTORC1 activation. This provides evidence for the potential therapeutic application of fraxetin in CKI.

Fraxetin attenuates ferroptosis in myocardial infarction via AKT/Nrf2/HO-1 signaling

BACKGROUND

Myocardial infarction (MI) is the principal cause of mortality globally. Fraxetin (Fra) has anti-oxidative and anti-inflammatory properties. Nevertheless, the functional action of Fra in the progression of MI has never been elucidated.

METHOD

The in vivo model of MI was set up by ligating left anterior descending artery. The gene expression was tested by qRT-PCR and WB. The 2,3,5-triphenyltetrazolium chloride staining was applied to assess MI size. The cell viability was tested by MTT assay. Commercial kits were utilized to detect the activity of serum LDH and the levels of Fe²⁺, malondialdehyde (MDA), and glutathione (GSH).

RESULTS

Fra treatment could reduce the infraction size and restrain ferroptosis in rats with MI. Moreover, Fra reduced the activity of serum LDH, the accumulation of iron and the MDA level, and increased GSH and glutathione peroxidase 4 (GPX4) in rats with MI. Furthermore, Fra protected H9C2 myocardial cells against OGD/R-induced ferroptosis by up-regulating HO-1. Moreover, Fra activated phosphorylation of AKT and Nrf2 nuclear accumulation in MI in vivo and in vitro models. Notably, silencing Nrf2 enhanced the ferroptosis in H9C2 cells induced by OGD/R, while LY, an inhibitor of AKT phosphorylation, diminished the inhibition of Fra.

CONCLUSION

Fra attenuated MI-induced ferroptosis via AKT/Nrf2/HO-1 signaling, providing a potential therapeutic agent for MI.

Fraxetin inhibits interleukin-1β-induced apoptosis, inflammation, and matrix degradation in chondrocytes and protects rat cartilage in vivo

Osteoarthritis (OA) is a disease characterized by degeneration of the joint complex due to cartilage destruction. Fraxetin, a widely used and studied coumarin compound extracted from a traditional Chinese herb (Qin Pi), has shown anti-inflammatory and antioxidant properties, but its effects on OA have not been studied. In the present study, western blotting, immunofluorescence, and terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) were used to evaluate the effects of fraxetin on IL-1β-induced apoptotic activity, inflammatory responses, and catabolism in rat chondrocytes. The results showed that fraxetin prevented IL-1β-induced apoptosis of chondrocytes and inhibited inflammatory mediator release by regulating the Toll-like receptor 4 (TLR4)/myeloid differentiation primary response 88 (MyD88)/nuclear factor (NF)-κB pathway in chondrocytes. Additionally, fraxetin suppressed the upregulation of matrix metalloproteinase 13 (MMP13) and degradation of collagen II in the extracellular matrix (ECM). Moreover, the effects of fraxetin in vivo were assessed in a monosodium iodoacetate (MIA)-induced rat model of OA using hematoxylin and eosin (H&E) and Safranin O-fast green staining and magnetic resonance imaging (MRI). The results showed that fraxetin protected the cartilage against destruction. In conclusion, fraxetin could be a potential therapeutic for OA.