Involvement of the HMGB1/TLR4/NF-κB axis in the protective effect of safflower yellow injection against myocardial ischemia/reperfusion injury via regulation of endoplasmic reticulum stress

Background Safflower yellow injection (SYI) has demonstrated cardioprotective effects on myocardial ischemia/reperfusion (MI/R) injury. This study aimed to explore its mechanistic basis. Methods H9c2 cells were pre-treated with 80 μg/mL SYI for 24 h before exposure to oxygen-glucose deprivation/reoxygenation (OGD/R). Protein levels related to endoplasmic reticulum (ER) stress and apoptosis were detected by western blot (WB). IL‑6 and TNF‑α protein and mRNA levels were determined by ELISA and qPCR. CCK-8 test and flow cytometry were used to measure cell viability and apoptosis, respectively. Moreover, the expression of proteins implicated in HMGB1/TLR4/NF-κB pathway was measured by WB assay. Finally, rescue validation was performed using recombinant HMGB1 (rHMGB1). Results SYI treatment alleviated OGD/R-induced ER stress and reduced IL-6 and TNF-α levels in H9c2 cells. These changes were accompanied by increased cell viability and reduced OGD/R‑induced apoptosis. Mechanistically, SYI significantly restrained activation of the HMGB1/TLR4/NF-κB signaling cascade in H9c2 cells triggered by OGD/R. Further rescue experiments with recombinant HMGB1 (rHMGB1) reversed the protective effects of SYI against OGD/R damage. Conclusion These findings indicate that the HMGB1/TLR4/NF‑κB axis mediates the protective effects of SYI against myocardial OGD/R injury, potentially through modulating ER stress and inflammatory responses. This study provides a mechanistic basis for the cardioprotective action of SYI in vitro and informs future investigations into its therapeutic potential. However, these results are derived from cell-based experiments alone, and further validation in animal models is needed to confirm the in vivo relevance of this mechanism.