〔Abstract〕 To explore the effects and mechanisms of Kobophenol A ( KPA) on lipopolysaccharide ( LPS) -induced M1 macrophage polarization，and to provide a theoretical basis for the treatment of inflammatory immune diseases and the development of new drugs． Methods The M1 macrophage polarization model of RAW264. 7 was established by LPS induction，and the peroxiredoxin 6 ( Prdx6) knockdown model was constructed using the Prdx6 inhibitor MJ33 and Prdx6-siRNA．RAW264. 7 cells，a mouse macrophage cell line，were treated with various concentrations of KPA． Cell viability was assessed using the CCK-8 assay．The expression levels of Prdx6 and M1 macrophage polarization-related proteins，including inducible nitric oxide synthase ( iNOS) and cy- clooxygenase-2 ( COX-2) ，were detected by Western blot and immunofluorescence staining．The expression levels of Prdx6 and M1 macrophage polarization-related genes iNOS，interleukin-6 ( IL-6) ，and tumor necrosis factor α ( TNF-α) ，were measured by RT-qPCR. Flow cytometry was employed to detect the expression of cluster of differ- entiation 86 ( CD86) ，a marker of M1 macrophages．Results Compared with the LPS-induced M1 macrophage po- larization model ， KPA significantly reversed the morphological changes of M1 macrophage polarization in RAW264. 7 macrophages and decreased the expression of M1 macrophage polarization-related proteins iNOS，COX- 2，CD86 and related genes iNOS，IL-6，TNF-α ( all P＜0. 05) ．In addition，LPS significantly downregulated the expression of Prdx6 in RAW264. 7 macrophages，while KPA upregulated the expression of Prdx6．Moreover，treat- ment with the Prdx6 inhibitor MJ33 significantly upregulated the expression of iNOS，a marker of M1 macrophage polarization，in RAW264. 7 macrophages，whereas treatment with KPA significantly downregulated the expression of iNOS ( all P＜0. 05) ．Conclusion KPA inhibits LPS-induced M1 polarization of RAW264. 7 macrophages by up- regulating the expression of Prdx6．