Objective:High-fat diet is one of the main risk factors that disrupt the balance of gut microbiota,which eventually will induce colorectal cancer(CRC).Evodiamine(EVO)is a wildly used multifunctional tradi-tional Chinese medicine extract.In this study,we investigated the role of gut microbiota in high-fat diet-propelled CRC and the potential of EVO for CRC chemoprevention.Methods:Gut microbiota,serum D-lactic acid and endotoxin from 38 patients with colon cancer and 18 healthy subjects were detected by quantitative real-time polymerase chain reaction and enzyme-linked immunosorbent assay(ELISA).In addition,body mass index,phospho-signal transducer and activator of transcription 3(p-STAT3)expression in cancer tissues and paracancerous tissues were detected by immunohistochemistry.A mouse intestinal inflammatory tumor model was established by azomethane/sodium dextran sulfate,followed by treatment with EVO and 5-aminosalicylic acid(ASA).Gut microbiota and inflammatory factors were detected by quantitative polymerase chain reaction,while serum D-lactic acid and endotoxin were detected by ELISA.Furthermore,cell proliferation,cell apoptosis,and interleukin(IL)-6/STAT3/P65 pathway were evaluated by 5-ethynyl-2'-deoxyuridine,terminal-deoxynucleotidyl transferase-mediated nick-end labeling,and Western blot assays.Results:In patients with colon cancer,the numbers of Enterococcus faecalis and Escherichia coli were increased,while those of Bifidobacterium,Campylobacter and Lactobacillus were decreased.Serum endo-toxin and D-lactic acid levels and p-STAT3 levels were significantly increased.In the mouse model,both EVO and ASA inhibited tumor formation,decreased the proliferation of tumor cells,and induced apopto-sis of tumor cells.Compared with the control group,the numbers of E.faecalis and E.coli were decreased,while Bifidobacterium,Campylobacter and Lactobacillus numbers were increased.In the EVO group,serum endotoxin and D-lactic acid levels and inflammatory factors were significantly decreased.Further,the IL6/STAT3/P65 signaling pathway was inhibited in the EVO group.Conclusion:EVO may inhibit the occurrence of colon cancer by regulating gut microbiota and inhibiting intestinal inflammation.The potential mechanism involves inhibition of the IL6/STAT3/P65 signaling pathway,revealing its potential therapeutic significance in clinical applications.