Background <p>The clinical application of sorafenib (Sora) in advanced hepatocellular carcinoma (HCC) is greatly limited due to its moderate efficacy and acquired resistance. Combination therapy with other agents holds promise to improve therapeutic efficacy.</p> Purpose <p>Our study aimed to screen alkaloids exerting synergistic anticancer effects with low-dose Sora in HCC treatment and underlie its molecular mechanisms.</p> Methods <p>CCK-8 assay was used to evaluate the inhibition rates of Sora combined with alkaloids. The most likely binding targets were predicted by molecular docking simulations, and further verified through CETSA and DARTS. ROS levels were measured by flow cytometry. IL-18 levels were detected using ELISA. Nude mouse xenograft models were employed to validate the synergistic anticancer effect.</p> Results <p>Co-administration of alkaloids, Cory showed prominent synergistic anticancer properties with Sora. Quantitative proteomic and molecular docking analyses suggested that NOS3 is a potential target of Cory. CETSA and DARTS assay revealed that Cory directly bound to NOS3. Cory increased NOS3 protein expression in a time- and concentration-dependent manner. Mechanistically, both in vitro and in vivo models showed that Cory increased the sensitivity of HCC cells to Sora through NOS3-mediated ROS production and IL-18 secretion. NOS3 knockdown could reverse the synergistic antitumor effect of Cory and Sora. The addition of antioxidant NAC reversed the increased ROS and IL-18 levels in Sora/Cory-treated Huh7 and HepG2 cells.</p> Conclusions <p>This study first revealed that Cory acted synergistically with Sora to inhibit HCC growth through NOS3-mediated ROS production and IL-18 secretion, suggesting the potential of Cory as a sorafenib sensitizer.</p>