Being　a　highly　conserved　catabolic　process,　autophagy　is　induced　by　various　forms　of　cellular　stress,　and　its　modulation　has　considerable　potential　as　a　cancer　therapeutic　approach.　In　the　present　study,　it　was　demonstrated　that　dicitrinone　B　(DB),　a　rare　carbon‑bridged　citrinin　dimer,　may　exert　anticancer　effects　by　blocking　autophagy　at　a　late　stage,　without　disrupting　lysosomal　function　in　MCF7　breast　cancer　and　MDA‑MB‑231　triple‑negative　breast　cancer　cells.　Furthermore,　it　was　discovered　that　DB　significantly　enhanced　intracellular　reactive　oxygen　species　(ROS)　production　and　that　the　removal　of　ROS　was　followed　by　the　attenuation　of　autophagy　inhibition.　In　addition,　DB　exerted　notable　inhibitory　effects　on　the　proliferation　and　promoting　effects　on　the　apoptosis　of　MCF7　and　MDA‑MB‑231　cells.　In　combination　with　conventional　chemotherapeutic　drugs,　DB　exhibited　a　further　enhanced　synergistic　effect　than　when　used　as　a　single　agent.　Overall,　the　data　of　the　present　study　demonstrate　that　DB　may　prove　to　be　a　promising　autophagy　inhibitor　with　anticancer　activity　against　breast　cancer.