Dicitrinone　D　is　a　novel　polyketide　isolated　from　a　marine-derived　fungus　Penicillium　citrinum.　In　this　study,　we　described　the　isolation,　structure　elucidation　and　antitumor　mechanism　of　this　compound.　Cell　proliferation　assay　showed　that　dicitrinone　D　was　safe　for　normal　cells,　but　effectively　inhibited　the　growth　of　multiple　tumor　cells,　especially　SPC-Al　cells.　Cell　cycle　and　immunofluorescence　analysis　suggested　that　dicitrinone　D　had　cellular　effects　similar　to　other　microtubule-targeting　agents.　Polymerization　assay,　electron　microscopy　and　time-lapsed　video　microscopy　assay　demonstrated　dicitrinone　D　was　a　microtubule-destabilizing　agent.　Finally,　the　docking　analysis　predicted　that　dicitrinone　D　may　bind　to　vinblastine　binding　site　on　tubulin.　(C)　2017　Published　by　Elsevier　Ltd.