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Indirubin, the active constituent of a Chinese antileukaemia medicine, inhibits cyclin-dependent kinases


Indirubin is the active ingredient of Danggui Longhui Wan, a mixture of plants that is used in traditional Chinese medicine to treat chronic diseases. Here we identify indirubin and its analogues as potent inhibitors of cyclin-dependent kinases (CDKs). The crystal structure of CDK2 in complex with indirubin derivatives shows that indirubin interacts with the kinase’s ATP-binding site through van der Waals interactions and three hydrogen bonds. Indirubin-3′-monoxime inhibits the proliferation of a large range of cells, mainly through arresting the cells in the G2/M phase of the cell cycle. These results have implications for therapeutic optimization of indigoids.

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Figure 1: Inhibition of CDK1–cyclin B by various indigoids.
Figure 2: Binding of indirubin-3′-monoxime and indirubin-5-sulphonate to CDK2.
Figure 3: Superposition of roscovitine and indirubin-5-sulphonate and staurosporine and indirubin-5-sulphonate bound to CDK2.
Figure 4: The Connolly molecular surface of CDK2–indirubin-5-sulphonate, calculated with a probe radius of 1.5 Å.
Figure 5: Movement of the conserved DFG loop accompanies indirubin-5-sulphonate binding to CDK2.
Figure 6: Indirubin-3′-monoxime inhibits proliferation of Jurkat cells, accumulates cells in G1 and G2/M and reduces phosphorylation of the retinoblastoma protein.
Figure 7: Cell-cycle-phase distribution of various cell lines following exposure to indirubin-3′-monoxime.


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We thank N. Xiuren for his help with Chinese ideogram; the fishermen of the Station Biologique de Roscoff for collecting the starfish; D. Alessi, M. Cobb, W. Harper, F. Hofmann, J. Lahti, S. Lohmann, H. Mett, D. Morgan, L. Pinna and H. Y. L. Tung for providing reagents and purified enzymes; D. Louvard, M. Mareel, M. Crepin and J.P. Moulinoux for providing cell lines; the scientists at the X-ray diffraction beamline, Elettra, Trieste; W. Burmeister for assistance during data collection on ID14-3 at the ESRF; and S. Lee, R. Bryan, K. Measures and I. Taylor for assistance. This research was supported by grants from the Association pour la Recherche sur le Cancer and the Conseil Régional de Bretagne (to L.M.), from the BBSRC, MRC and the Royal Society (to J.A.E. and M.E.M.N.) and from the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (to G.E.).

Correspondence and requests for materials should be addressed to L.M. or G.E.

Supplementary Information is available on Nature Cell Biology’s World-Wide Web site ( or as paper copy from the London editorial office of Nature Cell Biology.

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Correspondence to Laurent Meijer.

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Hoessel, R., Leclerc, S., Endicott, J. et al. Indirubin, the active constituent of a Chinese antileukaemia medicine, inhibits cyclin-dependent kinases. Nat Cell Biol 1, 60–67 (1999).

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