The present invention relates to the medical field. In a first aspect the present invention relates to novel water soluble cyclodextrin-curcumin complexes having a pharmacological activity, in particular an anti-tumor and/or anti-inflammatory activity, and improved physico-chemical properties. In a second aspect, the present invention relates to a method for preparation of said water soluble curcumin derivatives. The invention further relates in a third aspect to a pharmaceutical composition comprising an effective amount of said water soluble curcumin derivatives. In a fourth aspect, the present invention concerns the use of said water soluble cucumin derivatives as a medicament and the use of said water soluble curcumin derivatives for the preparation of a medicament for the treatment of cancer and inflammatory diseases. In a fifth aspect, the present invention relates to the use of a pharmaceutical composition comprising said water soluble curcumin derivatives in the treatment of cancer and inflammatory diseases and to a new pharmaceutical composition comprising said water soluble curcumin derivatives.