Host-guest inclusion system of rhein with polyamine-modified β-cyclodextrins: characterization and cytotoxicity

We report the preparation of inclusion complexes between rhein and four polyamine-modified β-cyclodextrins, namely amino-β-cyclodextrins (NH₂-βCD), ethylenediamine-β-cyclodextrins (EN-βCD), diethylenetriamine-β-cyclodextrins (DETA-βCD) and triethylenetetramine-β-cyclodextrins (TETA-βCD) using suspension method. The solution and solid state forms of the inclusion complexes of rhein with polyamine-β-cyclodextrins were characterized by multiple techniques. Additionally, saturated solution and MTT methods were implemented to assess the water solubilization and in vitro cytotoxicity of the inclusion complexes, respectively. The results suggested that rhein was encapsulated within the CD cavity to form a 1:1 host-guest inclusion complex. Notably, a significant enhancement of the water solubility and in vitro cytotoxicity of rhein was found in the form of inclusion complex with polyamine-β-cyclodextrin.