[A study on inclusion complexes of cyclodextrin with three anticancer xanthines by fluorescence].

The inclusion complexes of beta-Cyclodextrin (beta-CD) and HP-beta-Cyclodextrin (HP-beta-CD) with 6-Mercaptopurine (6-MP), Azathioprine (BAN) and 8-Azaguanine (Azan) were investigated by fluorescence. Various factors affecting the formation of inclusion complexes were discussed in detail including formation time and pH effect. The formation constants of their inclusion complexes were determined. The results indicated that their inclusion was affected significantly by laying time and pH. The formation time of beta-CD inclusion complexes is much longer than that of HP-beta-CD. The optimum pH is about pH = 7.7-12. Their maximum excitation wavelengths are all in the range of 276-285 nm and the maximum emission wavelengths are all in the range of 328-353 nm. The fluorescence signals are intensified with increasing concentration of CD. The stoichiometries of the inclusion complexes of CD with these three anticancer xanthines are all 1:1 and the formation constants are calculated.