Jinxia Li, Kenm ing Yu, Jianping Bai, Huizhi Zhang, Jianbin Chao

Aim: To determine the interaction of AP with ß-cyclodextrin (ß-CD) and 2-hydroxylpropyl (HP)-ß-CD was studied in detail based on fluorescence method and to determined the effect of the complex process on their antioxidant capacity. Methods: The formation of the complexes of apigenin (AP) with ß-cyclo dextrin (ß-CD) and 2-hydroxylpropyl (HP)-ß-CD was studied by fluorescence spectra in solution. The formation constants (Ks) of complexes were determined by fluorescence method and phase-solubility measurements. Results: The results showed that the inclusion ability of ß-CD and its derivative were the order: HP-ß-CD>ß-CD. In addition, the experimental resulted confirmed the existence of 1:1 inclusion complex of AP with CDs. Kinetic st udies of scavenging of 1, 1-Diphenyl2-picryl-hydrazyl free radical with AP and CDs complexes were done. Conclusion: The resul ts obtained indicated that the AP/HP-ß-CD complex was the most reactive form, then was ß-CD complex, and last was free AP.