Determination of dissociation constants of cyclodextrin-ligand inclusion complexes by electrospray ionization mass spectrometry

作者：Zhang Huarong; Zhang Hanqi; An Weiqun; Ding Lan^*

来源：European Journal of Mass Spectrometry, 2006, 12(5): 291-299.

DOI：10.1255/ejms.818

• dissociation constant
• cyclodextrin
• inclusion complex
• electrospray ionization
• mass spectrometry

The inclusion complexes of four ligands binding to cyclodextrins (CDs) were studied by electrospray ionization mass spectrometry (ESI-MS) and the dissociation constants of the complexes were obtained. The 1:1 stoichiometric inclusion complex was found in the system of CD and fenbufen or aspirin. The obtained K(D) values of the inclusion complexes of fenbufen binding to alpha-CD and to beta-CD are 4.38 x 10(-4) molL(-1) and 2.12 x 10(-4) molL(-1), respectively. The K(D) values of the inclusion complexes of alpha-CD-aspirin and beta-CD-aspirin are 3.33 x 10(-4) molL(-1) and 1.83 x 10(-4) molL(-1), respectively. A non-linear least squares regression method was applied to validate the results which were consistent with each other. For the system of tetracycline hydrochloride and CD, the 1:1 and 1:2 stoichiometric inclusion complexes were found in the mass spectra. The K(D,1) and K(D,2) values of the 1:1 and 1:2 stoichiometric inclusion complexes of alpha-CD and tetracycline hydrochloride are 4.47 x 10(-4) molL(-4) and 6.51 x 10(-4) molL(-1), respectively, and those of beta-CD and tetracycline hydrochloride are 2.26 x 10(-4) molL(-1) and 8.57 x 10(-4) molL(-1), respectively. For the system of norfloxacin and CD, besides the 1:1 and 1:2 inclusion complexes, the 1: 3 stoichiometric inclusion complex was also found. The K(D,1), K(D,2) and K(D,3), of alpha-CD and norfloxacin inclusion complexes are 4.61 x 10(-4) molL(-1), 6.05 x 10(-4) molL(-1) and 1.45 x 10(-3) molL(,)(-1) respectively. The three K(D) values of beta-CD and norfloxacin are 1.96 x 10(-4) molL(-4), 4.93 x 10(-4) mol L(-1) and 1.15 x 10(-3) molL(-1), respectively.

• 出版日期2006
• 单位吉林大学