Molecular Binding Ability and Selectivity of Natural alpha-,beta-,gamma-Cyclodextrins and Oligo(ethylenediamino) Modified beta-Cyclodextrins with Chinese Traditional Medicines

摘要

The binding ability and inclusion complexation behavior of natural aljpha-,beta-,gamma-cyclodextrins(1-3) and two mono[6-oligo(ethylenediamino)-6-deoxy]-beta-cyclodextrins(4,5)with four Chinese traditional medicines,that is,alpha-asarone(AS),ferulic acid (FA),magnolol(MA)and honokiol(HO),Hve been ivestigated in aqueous phosphate buffer solutions(pH=7.20).The spectral titations have been performed at 25 deg C by using fluorescence spectroscopy to calculate the comjplex stability constants(Ks)and gibbs free energy changes(triangle openG)for the stoichiometric 1:1 inclusion complexation of hosts 1-5 with guest medicines.The results obtained indicate that the different guest medicines fit in with hydrophobic cavities of different sizes snd the appended substitutes of host 4 and 5 change the hydrophobic microenvironment of beta-cyclodextrin 2,influencing the original binding ability and molecular selectivity of host 2 consequently.The binding ability and inclusion complexation behavior of these hosts 1-5 are discussed sccording to the size/shape fit concept and hydrogen bonding ineraction between hosrt cyclodextrins and guest medicine molecules.