The Molecular Recognition And Drug Inclusion Behavior Research Of Hydroxypropyl-β-Cyclodextrin

Due to the unique structure with hydrophobic central cavity, hydroxypropyl-β- cyclodextrins can selectively bind different guest molecules to form inclusion complexes in order to improve solubility, stability and other properties of guest molecules. Thus, hydroxypropyl-β-cyclodextrins have been widely used in many different fields, such as pharmaceutics, analytics, food and environment, etc. In this paper, the use of 2-hydroxypropyl-β-cyclodextrin with different substituted degree andβ-cyclodextrin as host molecules was investigated. The article studied the molecular recognition behaviors with the guest molecules such as para-aminobenzoic acid and the inclusion features with steroid drugs such as dexamethasone.The experiments can be divided into two parts:1. para-aminobenzoic acid, ortho-aminobenzoic acid, meta-aminobenzoic acid, 4-nitrobenzoic acid, sulfanilic acid were used as guest molecules to study the molecular recognition behaviors in the water with host molecules such asβ-cyclodextrin, 2-hydroxypropyl-β-cyclodextrin, mono-2-O-(2-hydroxypropyl)-β- cyclodextrin and di-2-O-(2-hydroxypropyl)-β-cyclodextrin. UV-Vis method was used to calculate the stability constants and molar ratios. The results showed that the host molecules and guest molecules formed inclusion complex with the molar ratios of 1:1; the stability of inclusion complexes was related to the guest molecules'space strctures, substituted fuctions and the hydrophobicity of the substituted fuctions; the mono-2-O-(2-hydroxypropyl)-β-cyclodextrin were more stable thanβ- cyclodextrin; The stability constants were influenced by the substituted degrees and positions of hydroxypropyl on the host molecules. The inclusion complexes ofβ-cyclodextrin with guest molecules were characterized through DSC and IR.2. Dexamethasone, dexamethasone acetate and betamethasone have been used as the steroid drug molecules investigated their solubilization and stabilization properties with host molecules 2-hydroxypropyl-β-cyclodextrin andβ-cyclodextrin in the phosphate buffer solution at pH=7.4. Phase-solubility method was used to calculate the stability constants and molar ratios of the inclusion complexes. The results demonstrated that in comparison withβ-cyclodextrin, 2-hydroxypropyl-β- cyclodextrin can effectively improve the stability and solubility of dexamethasone; the stability constants of 2-hydroxypropyl-β-cyclodextrin with drug molecules depended on the substituted degree and the substituted positions of host molecules.