Relative affinity of 5-methoxypsoralen and 8-methoxypsoralen towards beta-cyclodextrin: a fluorescence, circular dichroism and chromatographic study.
ABSTRACT The relative affinity of 5-methoxypsoralen (5-MOP) and 8-methoxypsoralen (8-MOP) towards beta-cyclodextrin, a good model for the study of lipophilic interactions in biological systems and a potential drug carrier, has been investigated using spectroscopic and chromatographic methods. The fluorescence emission of 5-MOP in aqueous solution containing beta-cyclodextrin (10(-2) M) is found to be markedly blue shifted and enhanced by a factor of 6 whereas no significant changes are observed for 8-MOP. The existence of an induced circular dichroism is evidence for the formation of a 1:1 inclusion complex (association constant K = 400 +/- 50 M-1). Moreover, chromatographic results obtained with a beta-cyclodextrin linked stationary phase are consistent with our spectroscopic results and might have interesting analytical implications. These results clearly demonstrate that, in contrast to 8-MOP, 5-MOP exhibits a strong affinity for hydrophobic medium. Interesting pharmacological and analytical applications may result from the possible inclusion of psoralen derivatives into beta-cyclodextrin.
- Emerging Technologies and Factory Automation, 1992. IEEE International Workshop on; 09/1992
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ABSTRACT: An inclusion complex was prepared between the local anesthetic lidocaine (LDC) and hydroxypropyl-β-CD (HP-β-CD). The complex was characterized by thermal analysis (differential scanning calorimetry, DSC), UV absorption and high-pressure liquid chromatography (HPLC). DSC results were indicative of complexation, due to the loss of the characteristic endothermic peak of LDC (77°C). Phase-solubility diagrams allowed the determination of the association constant between LDC and HP-β-CD (35.7±4.7M−1). The rate of LDC release decreased after complexation and thermodynamic parameters from the HPLC studies (ΔG°=−2.65kJ/mol) revealed that a stable complex was formed.Journal of Inclusion Phenomena 03/2007; 57(1):313-316. · 1.40 Impact Factor