Studies on α-, β-, and γ-cyclodextrin inclusion complexes of isoquinoline alkaloids berberine, palmatine and coralyne

• Published in: Journal of inclusion phenomena and macrocyclic chemistry 2014-04, Vol.78 (1-4), p.311-323
• Main Authors: Hazra, Soumitra, Hossain, Maidul, Kumar, Gopinatha Suresh
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Crystallography and Scattering Methods; Food Science; Organic Chemistry; Original Article
• ISSN: 1388-3127; 1573-1111
• DOI: 10.1007/s10847-013-0301-6

The complexation of three isoquinoline alkaloids berberine, palmatine and coralyne with α-, β-, and γ-CDs were studied by absorption, fluorescence, circular dichroism, NMR spectroscopy and microcalorimetric assay techniques. Their binding constant ( K BH ) values were determined by Benesi–Hildebrand equation. All the alkaloids formed 1:1 stoichiometry complexes with the cyclodextrins (CDs). The binding affinity is largest in β-CD followed by γ-, and α-CD for coralyne, followed by berberine and then palmatine. The thermodynamic parameters of the complexation were determined by calorimetry. The stoichiometry of complex formation and the variation of the apparent binding constant from spectroscopic studies were confirmed by calorimetry. The formation of the inclusion complexes was entropy driven in almost all the systems. Coralyne formed the strongest complex with all the CDs, followed by berberine and palmatine in that order. Coralyne-β-CD complex was studied through NMR, indicating more than one interaction mode.