Binding of chloroquine to ionic micelles: Effect of pH and micellar surface charge

Autor(es)

Santos, Marcela de Souza ^[1] ; Freire de Morais Del Lama, Maria Perpetua ^{[1, 2]} ; Ito, Amando Siuiti ^[3] ; Zumstein Georgetto Naal, Rose Mary ^{[1, 2]}

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Quim & Fis, Fac Ciencias Farmaceut Ribeirao Preto, BR-14040903 Sao Paulo - Brazil

^[2] Univ Estadual Campinas, Dept Quim Analit, Inst Nacl Ciencia & Tecnol Bioanalit, BR-13083970 Campinas, SP - Brazil

^[3] Univ Sao Paulo, Dept Fis, Fac Filosofia Ciencias & Letras Ribeirao Preto, BR-14040901 Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Luminescence; v. 147, p. 49-58, MAR 2014.
• Citações Web of Science: 8

Resumo

The pharmacological action of chloroquine relies on its ability to cross biological membranes in order to accumulate inside lysosomes. The present work aimed at understanding the basis for the interaction between different chloroquine species and ionic micelles of opposite charges, the latter used as a simple membrane model. The sensitivity of absorbance and fluorescence of chloroquine to changes in its local environment was used to probe its interaction with cetyltrimethylammonium micelles presenting bromide (CTAB) and sulfate (CTAS) as counterions, in addition to dodecyl sulfate micelles bearing sodium (SDS) and tetramethylammonium (TMADS) counterions. Counterion exchange was shown to have little effect on drug-micelle interaction. Chloroquine first dissociation constant (pKa(1)) shifted to opposite directions when anionic and cationic micelles were compared. Chloroquine binding constants (K-b) revealed that electrostatic forces mediate charged drug-micelle association, whereas hydrophobic interactions allowed neutral chloroquine to associate with anionic and cationic micelles. Fluorescence quenching studies indicated that monoprotonated chloroquine is inserted deeper into the micelle surface of anionic micelles than its neutral form, the latter being less exposed to the aqueous phase when associated with cationic over anionic assemblies. The findings provide further evidence that chloroquine-micelle interaction is driven by a tight interplay between the drug form and the micellar surface charge, which can have a major effect on the drug biological activity. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 05/53002-4 - Estudos fotofisicos de farmaco antimalarico em meio micelar: efeito do contraion do surfactante.
• Beneficiário: Marcela de Souza Santos
• Modalidade de apoio: Bolsas no Brasil - Iniciação Científica