Cyclodextrins nanocavities effects on basic and acid fluorescence quenching of hydroxy-indoles

A. GUILLERMO BRACAMONTE, ALICIA V. VEGLIA

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2013 vol. 261 p. 20 - 25

1010-6030

The cyclodextrins effects on the serotonin (5HT) and 5-hydroxy-3-indolyl acetic acid (5HIA) fluorescence emission in acid and alkaline quenching conditions were analyzed. From Stern-Volmer plots, the quenching constants (KQ) were determined in the presence and absence of β-cyclodextrin (bCD) and hydroxypropyl-β-cyclodextrin (HPbCD). In both media a decrease in the values of KQ was measured in the presence of CDs, as compared with their absence. In acid media, the decrease was: 36-39 % with bCD and 48-54 % with HPbCD for 5HIA and 5HT respectively. In basic media, with the neutral receptors, these values are 69-29 % with bCD and 56-43 % with HPbCD for 5HIA and 5HT respectively. Also, a complete quenching inhibition produced by ionized cyclodextrins was determined for both substrates. The results showed a net protective effect due to the guest inclusion into the cyclodextrin cavity. This study is particularly important for analytical determinations in such media.