Supramolecular cyclodextrin complexes of hydroxy-indoles applied as protectors of fluorescence quenching

A. G. BRACAMONTE; ALICIA V. VEGLIA*

Québec

Congreso; 96th Canadian Chemistry Conference; 2013

Hydroxy-indoles, as serotonin (5-hydroxytryptamine, 5HT) and 5-hydroxy-3-indolylacetic acid (5HIA) are metabolites of tryptophan. It is well known that the fluorescence emissionof indole compounds is affected by the media showing fluorescence quenching in basic and acidconditions. The study of these processes is particularly important for analytical determinations insuch media.In the present work we analyzed the cyclodextrin effect on the fluorescence emission of5HT and its main metabolite (5HIA) in acid and alkaline media. From Stern-Volmer plots,quenching constants (KQ) were determined in the presence and absence of β-cyclodextrin andhydroxypropyl-β-cyclodextrin, in water at 25,0 ºC. In both media a decrease in the values of KQwas measured in the presence of CDs, as compared with their absence. In acid media, thedecrease was: (36-39) % with βCD and (50-54) % with HPβCD for 5HIA and 5HT respectively.In basic media, with the neutral receptors, these values are 69-29 % with βCD and 56-43 % withHPβCD for 5HIA and 5HT respectively. Also, a complete quenching inhibition produced byionized cyclodextrins was determined for both substrates.