RESUMO
A thiol-ß-cyclodextrin was synthesized by a simple and environmentally friendly three-step method comprising epoxy activation of ß-cyclodextrin, thiosulfate-mediated oxirane opening, and further reduction of the S-alkyl thiosulfate to a thiol group. The final step was optimized by using thiopropyl-agarose, a solid phase reducing agent with many advantages over soluble ones. ß-Cyclodextrin thiolation was confirmed by titration with a thiol-reactive reagent, NMR studies, and MALDI-TOF/TOF. Thiolated cyclodextrin had an average value of one thiol group per molecule. Thiol-ß-cyclodextrin proved to be an excellent agent for controlling polyphenol oxidase activity. This copper-containing enzyme is responsible for browning in fruits and vegetables. Under the same conditions, thiol-ß-cyclodextrin generated a reductive microenvironment that increased the antibrowning effect on Red Delicious apples compared to unmodified ß-cyclodextrin.
