title: Novel β-cyclodextrin-eosin conjugates.
abstract: Eosin B (EoB) and eosin Y (EoY), two xanthene dye derivatives with photosensitizing ability were prepared in high purity through an improved synthetic route. The dyes were grafted to a 6-monoamino-β-cyclodextrin scaffold under mild reaction conditions through a stable amide linkage using the coupling agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride. The molecular conjugates, well soluble in aqueous medium, were extensively characterized by 1D and 2D NMR spectroscopy and mass spectrometry. Preliminary spectroscopic investigations showed that the β-cyclodextrin-EoY conjugate retains both the fluorescence properties and the capability to photogenerate singlet oxygen of the unbound chromophore. In contrast, the corresponding β-cyclodextrin-EoB conjugate did not show either relevant emission or photosensitizing activity probably due to aggregation in aqueous medium, which precludes any response to light excitation.
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd, Budapest, H-1097 Illatos út 7, Hungary; Department of Organic Chemistry, Faculty of Science, Charles University in Prague, Hlavová 8, 128 43, Prague 2, Czech Republic.
authors.forename: Gábor
authors.initials: G
authors.lastname: Benkovics
authors.affiliation: Laboratory of Photochemistry, Department of Drug Sciences, University of Catania, I-95125 Viale A. Doria 6, Italy.
authors.forename: Damien
authors.initials: D
authors.lastname: Afonso
authors.affiliation: Department of Pharmacognosy, Semmelweis University, H-1085 Üllői út 26, Hungary.
authors.forename: András
authors.initials: A
authors.lastname: Darcsi
authors.affiliation: Department of Pharmacognosy, Semmelweis University, H-1085 Üllői út 26, Hungary.
authors.forename: Szabolcs
authors.initials: S
authors.lastname: Béni
authors.affiliation: STMicroelectronics, Stradale Primosole 50, I-95121, Catania, Italy.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Conoci
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd, Budapest, H-1097 Illatos út 7, Hungary.
authors.forename: Éva
authors.initials: É
authors.lastname: Fenyvesi
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd, Budapest, H-1097 Illatos út 7, Hungary.
authors.forename: Lajos
authors.initials: L
authors.lastname: Szente
authors.affiliation: CycloLab, Cyclodextrin R&D Ltd, Budapest, H-1097 Illatos út 7, Hungary.
authors.forename: Milo
authors.initials: M
authors.lastname: Malanga
authors.affiliation: Laboratory of Photochemistry, Department of Drug Sciences, University of Catania, I-95125 Viale A. Doria 6, Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Sortino
keywords: fluorescence; photodynamic therapy; photosensitizers; singlet oxygen; xanthene; β-cyclodextrins