Photodynamic activity of indolenine-based aminosquaraine cyanine dyes: Synthesis and in vitro photobiological evaluation

Photophysicochemical Properties and In Vitro Phototherapeutic Effects of Iodoquinoline- and Benzothiazole-Derived Unsymmetrical Squaraine Cyanine Dyes

“…In the case of dye 13 ( Figure S8), two additional singlets were observed in that region of the spectrum (6.19, 6.04, 5.92 and 5.82 ppm) as result of the hindrance of free rotation of the N-methylamine group, due to the partial character of the double bond between the nitrogen atom and the carbon atom of the four-membered ring, that should promote the non-equivalence of chemical environments. This phenomenon was previously observed in the NMR spectra of several symmetrical aminosquaraine cyanine dyes [24,60] and unsymmetrical aminosquaraine cyanine dyes [25]. It is also noted that in the spectrum of 13 the peaks of the NCH 3 groups are under the water peak of the solvent but appear in the spectrum with D 2 O, at the chemical shifts of 3.35 and 3.32 ppm as two singlets of three protons each.…”

Quinoline- and Benzoselenazole-Derived Unsymmetrical Squaraine Cyanine Dyes: Design, Synthesis, Photophysicochemical Features and Light-Triggerable Antiproliferative Effects against Breast Cancer Cell Lines

“…This signals' duplication can be explained by the difficulty in the free rotation of the bond between the nitrogen atom of N-methylamine substituent and the carbon of the four-membered central ring, occurring from the partial character of the double bond, which should promote the non-equivalence of chemical environments. Our research group recently observed this phenomenon in the NMR spectra of several symmetrical [25,41] and unsymmetrical methylaminosquaraine cyanine dyes [37,48].…”

“…To that end, several squaraine cyanine dyes, commonly named as squaraine or squarylium dyes, a family of synthetic dyes first-synthesized in the 1960s [35], have been the subject of photodynamic studies [25,36,37] given their relevant photochemical and photophysical properties [38][39][40]. These dyes are known to possess good photoconductivity, great stability under light exposure, and narrow and intense absorption bands within the tissue transparency spectral region [38,41], singlet oxygen production and high molar absorption coefficient [42]. Although generally associated with this class of dyes, these properties may vary depending on their structural changes [41,43].…”

“…These dyes are known to possess good photoconductivity, great stability under light exposure, and narrow and intense absorption bands within the tissue transparency spectral region [38,41], singlet oxygen production and high molar absorption coefficient [42]. Although generally associated with this class of dyes, these properties may vary depending on their structural changes [41,43]. The structure of these dyes is also closely related to their phototherapeutic behavior, governed by the cell line to which they are applied.…”

“…The structure of these dyes is also closely related to their phototherapeutic behavior, governed by the cell line to which they are applied. Lima et al found that the effect on photocytotoxicity on MCF-7 cell line was dependent on the number of carbons in the N-alkyl chains of indolenine-based symmetrical squaraine cyanine dyes [25,41]. Bis(3,5-diiodo-2,4,6-trihydroxyphenyl) squaraine, one of the first to be synthesized and tested for this purpose, has also shown significant value in the photodynamic therapy of breast cancer [44,45].…”