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Synthesis and in vitro evaluation of the antitumoral phototherapeutic potential of squaraine cyanine dyes derived from indolenine

2019; Elsevier BV; Volume: 167; Linguagem: Inglês

10.1016/j.dyepig.2019.04.007

1873-3743

Eurico Lima, Octávio Ferreira, Vanessa S. D. Gomes, Adriana O. Santos, Renato E. Boto, José R. Fernandes, Paulo Almeida, Samuel Silvestre, Lucinda V. Reis,

Porphyrin and Phthalocyanine Chemistry

In this work several symmetrical indolenine squaraine dyes with different groups positioned on the four-membered central ring, such as sulfur, barbituric acid, amino and methylamino, were synthesized, and their structures were fully characterized. All dyes displayed intense and narrow absorption bands in the visible region. To evaluate their singlet oxygen formation ability, the 1,3-diphenylisobenzofuran assay was used. The degradation of these squaraine dyes upon light exposure was evaluated in order to infer about their photostability. The in vitro potential of these compounds as photosensitizers for photodynamic therapy was evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay in several tumor (Caco-2, MCF-7 and PC-3) and non-tumor (NHDF and N27) cell lines, using a custom-built LED based light exposure system emitting radiation with the central wavelength close to the maximum absorption wavelength of the squaraine dyes. The indolenine squaraine dyes showed a high ability to produce singlet oxygen and good photostability. The zwitterionic dyes, namely the unsubstituted dye, the barbituric acid derivative and the monothiosquaraine dye, showed relevant photodynamic activity. It was noteworthy that the unsubstituted squaraine dye exhibited a cytotoxic selectivity for the Caco-2 tumor cell line when compared to the NHDF normal cell line.