engleski

Zwitterionic biphenyl quinone methides in photodehydration reactions of 3-hydroxybiphenyl derivatives : laser flash photolysis and antiproliferation study

In aqueous media, photochemical excitation to S1 of 3-phenylphenols 4-8 leads to deprotonation of the phenol OH, coupled with protonation of the benzyl alcohol and overall dehydration that delivers zwitterions 17-21. The zwitterions react with nucleophiles (CH3OH, CF3CH2OH and ethanolamine) converting them in high quantum yields to the corresponding adducts and photosolvolysis products (for photomethanolysis  ~ 0.1-0.5). Zwitterions 20 and 21 were characterized by laser flash photolysis in CH3CN-H2O (τ~7.5 and 25μs, respectively) and the associated quenching rate constants with nucleophiles azide and ethanolamine determined. In vitro studies of antiproliferative activity of the photochemicaly generated QMs and zwitterions formed from 2-, 3- and 4-phenylphenols were carried out on three human cancer cell lines HCT 116 (colon), MCF-7 (breast), and H 460 (lung). Irradiation of cells incubated with 3, 6, and 26 showed enhanced antiproliferative activity compared to the cells that were not irradiated. 3-Phenylphenol derivatives 4-8 are photoreactive and give rise to the corresponding QMs with zwitterionic structures. Irradiation of cells incubated with alkyl derivatives of 4-phenylphenol 3 and 26, and 3-phenylphenol 6, leads to enhanced antiproliferative effect compared to the cells that were kept in dark.

3-hydroxybiphenyl derivatives ; quinone methides ; antiproliferative activity

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