DNA interactions, photocleavage, and cytotoxicity of fluorescein–porphyrinatozinc complexes with different lengths of links

Abstract

Three fluorescein–porphyrinatozinc complexes Zn(Fl-PPTPP) (1) (Fl-PPTPp = 5-(4-fluoresceinpropyloxy)phenyl-10,15,20-triphenylporphyrin), Zn(Fl-HPTPP) (2) (Fl-HPTPp = 5-(4-fluoresceinhexyloxy)phenyl-10,15,20-triphenylporphyrin) and Zn(Fl-DPTPP) (3) (Fl-DPTPp = 5-(4-fluoresceindecoxy)phenyl-10,15,20-triphenylporphyrin) have been synthesized and characterized by elemental analysis, IR, UV/Vis, Electrospray mass spectra, and ¹H NMR. The DNA-binding behaviors of these complexes with calf-thymus DNA (CT-DNA) were investigated by UV–vis absorption titration, fluorescence spectra, viscosity measurements, thermal denaturation, and circular dichroism. The results suggest that 1, 2, and 3 interact with CT-DNA by intercalation, and the conformation of fluorescein–porphyrin hybrids is an important factor affecting the DNA-binding affinities. The DNA-binding affinities (K _b values) follow the order 1 > 2 > 3. In addition, their photocleavage reactions with pBR322 supercoiled plasmid DNA were investigated by gel electrophoresis. All complexes exhibit significant DNA cleavage activity. These complexes have cytotoxic activities against myeloma cell (Ag8.653) and gliomas cell (U251) lines. Complex 1 was the most potent antitumor agent among the three complexes.

Keywords:

• Fluorescein
• Porphyrinatozinc
• Cytotoxicity
• DNA-binding
• Photocleavage

Acknowledgments

We gratefully acknowledge financial support for this work by the Science and Technology Research Project of Guangdong Province, P.R. China (No. 2012B031800431), the National Key Research Project of China (No. 2011zx09102-001-31) and the National Natural Science Foundation of P.R. China (Nos. 21101033 and 81102753).