In vitro study of the photocytotoxicity of some hypericin analogs on different cell lines

E. M. Delaey, R. Obermuëller, I. Zupkó, D. De Vos, H. Falk, P. A M De Witte

Research output: Contribution to journalArticle

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Abstract

In the present study, hypericin analogs with an increased hydrophilic character were synthesized. As chemical modifications alter the lipophilicity/hydrophilicity balance together with the photophysical/chemical background of the molecule the influence of these structural changes on the cellular uptake, retention and subcellular localization in HeLa cells was investigated. Besides, their photocytotoxic effects using three cell lines (HeLa, MCF-7, A431), as well as their plasma protein binding were also assessed. To assess the relative hydrophilic/lipophilic character of hypericin and analogs their retention times were determined on a reversed phase high performance liquid chromatography (C-18) column. The retention time of all the hypericin analogs was 200 min (solvent system: methanol/citrate buffer 30 mM pH 7; 70/30). Hypericin, hexa-, penta- and dibenzyltetramethylhypericin displayed a potent antiproliferative effect at the nanomolar range after photosensitization (3.6 J/cm2). On the contrary, photoactivated tetrasulfonhypericin and fringelite D had no antiproliferative effect on the three cell lines, whereas hypericin polyethylene glycol showed only an intermediate cytotoxic effect on A431 cells. In dark conditions no antiproliferative effect was observed for any photosensitizer. The antiproliferative photoeffect correlated well with the intracellular accumulation as measured using HeLa cells. In general, the photocytotoxic hypericin analogs concentrated to a large extent, while the noncytotoxic compounds were not taken up by the HeLa cells. Furthermore, confocal laser microscopy revealed that all photosensitizers mainly concentrated in the perinuclear region, probably corresponding with Golgi apparatus and the endoplasmic reticulum, except for tetrasulfonhypericin which located at the plasma membrane. In addition, the plasma protein binding studies illustrated that hypericin bind extensively to the low-density lipoproteins, while the other hypericin analogs were mainly bound to heavy proteins (mostly albumin) and to a small extent to low-density lipoproteins.

Original languageEnglish
Pages (from-to)164-171
Number of pages8
JournalPhotochemistry and Photobiology
Volume74
Issue number2
DOIs
Publication statusPublished - Aug 1 2001

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cultured cells
Cells
analogs
Cell Line
lipoproteins
proteins
cells
HeLa Cells
Photosensitizing Agents
laser microscopy
endoplasmic reticulum
LDL Lipoproteins
Protein Binding
Confocal Microscopy
liquid chromatography
Blood Proteins
citrates
albumins
glycols
polyethylenes

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Biochemistry
  • Biophysics

Cite this

In vitro study of the photocytotoxicity of some hypericin analogs on different cell lines. / Delaey, E. M.; Obermuëller, R.; Zupkó, I.; De Vos, D.; Falk, H.; De Witte, P. A M.

In: Photochemistry and Photobiology, Vol. 74, No. 2, 01.08.2001, p. 164-171.

Research output: Contribution to journalArticle

Delaey, E. M. ; Obermuëller, R. ; Zupkó, I. ; De Vos, D. ; Falk, H. ; De Witte, P. A M. / In vitro study of the photocytotoxicity of some hypericin analogs on different cell lines. In: Photochemistry and Photobiology. 2001 ; Vol. 74, No. 2. pp. 164-171.
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