Al. Vandenbogaerde et al., DIFFERENTIAL CYTOTOXIC EFFECTS INDUCED AFTER PHOTOSENSITIZATION BY HYPERICIN, Journal of photochemistry and photobiology.B, Biology, 38(2-3), 1997, pp. 136-142
The cytotoxic effects of the natural photosensitizing agent hypericin
were evaluated. A dramatic difference in the sensitivity of several di
fferent human and mouse cell lines towards photoactivated hypericin (4
J cm(-2)) was demonstrated using a neutral red assay (e.g. A431, IC50
= 0.14 +/- 0.02 mu M; HeLa, IC50 = 0.32 +/- 0.05 mu M; MCF7, IC50 = 1
.84 +/- 0.22 mu M). Dark cytotoxicity was absent, even at high hyperic
in concentration (25 mu M) The differential phototoxicity of hypericin
did not correlate with the expression of the epidermal growth factor
(EGF) receptor nor with the expression of the P170 glycoprotein in the
cell. The reduction of the intracellular glutathione content did not
enhance further the cytotoxic effects of photoactivated hypericin, as
investigated with the A431, HeLa and MCF7 cells. Conversely, using con
focal laser microscopy, it was shown that the phototoxicity correlated
well with the hypericin cellular uptake.