A comparative study on the photocytotoxicity of hypericin on A431 cells using three different assays
Ugwu, F.; Vandenbogaerde, A.L.; Merlevede, W.J.; de Witte, P.A.
Anticancer Research 18(2a): 1181-1184
1998
ISSN/ISBN: 0250-7005 PMID: 9615785 Document Number: 491013
Background: Three assay models were adopted for assessing the photocytotoxicity of hypericin on A431 cells. The cells were incubated for 1 hour or 24 hours with hypericin to evaluate the importance of the incubation period on the exerted photocytotoxicity. Materials and Methods: A neutral red, an antiproliferative and a tetrazolium-reduction (MTT) assay were used for the estimation of cytotoxicity. Results: IC50 values were 296, 321 and > 500 nM after 1 hour, and to 70, 54 and 277 nM after 24 hours, for the neutral red, antiproliferative and MTT assays, respectively. Conclusions: Our results clearly show that it is imperative to incubate cells for long periods to fully assess the hypericin photocytotoxicity, and that the neutral red assay is as sensitive as the antiproliferative assay but superior to the MTT assay at detecting hypericin cell damage.