ANTI-cancer activities of hypericin in the dark

Michael Blank, Mathilda Mandel, Sadick Hazan, Yona Keisari, Gad Lavie*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The potent photodynamic properties of hypericin (HY) elicit a range of light-dependent virucidal and tumoricidal activities. Yet, a relatively low reduction/oxidation potential endows HY with electron accepting and donating properties enabling it to act as both an oxidizing and a reducing agent. HY can thus compete as an electron acceptor from bioenergized reduction/oxidation reactions generating its excitation energy for biological activities from physiological reduction/oxidation reactions in the absence of light. Our studies show that HY can inhibit the growth of highly metastatic murine breast adenocarcinoma and squamous cell carcinoma tumors in culture. Furthermore, we show that HY can interfere with the growth of these tumors in mice reducing tumor size and prolonging animal survival in complete absence of light. While there is no evidence that HY induces apoptosis in these cells in the dark, 3H-thymidine incorporation into DNA was significantly reduced indicating effects that are apparently cytostatic in nature compared to the cytocidal effects of HY with light.

Original languageEnglish
Pages (from-to)120-125
Number of pages6
JournalPhotochemistry and Photobiology
Issue number2
StatePublished - 1 Aug 2001


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