St.-John’s-wort (Hypericum perforatum) has gained attention
recently as a possible tool in the treatment of both AIDS and
mild depression. Researchers are now learning that its active
constituent also may be a useful cancer treatment. Researchers
at the Catholic University in Leuven, Belgium, have found that
the herb’s active constituent, hypericin, may be valuable in
photodynamic therapy, which is used to make tumor tissues more
vulnerable to radiation. The researchers injected mice with
tumor cells, then divided the mice into two groups. One group
received hypericin, followed by radiation at the site of tumor
injection. The other group received radiation but not hypericin.
Although tumors developed as expected in the control group, no
tumors grew in the mice treated with hypericin and radiation.
Furthermore, the radiation had no toxic effect on the normal
skin next to the tumor. Researchers also found that hypericin
accumulated in the tumor tissue, meaning that it could sensitize
the tumor to radiation’s to