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 toxic effects without affecting the normal tissue.
These results show that hypericin may be useful as a tool for photodynamic therapy in cancer treatment.
Vandebogaerde, A. L., et al. “Antitumor Activity of Photosensitized Hypericin on A431 Cell Xenografts.” Anticancer Research 1996, 16:1619–1626.