Hypericin

Hypericin is obtained from St. John’s wort (Lat. Hypericum perforatum) and is a powerful, naturally occurring photosensitizer which is used in Photodynamic Therapy (PDT) to treat cancer. Hypericin is a red fluorescing photosensitizer with absorption maxima at 550-558 nm and 330 nm.

Even in antiquity, the reddish oil of hypericin was applied externally to promote wound healing. Today, hypericin is used mainly to treat psychovegetative disorders.

The side effect of taking hypericin is that the body becomes hypersensitive to light.
In modern treatment, this effect is used in oncology to combat cancer. Fluorescing hypericin accumulates progressively in cancer cells.
The reasons for the high accumulation of hypericin in the tumour tissue relate to the structural and the physiological features of a cancer cell.

In the field of the molecular mechanisms in cancer cells, studies have shown that excitation by the laser used in Photodynamic Therapy (PDT) with a wavelength specific to the hypericin gives rise to photocytotoxicity in the cancer tissue.
Toxicity for cancer cells is caused by the reaction between the hypericin photosensitizer and oxygen. Products of the chemical reaction are poisonous oxygen radicals, which initiate a process of apoptosis and necrosis for the cancer cells.