Hypericin

Hypericin (CAS 548-04-9) is a photosensitive antiviral, anticancer, and antidepressant agent derived from Hypericum perforatum (St. John’s wort). Hypericin and pseudohypericin are two natural products, structurally belonging to the chemical class of naphthodianthrones. St. John’s wort also contains protohypericin, protopseudohypericin, and cyclopseudohypericin. Protohypericin and protopseudohypericin are considered to be the biosynthetic precursors of hypericin and pseudohypericin. Hypericin has been extensively studied for its application in photodynamic therapy. Photodynamic therapy (PDT) involves administration of a tumor-localizing nontoxic drug, known as photosensitizer. The photosensitizer should accumulate in the tumor. The tissue/tumor is then illuminated with visible light in the presence of oxygen, during which the photosensitizer is activated and generating reactive oxygen species (ROS). These ROS are toxic to the tumor cells, which leads to tumor death and tissue destruction.