St. John’s Wort (Hypericum perforatum L.) is commonly accepted as a medicinal plant. The data on the physiological activities of the individual substances that are produced in different organs of H. perforatum are well known at present. The highest attention is focused on the characterization and phytochemical properties of hypericin and hyperforin. These organic compounds are used as antidepressant, anticarcinogenic (photodynamic), antimicrobial and virostatic agents. The review paper surveys the present knowledge of chemical and analytical methods for their identification and quantification, physiological activity, and pharmacological and biomedical applications of hypericin and hyperforin.

        Key words: St. John’s Wort – Hypericum perforatum – hypericin – hyperforin