Saint John’s Wort (Hypericum perforatum), also known as Goatweed, Hypericum and Klamath Wee, belongs to a group of about two hundred herbs of the family Hypericaceae. This aromatic perennial herb is found throughout Europe and the United States, producing golden yellow flowers that seem particularly abundant on June 24, the traditional birthday of John the Baptist. Ergo the name in honor of St. John.
St. John’s wort was popular with ancient medical authorities and was commonly recommended as a folk remedy for the treatment of infectious diseases such as colds, syphilis, tuberculosis, dysentery, whooping cough and worms. St. John’s wort has also been used as a folk remedy for the treatment of depression, anxiety, mania, hypochondriasis, fatigue, hysteria and insomnia.
Over time, with the advent of modern pharmaceutical science, St. John’s wort was nearly forgotten as a medicinal herb. Only recently has St. John’s wort gained a new reputation, particularly in Europe, as an effective nerve tonic for treatment of anxiety, depression, and unrest. A report in a leading German medical journal in 1984 demonstrated significant improvement in depression, anxiety and insomnia in nine people taking oral extracts of St. John’s wort. Recent studies have linked the antidepressant effects of St. John’s wort to various contained xanthones and flavonoids that act as monoamine oxidase (MOA) inhibitors. Tests on small animals and preliminary tests in humans have confirmed this activity.
In a study published in the Journal Proceedings of the National Academy of Sciences in 1988, researchers from The New York University Medical Center and The Weizmann Institute of Science reported the discovery of two substances in St. John’s Wort, hypericin and pseudohypericin, that displayed anti-viral activity against some retroviruses. Retroviruses include the human immunodeficiency virus (HIV), and the authors suggested that these herbal products could be useful in the treatment of AIDS.
Extracts of St. John’s wort are now known to inhibit the growth of Mycobacterium tuberculosis, the most common cause of tuberculosis, as well as the bacteria staphylococci, shigella and Escherichia coli. Researchers have also shown that St. John’s wort inhibits the growth of some strains bacteria that are highly resistant to antibiotics, such as Staphylococcus aureus, enterococcus and Pseudomonas aeruginosa. St. John’s wort has also been reported to have anti-viral activity against herpes simplex virus, influenza virus and hepatitis B virus.
Hypericin and pseudohypericin appear to be the active therapeutic components of St. John’s wort, though other substances, including protein, fat, tannin, vitamins A and C, carotenoids, rutin and pectin support it’s activies. The presence of hypericin and pseudohypericin distinguish St. John’s wort from other herbs, and both compounds are promising candidates for the treatment of HIV disease, including ARC and AIDS, as noted above.
The mechanism of viral inhibition by these substances is not known, but their chemical structures suggest that they may interact with viruses membranes, leading to increased fluidization which would would essentially inactivate the virus.
Chemical investigations have detected a number of other constituents in St. John’s wort, including about 1% of a volatile oil and approximately 10% of tannin. The tannin probably exerts some wound-healing effects through its astringent and protein-precipitating actions.
Unfortunately, hypericin may exert a much less desirable side effect, a form of photosensitivity characterized by dermatitis of the skin and inflammation of the mucous membranes on exposure to direct sunlight. There is evidence that the photosensitizing caused by St. John’s wort is due to the fluorescent pigment hypericin.
Purified hypericin, when given orally, can produce photosensitization in rats. It is the reaction of this substance with the ultraviolet rays of the sun that causes the problem. The photosensitization reaction is known as hvpericism or St. John’s wort poisoning. It is important to point out that photosensitization reactions have not been described in humans participating in studies using Hypericum extracts. This is most likely due to the fact that these subjects were not receiving doses high enough to cause the reaction. The photosensitizing dose for humans is not known.
Those taking St. John’s wort for extended periods should be aware of the possibility of inducing a photosensitization reaction and be prepared to discontinue use if symptoms occur.