The plant St. John's wort (Hypericum perforatum) is used for the treatment of mild to moderate depression. Hypericin is a compound found in the stems and petals of the flowers of St. John's wort. Over the past decade, research teams in Canada, the U.S., Israel and Europe have been conducting lab experiments using hypericin and other compounds extracted from St. John's wort. In these experiments, hypericin has shown activity against viruses that cause herpes, AIDS and diseases similar to hepatitis in animals. Based on these results, researchers in New York decided to conduct a study to find out about hypericin's antiviral effect in people with hepatitis C virus (HCV). According to the results, hypericin taken orally for two months had no detectable anti-HCV activity, but it caused "considerable" temporary side effects.
Researchers enrolled 19 HCV positive adults (4 female, 15 male) all of whom had high levels of the following in their blood:
None of the subjects was pregnant, actively abusing substances or had HIV infection. Twelve subjects received low-dose hypericin – 0.05 mg per kg of body weight per day for two months –and seven subjects received high-dose hypericin – 0.1 mg/kg of body weight/day for two months. As hypericin can make people sensitive to sunlight, all subjects were encouraged to wear hats, gloves and sun screen when outdoors.
Seven of 12 subjects receiving low-dose hypericin and all seven subjects who received high-dose hypericin developed side effects, usually a photosensitivity reaction associated with the following symptoms:
All side effects cleared after subjects stopped taking hypericin. No subject developed any toxicity that was detected by lab tests.
Hypericin had no impact on commonly used blood tests used to assess HCV infection, including the following:
This is the second study using purified hypericin supplied by VimRx Pharmaceuticals (Wilmington, Delaware) for the treatment of a viral infection in humans. The first study tested hypericin in HIV positive subjects and also found no beneficial effect(s). Some people might argue that the dose of hypericin used in the current study of HCV was not high enough. But in the study with HIV positive subjects, high doses of hypericin were associated with side effects, even though the drug in that study was taken twice or three times weekly.
In the current study on HCV, researchers regularly checked blood samples from subjects to assess levels of hypericin. They found that levels of this compound were high enough to, in theory, have anti-HCV activity. Yet the researchers are not sure why hypericin did not have significant antiviral activity in either study. Several research teams have found that in the lab it is necessary for hypericin to be exposed to light to have significant antiviral activity. It may also be that hypericin requires a great deal of exposure to light to have anti-HIV or anti-HCV activity in people. If this is the case, given the photosensitivity reaction associated with use of hypericin, this product when taken in large doses may not be safe as an antiviral drug in people.
It is worth noting that St. John's wort contains many compounds of which hypericin is merely one. The beneficial effects of the plant may depend on use of several of these compounds, not just one. St. John's wort and its extracts are being tested for their antibacterial and anticancer activity.
REFERENCES
1. Jacobson JM, Feinman L, Liebes L, et al. Pharmacokinetics, safety, and antiviral effects of hypericin, a derivative of St. John's wort plant, in patients with chronic hepatitis C virus infection. Antimicrobial Agents and Chemotherapy 2001;45(2):517-524
2. Lavie G, Valentine F, Levin B, et al. Studies of the mechanisms of action of the antiretroviral agents hypericin and pseudohypericin. Proceedings of the National Academy of Sciences USA 1989:86:5963-5967.
3. Hudson JB, Harris L and Towers G. The importance of light in the anti-HIV effect of hypericin. Antiviral Research 1993;20:173-178.
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Copyright © 2001 - TreatmentUpdate. Reproduced with permission. Reproduction of this article (other than one copy for personal reference) must be cleared through the Editor, The Canadian AIDS Treatment Information Exchange, 555 Richmond St. West, Suite 505, Box 1104, Toronto, ON, M5V 3B1 • Phone: 416-203-7122 • Toll Free: 1-800-263-1638 • Fax: 416-203-8284 http://www.catie.ca.
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