Hypericin and Cancer

Hypericin and Cancer

Achieving a medical breakthrough is like solving a mystery. You need a lot of clues before you can figure out the answer. Many SFU researchers are discovering clues that can lead to medical solutions. For example, Dr. Andrew Rawicz (Engineering Science) and his team are testing an extract of the herb St. John's wort, called "hypericin." It's quickly absorbed by cancer cells. Shine blue filtered light on them and cancer cells show up as an intense red spot. Shine an orange light and the hypericin kills cancer cells. Dr. Arvind Gupta (Computing Science) heads a group of mathematicians from the Pacific Institute for the Mathematical Sciences. Working with researchers at the B.C. Cancer Agency, they are developing a mathematical model of lung cancer that may one day predict carcinomas. Dr. Robert Cushley's group at SFU's Institute of Molecular Biology and Biochemistry have determined the three-dimensional structure of Apolipoprotein C-I (above), using nuclear magnetic resonance spectroscopy. This molecule activates an enzyme that may promote the removal of cholesterol from arteries.

http://www.sfu.ca/vpresearch/rm/maliketal.html

St. John's Wort For
AIDS & Cancer
by Cindy Jones

St. John's wort may prove beneficial in the treatment of many illnesses, including mild depression, AIDS and cancer.

Traditionally, St. John's wort (Hypericum perforatum) has been used to treat gastrointestinal problems and analgesia. It has also proven to be an effective sedative. More recently, a flurry of clinical trials have been studying its ability to alleviate depression. Now, researchers are even investigating this herb's value in AIDS and cancer treatment.

A Potent Mood Booster A recent meta-analysis of 23 randomized clinical trials involving 1,757 outpatients with mild to moderately severe depression evaluated St. John's wort. Despite difficulties in comparing varying doses and different subtypes of depression, the authors concluded that St. John's wort extracts were significantly superior to placebo. In addition, the efficacy of St. John's wort seems to approximate standard pharmaceutical treatments, but more research is needed to confirm this.¹ Although this preliminary data looks promising, St. John's wort may not be sufficiently effective for treating severe depression. One potential shortcoming of these studies is their duration. None went beyond six weeks, a brief time when you consider that treatment for depression typically lasts months to years. Some researchers have called for longer trials to confirm St. John's wort safety and efficacy.² Centuries of use have shown St. John's wort to be a relatively safe botanical for nonpregnant adults. A meta-analysis found that 19.8 percent of the St. John's wort patients had side effects compared to 35.9 percent of the patients receiving conventional antidepressant drugs. Documented side effects of St. John's wort include gastrointestinal symptoms, allergic reactions, fatigue and photosensitivity. Adverse effects of conventional antidepressants include sleepiness, weight gain, headaches and seizures. How St. John's wort exerts its antidepressant effects isn't yet fully understood. Early reports proposed that hypericin (an active ingredient) works as a monoamine oxidase inhibitor (MAOI), a model that hasn't been substantiated. More recent work suggests that the mechanism of action may be more like Prozac®, a member of a class of drugs called selective serotonin reuptake inhibitors or SSRIs.³ Both monoamines and serotonin are important neurotransmitters in mood regulation. Taking MAOIs with SSRIs can lead to a serious and possibly fatal effect known as "serotonin syndrome."⁴ Therefore, until the mechanism of action is determined, patients are advised not to mix St. John's wort with other antidepressants. St. John's wort also should not be taken with diet drugs such as phen-fen, as they also raise serotonin levels.⁵ Doses to treat depression range from 300 to 1,000 mg per day of total plant extract or 0.4 to 2.7 mg per day of hypericin. German monographs recommend an average daily dose for depression of 2 to 4 g of plant extract or 0.2 to 1.0 mg of hypericin per day.⁶

Beyond Depression Antiviral: Because hypericin has potent antiviral activity, it has gained attention as a possible tool in treating AIDS. It may work by inhibiting the binding and entry of the virus into the host cells. Clinical trials are underway using hypericin as a treatment for HIV infection, as well as other viral infections.^7,8 Recent reports show that hypericin may be useful in reducing viral infection in stored blood used for transfusion.⁹ Anticancer: St. John's wort can, in some individuals, increase sensitivity to light. Side effects aside, this photosensitivity makes hypericin a good candidate for cancer treatment. Photodynamic therapy is based on the ability of cancer cells to selectively take up a specific compound. This compound then makes the cancer cells more sensitive to specific wavelengths of light, so that irradiation kills only the cancer cells. In experiments using mice, hypericin was shown to accumulate specifically in tumor tissue. When these hypericin-treated mice were irradiated, tumor growth was inhibited.¹⁰ Similar results have been found in human tumor cell lines. Hypericin was taken up by the tumor cells, rendering them more vulnerable to the killing effects of specific types of light.¹¹ These results suggest that hypericin can be used as a phototherapy tool when treating cancer. St. John's wort has additional anticancer properties. For instance, hypericin inhibits various protein kinases that are involved in both cell growth and apoptosis (cell death).¹² This action has caught the attention of scientists who are studying the basic mechanisms of cell and tumor growth.

Skin Disease: Clinical trials are now underway to evaluate a synthetic form of hypericin for the topical treatment of several skin disorders.¹³ Hypericin-containing extracts may prove useful for the treatment of psoriasis, cutaneous T-cell lymphoma, warts, melanoma and Kaposi's sarcoma. A role for hypericin may also be found in the treatment of melanoma.¹⁴

Future Research: Although hypericin gets most of the attention as an active ingredient of hypericum extracts, some 10 other constituents of St. John's wort possess pharmacological activity. Among these are pseudohypericin, flavonoids, xanthones and bioflavonoids.¹⁵ Future research should evaluate possible medicinal uses for these compounds.

http://www.healthwell.com/hnbreakthroughs/nov97/understandingherbs.cfm