Wayne M. Berman

Document Type

Honors Project

First Advisor

Dr. Stephen Baron

Degree Award Date

Spring 1999

Keywords

St. John's Wort, Hypericin, in vitro Study, Liver Metabolism, depression, serotonin receptors

Disciplines

Biology | Pharmacology | Pharmacology, Toxicology and Environmental Health

Abstract

This Honors Project will study the antidepressant properties of the herb St. John's Wort, whose botanical name is Hypericum perforatum. This plant, which has been used for centuries by humankind, has recently gained widespread popularity as a safe, effective and natural alternative to synthetic drugs for the treatment of depression. Although the plant contains many compounds, the active substance is believed to be a chemical known as hypericin. However, there are still many unanswered questions as to what role the other components present in St. John's Wort extract have in producing its antidepressant effects. In a variety of clinical studies, most of which have taken place in Germany where the herb is frequently prescribed for depression, St. John's Wort extract (standardized to contain a minimum of 0.3% hypericin) has been proven to be just as effective as synthetic drugs in improving depressive symptoms -without causing the common side effects exhibited by the herb's pharmaceutical counterparts. My study will focus primarily on separating, isolating and identifying the various compounds present in an extract of St. John's Wort, and then testing the antidepressant potential of each of these substances by analyzing their ability to bind to serotonin receptors in vitro. This can be measured by observing the rate at which the compounds in question competitively bind to the receptors while in the presence of natural serotonin. Because many antidepressants work by binding to serotonin receptors, thus causing the neurotransmitter to remain in the brain at higher levels such that it improves depressive symptoms, I hope to show the anti depressant activity of the extracted compounds by analyzing their binding potential to the serotonin receptors. In addition, I will attempt to study the rate at which these compounds compete with endogenous serotonin when binding to receptors in vitro. By conducting these experiments, I will be able to show that the compounds present in St. John's Wort extract do (or do not) competitively bind to serotonin receptors, thus providing in vitro evidence for the bioactivity and efficacy of St. John's Wort as a natural alternative for the treatment of depression.

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