The renaissance of Hypericum perforatum: bio-medical research caches up with folk medicine.

The traditional use of Hypericum perforatum L. (St. John's wort, Clusiaceae) in Western medicine was well known even before the 1600s: St. John's extracts were used to relieve various types of nervous disease long before depression was recognized as a well described pathology. Today, random controlled trials clearly confirm the efficacy of this plant extract over placebo in the treatment of mild to moderately severe depression. Of the different classes of H. perforatum secondary metabolites, the prenylated acylphloroglucinol hyperforin has emerged as key player for anti-depressant activity. But as well as Hypericum's anti-depressant property, several other pharmacological actions have now been documented - examples include anti-bacterial, anti-proliferative and anti-inflammatory - many of which may be related to hyperforin. These findings add support to the effectiveness of St. John's wort as a folk remedy in common use for treating skin injuries, burns and neuralgias. This review gives a historical overview of the plant, including its medical uses, plus a look at the chemical structure of the most relevant phyto-constituents. This is followed by a close analysis of recent data regarding the biological effects of hyperforin, focusing on anti-inflammatory and anti-tumor activities. The compound's clear and proven actions qualify it as an interesting lead candidate for countering inflammatory disease and cancer.