ABSTRACT
St. John’s wort (SJW), known botanically as Hypericum perforatum, is a sprawling, leafy herb that grows in open, disturbed areas throughout much of the world’s temperate regions. The use of this species as an herbal remedy to treat a variety of internal and external ailments dates back to the time of the ancient Greeks. Since then, it has remained a popular treatment for anxiety, depression, cuts, and burns. Recent research suggests the effectiveness of this herb in treating other ailments,
11.1 Introduction .......................................................................................................................... 211 11.2 Taxonomy and Description ................................................................................................... 212 11.3 Traditional Origins ............................................................................................................... 212 11.4 Current Usage and Preparations ........................................................................................... 213 11.5 Active Ingredients ................................................................................................................. 214
11.5.1 Naphthodianthrones .................................................................................................. 215 11.5.2 Flavonoids ................................................................................................................. 215 11.5.3 Lipophilic Compounds ............................................................................................. 215 11.5.4 Additional Compounds ............................................................................................. 215
11.6 Health Effects: The Scienti˜c Evidence ............................................................................... 216 11.6.1 St. John’s Wort and Depression ................................................................................ 216
11.6.1.1 Active Principals: In Vitro Studies ............................................................ 216 11.6.1.2 Clinical Studies .......................................................................................... 217
11.6.2 Antibacterial and Antiviral Properties ..................................................................... 219 11.6.3 Anticancer Properties ...............................................................................................220 11.6.4 Antioxidant and Neuroprotective Properties ............................................................ 221 11.6.5 Anti-In©ammatory Activity ...................................................................................... 222 11.6.6 Effects as a Wound-Healing Agent........................................................................... 222 11.6.7 Effects on Reducing Opium Dependence ................................................................. 223
11.7 Adverse Effects and Interactions with Other Drugs .............................................................223 11.7.1 Adverse Effects ......................................................................................................... 223 11.7.2 Drug Interactions: Overview .................................................................................... 223
11.7.2.1 P-glycoprotein ............................................................................................224 11.7.2.2 Cytochrome P450 .......................................................................................224 11.7.2.3 Speci˜c Drug Interactions .........................................................................226
11.8 Future Research Needs .........................................................................................................228 11.9 Conclusions ...........................................................................................................................228 References ...................................................................................................................................... 229
including cancer, in©ammation-related disorders, and bacterial and viral diseases, and as an antioxidant and neuroprotective agent. Pharmaceutical companies, particularly in Europe, prepare standard formulations of this herb that are taken by millions of people. Worldwide annual sales of products made from SJW presently exceed several billion dollars. Further, SJW produces dozens of biologically active substances, although two-hypericin (a naphthodianthrone) and hyperforin (a lipophilic phloroglucinol)—have the greatest medical activity. Other compounds, including the ©avonoids rutin, quercetin, and kaempferol, also appear to have medical activity. H. perforatum has been intensively studied on isolated tissue samples, using animal models and through human clinical trials. The effectiveness of SJW as an antidepression agent is particularly well studied, and the underlying mechanisms are well understood. SJW preparations have relatively few adverse effects when taken alone at the recommended dosages. However, numerous interactions with other drugs have been reported. Recent research shows these interactions result from the ability of SJW constituents to induce intestinal or hepatic enzymes that either remove drugs from the body or metabolize them to inactive forms. This chapter examines the constituents, modes of action, and adverse interactions of SJW, providing an up-to-date synthesis of a large body of literature that has developed over the past 30 years regarding this widely taken herbal remedy. Some recommendations regarding future research needs are also presented.
