St. John's wort

St. John's wort
Name	St. John's wort
Regnum	Plantae
Ordo	Malpighiales
Familia	Hypericaceae
Genus	Hypericum
Species	H. perforatum
Binomial	Hypericum perforatum
Binomial authority	L.

St. John's wort is a flowering plant in the family Hypericaceae, scientifically known as Hypericum perforatum. It is a perennial herb native to Europe, Asia, and North Africa but has been widely naturalized in regions like North America and Australia. The plant is characterized by its bright yellow flowers and translucent leaf glands, and it has a long history of use in herbal medicine, particularly for mood disorders.

Description and taxonomy

The plant was formally described by Carl Linnaeus in his seminal work Species Plantarum. It is a member of the large genus Hypericum, which contains over 400 species. Key identifying features include opposite, oblong leaves with numerous translucent dots, which are oil glands containing the bioactive compounds. The five-petaled flowers, which bloom around the feast day of John the Baptist in late June, exhibit numerous stamens and produce a three-chambered capsule fruit. The species is highly variable, leading to the description of several subspecies and varieties by botanists like Norman Robson of the Natural History Museum, London.

Traditional and historical uses

Use of this herb dates to ancient Greece, where physicians like Dioscorides and Hippocrates recommended it for various ailments. In medieval Europe, it was associated with warding off evil spirits and was known as "Fuga Daemonum." The Eclectic medicine movement in 19th-century North America, exemplified by practitioners like John Milton Scudder, promoted its use for nervous conditions. Traditional applications across cultures included treating wounds, kidney and lung ailments, and as a balm for burns and insect bites.

Pharmacological research

Modern research has identified several biologically active constituents, primarily concentrated in the flowering tops. The most studied are the naphthodianthrones, such as hypericin and pseudohypericin, and the phloroglucinols, notably hyperforin. These compounds are believed to inhibit the synaptic reuptake of neurotransmitters like serotonin, dopamine, and norepinephrine, similar to some synthetic antidepressants. Research institutions like the Max Planck Institute and the National Institutes of Health have conducted extensive studies on its pharmacodynamics and pharmacokinetics.

Clinical efficacy and uses

Its most prominent modern use is for mild to moderate major depressive disorder. Numerous randomized controlled trials and meta-analyses, including those published in The Cochrane Library and The BMJ, have found it superior to placebo and comparable to standard SSRIs like fluoxetine and sertraline for short-term treatment. Some clinical guidelines in Germany, where it is commonly prescribed, recognize its use. It is also studied for conditions like somatic symptom disorder and menopause-related symptoms, though evidence is less robust.

Adverse effects and interactions

Common side effects are generally mild and include gastrointestinal upset, dizziness, dry mouth, and photosensitivity. The most significant concern is its potent induction of the cytochrome P450 enzyme system, particularly CYP3A4 and CYP1A2. This can drastically reduce the plasma concentration and efficacy of a wide range of critical medications, including HIV protease inhibitors like indinavir, immunosuppressants like cyclosporine, anticoagulants like warfarin, and many cardiovascular drugs. Concomitant use with SSRIs raises the risk of serotonin syndrome.

Cultivation and harvest

It is cultivated commercially in many regions, including Chile, China, and parts of Eastern Europe. The plant thrives in well-drained soils in full sun and can be invasive, as seen in its status as a noxious weed in California and the Pacific Northwest. Harvest typically occurs at the flowering stage in early summer. Post-harvest processing and standardization of extracts, such as LI 160 used in many clinical trials, are critical for consistent potency, with major producers including companies like Lichtwer Pharma.

Category:Herbal and fungal drugs Category:Flora of Europe Category:Hypericum