St. John's Wort

Hypericum: Description and origin

Hypericum, or St. John’s Wort, (Hypericum perforatum L.) is a perennial herbaceous plant that belongs to the hypericaceae family. Its leaves contain multiple glands visible against the light and its flowers have five golden yellow petals with numerous prominent stamen¹ that appear from May to August. It can grow up to one metre tall and mainly branches from the top of the stem; it has a woody, highly branched and fusiform root².

Hypericum is native to temperate regions of Europe. It can be found in almost all European countries, as far as eastern Russia, and has acclimatised in many parts of the world, such as China, Australia, North Africa and America².

Hypericum: History

Hypericum has been used for thousands of years: Hippocrates used this plant as an anti-inflammatory; Dioscorides cited it in his encyclopaedia, as did Galen and Pliny in their works³.

The name hypericum comes from the Greek hyperikon (“over images; over an apparition”), which, according to some, refers to hypericum’s ability to expel evil spirits; while for others the glands of its petals appeared to form images. Perforatum, meanwhile, refers to the fact that if the plant is observed against the light it has a perforated appearance due to the oil glands present in its leaves and sepals².

In the Middle Ages it was believed that the scent of hypericum drove away evil spirits, and it was hung from roofs to prevent lightning and fire. It was also believed that to obtain these magical properties, it should be harvested in the early morning on St. John’s Day (24 June), the date on which St. John the Baptist was beheaded, which also coincides with the plant’s flowering³.

Hypericum: Composition

The flowering tops* of hypericum contain essential oil, coumarins (umbelliferone), phytosterols (beta-sitosterol), flavonoids, naphthodianthrones (hypericin, pseudohypericin, isohypericin and protohypericin) and prenylated phloroglucinol derivatives (hyperforin and adhyperforin). According to French Pharmacopoeia and Deutscher Arzneimittel-Codex, the extract must contain at least 0.04% of naphthodianthrones calculated as hypericin⁴.

*Flowering top: the top of a plant when in flower.

Hypericum: Benefits

Hypericum is recommended mainly for mild and moderate depressive episodes, anxiety, night terrors, neurovegetative disorders associated with the menopause (hot flushes, night sweats etc.) and sleep disorders^{1, 4 ,5}.

Hypericum: Studies/research

Hypericum is often used to relieve the symptoms of mild to moderate depression, since the side effects are fewer than those of synthetic antidepressants, and hypericum, or St. John’s Wort, is one of the most widely used plants. In Germany, for example, prescriptions of hypericum account for 25% all antidepressant prescriptions⁶.

Multiple studies support the use of hypericum for mild to moderate depression. A review evaluating 29 clinical trials concluded that the effect of hypericum was greater than that of the placebo, and similar to synthetic antidepressants. It was also found that the side effects of hypericum were fewer than those of synthetic antidepressants⁷.

Depression is associated with decreased levels of the neurotransmitters serotonin, dopamine and norepinephrine⁶. The antidepressant effect of hypericum is due to several mechanisms of action^{1, 6}. For example, hypericum extract inhibits the monoamine oxidase (MAO-A and MAO-B) enzymes, which degrade serotonin and norepinephrine. It also inhibits the reuptake of neurotransmitters involved in depression (serotonin, dopamine, norepinephrine etc.). Both mechanisms promote increased availability of neurotransmitters.

Finally, hypericum extract is also used to relieve anxiety and sleep disorders⁸. In vitro studies indicate that hypericum compounds may interact with receptors that mediate anxiolytic effects, such as GABA receptors¹.