Hypericum

Hypericum (pronounced /ˌhaɪˈpɪərɨkəm/)[1] is a genus of about 400 species of flowering plants in the family Clusiaceae, subfamily Hypericoideae (formerly often considered a full family Hypericaceae).

The genus has a nearly worldwide distribution, missing only from tropical lowlands, deserts and polar regions. All members of the genus may be referred to as St. John's-wort, though they are also commonly just called hypericum, and some are known as tutsan. The marsh St. John's-worts are nowadays separated in Triadenum.

St. John's-worts vary from annual or perennial herbaceous herbs 5–10 cm tall to shrubs and small trees up to 12 m tall. The leaves are opposite, simple oval, 1–8 cm long, either deciduous or evergreen. The flowers vary from pale to dark yellow, and from 0.5–6 cm in diameter, with five (rarely four) petals. The fruit is usually a dry capsule which splits to release the numerous small seeds; in some species it is fleshy and berry-like.

Uses of Hypericum

Some species are used as ornamental plants and have large, showy flowers. Numerous hybrids and cultivars have been developed for use in horticulture, such as Hypericum × moserianum (H. calycinum × H. patulum) and Hypericum calycinum cv. 'Hidcote'.

St. John's-worts can occur as nuisance weeds in farmland and gardens. On pastures, some can be more than a nuisance, causing debilitating photosensitivity and sometimes abortion in livestock. The beetles Chrysolina quadrigemina, Chrysolina hyperici and the St. John's-wort Root Borer (Agrilus hyperici) like to feed on Common St. John's-wort (H. perforatum) and have been used for biocontrol where the plant has become an invasive weed.

Hypericum species are the only known food plants of the caterpillar of the Treble-bar, a species of moth. Other Lepidoptera species whose larvae sometimes feed on Hypericum include Common Emerald, The Engrailed (recorded on Imperforate St. John's-wort, H. maculatum), Grey Pug and Setaceous Hebrew Character.

Medical properties

Common St. John's-wort (H. perforatum) has long been used in herbalism. It was known to have medical properties in Classical Antiquity and was a standard component of theriacs, from the Mithridate of Aulus Cornelius Celsus' De Medicina (ca. 30 CE) to the Venice treacle of d'Amsterdammer Apotheek in 1686. Folk usages included oily extract ("St. John's oil") and Hypericum snaps.

H. perforatum is the most potent species and it is today grown commercially for use in herbalism and medicine; other St. John's-worts possess interesting properties and chemical compounds but are not well researched. As these secondary compounds appear to be related to deterring herbivores, they are present in varying and unpredictable quantities: still, a number of high-yield cultivars have been developed.

Two main compounds of interest have been studied in more detail: hyperforin and hypericin. However, the pharmacology of H. perforatum is not resolved, and at least its antidepressant properties are caused by a wide range of factors interacting. As psychiatric medication, it is usually taken as pills, or as tea. Few standardised preparations are available, and research has mainly studied alcoholic extracts and isolated compounds. What research data exists supports a noticeable effect in many cases of light and medium depression , but no significant improvement of severe depression and OCD.

Another common use of H. perforatum is as an oily extract: the ruby-red oil appears to be strongly antibiotic , assisting healing of wounds , first-degree burns and concussions . Both hypericin and hyperforin are reported to have antibiotic properties[2]. Justifying this view with the then-current doctrine of signatures, herbalist William Coles (1626-1662)[3] wrote in the 17th century that

"The little holes whereof the leaves of Saint Johns wort are full, doe resemble all the pores of the skin and therefore it is profitable for all hurts and wounds that can happen thereunto."

There is evidence that St. John's-worts can act as abortifacients since interference with the Combined oral contraceptive pill has occurred. Complications have also been observed in other human patients: high-dosage H. perforatum interacts with a wide range of medications due to activation of the Pregnane X receptor detoxification pathway, as well as causing photosensitivity. It is strongly recommended not to take St. John's-wort during pregnancy or when tanning, and it has caused a few deaths in patients undergoing anti-HIV/AIDS and cancer therapy. Extremely high doses (rarely reached with OTC preparations) are hepatotoxic.

Hypericum is a common treatment in homeopathy, used for the healing of deep wounds or as a relief from depression.

External links

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1. ^ Sunset Western Garden Book, 1995:606–607
2. ^ Schempp CM, Pelz K, Wittmer A, Schöpf E, Simon JC (June 1999). "Antibacterial activity of hyperforin from St John's wort, against multiresistant Staphylococcus aureus and gram-positive bacteria". Lancet 353 (9170): 2129. doi:10.1016/S0140-6736(99)00214-7. PMID 10382704.
3. ^ William Coles. "Adam in Eden, or: earth's Paradise". http://copac.ac.uk/wzgw?id=09040327d555a7d0a9d3e2c741c82c07ca3d38&rsn=2&esn=F&f=u&rn=1. Retrieved 2009-04-04.

University of Illinois Extension. "Selecting Shrubs for Your Home - Kalm St. Johnswort (Hypericum kalmianum)". http://www.urbanext.uiuc.edu/shrubselector/detail_plant.cfm?PlantID=359.