|Hypericum androsaemum, tutsan|
Hypericum androsaemum, commonly known as tutsan, is a plant in the genus Hypericum native to open woods and hillsides in Eurasia. It is a perennial shrub reaching up to 1.5 m in height.
The common name tutsan appears to be a corruption of toute saine literally meaning all-healthy. This is probably in reference to its healing properties. The leaves were applied to wounds, and as a stomachic. Nicholas Culpeper, in his 1653 publication Culpeper's Complete Herbal, says "Tutsan purgeth choleric humours ... both to cure sciatica and gout, and to heal burnings by fire." The berries which turn from white/green, to red, to black are poisonous.
Xanthonoids biosynthesis in cell cultures of Hypericum androsaemum involves the presence of a benzophenone synthase condensing a molecule of benzoyl-CoA with three malonyl-CoA yielding to 2,4,6-trihydroxybenzophenone. This intermediate is subsequently converted by a benzophenone 3′-hydroxylase, a cytochrome P450 monooxygenase, leading to the formation of 2,3′,4,6-tetrahydroxybenzophenone.
In New Zealand tutsan was recognised as a pasture weed as early as 1955. Biological control methods were investigated about 60 years ago. In 2008 Landcare Research will begin investigating the feasibility of a biological control.
It is also a declared species in Western Australia and Victoria, where it occurs in the wettest regions such as the Otway Ranges and the karri forests. It does not usually invade improved pastures, but is common in run-down pastures and in native forests. When established, tutsan can be dangerous because it is very difficult to remove and is very unpalatable to both native and introduced herbivores.
- Alternative pathways of xanthone biosynthesis in cell cultures of Hypericum androsaemum L. Werner Schmidt and Ludger Beerhues, FEBS Letters, Volume 420, Issues 2-3, 29 December 1997, Pages 143-146, doi:10.1016/S0014-5793(97)01507-X