Pinosylvin (PS)

Pinosylvin is a pre-infectious stilbenoid toxin (i.e. synthesized prior to infection), contrary to phytoalexins which are synthesized during infection. It is present in the heartwood of Pinaceae. It is a fungitoxin protecting the wood from fungal infection. It is also found in Gnetum cleistostachyum. Injected in rats, pinosylvin shows a rapid glucuronidation and a poor bioavailability. Pinosylvin synthase is an enzyme that catalyzes the chemical reaction 3 malonyl-CoA + cinnamoyl-CoA → 4 CoA + pinosylvin + 4 CO2
This biosynthesis is noteworthy because plant biosyntheses employing cinnamic acid as a starting point are rare compared to the more common use of p-coumaric acid. Only a few identified compounds, such as anigorufone and curcumin, use cinnamic acid as their start molecule.