Pinosylvin and monomethylpinosylvin, constituents of an extract from the knot of Pinus sylvestris, reduce inflammatory gene expression and inflammatory responses in vivo.

Scots pine (Pinus sylvestris) is known to be rich in phenolic compounds, which may have anti-inflammatory properties. The present study investigated the anti-inflammatory effects of a knot extract from P. sylvestris and two stilbenes, pinosylvin and monomethylpinosylvin, isolated from the extract. Inflammation is characterized by increased release of pro-inflammatory and regulatory mediators including nitric oxide (NO) produced by the inducible nitric oxide synthase (iNOS) pathway. The knot extract (EC50 values of 3 and 3 μg/mL) as well as two of its constituents, pinosylvin (EC50 values of 13 and 15 μM) and monomethylpinosylvin (EC50 values of 8 and 12 μM), reduced NO production and iNOS expression in activated macrophages. They also inhibited the production of inflammatory cytokines IL-6 and MCP-1. More importantly, pinosylvin and monomethylpinosylvin exerted a clear anti-inflammatory effect (80% inhibition at the dose of 100 mg/kg) in the standard in vivo model, carrageenan-induced paw inflammation in the mouse, with the effect being comparable to that of a known iNOS inhibitor L-NIL. The results reveal that the Scots pine stilbenes pinosylvin and monomethylpinosylvin are potential anti-inflammatory compounds.