Forsythin is an inhibitor of PDE4.

<p><b>A–C.</b> The chemical structure of Forsythin extracted from <i>Forsythia suspensa</i> seeds. Forsythin is an o-linked β-D-glucopyranosylated lignin that can be hydrolyzed (Red line). <b>D.</b> Predicted docking site of Forsythin with PDE4. <b>E.</b> Predicted residue electrostatic and van der Waals interactions between PDE4 amino acids and Forsythin. Using ZINCPharmer <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115937#pone.0115937-Koes1" target="_blank">[24]</a>, a pharmacophore model was generated (upper left) and used to screen the lead compounds from an 18.3 million purchasable compound library.