Fig. 1.

Inhibitory activity of arctigenin against PDE4D and ligand binding identification revealed by ITC and X-ray crystallography. (A) Inhibitory activity of arctigenin against PDE4D catalytic domain. (B) Detailed interactions of arctigenin (green stick) with PDE4D (grey cartoon). Black dash lines indicate hydrogen bonds between ligand and residues. 2Fo-Fc electron density map contoured at 1σ is presented as blue mesh. (C) ITC profiles for the binding of arctigenin to PDE4D catalytic domain. (D) Inhibitory activity of arctigenin on LPS-induced production of TNF-α in human PBMCs. Data were shown as means ± SEM (n = 3).