Fig. 7

Molecular docking results of AB4, jatrorrhizine, epiberberine, and phellodendrine in the binding site of PD-1 with the lowest calculated binding energy conformations. In the 2D images, the polar and nonpolar residues of the active site in the PD-1 protein are shown in purple and green, respectively. Hydrogen bonds in the sidechain are shown by red arrows; the arrows point to the H-acceptor. The π-H interactions are marked with a red line and an arene-H label. The π-π interactions are marked with a red line and arene-arene label. The metal contact interactions are shown with a purple line. In the 3D images, the carbon atoms of the compounds are shown in yellow, and other atoms (e.g., oxygen, nitrogen, and sulfur atoms, etc.) are shown in blue. The residues of the PD-1 protein that interacted with the compounds are shown in green. The formation of hydrogen bonds and π-H and π-π interactions are shown by the red dotted line