FIGURE 1.

The structures of small molecular exemestane, letrozole, and ursolic acid in binding simulations with CYP19A1/Ar. (A) Structures of exemestane (left‐hand), letrozole (middle), and ursolic acid (right‐hand). The binding energies and Ki values of the compounds are listed in the table below. (B) In one simulation, ursolic acid (green stick) was docked into the active site of human placental aromatase (CYP19A1, PDB ID: 3S7S). Ursolic acid forms a hydrophobic interaction (dashed purple line) with the amino acids (white sticks) Ile133, Trp224, Ala306, Val370, Leu372, Val373, Met374, Cys437, Ala438, and Leu477. (C) In another simulation, exemestane (purple stick) was docked into the active site of human placental aromatase. Exemestane forms hydrogen bonds (dashed green line) with the amino acids Arg115 and Met374. On the other hand, exemestane forms hydrophobic interactions with the amino acids Phe134, Phe221, Trp224, Val370, and Val373. (D) In another simulation, letrozole (pink stick) was docked into the active site of human placental aromatase. Letrozole forms hydrogen bond interactions with the amino acids Trp141, Arg145, and Phe430. Furthermore, it forms hydrophobic interactions with the amino acids Ile133 and Val373. Lastly, it also forms pi–cation charge interactions (dashed orange line) with the amino acid Arg115