A molecular modeling analysis of diethylstilbestrol conformations and their similarity to estradiol-17 beta

Crystallographic and computer modeling studies throughout the last 25 years have shown the structure of diethylstilbestrol (DES) to exist in two symmetrical or one asymmetrical conformation. As a result of specific comparisons to estradiol-17 beta (E2), the asymmetrical DES conformer has been suggested as the geometry possessing estrogenic activity. In the present study, a more complete set of DES conformations has been elucidated through the use of computer modeling. All previously defined DES geometries were found within this new set of ten structural forms. Differences between the molecular mechanics heat of formation energies of the ten conformers, as well as the transition energies separating them from each other, were found to be less than 1 kcal/mol. Additionally, a computer-based molecular alignment method was employed to quantitatively compare the steric and electrostatic molecular features of each DES conformer relative to E2. All ten DES structures were found to have shape relationships similar to E2. Thus, a model for the estrogen action of DES is presented whereby this stilbene can favorably interact with the estrogen receptor regardless of the conformation or orientation of the initial ligand-receptor association.