Background and Aim: Molecular modeling is a powerful tool for the study of structure-activity
relationships (SAR) in the research-based pharmaceutical industry. According to the results of our
previous research, the analgesic effect of intra-paragigantocellularis lateralis 17β-estradiol on the
formalin-induced inflammatory pain might be mediated via GABAA receptors in Male Rats. This
study investigated the antinociceptive role of 17β-estradiol and its interaction with the GABAA
receptor by molecular docking.
Methods: GABAA receptor pdb file was downloaded from Protein Data Bank (PDB) with the
code 6DW1. Also, 20 SDF files for 17β-estradiol were downloaded from the ZINC database. The
active site was delimited based on reported residues at PDB and complemented with searching of
close residues until 6 Å far crystallized protein supported by Molegro Virtual Docker Tools. Thus,
active site was constituted by following residues: 6DW1 (chain D); Asp-120, Trp-123, IIe-124,
Thr-146, Lys-118, Pro-127, Asn-128, His-122, Arg-144, Ala-121, Thr-125, Thr-126, and 6DW1
(chain C); Asn-110, His-109, Ala-108, Gly-103, Lys-104, Lys-105, Ser-106, Val-107, Leu-132.
All molecular docking assays were carried out using flexible residues. Ligand and protein were
docked employing Molegro Virtual Docker. The strongest docked pose, residual interactions maps
were obtained with Molegro Molecular Viewer for compounds that exhibited the highest affinity
energy.
Results: The results of molecular docking were first analyzed in terms of affinity energy. 20
compounds of 17β-estradiol were tested via molecular docking. From docked compounds, the
second top pose of 17β-estradiol with the code ZINC000058475582 was found strongest docked
pose, which demonstrated to achieve an important strong affinity with GABAA (–80.6682
kcal/mol). Two hydrogen bondings (Lys-104 C, and His-122 D) and four steric interactions (Trp-
123 D, His-122 D, Ser-106 C, and Lys-104 C) between amino groups of GABAA and this pose
wer