Computational and experimental insights into the interaction of the seaweed-derived steroidal metabolite 11α-hydroxyprogesterone with the glucocorticoid receptor

Seaweed-derived metabolites offer a rich source of bioactive compounds with therapeutic potential. In this study, 112 steroidal metabolites from <i>Sargassum polycystum</i>, <i>Gracilaria fisheri</i>, and <i>Caulerpa lentillifera</i> were computationally screened to identify candidates interacting with the glucocorticoid receptor (GR), a key molecule regulating inflammatory signaling. Among them, 11α-hydroxyprogesterone (SW052) from <i>S. polycystum</i> exhibited the favorable predicted GR binding affinity (-11.6 kcal/mol), comparable to hydrocortisone and medrysone. Molecular docking and 500 ns molecular dynamics simulations revealed a stable GR-SW052 complex stabilized by hydrophobic and van der Waals interactions with MET560, LEU563, LEU566, MET601, MET604, LEU608, LEU732, TYR735, and CYS736. Free energy analysis (MM/PBSA) supported favorable thermodynamic binding, and <i>in silico</i> ADMET evaluation predicted good oral absorption and low toxicity. <i>In vitro</i> assays showed that both SW052 and seaweed lipophilic extract were non-cytotoxic (>70 % cell viability) and significantly inhibited nitric oxide (NO) production in lipopolysaccharide-stimulated RAW 264.7 macrophages (IC₅₀ = 144.05 ± 8.06 and 108.24 ± 4.64 µg/mL, respectively). This study establishes an integrated computational-experimental framework for prioritizing seaweed-derived steroidal metabolites targeting the GR. Using this framework, SW052 was identified as a potential natural compound with stable predicted GR engagement, favorable <i>in silico</i> pharmacokinetic properties, and NO suppression, providing a structure-guided basis for further mechanism and <i>in vivo</i> validation.