Oleanolic acid-derived triterpenoids with dual TGR5 agonistic and RORγ inverse agonistic activity

The Takeda G protein-coupled receptor 5 (TGR5) and the retinoid-related orphan receptor γ (RORγ) are key regulators of metabolic and immune pathways. This makes them attractive targets for developing anti-inflammatory and metabolic therapeutics. In this study, we designed and synthesised a series of oleanolic acid-derived triterpenoid derivatives to explore their potential as dual modulators of these receptors. The focus of the structural modifications was on the double bond, C-3 substitution, and A-ring rearrangements in order to investigate their impact on biological activity and establish structure-activity relationships within the pentacyclic triterpene scaffold. Biological evaluation using CRE-luciferase reporter assays identified oleanolic acid (1), oleanonic acid (5), and compounds 7 and 8 as TGR5 agonists with concentration-dependent activities. Oleanolic acid (1) and the newly identified seco-derivative 8 displayed the most favourable potency and efficacy profiles. Gal4-RORγ reporter assays demonstrated inverse agonistic activity for oleanolic acid (1) and compounds 7 and 8. Although 7 and 8 exhibited lower potency than 1, both retained pronounced inhibitory efficacy, indicating that substantial scaffold rearrangement remains compatible with RORγ modulation. A resazurin conversion assay showed no evidence of cytotoxicity under the conditions tested, supporting that the observed receptor effects were not attributable to general cytotoxicity. Molecular modelling and Nwat-MMGBSA calculations supported the experimental findings and emphasized the role of conserved buried water molecules in stabilising ligand-receptor interactions in both targets. Overall, these findings identify oleanolic acid-derived triterpenoids as promising scaffolds for dual TGR5/RORγ modulation and provide valuable insights for the future development of multitarget-directed ligands targeting inflammatory and metabolic disorders.