Celastrol Derivatives: A Reverse Docking Study Targeting RORα and RORγ for Anti-inflammatory and Anti-tumor Activity

Celastrol (CSL) is a pentacyclic triterpenoid terpene extracted from the root bark of Tripterygium wilfordii, which has shown remarkable efficacy in anti-cancer and cerebral neurology. However, its toxicity limits its clinical use. To address this issue, we have obtained a series of derivatives with reduced toxicity and increased efficacy through biotransformation.

In this study, we used AlphaFold DB and the Schrödinger platform Small Molecule Drug Discovery to perform reverse docking with the basic scaffold of CSL to discover the pharmacological activity of its derivatives. We selected the RORα and RORγ of Retinoic Acid Related-Orphan Receptors (RORs) family as the targets for study based on the drug target database. We filtered the series of compounds through QikProp, docked for dynamics simulation and molecular mechanics-generalized born surface area (MMGBSA) binding energy calculations. We also performed fluorescence polarization assay (FP assay), luciferase reporter gene assay, and the CCK8 assay.

Our results showed that CSL targets RORα and RORγ to explain its anti-inflammatory and anti-tumor effects. We found the binding sites GLN19, ARG97, ARG100 for RORα-Ligand binding domain (LBD) and GLN25, LEU26, ARG103, ARG106 for RORγ-LBD and screened for the highest affinity derivatives. The luciferase reporter gene assay showed that 2 μM 18-OH-CSL and 28-OH-CSL had the strongest agonistic effect on RORα-LBD, and 12-OH-CSL and a-ring aromatized 15-OH-CSL had the strongest inhibitory effect on RORγ-LBD. The positive and negative coulomb energy in MMGBSA supported these experimental results.

In summary, our study provides insights into the pharmacological activity of CSL derivatives and their potential as anti-inflammatory and anti-tumor agents.