Insights from the predicted interactions of plant derived compounds to the gluco-corticoid receptor as an alternative to dexa-methasone

Dexamethasone (DEX) an anti-inflamatory 9-fluoro-glucocorticoid, activates the cytosolic glucocorticoid receptor (GR) binding to its Ligand Binding Domain (LBD). The GR-ligand complex then translocates to the nucleus and binds to the Glucocorticoid Response Element (GRE) resulting up-regulation of target gene expression of anti-inflamatory proteins. DEX is one of the most effective ligand for GR activation but comply to side effects. Therefore, alternative for DEX - plant metabolites of Calotropis sp and Swertia chirata were screened using docking appraoch. These plants compounds were selected because; parts of these plants are widely used againsts inflamation, allergy, asthma etc. Three metabolites of Swertia chirata namely Gentianine (GENT), Xanthone (XANT) and Swerchirin (SWER) are found to be occupying the same binding pocket in the LBD of the GR (PDB ID 1M2Z). The binding affinity as reflected by binding energies of GENT-1M2Z, XANT-1M2Z and SWER-1M2Z are -5.6, -6.7 and -6.7, and all the output parameter of the respective compounds positively correlates with that of DEX-1M2Z with r = 0.9, 0.6 and 0.6 respectively indicating similar GR activation function. Visualization analysis of the models clearly indicates that GENT and SWER may be GR activators. Rest of the compounds mostly docked onto the surface of the receptor molecule.