Antcin A, a steroid-like compound from Antrodia camphorata, exerts anti-inflammatory effect via mimicking glucocorticoids.

AIM

To determine the active ingredient of Niuchangchih (Antrodia camphorata) responsible for its anti-inflammatory effects and the relevant molecular mechanisms.

METHODS

Five major antcins (A, B, C, H, and K) were isolated from fruiting bodies of Niuchangchih. Structural similarity between the antcins and 2 glucocorticoids (cortisone and dexamethasone) was compared. After incubation with each compound, the cytosolic glucocorticoid receptor (GR) was examined for its migration into the nucleus. Mo lecular docking was performed to model the tertiary structure of GR associated with antcins.

RESULTS

Incubation with cortisone, dexamethasone or antcin A (but not antcins B, C, H, and K) led to the migration of glucocorticoid receptor into the nucleus. The minimal concentration of antcin A, cortisone and dexamethasone to induce nuclear migration of glucocorticoid receptor was 10, 1, and 0.1 mol/L, respectively. The results are in agreement with the simulated binding affinity scores of these three ligands docking to the glucocorticoid receptor. Molecular modeling indicates that C-7 of antcin A or glucocorticoids is exposed to a hydrophobic region in the binding cavity of the glucocorticoid receptor, and the attachment of a hydrophilic group to C-7 of the other four antcins presumably results in their being expelled when docking to the cavity.

CONCLUSION

The anti-inflammatory effect of Niuchangchih is, at least, partly attributed to antcin A that mimics glucocorticoids and triggers translocation of glucocorticoid receptor into nucleus to initiate the suppressing inflammation.