In silico exploration of anti-inflammatory activity of natural coumarinolignoids.

Natural coumarinolignoids isolated from the seeds of Cleome viscosa consist of a racemic mixture of cleomiscosins A, B and C. To screen out potential lead, anti-inflammatory activity of the isolated compounds was evaluated through molecular docking and QSAR studies by using reported in vivo activity of Swiss albino mice. Based on docking binding affinity, a possible mechanism of action has been hypothesized which constitute toll-like receptors (TLR-4), cluster of differentiation molecules (CDs), iNOS, COX-2 and STAT-6 proteins. It was very interesting to find that the 3D topology of the active site of COX-2 from the docking was in good agreement with QSAR model and in silico ADME/T parameters. A forward feed multiple linear regression model was developed with r(2) = 0.92 and rCV(2) = 0.87. This study showed that chemical descriptors, for example dipole vector-X, dipole vector-Y, steric energy, LUMO energy, size of smallest ring, size of largest ring and carboxyl group count, correlate reasonably well with experimental in vivo activity (logLD(50) ). QSAR study indicates that dipole vector-Y and carboxyl group count have negative correlation with activity. Cleomiscosins also showed compliance with 95% of in silico ADME/T properties of available drugs, e.g. serum protein binding, blood-brain barrier, CNS activity, HERG K+ channel activity, apparent Caco-2 permeability, apparent MDCK permeability, skin permeability and human oral absorption in GI. Besides, toxicity screening study suggests that cleomiscosin molecules possess no toxicity risk parameters. This study offer useful references for understanding and molecular design of inhibitors with improved anti-inflammatory activity.