Abstract

Background: Andrographolide, a labdone diterpene extracted from Andrographis paniculata possesses various medicinal properties and has been used in treatment of number of chronic diseases, in humans.

Objectives: Evaluation of the effects of andrographolide on COX-2 enzyme (in silico and in vitro studies).

Materials and Methods: The interactions of andrographolide with COX-2 protein were evaluated (in silico) by molecular docking using Auto Dock Vina, version 4.0 software and visualized using pyMOL. An isocratic based HPLC method was developed for characterization of the purified andrographolide using mobile phase [methanol: water: acetonitrile (65:10:25)] and its UV absorption at different wavelengths. This compound was further tested in vitro against human recombinant COX-2 enzyme for its effect at various concentrations (10, 25, 50, 75, 100, 150, 200 nM). Celecoxib was used as a reference standard for comparison in both studies.

Results: The in silico studies revealed that andrographolide exhibited higher binding score of -10.3 K cal/mol and formation of hydrogen bonds with His 90 and Arg 120 amino acid residues of COX-2 indicating its binding to the protein. A relatively rapid, accurate and precise HPLC method was developed for andrographolide with the retention time of 3.255 min. The in vitro studies revealed a concentration dependent inhibitory effect of andrographolide on the COX-2 activity with an IC₅₀ value of 50 nM.

Conclusion: Our studies confirmed the inhibitory effects of andrographolide on COX-2 enzyme (in silico and in vitro), as the basis for its anti-inflammatory potentials.

Keywords: Andrographolide, anti-inflammatory agents, cyclooxygenase-2, celecoxib.

Graphical Abstract