Synthesis, anti-inflammatory activity and modeling studies of cycloartane-type terpenes derivatives isolated from Parthenium argentatum.

The 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced edema model in mice determined the anti-inflammatory activities in vivo of argentatins A, B and D, the main cycloartenol-type triterpenes present in Parthenium argentatum. Our results showed that argentatin B (ED50=1.5×10(-4)mmol/ear) and argentatin A (ED50=2.8×10(-4)mmol/ear) were more potent anti-inflammatory agents than indomethacin (ED50=4.5×10(-4)mmol/ear), the reference drug. Based on these findings, we decided to evaluate 13 derivatives of argentatins A and B. All the derivatives showed anti-inflammatory activity in the TPA-induced edema model in mice. The most active compound was 25-nor-cycloart-3, 16-dione-17-en-24-oic acid, obtained from argentatin A (ED50=1.4×10(-4)mmol/ear). Argentatin B was assayed as inhibitor of COX-2 activity one of the key enzymes involved in the TPA assay. The results showed that argentatin B at 15μM doses inhibited 77% COX-2 activity. Docking studies suggest that argentatin B interacts with Arg 120, a key residue for COX-2 activity.