Pimaric acid is a resin acid that has been found in A. cordata and various pines. It reduces mRNA expression, protein levels, and promoter activity of matrix metalloproteinase-9 (MMP-9) in TNF-α-stimulated human aortic smooth muscle cells (HASMCs) in a concentration-dependent manner when used at concentrations ranging from 5 to 20 μM. Pimaric acid (10-20 μM) reduces nuclear expression and binding of the transcription factors NF-κB and AP-1 to the MMP-9 promoter in HASMCs. Pimaric acid also reduces TNF-α-induced HASMC migration to control levels when used at a concentration of 20 μg/ml.