Cell-permeable. An antioxidant and dual inhibitor of 5-lipoxygenase (IC₅₀ = 8 µM) and cyclooxygenase (COX) (IC₅₀ = 52 µM). Also inhibits glutathione S-transferase, induction of nitric oxide (NO) in activated macrophages and inhibits EGF-induced tyrosine phosphorylation of EGF receptors. Also shown to be a p300/CREB-binding protein-specific inhibitor of histone acetyltransferase, inhibiting the acetylation of histones H3 and H4 with an IC₅₀ of ~25 µM. Does not affect p300/CREB binding protein-associated factor (PCAF).