Bunaprolast has been described as the most potent antioxidant inhibitor of endothelial activation of NF-kB and gene expression of E-selectin and vascular cell adhesion molecule-1. Bunaprolast is a potent inhibitor of leukotriene B4 production in human whole blood and undergoes deacetylation to an initial metabolite with similar pharmacological potency. The in vivo demonstration of inhibition of pulmonary bronchoconstriction by this compound, in a model known to be leukotriene sensitive, coupled with its potent in vitro inhibition of 5-lipoxygenase enzymes, suggests bunaprolast may be of use in 5-lypoxygenase-mediated models of asthma.