3,4-Dihydroxychalcones as potent 5-lipoxygenase and cyclooxygenase inhibitors.

A novel series of 3,4-dihydroxychalcones was synthesized to evaluate their effects against 5-lipoxygenase and cyclooxygenase. Almost all compounds exhibited potent inhibitory effects on 5-lipoxygenase with antioxidative effects, and some also inhibited cyclooxygenase. The 2',5'-disubstituted 3,4-dihydroxychalcones with hydroxy or alkoxy groups exhibited optimal inhibition of cyclooxygenase. We found that 2',5'-dimethoxy-3,4-dihydroxychalcone (37; HX-0836) inhibited cyclooxygenase to the same degree as flufenamic acid and 5-lipoxygenase, more than quercetin. Finally, these active inhibitors of 5-lipoxygenase inhibited arachidonic acid-induced mouse ear edema more than phenidone.