Effect of Cleome arabica leaf extract, rutin and quercetin on soybean lipoxygenase activity and on generation of inflammatory eicosanoids by human neutrophils

The effects of Cleome arabica leaf extract, rutin and quercetin on soybean lipoxygenase (Lox) activity and on calcium ionophore (A23187)-stimulated generation of the leukotriene B4 and prostaglandin E2 by human neutrophils were examined. The extract (25 μg/ml), rutin (25 μM) and quercetin (25 μM) inhibited LTB4 synthesis at all concentrations of A23187 used. The extract at 1-100 μg/ml and rutin at 1-100 μM inhibited LTB4 generation by neutrophils stimulated with 1 μM A23187 by about 50%. PGE2 production in response to different concentrations of A23187 was affected in a biphasic manner by the extract and rutin. Quercetin at 1-100 μM caused concentration-dependent inhibition of LTB4 and PGE2 production. The extract, rutin and quercetin caused concentration-dependent inhibition of soybean Lox activity. These results indicate that rutin, quercetin and an extract of C. arabica containing these compounds inhibit Lox activity, consequently decreasing LTB4 production. Thus, these compounds or extracts containing them may be beneficial for the treatment of inflammatory conditions, particularly those characterised by excessive leukotriene generation.