Polar constituents of <Emphasis Type="Italic">Ligustrum vulgare</Emphasis> L. and their effect on lipoxygenase activity

The present work summarizes results of isolation and identification of polar constituents of the methanolic extract of Ligustrum vulgare L. leaves and of the evaluation of inhibiting activity of selected isolates on rat lung cytosol fraction lipoxygenase. Six different compounds were isolated from the ethylacetate and butanol portions of the methanolic extract (hydroxytyrosol and its glucoside, ligustroflavon, oleuropein, acteoside, echinacoside). The inhibitory activity of oleuropein, echinacoside and the water infusion of Ligustrum vulgare leaves tested on LOX was expressed as IC₅₀. Kinetic parameters (K _M, V _max) and type of inhibition were determined. As the most effective in competitive inhibition of LOX, oleuropein was proved.