The effects of resorcinolic lipids (5-n-alk(en)ylresorcinols) isolated from cereal grains on the phospholipase A2 catalyzed hydrolysis of phospholipid vesicles were examined. Studied compounds inhibited the apparent enzyme activity at the molar fraction in the membrane as low as 0.025, which is equivalent to the concentration of 3 μᴍ . This effect was visualized by dramatic increase (over ten-fold) of the latency period of the reaction progress. This makes resorcinolic lipids one of the most

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... ent inhibitors of phospholipase A2 among already studied compounds. Highest inhibitory activities were shown for dienoic and monoenoic homologs of 17 carbon atoms in the aliphatic chain. Both saturation of the chain and the increase of its length reduced inhibitory properties of resorcinolic lipids. The data suggest that the compounds studied in this paper like other known amphiphilic inhibitors of phospholipase A2 owe most of their effects to the ability to modify the quality of the substrate interface. These are the alteration of the enzyme binding, velocity of the formation and redistribution of the products. However part of the effect seems to be attributed to direct interaction and modification of enzyme properties by alk(en)ylresorcinols.