Resorcinolic lipids, amphiphilic compounds from cereal grains show strong effects upon the activity of membrane enzymes. The concentrations for 50% inhibition of erythrocyte membrane acetylcholinesterase were in the range of 18 -90 μᴍ and were dependent on the length of the aliphatic side chain of the homologue and on the modification of hydroxyl groups in the benzene ring. Sulfonation of OH groups resulted in a drastic decrease of the inhibitory potency. The effect of resorcinolic lipids on

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... activity of Ca2+(calmodulin)-ATPase was the opposite. Up to concentrations of 50 μᴍ alk(en)ylresorcinols stimulated the activity of this enzyme and only slight inhibition (approx. 30%) was observed above 100 μᴍ. The results suggest that the effect of resorcinolic lipids might depend on their ability to alter the bilayer properties. Most probably these compounds decrease the mobility of membrane phospholipid molecules.