BETA-ETHOXYACROLEIN CONTAMINATION INCREASES MALONDIALDEHYDE INHIBITION OF MILK XANTHINE-OXIDASE ACTIVITY

beta-Ethoxyacrolein (BEA), a side product that forms during the prepar ation of malondialdehyde (MDA) by acidic hydrolysis of tetraethoxpropa ne (TEP), has been found to be an inhibitor of milk xanthine oxidase ( XO) several times more potent than pure MDA (NaMDA). The incubation of XO with 10 mu M BEA abolished 50% of the enzyme activity within 1 min ; the inhibited enzyme was totally regenerated by dialysis and filtrat ion through Sephadex. The BEA inhibition mode of the enzyme was mixed- type with the apparent inhibition constants (K-i) of 2.3 x 10(-6) M. A n HPLC method for quantitation of BEA in the crude commonly used MDA p reparation was set up. (C) 1998 Elsevier Science Inc.