THE EFFECTS OF A THIOL-CONTAINING QUINAZOLINEDIONE DERIVATIVE (MECH) ON THE LIPID OXIDATION IN BILAYER LIPOSOMES

In order to investigate the radical chemistry of 3-(2-mercaptoethyl)qu inazoline-2,4(1H,3H)-dione (MECH) in homogeneous and liposomal solutio ns experiments were performed with pulse radiolysis, gamma radiolysis and the chemical radical initiator 2,2'-azobis(2-amidinopropane)dihydr o chloride (AAPH). It is shown that the thiol group represents the mos t sensitive group to radical attack. The thiyl radical originating fro m MECH is detected indirectly by product analysis and by pulse radioly sis. The thiyl radical can abstract bisallylic hydrogens from polyunsa turated fatty acids. This is shown by pulse radiolysis in homogeneous and liposomal solutions via the formation of the pentadienyl radical w hich has a strong and characteristic absorption band at 280 nm.