CHARACTERIZATION OF NOVEL INDENOINDOLES .1. REDOX-RECYCLING WITH ASCORBATE

In the accompanying paper it was shown that the new antioxidant, H 290 /51 tetrahydro-9-methoxy-7-methylindeno[2,1-b]indole), is a powerful a ntioxidant in several pharmacological models of lipid peroxidation and could be useful as a therapeutic agent in pathophysiological situatio ns where lipid peroxidation plays an important role. In the present st udy, we characterised H 290/51 as an inhibitor of peroxidation of pure methyl linoleate H 290/51 almost completely inhibited peroxidation in duced by a lipid-soluble initiator at 37 degrees C during the inductio n period, both in an aqueous solution of micelles in the presence of d etergents and in a homogeneous ethanol solution. In both systems, the time of che induction period was linearly related to the concentration of H 290/51. In the ethanol solution, ascorbic acid had a sparing eff ect on H 290/51, indicating effective interference with radical chain propagation. In aqueous solution with micelles of methyl linoleate mad e with the nonionic detergents Triton X-100 or Lubrol PX, ascorbic aci d did not inhibit peroxidation. However, in these micelles, H 290/51 s howed a concentration-dependent extension of the induction period by a scorbic acid, suggesting recycling. In the presence of the zwitterioni c detergent CHAPS, although a clear induction period is seen with H 29 0/51, no recycling by ascorbic acid was found. The ability of H 290/51 to recycle in aqueous solutions, thus depends on the micellar composi tion.