MAGNOLOL AND HONOKIOL ISOLATED FROM MAGNOLIA-OFFICINALIS PROTECT RAT-HEART MITOCHONDRIA AGAINST LIPID-PEROXIDATION

In isolated rat heart mitrochondria lipid peroxidation was induced wit h ADP and ferrous sulfate (FeSO4). Oxygen consumption and malondialdeh yde (MDA) production were measured to quantitate lipid peroxidation. T he antioxidant effects of magnolol and honodiol purified from Magnolia officinalis were 1000 times higher than that of alpha-tocopherol. The IC50 values of magnolol and honokiol for inhibition of oxygen consump tion were 8.0 x 10(-8) M and 1.0 x 10(-7) M, respectively, while that of alpha-tocopherol was 1.0 x 10(-4) M. Magnolol at 0.5 mu M at 0.5 mu M inhibited 71.4 +/- 9.4% of oxygen consumption and 59.3 +/- 4.6% MDA production. At the same concentration, honokiol inhibited 78.1 +/- 4. 7% of oxygen consumption and 86.9 +/- 4.0% of MDA production. Of conju gated diene formation 48.4 +/- 4.6% and 53.1 +/- 3.4% were inhibited b y 0.5 mu M magnolol and honokiol, respectively. Also both magnolol and honokiol exhibited free radical scavenging activities as shown by the diphenyl-p-picrylhydrazyl assay, but they were less potent than alpha -tocopherol.