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

In isolated rat heart mitrochondria lipid peroxidation was induced with ADP and ferrous sulfate (FeSO4). Oxygen consumption and malondialdehyde (MDA) production were measured to quantitate lipid peroxidation. The 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 consumption 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 conjugated diene formation 48.4 +/- 4.6% and 53.1 +/- 3.4% were inhibited by 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.