C-METHYLATED DIHYDROCHALCONES FROM MYRICA-GALE L - EFFECTS AS ANTIOXIDANTS AND AS SCAVENGERS OF 1,1-DIPHENYL-2-PICRYLHYDRAZYL

A number of isomeric or chemically closely related C-methylated dihydr ochalcones, which is a rare substance class, has been isolated from th e fruit exudate of Myrica gale L. and subjected to the following tests : 1) inhibition of lipid peroxidation induced by tert-butyl hydroperox ide or bromotrichloromethane in isolated rat hepatocytes, 2) inhibitio n of peroxidation induced by Fe2+ ions in a cell free system with lino lenic acid as substrate, 3) scavenging activity against the diphenylpi crylhydrazyl radical, and 4) inhibition of enzymatic lipid peroxidatio n in linoleic acid by soybean 15-lipoxy-genase. One of the compounds ( myrigalone B = MyB; ihydroxy-4'-methoxy-3',5'-dimethyldihydrochalcone) showed good activity in all tests, whereas the others were inactive o r slightly active, except that myrigalone A (MyA; -(1-oxo-3-phenylprop yl)-1,1,5-trimethylcyclohexane like its synthetic analogue MyA (the p olar part of MyA) was nearly as active as MyB in 4). The antioxidant p roperties of MyB are probably due to its radical scavenging activity a nd may be related to its conformation, which differs from that of the other compounds.