Abstract
Antioxidative components in the methanol extract of seeds of Plantago asiatica L. were investigated by using our test method based on the air oxidation of linoleic acid. Geniposidic acid, an iridoid glucoside, was found to be the most potent antioxidative component. The 50% inhibitory concentration (IC50) of geniposidic acid was 1.56×10-2% (thiobarbituric acid value), and this value was superior to that of dl-α-tocopherol (IC50 : 1.95×10-1%). The antioxidative effects of other related iridoid glucosides (aucubin, geniposide, gardenoside) were also tested, but their activities were clearly weaker than that of geniposidic acid.
