Abstract
In order to make clear the so-called thermostable antithiamine factor of bracken, the properties of flavonoid pig-
ments therein have been studied. The results obtained are as follows:
1. From the ethyl acetate soluble fraction of alcoholic extract of bracken, astragalin (kaempferol-3-glucoside) and isoquercitrin (quercetin-3-glucoside) were isolated in the form of yellow and needle crystals respectively.
2. In addition, rutin and two unknown flavonoid pigments were detected by the paper chromatography.
3. Among these pigments, isoquercitrin and rutin have the marked thiamine-decomposing activity.
4. It is, therefore, presumed that a portion of the thermostable antithiamine factor of bracken is the flavonoid pigments such as isoquercitrin and rutin therein.
