Abstract
The thiamine-decomposing thermostable factor (SF) of ferns was isolated in a crystalline form. The absorption spectrum in the ultraviolet region agrees quite well with that of astragalin, but the infrared absorption spectrum showed minor differences in spite of general resemblance. The melting points, elementary analysis and Rf values of paper chromatography were found to be somewhat different. It is therefore concluded that the major part of bracken SF is a flavnnol, akin to astragalin. Further, it was proved by paper chromatography quercetin and isoquercitrin, the compounds which have already been reported by the author to have very potent SF activity.
