Abstract
Studies on the SF's of horsetails revealed the existence of substances A and B and many fluorescent substances. Substance A was isolated as yellow crystals, which was disignated by the author as articulatin. Hydrolysis of articulatin gave the substance B, which was named by the author articulatidin. Analyses showed articulatin to be a glycoside of articulatidin having the structure of pentahydroxyanthraquinone-glucoside. It was proved to have a strong thiamine-decomposing activity. It is clarified that a part of the SF's of horsetails is articulatin and articulatidin, whereas no flavonoid is detected in horsetails.
Flavonoids (1, 2), phenols (5, 1) and tannins (8) have thus far been known as SF's of plants, but it has now been clarified by the present study that hydroxyanthraquinones which occur widely in animals, plants and microorganisms, belong also to SF's. Notwithstanding the fact the thiamine-decomposing activity of alizarin having o-dihydroxy structure is quite low compared with that of flavonoids having o-dihydroxy structure, both articulatin and articulatidin show a very strong thiamine-decomposing activity, possibly due to the special arrangement of OH radicals.
