Antithiamine Factors of Ferns1

That Pteris aquilina, a spccies of fern, destroys thiamine, or possesses "anti thiamine activity" or "antianeurine factor" has been reported by Weswig (1), Thomas (2) and Evans (3). Similar factors, though somewhat weaker in activity, have also been found in Aspidium filix mas, Dryapteris austriaca and Nephrolepsis exaltata by Somogyi (4, 5, 6) and in Equisetum arvense by Evans et al. (7). According to Evans et al., the antithiamine factor in Pteris is enzymic in nature and therefore a vegetable thiaminase. Miura and Fuji wara (8) have shown that a similar antithiamine factor exists in the Japanese fern, Pteridium aquilium Kuhn var. japonicum Nakai. This was found to possess properties of thiaminase, and they ascribed it to a vegetable thiamin ase, although its characteristics did not perfectly accord with the enzymic nature. In Europe when the feeds for rats and horses contained dried green ferns, the animals were found to suffer from hypothiaminosis, while there is a sufficient amount of thiamine in the feed. Also most cases of fern poison ing of cows were ascribed by Evans to hypothiaminosis. As to the properties of the antithiamine factor of ferns, reports can be found in proceedings of biochemical meetings, but the description are not at all exhaustive. Even the question whether it is an enzyme or not seems to have not yet been answered conclusively. The authors undertook this investigation in August 1950, when the season of sprouting had passed. The materials used were therefore mostly ferns collected months before in Nagano Prefecture, dried and kept in dessicators containing calcium chloride. The potency of the specimens may have been fallen considerably, but some interesting results were obtained.