Prevention of amethopterin inhibition by 2-methyladenine.

Amethopterin has been shown to be a folic acid antagonist in certain organisms (Franklin et al., 1948; Hitchings et al., 1952; Collier and Phillips, 1954). Hakala and Welch (1957) extracted a triglutamate form of folinic acid from Bacillus subtilis but these investigators did not study the possible antagonism of this compound and amethopterin in the same organism. In B. subtilis, the test organism of this investigation, amethopterin was inhibitory, but no form of folic acid tested was found to prevent the inhibition. Guthrie et al. (1956) have shown that another group of compounds, cocarboxylase, thiamine, and thiamine pyrimidine, will, however, prevent the inhibitory effect of amethopterin on B. subtilis. This investigation concerns a group of compounds (certain substituted purines) which was also active in preventing the inhibition of amethopterin, although much less effectively than thiamine or the thiamine pyrimidine. Of these, 2-methyladenine was the most active.