7-Hydro-8-methylpteroylglutamylglutamic acid, a new anti-folate from an actinomycete. Fermentation, isolation,...

A new anti-folate, 7-hydro-8-methylpteroylglutamylglutamic acid, was isolated from the culture broth of a soil actinomycete. The antibiotic inhibited the growth of Enterococcus faecium which requires folic acid. The inhibitory action was reversed by thymidine or excess amounts of folate-related compounds such as pteroic acid, folic acid, dihydrofolic acid and leucovorin. It inhibited thymidylate synthase from E. faecium, Bacillus subtilis and Ehrlich ascites carcinoma cells.