Two novel analogues of aminopterin with a single fluorine substitution in the 2'(compound 8) or in the 3'(compound 9) position of the p-aminobenzoyl group were synthesized and evaluated as inhibitors of dihydrofolate reductase from two bacterial species and from human HeLa cells. The 2'-fluoro compound was bound essentially the same as aminopterin itself, while the 3'-fluoro derivative bound two-to threefold more tightly in all cases. UV ...
