However, they also act indirectly as protein synthesis inhibitors (because tetrahydrofolate is also involved in the synthesis of amino acids serine and methionine), so they are sometimes considered as their own category, antimetabolites.
Međutim, oni isto tako dejstvuju indirektno kao inhibitori proteinske sinteze (zato što tetrahidrofolat isto tako učestvuje u sintezi amino kiselina serina i metionina), tako da se oni nekad razmatraju kao posebna kategorija, antimetabolita.