Figure 1

Structural formulas of tetrahydrofolate (THF), methotrexate (MTX), and pemetrexed (PTX). The compounds are divided into P-, B-, and E-moieties, as referenced throughout the text.

Structural formulas of tetrahydrofolate (THF), methotrexate (MTX), and pemetrexed (PTX). The compounds are divided into P-, B-, and E-moieties, as referenced throughout the text.