Folate analogues. 34. Synthesis and antitumor activity of non-polyglutamylatable inhibitors of dihydrofolate reductase

J Med Chem. 1991 Jan;34(1):222-7. doi: 10.1021/jm00105a035.


Five analogues of methotrextate (MTX), 10-deazaaminopterin (10-DAM), and 10-ethyl-10-deazaaminopterin (10-EDAM) in which the glutamate moiety was replaced by either a gamma-methyleneglutamate or beta-hydroxyglutamate were synthesized and evaluated for their antifolate activity. These analogous are 4-amino-4-deoxy-N10-methylpteroyl-beta-hydroxyglutamic acid (1), 4-amino-4-deoxy-10-deazapteroyl-beta-hydroxyglutamic acid (2), 4-amino-4-deoxy-N10-methylpteroyl-gamma-methyleneglutamic acid (3, MMTX), 4-amino-4-deoxy-10-deazapteroyl-gamma-methyleneglutamic acid (4, MDAM), and 4-amino-4-deoxy-10-ethyl-10-deazapteroyl-gamma-methyleneglutamic acid (5, MEDAM). None of these compounds were metabolized to the respective polyglutamate derivative as judged by their inability to serve as substrates for CCRF-CEM human leukemia cell folylpolyglutamate synthetase (FPGS) in vitro. All compounds inhibited recombinant human-dihydrofolate reductase (DHFR) at nearly equivalent magnitude as MTX. Growth-inhibition studies with H35 hepatoma, Manca human lymphoma, and CCRF-CEM human leukemia cells established greater cytotoxic effects with compounds 3-5 than with compounds 1 and 2. gamma-Methyleneglutamate derivatives 3-5 were transported to H35 hepatoma cells better than MTX or beta-hydroxyglutamate derivatives 1 and 2. Compound 3 was 2.5 times better than MTX in competing with folinic acid transport in H35 hepatoma cells. Compound 1 did not have a significant inhibitory effect on folinic acid transport even at 50 microM under identical conditions. The IC50 for compound 1 against H35-hepatoma cell growth was 8.5-fold higher than MTX. Compounds with the gamma-methyleneglutamate moiety (3-5) exhibited almost equal or lower IC50 values than MTX against the growth of CCRF-CEM human leukemia cells. These studies show that on continuous exposure, the non-polyglutamylatable inhibitors DHFR (3-5) can exhibit superior antifolate activity compared to the polyglutamylatable methotrexate, presumably due to their enhanced transport to these cell lines. Compounds 3-5 appear to be excellent models to study the role of polyglutamylation of antifolates in antitumor activity and host toxicity.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antimetabolites, Antineoplastic / chemical synthesis*
  • Antimetabolites, Antineoplastic / chemistry
  • Antimetabolites, Antineoplastic / pharmacology
  • Cell Division / drug effects
  • Cell Line
  • Drug Screening Assays, Antitumor
  • Folic Acid Antagonists* / chemical synthesis*
  • Folic Acid Antagonists* / chemistry
  • Folic Acid Antagonists* / pharmacology
  • Humans
  • Indicators and Reagents
  • Methotrexate / pharmacology
  • Molecular Structure
  • Recombinant Proteins / antagonists & inhibitors
  • Structure-Activity Relationship


  • Antimetabolites, Antineoplastic
  • Folic Acid Antagonists
  • Indicators and Reagents
  • Recombinant Proteins
  • Methotrexate