Synthesis and biological activity of open-chain analogs of 5,6,7,8-tetrahydrofolic acid-potential antitumor agents

Abstract

This study describes the synthesis and in vitro antitumor activity of inhibitors of purine de novo biosynthesis that are analogues of N-[4-[[3-(2,4-diamino-1,6-dihydro-6-oxo-5-pyrimidinyl) propyl]amino]benzoyl-L-glutamic acid (5-DACTHF). Benzene ring substituted analogues were synthesized from a protected pyrimidinyl propionaldehyde and a substituted benzoyl glutamate moiety by a key reductive amination step. Pyrimidine and linking chain substituted analogues were built up stepwise from p-aminobenzoic acid or analogues. The compounds were tested as inhibitors of methotrexate uptake as a measure of binding to the reduced folate transport system, as inhibitors of glycinamide ribonucleotide transformylase, as substrates for folylpolyglutamate synthetase, and as inhibitors of tumor cell growth in cell culture. With the exception of 2'-F substituent, the ring-substituted analogues are less active than the parent compound. Replacement of the 10-nitrogen by carbon, sulfur, or oxygen produced less than 2-fold changes to biological activity in vitro. A four-atom linking chain and an amino group at the 2-position on the pyrimidine ring are important for good activity.

Structure of Avian AICAR Transformylase with a Multisubstrate Adduct Inhibitor β-DADF Identifies the Folate Binding Site,

“…Therefore, with a K m of 16.8 µM for AICAR (30) and 68 µM for 10-f-THF (7,31), the inhibition of β-DADF on AICAR transformylase could approximate a 1 nM K d . It was possible to approach picomolar inhibition for glycinamide ribonucleotide (GAR) transformylase (GAR Tfase) MAIs BW1476U89 (32,33) and β-thio-GAR-dideazafolate (β-TGDDF) (34,35) as their substrate GAR and folate cofactor K m 's are approximately 10-fold lower than the comparable values for ATIC. However, the anticipated gain in binding an MAI may not be realized due to enthalpically-diminished binding capabilities (36).…”

“…In comparison to the various structures of E. coli GAR Tfase in complex with antifolates BW1476U89 (K i ∼ 100 pM) (PDB entry 1GAR) (33), β-TGDDF (K d ∼ 250 pM) (34,35) and 10-formyl-5,8,10-trideazafolic acid (10-f-TDAF, K i ) 260 nM) (PDB entry 1C3E) (42), as well as the epoxide-derived MAI of β-GAR and 10-bromo-10-bromomethyl-5,8,10-trideazafolic acid (K i ) 20 µM) (PDB entry 1JKX) (43), substantial differences are observed in the ways in which these related folates interact within the different active sites, and whether conformational changes in the protein accompany ligand binding. Unlike the epoxidederived MAI which mimics the transition state, BW1476U89 was designed to incorporate only the structural features of GAR and 10-f-THF that were thought to contribute significantly to binding in the GAR Tfase active site (32,33) and were then connected via a flexible linker. In general, both AICAR Tfase and GAR Tfase folate-binding pockets sandwich the pterin ring between hydrophobic residues from both above and below, while hydrogen bonds interact with the plane of the heterocyclic ring further anchoring the inhibitor.…”

Biological and Structural Evaluation of 10R- and 10S-Methylthio-DDACTHF Reveals a New Role for Sulfur in Inhibition of Glycinamide Ribonucleotide Transformylase

“…The growth inhibition activity of the compounds was measured using CCRF-CEM human leukemia cell lines as previously described (15, 41, 48) .…”

Utilization of Cyclic Amides as Masked Aldehyde Equivalents in Reductive Amination Reactions

“…Ethyl 4-(2-Oxopyrrolidin-1-yl)benzoate (1g, White Solid, 3.6 g, Yield: 67%). 27 1 H NMR (DMSO-d 6 , 500 MHz): δ 8.00−7.93 (2H, m), 7.85−7.80 (2H, m), 4.29 (2H, q, J = 7.1 Hz), 3.87 (2H, t, J = 7.3 Hz), 2.54 (2H, t, J = 8.2 Hz), 2.12−2.03 (2H, m), 1.31 (3H, t, J = 7.0 Hz). LRMS (ESI) + : 234.2.…”