Synthesis of classical and nonclassical, partially restricted, linear, tricyclic 5-deaza antifolates.

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Gangjee A, Zeng Y, McGuire JJ, Kisliuk RL

Synthesis of classical and nonclassical, partially restricted, linear, tricyclic 5-deaza antifolates.

J Med Chem. 2002 Nov 7;45(23):5173-81.

PubMed ID
12408727 [ View in PubMed
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Abstract

Seven novel 2,4-diamino-5-deaza-6,7,8,9-tetrahydropyrido[3,4-g]pteridine derivatives 3-9 with different benzyl and a benzoyl substitution at the N7 position were designed and synthesized, as classical and nonclassical, partially restricted, linear tricyclic 5-deaza antifolates. The purpose was to investigate the effect of conformational restriction of the C6-C9 (tau(1)) and C9-N10 (tau(2)) bonds via an ethyl bridge from the N10 to the C7 position of 5-deaza methotrexate (MTX) on the inhibitory potency against dihydrofolate reductase (DHFR) from different sources and on antitumor activity. The synthetic methodology for most of the target compounds was a concise five-step total synthesis to construct the tricyclic nucleus, 2,4-diamino-5-deaza-7H-6,7,8,9-tetrahydropyrido[3,4-g]pteridine (23), followed by regioselective alkylation of the N7 nitrogen. Biological results indicated that this partial conformational modification for the classical analogue N-[4-[(2,4-diamino-5-deaza-6,7,8,9-tetrahydropyrido[3,4-g]pteridin-7-yl)methyl]be nzoyl]-L-glutamic acid 3 was detrimental to DHFR inhibitory activity as well as to antitumor activity compared to MTX or 5-deaza MTX. However, the classical analogue 3 was a better substrate for folypolyglutamate synthetase (FPGS) than MTX. These results show that a classical 5-deaza folate partially restricted via a bridge between the N10 and C7 positions retains FPGS substrate activity and that the antitumor activity of classical tricyclic analogues such as 3 would be influenced by FPGS levels in tumor systems. Interestingly, the nonclassical analogues 4-9 showed moderate to good selectivity against DHFR from pathogenic microbes compared to recombinant human DHFR. These results support the idea that removal of the 5-methyl group of piritrexim along with restriction of tau(1) and tau(2) can translate into selectivity for DHFR from pathogens.

DrugBank Data that Cites this Article

Binding Properties
DrugTargetPropertyMeasurementpHTemperature (°C)
MethotrexateDihydrofolate reductaseIC 50 (nM)22N/AN/ADetails
TrimethoprimDihydrofolate reductaseIC 50 (nM)340000N/AN/ADetails
TrimetrexateDihydrofolate reductaseIC 50 (nM)18N/AN/ADetails