3nu0
From Proteopedia
Design, Synthesis, Biological Evaluation and X-ray Crystal Structure of Novel Classical 6,5,6-TricyclicBenzo[4,5]thieno[2,3-d]pyrimidines as Dual Thymidylate Synthase and Dihydrofolate Reductase Inhibitors
Structural highlights
Disease[DYR_HUMAN] Defects in DHFR are the cause of megaloblastic anemia due to dihydrofolate reductase deficiency (DHFRD) [MIM:613839]. DHFRD is an inborn error of metabolism, characterized by megaloblastic anemia and/or pancytopenia, severe cerebral folate deficiency, and cerebral tetrahydrobiopterin deficiency. Clinical features include variable neurologic symptoms, ranging from severe developmental delay and generalized seizures in infancy, to childhood absence epilepsy with learning difficulties, to lack of symptoms.[1] [2] Function[DYR_HUMAN] Key enzyme in folate metabolism. Contributes to the de novo mitochondrial thymidylate biosynthesis pathway. Catalyzes an essential reaction for de novo glycine and purine synthesis, and for DNA precursor synthesis. Binds its own mRNA and that of DHFRL1.[3] [4] Publication Abstract from PubMedClassical antifolates (4-7) with a tricyclic benzo[4,5]thieno[2,3-d]pyrimidine scaffold and a flexible and rigid benzoylglutamate were synthesized as dual thymidylate synthase (TS) and dihydrofolate reductase (DHFR) inhibitors. Oxidative aromatization of ethyl 2-amino-4-methyl-4,5,6,7-tetrahydro-1-benzothiophene-3-carboxylate (+/-)-9 to ethyl 2-amino-4-methyl-1-benzothiophene-3-carboxylate 10 with 10% Pd/C was a key synthetic step. Compounds with 2-CH(3) substituents inhibited human (h) TS (IC(50)=0.26-0.8muM), but not hDHFR. Substitution of the 2-CH(3) with a 2-NH(2) increases hTS inhibition by more than 10-fold and also affords excellent hDHFR inhibition (IC(50)=0.09-0.1muM). This study shows that the tricyclic benzo[4,5]thieno[2,3-d]pyrimidine scaffold is highly conducive to single hTS or dual hTS-hDHFR inhibition depending on the 2-position substituents. The X-ray crystal structures of 6 and 7 with hDHFR reveal, for the first time, that tricyclics 6 and 7 bind with the benzo[4,5]thieno[2,3-d]pyrimidine ring in the folate binding mode with the thieno S mimicking the 4-amino of methotrexate. Design, synthesis, biological evaluation and X-ray crystal structure of novel classical 6,5,6-tricyclic benzo[4,5]thieno[2,3-d]pyrimidines as dual thymidylate synthase and dihydrofolate reductase inhibitors.,Zhang X, Zhou X, Kisliuk RL, Piraino J, Cody V, Gangjee A Bioorg Med Chem. 2011 Apr 9. PMID:21550809[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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