5-deaza-5-6-7-8-tetrahydrofolic-acid and lometrexol

We recently described the syntheses of 12a-c, 4-amino-7-oxo substituted analogues of 5-deaza-5,6,7,8-tetrahydrofolic acid (5-DATHF), and 5,10-dideaza-5,6,7,8-tetrahydrofolic acid (DDATHF), in six steps from commercially available p-substituted methyl benzoates in 20-27% overall yields. Such analogues were tested in vitro against CCRF-CEM leukemia cells and showed that they are completely devoid of any activity, the IC(50) being higher than 20 microg/mL for all cases. To clarify if the presence of the carbonyl group in position C7, the distinctive feature of our synthetic methodology, is the reason for this lack of activity, we have now obtained the 7-oxo substituted analogues of 5-DATHF and DDATHF, 18a-c, in 10-30% overall yield. Testing of 18a-c in vitro against CCRF-CEM leukemia cells revealed that these compounds are totally inactive. A molecular modeling study of 18b inside the active site of the complex E. coliGARTFase-5-DATHF-GAR pointed to an electronic repulsion between the atoms of the 7-oxo group and the carbonyl group of Arg90 as a possible explanation for the inactivity of 18a-c.

Topics: Antineoplastic Agents; Crystallography, X-Ray; Drug Screening Assays, Antitumor; Escherichia coli; Folic Acid Antagonists; Humans; Hydroxymethyl and Formyl Transferases; Models, Molecular; Phosphoribosylglycinamide Formyltransferase; Ribonucleotides; Structure-Activity Relationship; Tetrahydrofolates; Tumor Cells, Cultured

The 4-amino-7-oxo-substituted analogues of 5-deaza-5,6,7, 8-tetrahydrofolic acid (5-DATHF) and 5,10-dideaza-5,6,7, 8-tetrahydrofolic acid (DDATHF) were synthesized as potential antifolates. Treatment of the alpha,beta-unsaturated esters 11a-c, obtained in one synthetic step from commercially available para-substituted methyl benzoates (9a-c) and methyl 2-(bromomethyl)acrylate (10), with malononitrile in NaOMe/MeOH afforded the corresponding pyridones 12a-c. Formation of the pyrido[2,3-d]pyrimidines 13a-c was accomplished upon treatment of 12a-c with guanidine in methanol. After the hydrolysis of the ester group present in 13a-c, the resulting carboxylic acids 14a-c were treated with diethyl cyanophosphonate in Et3N/DMF and coupled with L-glutamic acid dimethyl ester to give 15a-c. Finally, the basic hydrolysis of 15a-c yielded the desired 4-amino-7-oxo-substituted analogues 16a-c in 20-27% overall yield. Compounds 16a-c were tested in vitro against CCRF-CEM leukemia cells. The results obtained indicated that our 4-amino-7-oxo analogues are completely devoid of any activity, the IC50 being higher than 20 microg/mL for all cases except 14c for which a value of 6.7 microg/mL was obtained. These results seem to indicate that 16a-c are inactive precisely due to the presence of the carbonyl group in position C7, the distinctive feature of our synthetic methodology.

Topics: Antimetabolites, Antineoplastic; Antineoplastic Agents; Cell Survival; Drug Screening Assays, Antitumor; Folic Acid Antagonists; Humans; Structure-Activity Relationship; Tetrahydrofolates; Tumor Cells, Cultured

Prompted by recent disclosures concerning the potent antitumor activities of 5-deaza-5,6,7,8-tetrahydrofolic acid and 5,10-dideaza-5,6,7,8-tetrahydrofolic acid (DDATHF), we have prepared 5-deazaisofolic acid (3a) and 5-deaza-5,6,7,8-tetrahydroisofolic acid (4a). Reductive condensation of 2,6-diamino-3,4-dihydro-4- oxopyrido[2,3-d]pyrimidine with di-tert-butyl N-(4-formylbenzoyl)-L-glutamate and subsequent deprotection with trifluoroacetic acid yielded 5-deazaisofolic acid in good yield. Catalytic hydrogenation of this analogue then gave 4a. The 9-CH3 and 9-CHO modifications of 3a and the 9-CH3 derivative of 4a were also synthesized. Each of the new analogues was evaluated with a variety of folate-requiring enzymes as well as MCF-7 cells in culture. Compound 4a had an IC50 of ca. 1 microM against MCF-7 cells and was nearly 100-fold less potent than DDATHF in this regard. The three oxidized isofolate analogues were all poor inhibitors of tumor cell growth.

Topics: Animals; Antineoplastic Agents; Folic Acid; Folic Acid Antagonists; Humans; Structure-Activity Relationship; Swine; Tetrahydrofolates; Thymidylate Synthase