Studies on analogs of classical antifolates bearing the naphthoyl group in place of benzoyl in the side chain

Abstract

Analogues of classical antifolates with the 4-aminobenzoyl group replaced by 4-amino-1-naphthoyl were synthesized for study after molecular modeling indicated ample spatial accommodation for the naphthalene ring and even larger groups in models based on reported X-ray crystallographic data describing the binding of methotrexate to human dihydrofolate reductase (DHFR). The side-chain precursors, N-(4-amino- and 4-(methylamino)-1-naphthoyl)-L-glutamic acid diethyl esters, were synthesized, and the 2,4-diamino-substituted heterocyclic groups were attached using several methods. Target compounds included naphthoyl analogues of aminopterin (AMT), methotrexate (MTX), 5-deazaAMT, 5-deazaMTX, 5-methyl-5-deazaAMT, 5-methyl-5-deazaMTX, and 5,8-dideazaAMT. A 5,6,7,8-tetrahydronaphthoyl analogue of 5-deazaAMT was also prepared. None of the naphthoyl analogues showed loss in binding to DHFR compared with the corresponding antifolate bearing the benzoyl group, thus confirming the anticipated bulk tolerance. Only the 5,6,7,8-tetrahydronaphthoyl analogue displayed reduced antifolate effects. Substrate activity toward folylpolyglutamate synthetase was, however, severely compromised. The naphthoyl compounds were transported into L1210 cells 3-6 times more readily than MTX, and despite apparently low levels of intracellular polyglutamylation, each compound was found to be significantly more potent than MTX in inhibiting tumor cell growth in vitro in three lines (L1210, HL60, and S180). The MTX, 5-methyl-5-deazaAMT, and 5-methyl-5-deazaMTX analogues were evaluated in vivo alongside MTX against E0771 mammary adenocarcinoma in mice. All three proved more effective than MTX in retarding the tumor growth. The naphthoyl analogue of 5-deazaAMT strongly inhibited DHFR from Pneumocystis carinii, Toxoplasma gondii, and rat liver giving IC50 (pM) values of 0.53, 2.1, and 1.6 respectively, but this compound did not inhibit in vitro growth of T. gondii, thus indicating lack of transport.

Lipophilic Antifolates as Agents against Opportunistic Infections. 1. Agents Superior to Trimetrexate and Piritrexim against Toxoplasma gondii and Pneumocystis carinii in in Vitro Evaluations

“…The procedure for the preparation of 2,4-diamino-5-methyl-6-[(1-naphthylthio)methyl]pyrido [2,3-d]pyrimidine (13c) is representative. A mixture of K2CO3 (3.88 g, 28.1 mmol of anhydrous powder) and 1-naphthalenethiol (4.50 g, 28.1 mmol) in Me2NAc (42 mL) was stirred at 20-23 °C for 2 h before pulverized 2 (3.70 g, 8.50 mmol as 2‚1.7HBr‚0.5AcOH 27,28 ) was added. The mixture was stirred under N2 in a stoppered flask for 24 h. The mixture, now containing solid 13c, was filtered, and the solid was washed on the funnel with a little Me2NAc.…”

“…Table 4 shows results on three 5-unsubstituted-5-deaza analogues (15a-c) and four quinazoline (5,8-dideaza) analogues (16a-d) along with side-by-side comparisons with side-chain analogues from the 5-methyl-5-deaza group. , [25][26][27][28] and 3, 27,28 the nitriles 4 25 and 5, 25 and the aldehyde 7. 27,30 2,4-Diaminoquinazoline-6-carbonitrile (6) was reported by Davoll and Johnson.…”

EO771, is it a well‐characterized cell line for mouse mammary cancer model? Limit and uncertainty

“…Thus, methotrexate, an antifolate, is tested in the mouse model of EO771 mammary cancer showing a sensitivity of this tumor to this drug. 92 This animal model is also tested for the development of a novel antifolate family as analogues of aminopterin 91,[93][94][95][96][97][98][99] whose antitumor activity is superior to methotrexate in EO771 tumor-bearing mice.…”

Synthesis and Pharmacological Evaluation of Novel GABAA Subtype Receptor Ligands with Potential Anxiolytic‐like and Anti‐hyperalgesic Effect

“…A suspension of 3‐carboxy‐7‐nitropyrazolo[5,1‐c][1,2,4]benzotriazine 5‐oxide 9 (0.350 mmol) in THF anhydrous (10 mL) was maintained at 0°C for 30 min, and then 0.1 mL of borane‐dimethylsulfide complex in THF was slowly added . The solution was gentle heated to reflux until the starting material disappeared and again cooled in an ice bath, added with 10 mL of methanol and stirred for 1 h. After, the solution was acidified with hydrochloride acid and was again refluxed for 30 min.…”