Methotrexate analogues. 19. Replacement of the glutamate side chain in classical antifolates by L-homocysteic acid and L-cysteic acid: effect on enzyme inhibition and antitumor activity.
Methotrexate analogues. 19. Replacement of the glutamate side chain in classical antifolates by L-homocysteic acid and L-cysteic acid: effect on enzyme inhibition and antitumor activity.
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甲氨蝶呤类似物。
DOI：
10.1021/jm00371a008
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发表时间：
1984
影响因子：
7.3
通讯作者：
Wick,M
中科院分区：
文献类型：
--
作者：
Rosowsky,A;Forsch,RA;Freisheim,JH;Moran,RG;Wick,M
合成了甲氨蝶呤（MTX）和氨基蝶呤（AMT）类似物，它们分别含有L-同型半胱氨酸或L-半胱氨酸替代L-谷氨酸，并作为L1210细胞二氢叶酸还原酶和小鼠肝脏叶酰聚谷氨酸合成酶的抑制剂进行了实验。MTX和AMT类似物对二氢叶酸还原酶的ID50相当（0.04 - 0.07 µ），而AMT类似物对叶酰聚谷氨酸合成酶的IDW（40 - 60 µ）比MTX类似物（100 - 200 µ）低3 - 4倍。因此，N10-取代比二氢叶酸还原酶对与叶酰聚谷氨酸合成酶的结合具有更大的影响。这些化合物的细胞毒性在体外对L1210细胞进行了测定，AMT类似物再次证明比MTX类似物（ID50 = 0.1 - 0.4 µ）更有效（ID60 = 0.03 - 0.05 µ）。在体内观察到AMT类似物对L1210白血病的类似增加的效力。虽然不能排除差异细胞摄取是增加效力的基础，但AMT类似物的部分活性可能涉及干扰还原叶酸辅因子的细胞内多谷氨酸化，即它们是"自我增强抗叶酸剂"。在所报道的四种化合物中，活性最高的是N-（4-氨基-4-脱氧蝶酰基）-L-同型半胱氨酸，当以2 mg/kg的剂量按改良的bid × 10方案给药时，其使L1210白血病小鼠的寿命（ILS）增加138%。AMT本身在0.24 mg/kg时获得了相当的ILS。因此，用7-SO3H取代侧链中的-O 2不会降低治疗效果。然而，需要更高的剂量，可能是为了抵消反映磺酸盐基团不能被聚谷氨酸化的药理学差异。(AMT)我们感兴趣的是制备和评价其中谷氨酸部分的7-羧基被另一个酸性基团取代的化合物的生物活性。用SO3H代替CO2H似乎是有吸引力的，因为L-高半胱氨酸容易获得。我们对这种结构修饰的基本原理是，它将产生不能在细胞内形成聚谷氨酸缀合物的类似物，同时保留对二氢叶酸还原酶的良好亲和力。MTX和其他经典抗叶酸剂的多聚谷氨酸化已广泛应用于临床。
Methotrexate (MTX) and aminopterin (AMT) analogues containing L-homocysteic acid or L-cysteic acid in place of L-glutamicacid were synthesized and tested as inhibitors of dihydrofolate reductase from L1210 cells and folyl polyglutamate synthetase from mouse liver. The ID50 against dihydrofolate reductase was comparable for the MTX and AMT analogues (0.04-0.07 µ), whereas the IDW against folyl polyglutamatesynthetase was 3-to 4-fold lower for the AMT analogues (40-60 µ) than for the MTX analogues (100-200 µ). Thus, N10-substitution has a greater effect on binding to folyl polyglutamate synthetase than dihydrofolate reductase. The cytotoxicity of these compounds was assayed in vitro against L1210 cells, and the AMT analogues again proved more potent (ID60= 0.03-0.05 µ) than the MTX analogues (ID50= 0.1-0.4 µ). A similarly increased potency was observed for the AMT analogues against L1210 leukemia in vivo. Though differential cell uptake cannot be ruled out as the basis of increased potency, it is possible that part of the activity of the AMT analogues involves interference with the intracellular polyglutamation of reduced folate cofactors, ie, that they are “self-potentiating antifolates”. Of the four compounds reported, the most active was N-(4-amino-4-deoxypteroyl)-L-homocysteic acid, which produced a 138% increase in life span (ILS) in L1210 leukemic mice when given on a modified bid X 10 scheduleat a dose of 2 mg/kg. A comparable ILS was obtained with AMT itself at 0.24 mg/kg. Thus, replacement of-0 2 by 7-SO3H in the side chain does not decrease therapeutic effect. However, a higher dose is required, presumably to offset pharmacological differences reflecting the inability of the sulfonate group to be polyglutamated.(AMT), 1" 4 we were interested in preparing and evaluating the biological activity of compounds in which the 7-carboxyl of the glutamate moiety is replaced by another acidic group. Replacement of C02H by S03H seemed attractive because of the ready availability of L-homocysteic acid. Our rationale for this structural modification was that it would yield analogues that are incapable of forming po-lyglutamate conjugates inside the cell, whileretaining a good affinity fordihydrofolate reductase. Polyglutamation of MTX and other classical antifolates has become widely