Reitz A B, Goodman M G, Pope B L, Argentieri D C, Bell S C, Burr L E, Chourmouzis E, Come J, Goodman J H, Klaubert D H
Medicinal Chemistry Department, R. W. Johnson Pharmaceutical Research Institute, Spring House, Pennsylvania 19477.
J Med Chem. 1994 Oct 14;37(21):3561-78. doi: 10.1021/jm00047a014.
A series of 7,8-disubstituted guanosine derivatives was designed and prepared as potential B-cell-selective activators of the humoral immune response. These compounds were evaluated for their ability to act as B-cell mitogens and to augment the antibody response of B cells to sheep red blood cell (SRBC) challenge (adjuvanticity). In addition, they were tested for their ability to stimulate the natural killer (NK) cell response in murine in vitro cell assays. Certain of the compounds demonstrated in vivo activity when administered either intravenously, subcutaneously, or orally. Analogues with a medium-length alkyl chain (2-4 carbons, 5-7) on the 7-position of 7-alkyl-8-oxoguanosines were found to be particularly potent. Compounds bearing hydroxyalkyl, aminoalkyl, or substituted aminoalkyl substituents on this 7-position were weakly active. However, benzyl groups, including those substituted with heteroatoms (e.g., p-nitrobenzyl, 14), were active. Oxo, thioxo, and seleno groups on C-8 of the guanosine ring all imparted strong activity, whereas other larger substituents did not (e.g., N = CN). Stereochemical inversion of the 2'-hydroxyl on the ribose ring in this series, giving arabinose analogue 70, lessened activity. However, removal of the 2'-hydroxyl, either with (64) or without (73) removal of the 3'-hydroxyl, resulted in excellent activity and improved solubility; 64 also displayed good oral in vivo activity as well. A series of ketals involving the 2',3'-hydroxyls were prepared; certain of the nonpolar ketals (e.g., 48) were remarkably active, pointing to an ancillary hydrophobic binding region that can augment activity. 5'-Phosphate derivative 57 was fairly active, and acyclovir analogue 90 displayed good NK-selective activity: other N-9 sugar mimetics were also active (97-104), although this activity did not carry over into the human B-cell assay. A total of 80 compounds were prepared and evaluated for their immunostimulating activity. Within this group, compounds could be divided into those that were active in all three assays, those that displayed some measure of selectivity for the adjuvanticity assay, and those that preferentially activated NK responses. Because of its overall biological profile and ease of synthesis, 7-allyl-8-oxoguanosine (6; loxoribine, RWJ-21757) was chosen for further development. It is among the most potent compounds evaluated in the three biological assays.
设计并制备了一系列7,8-二取代鸟苷衍生物，作为体液免疫反应潜在的B细胞选择性激活剂。评估了这些化合物作为B细胞促有丝分裂原的能力，以及增强B细胞对绵羊红细胞（SRBC）攻击的抗体反应（佐剂活性）的能力。此外，还在小鼠体外细胞试验中测试了它们刺激自然杀伤（NK）细胞反应的能力。某些化合物经静脉、皮下或口服给药后表现出体内活性。发现7-烷基-8-氧代鸟苷7位上具有中等长度烷基链（2-4个碳，5-7）的类似物特别有效。在该7位上带有羟烷基、氨烷基或取代氨烷基取代基的化合物活性较弱。然而，苄基，包括那些被杂原子取代的苄基（例如对硝基苄基，14），具有活性。鸟苷环C-8上的氧代、硫代和硒代基团均赋予强活性，而其他较大的取代基则没有（例如N = CN）。该系列中核糖环上2'-羟基的立体化学翻转，得到阿拉伯糖类似物70，活性降低。然而，去除2'-羟基，无论是否同时去除3'-羟基（分别为64和73），都产生了优异的活性并提高了溶解度；64在体内口服时也表现出良好的活性。制备了一系列涉及2',3'-羟基的缩酮；某些非极性缩酮（例如48）具有显著活性，表明存在一个可以增强活性的辅助疏水结合区域。5'-磷酸衍生物57活性相当高，阿昔洛韦类似物90表现出良好的NK选择性活性：其他N-9糖模拟物也有活性（97-104），尽管这种活性在人B细胞试验中未得到体现。总共制备了80种化合物，并评估了它们的免疫刺激活性。在这一组化合物中，可分为在所有三种试验中均有活性的化合物、对佐剂活性试验表现出一定选择性的化合物以及优先激活NK反应的化合物。由于其整体生物学特性和易于合成，7-烯丙基-8-氧代鸟苷（6；洛索立宾，RWJ-21757）被选择进行进一步开发。它是在这三种生物学试验中评估的最有效化合物之一。
