A series of N1-modified imidazoquinolines were synthesized and screened for Toll-like receptors (TLR) 7 and 8 activities to identify recognition elements that confer high affinity binding and selectivity. These receptors are key targets in the development of immunomodulatory agents that signal the NF-κB mediated transcription of pro-inflammatory chemokines and cytokines. Results are presented showing both TLR7/8 activations are highly correlated to N1-substitution, with TLR8 selectivity achieved through inclusion of an ethyl-, propyl-, or butylamino group at this position. While the structure–activity relationship analysis indicates TLR7 activity is less sensitive to N1-modification, extension of the aminoalkyl chain length to pentyl and p-methylbenzyl elicited high affinity TLR7 binding. Cytokine profiles are also reported that show the pure TLR8 agonist [4-amino-2-butyl-1-(2-aminoethyl)-7-methoxycarbonyl-1H-imidazo[4,5-c]quinoline] induces higher levels of IL-1β, IL-12, and IFNγ when compared with TLR7 selective or mixed TLR7/8 agonists. The results are consistent with previous work suggesting TLR8 agonists are Th1 polarizing and may help promote cell-mediated immunity.

中文翻译：

---

N1修饰的咪唑并喹啉激动剂的设计与合成，以选择性激活Toll样受体7和8

合成了一系列N1修饰的咪唑并喹啉，并筛选了Toll样受体（TLR）7和8的活性，以识别赋予高亲和力结合和选择性的识别元件。这些受体是免疫调节剂开发中的关键靶标，这些信号指示NF-κB介导的促炎性趋化因子和细胞因子的转录。结果表明，TLR7 / 8活化与N1-取代高度相关，TLR8选择性是通过在该位置包含乙基，丙基或丁基氨基来实现的。虽然结构-活性关系分析表明TLR7活性对N1-修饰不那么敏感，但氨基烷基链长度扩展到戊基和p-甲基苄基引起高亲和力的TLR7结合。还报道了细胞因子谱，表明纯的TLR8激动剂[4-氨基-2-丁基-1-（2-氨基乙基）-7-甲氧基羰基-1 H-咪唑[4,5- c ]喹啉]诱导更高水平的IL与TLR7选择性或混合TLR7 / 8激动剂相比，-1β，IL-12和IFNγ。该结果与先前的研究结果一致，表明TLR8激动剂具有Th1极化作用，可能有助于促进细胞介导的免疫力。