Toll-like receptor-8 agonistic activities in C2, C4, and C8 modified thiazolo[4,5-c]quinolines
作者:Hari Prasad Kokatla、Euna Yoo、Deepak B. Salunke、Diptesh Sil、Cameron F. Ng、Rajalakshmi Balakrishna、Subbalakshmi S. Malladi、Lauren M. Fox、Sunil A. David
DOI:10.1039/c2ob26705e
日期:——
Toll-like receptor (TLR)-8 agonists typified by the 2-alkylthiazolo[4,5-c]quinolin-4-amine (CL075) chemotype are uniquely potent in activating adaptive immune responses by inducing robust production of T helper 1-polarizing cytokines, suggesting that TLR8-active compounds could be promising candidate vaccine adjuvants, especially for neonatal vaccines. Alkylthiazoloquinolines with methyl, ethyl, propyl and butyl groups at C2 displayed comparable TLR8-agonistic potencies; activity diminished precipitously in the C2-pentyl compound, and higher homologues were inactive. The C2-butyl compound was unique in possessing substantial TLR7-agonistic activity. Analogues with branched alkyl groups at C2 displayed poor tolerance of terminal steric bulk. Virtually all modifications at C8 led to abrogation of agonistic activity. Alkylation on the C4-amine was not tolerated, whereas N-acyl analogues with short acyl groups (other than acetyl) retained TLR8 agonistic activity, but were substantially less water-soluble. Immunization in rabbits with a model subunit antigen adjuvanted with the lead C2-butyl thiazoloquinoline showed enhancements of antigen-specific antibody titers.
以2-烷基噻唑并[4,5-c]喹啉-4-胺(CL075)为化学类型的Toll样受体(TLR)-8激动剂,能独特地激活适应性免疫反应,通过诱导强大的T辅助1型细胞因子产生,表明TLR8激活化合物可能是有前景的候选疫苗佐剂,尤其是新生儿疫苗。在C2位带有甲基、乙基、丙基和丁基的烷基噻唑喹啉显示出相当的TLR8激动效力;C2戊基化合物的活性急剧下降,更高同系物则无活性。C2-丁基化合物独特地拥有显著的TLR7激动活性。在C2位带有支链烷基的类似物显示出对末端立体障碍的差耐受性。几乎所有在C8位的修饰都会导致激动活性的消除。C4-胺上的烷基化不被接受,而带有短酰基(除乙酰基外)的N-酰胺类似物保持了TLR8激动活性,但水溶性大大降低。用导联C2-丁基噻唑喹啉增强的模型亚单位抗原免疫兔子,显示出抗原特异性抗体滴度的增强。