TY - JOUR
T1 - Toll-like receptor-8 agonistic activities in C2, C4, and C8 modified thiazolo[4,5-c]quinolines
AU - Kokatla, Hari Prasad
AU - Yoo, Euna
AU - Salunke, Deepak B.
AU - Sil, Diptesh
AU - Ng, Cameron F.
AU - Balakrishna, Rajalakshmi
AU - Malladi, Subbalakshmi S.
AU - Fox, Lauren M.
AU - David, Sunil A.
PY - 2013/2/21
Y1 - 2013/2/21
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=84873398735&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84873398735&partnerID=8YFLogxK
U2 - 10.1039/c2ob26705e
DO - 10.1039/c2ob26705e
M3 - Article
C2 - 23314908
AN - SCOPUS:84873398735
SN - 1477-0520
VL - 11
SP - 1179
EP - 1198
JO - Organic and Biomolecular Chemistry
JF - Organic and Biomolecular Chemistry
IS - 7
ER -