RCAI-8, 9, 18, 19, and 49–52, conformationally restricted analogues of KRN7000 with an azetidine or a pyrrolidine ring: Their synthesis and bioactivity for mouse natural killer T cells to produce cytokines Original Research Article

Conformationally restricted analogues of KRN7000, an α-d-galactosyl ceramide, were synthesized to examine their bioactivity for mouse natural killer (NK) T cells to produce cytokines. RCAI-8, 9, 51, and 52 are the analogues with a pyrrolidine ring, and RCAI-18, 19, 49, and 50 are those with an azetidine ring. RCAI-18 was shown to be a potent inducer of cytokine production by mouse NKT cells, while RCAI-51 was a moderately active inducer.