RCAI-84, 91, and 105-108, ureido and thioureido analogs of KRN7000: Their synthesis and bioactivity for mouse lymphocytes to produce Th1-biased cytokines

RCAI-84, 91, and 105-108 (1–6), the analogs of KRN7000 (A) with a ureido or a thioureido linkage instead of a carboxamido bond, were synthesized to examine their immunostimulatory activity against mouse lymphocytes. According to their bioassay, the ureido analog of KRN7000 [RCAI-105 (1)] and its 6′-O-methylated derivative [RCAI-106 (4)] induced a large amount of IFN-γ in mice in vivo. The hexadecyl ureido analog [RCAI-84 (2)] was comparable to KRN7000 in its bioactivity. The octylureido [RCAI-107 (3)], 5-phenylpentylureido [RCAI-108 (5)], and thioureido [RCAI-91 (6)] analogs were almost inactive.

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