Synthesis and biological activity of hydroxylated analogs of RCAI-80

RCAI-80 is one of the ester analogs of KRN7000 (α-galactosylceramide). This compound released mainly T helper 2 (Th2) cytokines, such as IL-4 rather than T helper 1 (Th1) cytokines, such as IFNγ from the invariant natural killer T (iNKT) cells. In addition, it has been known that some of the hydroxylated derivatives of KRN7000 make the cytokine secretion bias to Th2 by decreasing the IFNγ production to almost zero. This time, the three compounds having these two characteristic properties, namely an ester group and also some extra hydroxy groups existing on the ester side chain and/or on the 2-acyloxy-3,4-dihydroxyoctadecyl main chain of RCAI-80, were synthesized to examine the biological activities. As a result, it was found that these compounds made the cytokine secretion skew to Th2. Therefore, their effectiveness for experimental autoimmune encephalomyelitis (EAE) was examined. It was recognized that one of them showed moderate suppression of EAE symptom.