Marine natural products and immune-acting substances, basic research of α-galactosylceramides

Abstract

 Marine organisms produce second metabolites with unique chemical structures because of their complexed symbiotic systems different from that of land organisms.

 Unique glycosphingolipids with α-galactosylceramide structure, agelasphins, were obtained from Okinawan marine sponge Agelas mauritianus by the in vivo antitumor substance screening system. Agelasphines and the developmental candidate, KRN7000 (α-GalCer), markedly showed antitumor activity against tumor bearing mouse by activating host's immune system. The discovery of agelasphins and the development of KRN7000 revealed the detail of NKT cell functions. Unfortunately, development of KRN7000 intended to the antitumor drug by the systemic injection was abandoned because of several limitations. Now it is strongly expected that agelasphin or its derivative to be developed as a novel immunomodulator by conquering the limitations.