New glycolipids (chitooligosaccharide derivatives) possessing immunostimulating and antitumor activities

New glycolipids, derived from chitooligosaccharides of dp 2-4 and containing both free and acylated amino groups, were synthesized. The structure of the key compounds (di-, tri-, and tetra-saccharides acylated with different fatty acids) were elucidated by 13C NMR spectroscopy. Only the amino group of the reducing end of the chitooligosaccharides was found to be acylated when equimolecular amounts of reagents were used. The compounds obtained were shown to possess a low toxicity and certain immunostimulatory and antitumor activities. An induction of interleukin-1 and tumor necrosis factor by the immunocompetent cells and an augmentation by 140-180% of the mean life of mice with the Erlich carcinoma were observed.