Biological activities of chemically-treated glycolipids from Salmonella minnesota Re-mutant

Endotoxic glycolipid (ReGl) extracted from the heptose-less Re mutant of Salmonella minnesota was hydrolyzed with each of alkali or acid reagents, and the products were analyzed for several biological activities. Treatment of ReGl with NH2OH caused the liberation of all O-ester-linked fatty acids resulting in abrogation of toxicity (lethality to chick embryos), pyrogenicity, activity of Limulus amoebocyte lysate (LAL) gelation, ability of macrophage activation, and mitogenicity. ReGl treated with HCl, which splits off KDO and glycosidic phosphate, retained only two biological activities (LAL gelation activity and ability of macrophage activation). NaOH-treated or CH3COONa-treated ReGl possessed similar activities to those of untreated ReGl. On the other hand, ReGl or ReGl-HCl, in combination with cord factor, showed effectively regressive activities (about 50% cures) to the methylcholanthrene-induced tumor of rats, while ReGl-NH2OH showed only prolongation of life in comparison with that of tumor-bearing rats without treatment.