PREPARATION AND PROPERTIES OF POLYSACCHARIDE–LIPID COMPLEXES FROM SERRATIA MARCESCENS

Abstract

Several polysaccharide fractions possessing pronounced antitumor activity were isolated from the polysaccharide–lipid–protein complex elaborated by Serratia marcescens. These fractions were obtained after phenol extraction of the cellular material, by ultracentrifugation and precipitation with ethanol and Cetavlon. They contained glucose, mannose, rhamnose, glucosamine, glucuronic acid, and mannuronic acid in different proportions. Each representative fraction caused regression of well-established solid tumors in mice but the dosage requirements varied considerably. One fraction containing glucose, mannose, and glucosamine, but no uronic acids, and having a high solubility in dilute sodium chloride solution and in aqueous acetone, was an exceptionally potent antitumor agent. Another fraction containing galactose and arabinose in addition to several of the usual components was found to be least active. From this work and that of other investigators, it is apparent that Serratia marcescens produces a spectrum of polysaccharides and lipopolysaccharides, the chemical composition and biological properties of which depend on the strain of organism, the culture conditions, and the methods employed for isolation of the active agents.