ISOLATION AND CHARACTERIZATION OF A NEW ANTITUMOR POLYSACCHARIDE, KS-2, EXTRACTED FROM CULTURE MYCELIA OF LENTINUS EDODES

Abstract

A new antitumor and antiviral substance, KS-2, was prepared by ethanol precipitation
of the hot water extract of culture mycelia of Lentinus edodes KSLE 007. It was further
purified by ECTEOLA-cellulose and Sephadex G-100 column chromatography based on the interferon-inducing activity. Its homogeneity was revealed by CsCl density gradient centrifugation, electrophoresis on cellulose acetate and Sephadex G-100 and ECTEOLA-cellulose column chromatography. KS-2 is mainly composed of α-linked mannose and contains a small amount of peptide which consists of serine, threonine and alanine with residual amounts of the other amino acids. The estimated molecular weight of KS-2 is between 6.0×10⁴ and 9.5×10⁴. KS-2 suppressed the growth of EHRLICH as well as Sarcoma-180 tumors in mice when given either orally or intraperitoneally. It is also capable of inducing an interferon in mice when dosed orally or intraperitoneally. The acute LD₅₀ of KS-2 was found to be extremely low, more than 12, 500 mg/kg when administered orally to mice.