Antitumor activity of polysaccharide TC-13 extracted from rare actinomycetes

The antitumor activities of mycelia and a hot-water extract of mycelia of rare actinomycetes were examined by three different antitumor assays in ddY mice with Ehrlich solid tumor. A new antitumor polysaccharide, TC-13, was prepared from the hot-water extract of Microellobosporia grisea by precipitation with cetylpyridinium chlorideborate complex and gel filtration. TC-13 was mainly composed of glucose and mannose with peptideglycan. Its molecular weight was determined to be 2-30 X 10(4) by gel filtration. Comparative studies suggested that the antitumor activity of TC-13 was equal to, or stronger than those of other antitumor agents (e.g., lentinan, PS-K, OK432 and yeast mannan). Screening methods for antitumor activity of actinomycetes were also discussed.