ANTITUMOR-ACTIVITY OF CELL-WALL BETA-1,3 1,6-GLUCANS FROM PHYTOPHTHORA SPECIES/

From the cell walls of various Phytophthora species (Oomycetes) differ ent water-soluble beta-1,3/1,6-glucans were isolated and characterized . The glucans with relative molecular masses between 13 and 50 kd exhi bited varying degrees of branching in the beta-1,3-linked glucan backb one ranging from 14 to 50%. The dose-dependent antitumor activity of t he glucans against allogeneic sarcoma-180 was investigated. It could b e demonstrated that beta-1,3/1,6-glucans with relative molecular masse s below 50 kd can exhibit a prominent antitumor activity (inhibition r ate up to 99%), being comparable to that of the high relative molecula r mass (450 kd) beta-1,3/1,6-glucans. Biological activity of the gluca ns could be shown to be correlated with a low degree of branching. The most potent glucan with a degree of branching of 14% also was active against the syngeneic DBA/2-MC.SC-1 fibrosarcoma (inhibition rate up t o 90%) and in combination with a suboptimum dose of diethylstilbestrol against Noble-Nb prostate carcinoma (inhibition rate up to 90%).