Synthesis and antitumour activity of sulfoalkyl derivatives of curdlan and lichenan.

2-Sulfoethyl, 3-sulfopropyl, and 4-sulfobutyl derivatives of the (1----3)-beta-D-glucan curdlan and the (1----3/1----4)-beta-D-glucan lichenan have been synthesised. The substituents are located mainly at positions 6. The curdlan derivatives strongly inhibited the growth of the Sarcoma 180 tumour, whereas the lichenan derivatives were inactive, indicating that a (1----3)-linked beta-D-glucan backbone is essential for activity.