Antitumor glycogen from scallops and the interrelationship of structure and antitumor activity

Hot water extract of scallop was treated with actinase E and fractionated b y Sephadex G-25 gel-filtration and DEAE Sephadex A-25 ion-exchange chromato graphy. The antitumor activity of these fractions against Meth-A fibrosarco ma was examined. The nonadsorbed fraction (SCA25A) and weakly adsorbed frac tion (SCA25B) obtained on DEAE Sephadex A-25 anion-exchange gel showed stro ng antitumor activity. Chemical analyses and NMR spectra identified SCA25A and SCA25B as glycogen. However, glycogen extracted from the scallop with t richloroacetic acid and from abalone showed no antitumor activity. This dif ference was thought to be due to variations in the fine structure of the gl ycogen molecule. The fine structure of glycogen was investigated by a seque ntial enzyme digestion method using P-amylase and pullulanase, while the un it chain was analyzed by high performance anion exchange chromatography. Th e results showed that the antitumor active glycogen was highly branched wit h a shorter chain than glycogens without antitumor activity.