Physicochemical Properties and Antitumor Activities of Chemically Modified Derivatives of Antitumor Glucan "Grifolan LE" from Grifola frondosa

Abstract

Antitumor glucan, grifolan LE (GRN LE), from Grifola frondosa was chemically modified to examine the structure-function relationship of the products. Modification by periodate, borohydride and acid hydrolysis of side chains of GRN LE did not alter properties such as helical conformation and antitumor activity of GRN LE. Introduction of carboxylic acid groups into the side chains by oxidation with periodate and with sodium chlorite (GRN LE-PC), and substitution with carboxymethyl (CM) or hydroxyethyl (HE) groups abolished the gel-forming ability of GRN LE.Significant antitumor activity was observed in all of the derivtives having gel-forming ability as well as some derivatives having no such ability. These results suggested that essential factors required for antitumor activity were (1→3)-β-D-glucosy linkages and high molecular weight, and that accessory groups could be linked to the main chain without loss of antitumor activity in a higher ratio than that of gel-forming ability.