The present invention relates to the preparation of novel polysaccharide derivatives containing double bonds at the 4- and 5-positions of the pyranose ring. The preparation method consists of the oxidation of the 6-position OH group to an aldehyde followed by the elimination of the 4- and 5-position double bonds —C═C— and the original alcohol of the last 6-position aldehyde group. Consisting of a reduction to The polysaccharide derivatives prepared according to the present invention show enhanced antioxidant activity, some of which also have a selective adverse effect on cancer cell viability. (Wherein R represents —NH—CO—CH 3 or —OH)本発明はピラノース環の４位及び５位に二重結合を含む新規な多糖誘導体の調製に関する。該調整法は，６位のＯＨ基のアルデヒドへの酸化と，それに続く４位及び５位の二重結合－Ｃ＝Ｃ－を生じる脱離，そして最後の６位のアルデヒド基の元のアルコールへの還元からなる。本発明により調製される多糖の誘導体は，増強された抗酸化活性を示し，それらのいくつかはがん細胞の生存率に対して選択的な悪影響をも示す。（式中，Ｒは－ＮＨ－ＣＯ－ＣＨ３又は－ＯＨを表す）
