Effects of intrinsic metal ions of lentinan with different molecular weights from Lentinus edodes on the antioxidant capacity and activity against proliferation of cancer cells.

In this study, effects of intrinsic metal ions in lentinan on its bioactivities were evaluated. Lentinan extracted from Lentinus edodes was separated to four fractions with different molecular weights with Sephadex G-200 gel chromatography, and intrinsic metal ions were removed by EDTA. The ferrous ion chelating capacity of ELWs was measured to estimate EDTA residue after extensive dialysis. Antioxidant and antitumor activities of the isolated lentinans (LWs and ELWs) were investigated in vitro and compared, respectively. The results indicated that all of the isolated lentinan contained a large amount of intrinsic metal ions and the fraction with the lowest Mw had highest metal content. After removing intrinsic metal ions, the polysaccharides showed lower ABTS and DPPH radicals scavenging capacity and the reduced inhibition of the proliferation of BXPC-3 and Hela cells. Our results indicated that the metal ions in lentinan had positive effects on its bioactivities.