Structural Characteristics and in vitro Antitumor Activity of Water-Soluble Polysaccharides from Brown Algae of the Russian Far East and Vietnam

Abstract

Laminarans and fucoidans from two Russian Far-East (Desmarestia viridis and Dictyota dichotoma) and four Vietnam species (Dictyota divaricata, Padina boryana, Sargassum duplicatum, and S. feldmannii) of brown algae were isolated and studied. Water-soluble polysaccharides from D. divaricata, P. boryana, and S. feldmannii were mainly fucoidans; from D. viridis, D. dichotoma, and S. duplicatum, approximately equal amounts of laminarans and fucoidans. All studied laminarans had a main chain of 1,3-bonded glucose residues with branching on C-6 with various ratios of 1,3:1,6 bonds. Fucoidans from D. viridis and D. dichotoma were medium- and low-sulfated heterogeneous polysaccharides; from D. divaricata, P. boryana, S. duplicatum, and S. feldmannii, sulfated galactofucans containing traces of mannose, xylose, and glucose. Galactofucans from D. divaricata, P. boryana, S. duplicatum, and S. feldmannii were not cytotoxic and exhibited antitumor activity against DLD-1 human colon carcinoma cells.