Abstract

Blades of Lessonia vadosa (Phaeophyta) were extracted with 2% CaCl2 solution, affording in 4.4% yield a polysaccharide which contained fucose and sulfate groups in the molar ratio 1.0:1.12. The high negative optical activity value ([ α ]D 22 = -134.0°), FT-IR and NMR analysis suggest the presence of a fucoidan. 13C NMR spectrum of the polysaccharide obtained by solvolytic desulfation of native fucoidan indicated the major presence of 1 → 3 linked α-l-fucan. Depolymerization of the native fucoidan with H2O2 in the presence of copper(II) acetate gave in 54.8% yield a fraction with 33.7% of sulfate content. The native fucoidan (MW 320,000) showed good anticoagulant activity whereas the radical depolymerized fraction (MW 32,000) presented a weak anticoagulant activity. These polysaccharides showed significant activation of phenylalanine-ammonia lyase (PAL), lipooxygenase (LOX) and glutathione-S-transferase (GST) defence enzyme activities in tobacco plants. © 2007 Elsevier B.V. All rights reserved.