Preparation, structure and anticoagulant activity of a low molecular weight fraction produced by mild acid hydrolysis of sulfated rhamnan from Monostroma latissimum

A low molecular weight fraction, designated LMWP, was prepared by mild acid hydrolysis of sulfated rhamnan from Monostroma latissimum and purified by anion-exchange and gel-permeation chromatography. Chemical and spectroscopic analyses showed that LMWP was mainly composed of rhamnose, and its molecular weight was about 33.6 kDa. The backbone of LMWP consists of 1,3-linked α-l-rhamnose units with partially sulfate groups at the C-2 position. Approximately 25% of 1,3-linked α-l-rhamnose units is substituted at C-2 by sulfated or non-sulfated 1,3-linked α-l-rhamnose and 1,2-linked α-l-rhamnose units. LMWP effectively prolonged clotting time as evaluated by the activated partial thromboplastin time assay and was a potent thrombin inhibitor mediated by heparin cofactor II. The investigation demonstrated that LMWP is a novel sulfated polysaccharide with anticoagulant activity.