A HIGHLY SULFATED PYRANOSIC (1→3)- β- L ARABINAN WITH ANTICOAGULANT ACTIVITY. MECHANISM OF ACTION

CIANCIA, MARINA; FERNÁNDEZ, PAULA VIRGINIA; QUINTANA, I.L.; CEREZO, ALBERTO S.; ESTEVEZ, JOSÉ MANUEL

Sorrento

Simposio; 16th European Carbohydrate Symposium; 2011

University of Naples Federico II

The room temperature water extract obtined from grenn seaweed Codium  vermilara  was fractionated by addition of KCl  to give solutions of  increasing concentrations of  this salt. Only one insoluble product was obtained at 0.115 M  (Ab)  in 31% yield, which contained 97% of L-arabinose, a sulfate/arabinose molar ratio of 1.8/1, an [α]D = + 167.5 º, and a number average molecular weight of 180 KDa. Methylation analysis of Ab and its desulfated derivative (DAb) showed that this polysaccharide is mainly constituted by 3-linked 2,4-disulfated arabinopyranosyl residues, although some mono- and non-sulfated units are also present. Analysis of the corresponding NMR spectra confirmed this structure and showed that these units are in β- configuration. This product showed a high anticoagulant activity, but lower than that of heparin, as 5 and 0.65 mg/ml, respectively were necessary  to  increase  the clotting  time  in APTT assay  in 2.5  times. The coagulation mechanism is in part through the direct inhibition of thrombin, althoughinhibition of thrombin by potentiation of antithrombin and heparin cofactor II was also found by amydolitic methods.In  conclusion, a highly  sulfated pyranosic β L arabinan was  isolated  from  the  cell walls of a green seaweed. It showed anticoagulant behaviour by a mechanism different to that of heparin. To the best of our knowledge, this is the first report in nature of a polysaccharide constitutedonly by arabinose residues in the pyranosic form.