Structure, fluorescence quenching and antioxidant activity of a carbohydrate polymer from Eugenia jambolana.

Natural products provide an excellent source for novel antioxidants. Herein, we have studied the water-extracted carbohydrate polymer (WE) of Eugenia jambolana using chemical, chromatographic, and spectroscopic methods. A 116 kDa arabinogalactan containing p-coumaric and ferulic acids in monomeric and dimeric forms has been isolated. Cellulase generated oligomeric fragments containing ester linked phenolic acids were also characterized. The antioxidant capacity of this carbohydrate polymer is comparable to butylated hydroxy anisole and butylated hydroxy toluene. Interaction of WE with bovine serum albumin (BSA) was studied by fluorescence quenching measurement. Conformational change of BSA at high carbohydrate polymer concentration was indicated.