Antioxidant and antiproliferative activities of polysaccharide fractions from litchi pulp.

Three litchi polysaccharide fractions (LPFs), LP-4, LP-6 and LP-8, were obtained by fractional precipitation using 40%, 60% and 80% ethanol, respectively. The physicochemical properties, chemical antioxidant, and cellular antioxidant and antiproliferative activities of the three polysaccharide fractions were compared. LP-6 contained the highest contents of uronic acid and binding protein among the three fractions, whereas LP-8 contained the least. Amino acid composition analysis of the binding protein revealed that LP-6 contained the most acidic and aromatic amino acids. However, LP-8 contained more galactose and mannose than LP-4 and LP-6. LP-6 exhibited the highest chemical antioxidant activities, with an oxygen radical absorbance capacity of 28.14 μmol TE per g DW. LP-8 exhibited higher cellular antioxidant activity and a greater inhibitory effect on the proliferation of A549, HepG2 and MGC-803 cells at a concentration of 100-800 μg mL(-1) than LP-4 and LP-6. In summary, the different LPFs exhibited different antioxidant and antiproliferative activities with differential physicochemical properties.