Abstract:

The present study aimed to isolate and purify polysaccharides (TPS) from taro (Colocasia esculenta). The
chemical characteristics and immunoregulatory property of purified fractions were explored. The crude TPS was extracted
with hot water and then subjected to protein removal by the enzymatic-assisted Sevag method. TPS obtained after dialysis
and freeze-drying underwent further purification by DEAE-52 and Sephadex G-75 column chromatography and three
homogeneous components were obtained. The purity and chemical composition were determined by UV spectroscopy and
HPLC and by gas chromatography (GC), respectively. The viability of mouse spleen cells treated with TPS fraction was
determined by MTT assay and the activation of peritoneal macrophages were analyzed by neutral red phagocytosis assay.
The results showed that TPS contained 95.21% carbohydrate. Three fractions TPS1p, TPS2p1 and TPS3p2 were obtained after
separation and purification. Data from UV spectroscopy and HPLC analysis revealed that TPS1p and TPS2p1 were two
types of homogeneous polysaccharides while TPS3p2 might be a glycoprotein. All the three homogeneous polysaccharides
were made of arabinose, mannose, glucose and galactose as demonstrated by GC analysis. The MTT assays showed
that at the doses of 25, 50 μg/mL and 100 μg/mL, TPS1p could function synergistically with ConA to promote the cell
proliferation of spleen lymphocytes in normal mice, while this synergy was also observed for TPS2p1 only at 100 μg/mL
and TPS3p2 at 50 μg/mL and 100 μg/mL. Meanwhile, TPS1p at varying doses could markedly improve the phagocytotic
capacity of macrophages in mice. At 50 μg/mL, TPS2p1 and TPS3p2 also showed this activity.

Key words: Colocasla antiquorum, polysaccharides, separation, purification, immunity regulation