ISOLATION AND ANALYSIS OF A NOVEL ACIDIC POLYSACCHARIDE WITH GLUCOKINASE-STIMULATING ACTIVITY FROM COARSE GREEN TEA

Water‐soluble polysaccharides from coarse green tea were separated by anion‐exchange chromatography into five fractions (fraction A FA], fraction B, fraction C FC], fraction D and fraction E). Two of these fractions, FA and FC, contained significant glucokinase‐stimulating activity (P < 0.05). The major component, FC, showed the most activity, and thus, was further purified by gel filtration chromatography, thereby obtaining fraction C‐1 (FC‐1) and fraction C‐2 (FC‐2). The biological activity of the two fractions was investigated, and FC‐1 displayed higher glucokinase‐stimulating activity (P < 0.01). Chemical tests combined with IR and UV spectroscopy revealed that FC‐1 is an acidic polysaccharide without conjugation to protein. Sugars of FC‐1 are composed of rhamnose, arabinose, mannose, glucose and galactose in the ratio of 12.57:22.95:4.4:39.34:20.77. Uronic acid analysis by ion chromatography showed that FC‐1 contains 8% galacturonic acid, and its molecular weight was estimated to be approximately 6 × 10⁴ using a Sephacryl S200 column. These results are different from the observations previously reported, therefore suggesting that FC‐1 is a novel polysaccharide.