Structural characterisation and antimutagenic activity of a novel polysaccharide isolated from Sepiella maindroni ink

A new heteropolysaccharide, named as SIP, was isolated from the ink of cuttlefish, Sepiella maindroni, by enzymolysis, anion-exchange and gel-permeation chromatography and tested for its antimutagenic activity. It was homogeneous with a molecular weight of 1.13×10(4)Da by HPSEC-MALLS analysis. SIP contained glucuronic acid, mannose, N-acetylgalactosamine, and fucose in a molar ratio of 1:1:2:2. Its structural characteristics were investigated and elucidated by methylation analysis, GLC-MS, and NMR ((1)H, (13)C, H-H COSY, HMQC, HMBC, TOCSY and NOESY). The hexasaccharide repeating unit of SIP was found to be a backbone composed of fucose, N-acetylgalactosamine and mannose in a molar ratio of 2:2:1, and with a single branch of glucuronic acid at the C-3 position of mannose. According to the micronucleus test, SIP could significantly reduce the frequency of micronucleated cells in polychromatic erythrocytes and reticulocytes induced by cyclophosphamide in tumor-bearing mice, which revealed that SIP presented strong antimutagenic activity.