Structural studies on -carrageenan derived oligosaccharides

Oligosaccharides were prepared through mild hydrochloric acid hydrolysis of -carrageenan from Kappaphycus striatum carrageenan. Three oligosaccharides were purified by strong-anion exchange high-performance chromatography. Their structure was elucidated using mass spectral and NMR data. Negative-ion electrospray ionization (ESI) mass spectra at different fragmentor voltages provided the molecular weight of the compounds and unraveled the fragmentation pattern of the -carrageenan oligosaccharides. 2D NMR techniques, including H–H COSY, H–H TOCSY and C–H HMQC, were performed to determine the structure of a trisulfated pentasaccharide. 1D NMR and ESIMS were used to determine the structures of a -carrageenan-derived pentasaccharide, heptasaccharide, and an undecasaccharide. All the oligosaccharides characterized have a 4-O-sulfo-D-galactopyranose residue at both the reducing and nonreducing ends. © 2002 Elsevier Science Ltd. All rights