Synthesis, NMR and Conformational Studies of Fucoidan Fragments. V.[1] Linear 4,4′,4″‐Tri‐O‐Sulfated and Parent Non‐sulfated (1→3)‐Fucotrioside Fragments

Abstract

Propyl 4,4′,4″‐tri‐O‐sulfated and non‐sulfated (1→3)‐α‐l‐fucotriosides which are related to fragments of natural fucoidans have been synthesized. Their spectral and conformational properties have been investigated by ¹H and ¹³C NMR, NOE and molecular modeling. Molecular mechanics calculations of the tri‐O‐sulfated compound as a trianion did not give agreement with the experimental NOE values, while the model with the non‐dissociated sulfo group on the non‐reducing end worked successfully. (1→3)‐Fucobioside fragments in both trisaccharides investigated were shown to have the same range of conformations as in previously described propyl (1→3)‐α‐l‐fucobiosides, but with the increase of the relative population of the conformer with the spatial proximity of H‐1′ and H‐4 in the case of non‐sulfated fucotrioside.

Keywords:

• Fucoidan fragments
• Synthesis
• NMR
• Conformational analysis
• NOE

Acknowledgments

This work was supported by GlycoSense AG (Jena, Germany), the Russian Foundation for Basic Research (grants 01‐03‐33059a, 01‐04‐48401a, 02‐03‐06588 and 02‐03‐06589) and Russian Academy of Sciences (grant 129‐6‐1999 for young researchers). We are grateful to Natalya S. Zlotina (Higher Chemical College, Moscow) for technical assistance. We thank Professor J. W. Ponder (Department of Biochemistry and Molecular Biophysics, School of Medicine, Washington University, St. Louis, Missouri, USA) for providing us with TINKER software.