NMR characterization of the structure of a β-(1→3)-D-glucan isolate from cultured fruit bodies of Sparassis crispa

SCG, a purified beta-D-glucan, obtained from Sparassis crispa, exhibits various biological activities including an antitumor effect, enhancement of the hematopoietic response in cyclophosphamide-induced leukopenic mice, and induction of the production of cytokines. The mechanisms of these effects have been extensively investigated; however, an unambiguous structural characterization of SCG is yet to be achieved. It is well accepted that the biological effects of beta-glucan depend on its primary structures, conformation, and molecular weight. In the present study, we examine the difference of biological effects among beta-glucans, elucidate the primary structure of SCG, and compare with SPG from Schizophyllum commune using NMR spectroscopy. Our data reveal that SCG but not SPG induce cytokine production from bone marrow-derived dendritic cells (BMDCs) and their major structural units are a beta-(1 -> 3)-D-glucan backbone with single beta-(1 -> 6)-D-glucosyl side branching units every three residues. (c) 2007 Elsevier Ltd. All rights reserved.