Composition Analysis and Immunomodulatory Capacity of Peptidoglycan from Ling Zhi or Reishi Medicinal Mushroom, Ganoderma lucidum (W. Curt.: Fr.) P. Karst. Strain 119 (Aphyllophoromycetideae)

Abstract

LZ-B-1, a water-soluble peptidoglycan, was prepared from the fruiting bodies of Ling Zhi or Reishi medicinal mushroom, Ganoderma lucidum, by ultrafi ltration, DEAE-Sepharose Fast-Flow column, and Sepharose CL-6B column. To develop functional food or pharmaceuticals using LZ-B-1 and to investigate the relationship between the structure and bioactivity of LZ-B-1, the composition and immunomodulatory capacity of LZ-B-1 were studied herein. The peptidoglycan had a relative molecular weight of 1.12 × 10 4 Da, and total carbohydrate and peptide percentages were determined to be ~94.2% and ~5.4%, respectively. The carbohydrate moiety was mainly composed of L-fucose, D-galatose, and D-glucose in a molar ratio of approximately 1:5:2, together with small amounts of L-arabinose and D-mannose. The peptide moiety mainly contained arginine, threonine, glycine, ser- ine, and aspartic acid in a molar ratio of approximately 1:1:2:2:1. Methylation reaction and GC-MS analysis indicated that the carbohydrate moiety mainly consisted of 1,6-disubstituted-galactopyranosyl, 1,2,6-trisubstituted-galactopyranosyl, 1-substituted-fucopyranosyl, 1,3-disubstituted- glucopyranosyl, 1,4,6-trisubstituted-glucopyranosyl, and 1-substituted-glucopyranosyl. Mouse spleen cell proliferation assay in vitro showed that a concentration of 200 μg/mL of LZ-B-1 was the optimum concentration to promote the proliferation of mouse spleen lymphocytes (MSLs). In general, the higher the mouse spleen cell proliferation rate, the stronger the immunomodulatory activity. How the peptidoglycan stimulates the proliferation of MSLs and the bioactivity-structure relationship requires more research.