Biological study on carboxymethylated (1 → 3)-α-D-glucans from fruiting bodies of Ganoderma lucidum

Water-insoluble, alkali-soluble polysaccharides (ASPs) were isolated from three fruiting bodies of the macromycete fungus Ganoderma lucidum. The structure of ASPs was determined using composition analysis, methylation analysis. Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. The analysis of the biological activity of the carboxymethylated (CM) (1 -> 3)-alpha-D-glucans was based on an assessment of their cytotoxic, mitochondrial metabolism-modulating, and free radical scavenging effects against a tumor cell line (human cervical carcinoma HeLa), and two normal human cell lines (colon myofibroblasts CCD-18Co and epithelial cells CCD 841 CoTr). The chemical and spectroscopic investigations indicated that the ASPs from G. lucidum were (1 -> 3)-alpha-D-glucans. After carboxymethylation (1 -> 3)-alpha-D-glucans were tested in the range of 25-250 mu g/mL concentrations. All the tested CM-(1 -> 3)-alpha-D-glucans decreased the cellular metabolism of tumor and normal cells after 24h of incubation. The CM-(1 -> 3)-alpha-D-glucans had no toxic effects on cervical carcinoma cells but reduced the viability of normal cells. The cytotoxic activity of the CM-(1 -> 3)-alpha-D-glucans was concentration- and cell-type-dependent with normal cells more sensitive to their action than tumor cells. Generally, the CM-(1 -> 3)-alpha-D-glucans tested did not have a free radical scavenging effect. It was concluded that the carboxymethylated derivatives of (1 -> 3)-alpha-D-glucans isolated from the G. lucidum fruiting bodies are biologically active and after further detailed studies may be regarded as a dietary or therapeutic supplements. (C) 2012 Elsevier B.V. All rights reserved.