Comparison of the Anti-Inflammatory and Antioxidant Activities of Mycelial Polysaccharides from Different Strains of Lingzhi or Reishi Medicinal Mushroom, Ganoderma lucidum (Agaricomycetes)

Ganoderma lucidum is a popular tonic medicine in China, and its polysaccharides are believed to promote health benefits. However, G. lucidum and the composition, structure, and molecular weight of G. lucidum polysaccharides (GLPs) are very heterogeneous. There are limited studies on the relationship between GLPs and their function. Therefore, this study sought to evaluate the cosmetic efficacy of six types of GLPs and analyze the structure of the identified polysaccharides. GLPs (GLP1-GLP6) were prepared with conventional methods by selecting six G. lucidum strains. The 8-methoxypsoralan-induced melanin model of B16 cells, the lipopolysaccharide-induced inflammation model of HaCaT cells, and the hydrogen peroxide-induced oxidative stress model of human skin fibroblasts (HSFs) were used. The whitening, anti-inflammatory, and antioxidative effects of GLP1-GLP6 were determined. After initial screening, promising GLPs were selected for further analysis. These were purified and their structure was characterized. GLP1-GLP6 had no whitening effect as assessed by cellular tyrosinase level and melanin content. Meanwhile, GLP1 and GLP4 had strong inhibitory effect on hyaluronidase, and GLP1 and GLP2 significantly reduced the relative expression of inflammatory cytokine interleukin-1α. All GLPs could significantly increase the activity of HSFs and reduce the proportion of senescent cells. The comprehensive score of GLP1 was the highest. GLP1-I and GLP1-II were obtained by DEAE-52 ion exchange resin. Morphological analysis showed that there were significant differences between GLP1 and its two components. The results of infrared spectroscopy showed that GLP1-I had a β-glycosidic bond, and high-performance gel penetration chromatography showed that GLP1-I had a low molecular weight. GLPs showed no whitening but had significant antioxidant activity. GLPs are promising compounds to be developed into natural antioxidants and potentially used in cosmetics, health products, and functional foods.