Extraction of polysaccharides and proteins from selenium rich Ganoderma lucidum mycelium and their in vitro antioxidant and anti-tumor activities
In recent years, 90% of patients with malignant tumors have died from cancer cell metastasis. There is a causal relationship between the occurrence and development of tumors and the low immune function of the body. According to reports, selenium can enhance the body’s immune system and resist the occurrence of tumor diseases, but the human body can only rely on external intake of organic selenium, which is mainly composed of selenium polysaccharides and selenium proteins. According to previous reports, selenium polysaccharides from black fungus and tea have strong antioxidant activity. Selenium polysaccharide can also inhibit the activity of tumor cells: Shang et al found that pumpkin selenium polysaccharide has a certain inhibitory effect on the growth of breast cancer cells. In addition to having a certain ability to scavenge free radicals, selenoproteins also have a significant role in inhibiting tumor growth: the selenoprotein from Brassica napus has strong free radical scavenging ability and total reducing power; Selenium rich soy protein peptides can significantly inhibit tumor growth in mice.

Ganoderma lucidum belongs to the phylum Basidiomycota, family Actinobacteriaceae, and genus Ganoderma (Leyss. ex Fr.) Karst Medicinal fungi are traditional food and medicine dual-use fungi in China, including various active ingredients such as triterpenes, polysaccharides, proteins, etc. They have a wide range of pharmacological activities such as anti-tumor, antioxidant, and immune regulation. Lingzhi has a strong ability to enrich selenium. Selenium rich Ganoderma lucidum is obtained by culturing Ganoderma lucidum as a carrier for selenium conversion, which combines the biological activity of Ganoderma lucidum and selenium. At present, scholars’ research mainly focuses on the cultivation and strain cultivation of selenium rich Ganoderma lucidum, and related biological activity research is mainly conducted through animal experiments, with relatively few in vitro anti-tumor experiments. This study utilized ultrasound assisted alkaline extraction, water extraction, and alcohol precipitation methods to extract polysaccharides from selenium rich Ganoderma lucidum mycelium, and extracted soluble proteins from mycelium using phosphate buffer solution as the solvent. We investigated the scavenging ability of selenium rich Ganoderma lucidum mycelium polysaccharides and proteins against DPPH free radicals and ABTS free radicals, iron reducing ability, and the inhibitory effect on the proliferation of liver cancer cells HCCLM, lung cancer cells A549, and oral cancer cells HSC-3. The selenium group was used as a control to explore the effects of selenium on the active ingredients and antioxidant and anti-tumor activities of Ganoderma lucidum. Provide theoretical basis for the further development and application of selenium resources.

Using Ganoderma lucidum mother seeds as raw materials, appropriate exogenous selenium was added for liquid fermentation to obtain selenium rich Ganoderma lucidum mycelium, and its polysaccharide and protein activities were investigated. During the experiment, selenium free Ganoderma lucidum was used as the corresponding control. The results showed that the content of polysaccharides extracted by ultrasound assisted alkaline extraction was higher than that extracted by water extraction; The content of selenium polysaccharides is higher than that of polysaccharides, and the content of selenium proteins is higher than that of proteins; The content of selenium in selenoproteins is higher than that in selenium polysaccharides. The addition of selenium is beneficial for the generation of selenoproteins, and both selenoproteins and selenium polysaccharides have certain antioxidant effects. In vitro anti-tumor experiments, both selenium polysaccharides and selenoproteins have certain anti-tumor effects, and selenium polysaccharides have a significant anti-tumor effect compared to polysaccharides, while selenoproteins have poorer anti-tumor effects.

This study explores the antioxidant and anti-tumor activities of Ganoderma lucidum selenium polysaccharides and selenoproteins, which have certain reference value in the research of Ganoderma lucidum extract activity and help promote the further development and utilization of selenium rich Ganoderma lucidum and selenium resources.