# Current Progress Regarding _Cordyceps militaris_, Its Metabolite Function, and Its Production
## 2 Biological Compounds of _C. militaris_
### Polysaccharides  
Polysaccharides are some of the most abundant and important bioactive components in _Cordyceps_, exhibiting a wide range of pharmacological activities and applications, including antioxidant [105], anti-inflammatory [106], antiviral [107], antiaging [108], and antitumor [107] effects. Polysaccharides can be extracted and isolated from _Cordyceps_ fruiting bodies, mycelia, and fermentation broth, with different physicochemical properties, making them a targeted product for the development and quality control of _Cordyceps_-related health supplements [108]. In recent years, the isolation, purification, structural identification, and biological activities of _Cordyceps_ polysaccharides have been extensively studied. However, due to variations in raw materials, extraction methods, and purification procedures, the structures and biological activities of polysaccharides obtained from _Cordyceps_ exhibit significant differences, making it difficult to establish a correlation between structure, chain conformation, and biological activity. Therefore, it is necessary to develop a standardized preparation method for _Cordyceps_ polysaccharides. Microbial polysaccharides can be categorized based on their location within the cell, as follows:  
* Structural polysaccharides, such as teichoic acids, LPSs, and peptidoglycans, form the cell wall to provide protection and maintain the microorganism's structure. * Intracellular polysaccharides, also known as cytosolic polysaccharides, serve as a source of energy and carbon for the cell. * Exopolysaccharideacharides (EPSs) are secreted into the extracellular medium either as a secondary metabolite or in the form of a biofilm to protect against environmental stress [109; 110]. With respect to the antioxidant activities of polysaccharides from _C. militaris_, the presence of certain monosaccharides may have a significant impact. In particular, a purified polysaccharide consisting primarily of glucose, mannose, galactose, and arabinose in an \(\alpha\)-type glycosidic linkage was found to exhibit _in vitro_ scavenging activities against DPPH, hydroxyl, and superoxide radicals [49; 50]. CPS-1, a polysaccharide with a molecular weight of 2.3 \(\times\) 10\({}^{4}\) Da, is composed of rhamn, xylose, mannose, glucose, and galactose, and was shown to have anti-inflammatory and humoral immunity-reducing properties [15]. An acidic polysaccharide extracted from _C. militaris_ cultivated on germinated soybeans was found to possess antiviral properties against the influenza A virus. This effect was believed to be partly attributable to its ability to modulate the immune response of macrophages. The polysaccharide was shown to reduce viral titers in both bronchoalveolar lavage fluid and lung tissues. In addition, it was observed to enhance the production of tumor necrosis factor (TNF)-\(\alpha\) and interferon (INF)-\(\gamma\) in vivo, as well as to stimulate nitric oxide (NO) production and induce expressions of inducible NO synthase (iNOS) messenger (m)RNA and protein _in vitro_. Furthermore, the polysaccharide was shown to modulate mRNA expressions of IL-1B, IL-6, IL-10, and TNF-\(\alpha\)[53]. Cultivated fruiting bodies of _C. militaris_ containing polysaccharides were found to have effects on the activities of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), and anti-hydroxyl radicals when assayed in vivo using commercial monitoring kits. These polysaccharides inhibited the mitochondrial injury and swelling induced by Fe\({}^{2+}\)-L-cysteine in a concentration-dependent manner and had a significant superoxide anion scavenging effect. Additionally, they significantly increased the activities of CAT, SOD, GPx, and anti-hydroxyl radicals in mice liver. These findings indicated that polysaccharides extracted from _C. militaris_ may have pharmaceutical value in protecting mitochondria, scavenging ROS, and increasing the activities of antioxidants, which could potentially contribute to antiaging effects [54].