Introduction
Ganoderma is an ancient genus of fungi whose name is derived from the Greek words meaning “shiny skin”. The genus was defined in 1881 by P. A. Karsten to classify a single species, Polyporus lucidus (now known as Ganoderma lucidum). Ganoderma lucidum belongs to the family Ganodermataceae and is the type species of the genus; it is commonly known by various names such as lingzhi, reishi, and youngzhi, and has a worldwide distribution originating in the tropics and extending to temperate zones.
Ganoderma species are typically found on woody plants and logs. They have a long history of medicinal use in countries such as China, Japan, South Korea, and the French West Indies. The genus contains many species, with about 80 species recorded in Chinese mushrooms. While G. lucidum and G. sinense are recognized as medically useful macrofungi in Chinese medicine, other species such as G. capense, G. cochlear, and G. tsugae are also important in traditional folk medicine. Pharmacological studies have investigated the extract and chemical constituents of various Ganoderma species, indicating their potential therapeutic applications.
Ganoderma lucidum is a medicinal mushroom that has been used in traditional Chinese medicine for centuries to improve health, increase vitality, and prolong life.
Bioactive compounds
Ganoderma lucidum is an important source of biologically active compounds such as polysaccharides, triterpenes, steroids, glycoproteins, peptides, sterols, fatty acids and trace elements. Polysaccharides obtained from Ganoderma lucidum show a wide range of pharmacological properties: antioxidant, immunomodulatory, antineurodegenerative, antidiabetic, anti-inflammatory, anticancer and antibacterial. Polysaccharides are a type of natural polymer composed of monosaccharides linked by α and β glycosidic bonds to form main and side chains. The central chemical structure of polysaccharides is β-glucan with various β-glycosidic bonds. In addition to pure β-glucans, mainly isolated from the fruiting bodies of G. lucidum, there are also heterofucans, heteromannans and their complexes with peptides.
Triterpenes are an important class of secondary metabolites widely present in nature derived from the acyclic precursor squalene. Over 30,000 triterpene structures have been identified including dammarane, lanostane, lupine, oleanane and ursane types. Triterpenoids isolated from Ganoderma spp. have complex structures consisting of lanostane carbon skeletons and pentacyclic triterpenoids. Based on the number of carbon atoms in their skeleton, Ganoderma triterpenoids are classified into three types: C30, C27 and C24. They are further classified into various groups including triterpenoid acids, triterpenoid alcohols and triterpenoid lactones based on their substituent groups. Ganoderma triterpenoids (GT) are complex small molecules with intricate structures and diversified sites that make them promising candidates for drug screening.
Antioxidant activity
The balance between reactive oxygen species (ROS) and their elimination is crucial for maintaining healthy physiological conditions. When ROS levels become excessive, oxidative stress occurs, leading to tissue damage and the development of diseases. The long-term effects of oxidative stress contribute to accelerated aging and are associated with neurodegenerative diseases, metabolic syndromes, and neoplasms.
Ganoderma lucidum possesses antioxidant properties that make it suitable for the prevention of certain diseases and/or conditions. Specifically, polysaccharides derived from G. lucidum exhibit antioxidant activity, reducing lipid peroxidation levels and increasing antioxidant enzyme activity, thus protecting tissues from ROS toxicity. These polysaccharides have demonstrated anti-inflammatory and protective effects against oxidative stress in various organs, including the heart, liver, spleen, and skeletal muscles.
Considering these properties, a polysaccharide-based drug derived from G. lucidum has been approved by the Chinese Food and Drug Administration (CFDA) for the treatment of polymyositis, dermatitis, and muscular dystrophy.
Low molecular mass polysaccharides from G. lucidum exhibit higher antioxidant and immunomodulatory activity and have been shown to enhance hematopoiesis and increase immunoglobulin levels. Additionally, G. lucidum polysaccharides have been found to improve antioxidant enzyme activity and decrease malondialdehyde levels in mice fed a high-fat diet.
Although the CFDA has approved the use of G. lucidum polysaccharides as a drug, further investigations are needed to fully explore the effect of this drug on human health.
Immunomodulatory Activity
Recent biochemical and clinical studies have provided evidence of the potent immunomodulatory activity of polysaccharides derived from Ganoderma lucidum. These polysaccharides have been shown to modulate the immune response by influencing various effector cells, including macrophages, B and T lymphocytes, Natural Killer cells (NK cells), and dendritic cells. The immunomodulatory effects of G. lucidum polysaccharides are mediated through interactions with Toll-like receptor 4 (TLR4) and TLR2 receptors, leading to the activation of signaling pathways such as p38 mitogen-activated protein kinase (p38 MAPK). Additionally, G. lucidum polysaccharides induce the maturation and activation of dendritic cells through nuclear factor κ-light-chain-enhancer of activated B cells (NF-ĸB) signaling and MAPK protein kinases. The function of chemotaxis and phagocytosis in neutrophils is also enhanced by G. lucidum polysaccharides, involving the phosphorylation of various protein kinases. Moreover, cell-wall polysaccharides from G. lucidum stimulate the production of innate immune cytokines, including tumor necrosis factor-α (TNF-α), interferon γ (IFN-ɣ), and interleukin-2 (IL-2) in human peripheral blood mononuclear cells. These findings highlight the potential of G. lucidum polysaccharides as valuable immunomodulators with the ability to enhance immune cell proliferation, activation, and cytokine production.
Macrophages play a crucial role in phagocytosing pathogens, and their activation is regulated by serine-threonine kinases. Macrophage polarization can be classified as M1 or M2, depending on the activation stages and stimuli present. Ganoderma lucidum polysaccharides have been found to modulate the activation of macrophages, with the rFIP-glu polysaccharide showing a dose-dependent effect on macrophages. Studies have also demonstrated the synergistic immunostimulatory effects of β-glucans derived from different medicinal mushrooms, including G. lucidum, on human macrophages. These findings shed light on the bioactivity of complex natural preparations and their potential application in the development of bioactive drugs.
Anti-Aging Effects
Recent studies have shown that Ganoderma lucidum has anti-aging effects. One of the main mechanisms of Ganoderma lucidum’s anti-aging effects is its ability to modulate the expression of genes related to aging and longevity. Ganoderma lucidum can activate the sirtuin family of proteins, which are involved in DNA repair, oxidative stress resistance, and cellular senescence. Ganoderma lucidum can also inhibit the mTOR pathway, which regulates cell growth, proliferation, and survival. By modulating these pathways, Ganoderma lucidum can delay the onset of age-related diseases and extend the lifespan of animals and cells.
Another mechanism of Ganoderma lucidum’s anti-aging effects is its antioxidant and anti-inflammatory properties. Ganoderma lucidum contains various bioactive compounds, such as polysaccharides, triterpenoids, and phenols, that can scavenge free radicals and reduce oxidative damage to the cells and tissues. Ganoderma lucidum can also suppress the production of pro-inflammatory cytokines and modulate the activity of immune cells, such as macrophages and T cells. By reducing inflammation and oxidative stress, Ganoderma lucidum can protect the skin from wrinkles and sagging, the brain from cognitive decline and neurodegeneration, the immune system from dysfunction and infection, and the metabolism from dysregulation and obesity.
Thus, Ganoderma lucidum can enhance the quality and quantity of life by slowing down the aging process and preventing age-related diseases.