Bioactive Compounds in Medicinal Mushrooms

 

 

How are Mushrooms different from other plants?

Mushrooms are taxonomically distinct entities that do not fall under the categorization of either plants or animals. They represent the conspicuous reproductive structures of the fungal kingdom, manifesting as the above-ground spore-bearing fruiting bodies. Fungi generate mushrooms as a mechanism for spore dissemination and the colonization of new environments.

Contrary to historical associations placing fungi in closer proximity to plants, advancements in phylogenetic research have revealed a closer evolutionary relationship between fungi and animals. While plants utilize carbon dioxide and sunlight for photosynthesis, fungi, and animals both obtain carbon and energy through the enzymatic breakdown of organic substances. In evolutionary terms, animals have adopted the process of internal digestion, whereas fungi release enzymes into the adjacent substrate, facilitating the breakdown of organic matter, followed by the absorption of resultant smaller molecules derived from enzymatic hydrolysis.

Despite metabolic similarities with animals, mushrooms exhibit structural affinities with plants. Similar to plants, mushrooms feature a robust cell wall primarily composed of extended chains of sugar molecules (polysaccharides) connected by beta linkages. This structure renders them resistant to degradation by human digestive enzymes, which are designed to handle alpha-linked polysaccharides prevalent in the human diet.

Furthermore, mushrooms deviate from typical plant forms in the composition of their cell walls. While plants produce cellulose with β 1→4 linked glucose molecules, mushrooms predominantly consist of polysaccharide chains with a β 1→3 linkage and β 1→6 linked side chains, commonly referred to as (1→3), (1→6) β-glucan. This distinction highlights the unique structural composition of mushroom cell walls compared to other plant varieties.

 

Polysaccharides

Polysaccharides (complex sugars) are carbohydrate molecules composed of long chains of smaller monosaccharides (simple sugars) linked by glycosidic bonds. These naturally occurring compounds serve diverse functions, including energy storage, cellular communication, and structural reinforcement.

Within the realm of medicinal mushrooms, a plethora of polysaccharides exists, with a particular emphasis on a specific type known as beta-D-glucans. It is noteworthy that these beta-D-glucans predominantly contribute to the manifold health benefits associated with medicinal mushrooms.

Beta-Glucans

Beta-glucans, technically referred to as beta-D-glucans, represent a distinct category of non-digestible polysaccharide fibers. While present in various sources, including bacteria and plants like oats and barley, it is noteworthy that the unique β-(1→6) branching structure exclusively characterizes the beta-glucans derived from fungi, particularly mushrooms. This specific structural attribute is associated with heightened medicinal potential.

The specialized 1-6 beta-D-glucans play a pivotal role in conferring numerous health-promoting properties to medicinal mushrooms. These properties encompass antioxidant activity, enhanced immune system functionality, and regulation of blood sugar and cholesterol levels. Notably, medicinal mushrooms such as Lions Mane, Reishi, Chaga, and Cordyceps universally contain these distinctive beta-glucans, underscoring their significance in the therapeutic attributes of these fungi.

Proteins

In addition to their incorporation into protein-bound polysaccharides, certain proteins derived from mushrooms have exhibited therapeutic biological activity. These activities encompass immune modulation, ribosome inactivation, as well as antiviral, antifungal, and nuclease activities.

Triterpenes

Triterpenes represent a substantial class of compounds characterized by a four- or five-ring configuration comprising 30 carbons, with multiple oxygen attachments. These compounds exhibit diverse biological activities, including anti-cancer, anti-inflammatory, antioxidative, antiviral, antibacterial, and antifungal properties.

Prominently recognized within the realm of triterpenes are the ganoderic and lucidenic acid families derived from Reishi mushrooms. These compounds play a pivotal role in underpinning many of Reishi's distinctive therapeutic properties.

In the case of Chaga mushrooms, the terpenoid compounds present encompass derivatives of betulin and betulinic acid obtained from the bark of the birch trees hosting the Chaga growth. Similar to Reishi's triterpenes, botulin and betulinic acid showcase a broad spectrum of biological activities, including anti-cancer, anti-inflammatory, and antiviral properties.

Phenols

Phenols constitute a group of organic compounds distinguished by the presence of a hydroxyl group attached to a carbon atom within an aromatic ring structure. Among the various phenolics occurring in mushroom species, phenolic acids and flavonoids are particularly prevalent. These compounds play a central role in the manifestation of bioactivities associated with mushrooms, including but not limited to antioxidant, anti-inflammatory, antitumor, anti-hyperglycemic, anti-osteoporotic, anti-tyrosinase, and anti-microbial activities. Notably, Chaga mushrooms exhibit a noteworthy abundance of phenols.

Sterols

Sterols represent solid steroid alcohols, including cholesterol, and are widely distributed in animal and plant lipids. Ergosterol, a specific type of sterol prevalent in edible mushrooms, holds significant nutritional value and pharmacological activity. Serving as a provitamin, ergosterol is a well-established precursor to vitamin D2, particularly in edible mushrooms, where it undergoes conversion to vitamin D2 upon exposure to ultraviolet radiation.

The pharmacological effects associated with ergosterol encompass antimicrobial, antioxidant, anticancer, antidiabetic, and anti-neurodegenerative properties. Additionally, derivatives of ergosterol have been documented to exhibit anti-aging activity akin to that observed with resveratrol.

Statins

Statins represent protein-based bio compounds designed to mitigate elevated levels of fats, including triglycerides and cholesterol, within the bloodstream. Renowned as inhibitors of the hydroxymethylglutaryl-CoA reductase enzyme, statins effectively reduce total cholesterol, low-density lipoprotein (LDL), and triglyceride concentrations, while concurrently elevating concentrations of high-density lipoprotein (HDL). In particular, Reishi mushrooms exhibit notable levels of statins, with higher concentrations observed in the mycelium compared to the fruiting body.

Chitin

Chitin, the second most prevalent polysaccharide in nature following cellulose, serves as a fundamental constituent in the cell walls of fungi, certain bacteria, and the exoskeletons of insects, arachnids, and crustaceans. This polysaccharide has been found to exert notable effects on both innate and adaptive immune responses. It demonstrates the capacity to recruit and activate innate immune cells, along with the induction of cytokine and chemokine production. Moreover, chitin exhibits antimicrobial and antioxidant properties and has been documented to accelerate the process of wound healing.

It is essential to note that chitin is a recurring component in allergens known to trigger allergies, notably in substances such as shrimp, crab, and house dust mites. Additionally, chitin may play a role in the allergic reactions observed in a limited number of individuals upon consuming mushrooms.

 

Enzymes

Enzymes, proteins that facilitate the acceleration of chemical reactions within the human body, play a crucial role in various physiological processes. Mushrooms exhibit a diverse repertoire of enzymes, encompassing digestive and antioxidant enzymes. There is a proposition that the enzymatic activity inherent in mushrooms may contribute to the therapeutic efficacy of both the fruiting body and mycelial biomass.

 

-Abdelshafy, Asem Mahmoud et al. “A comprehensive review on phenolic compounds from edible mushrooms: Occurrence, biological activity, application and future prospective.” Critical reviews in food science and nutrition vol. 62,22 (2022): 6204-6224. doi:10.1080/10408398.2021.1898335

-Bell V., Silva C. R. P. G., Guina J., Fernandes T. H.  ”Mushrooms as future generation healthy foods”, Frontiers in Nutrition, Vol 9 (2022), doi; 10.3389/fnut.2022.1050099. https://www.frontiersin.org/articles/10.3389/fnut.2022.1050099                     

-Chudzik, Malwina et al. “Triterpenes as potentially cytotoxic compounds.” Molecules (Basel, Switzerland) vol. 20,1 1610-25. 19 Jan. 2015, doi:10.3390/molecules20011610

- El-Gendi, Hamada et al. “A Comprehensive Insight into Fungal Enzymes: Structure, Classification, and Their Role in Mankind's Challenges.” Journal of fungi (Basel, Switzerland) vol. 8,1 23. 28 Dec. 2021, doi:10.3390/jof8010023

- Elieh Ali Komi, Daniel et al. “Chitin and Its Effects on Inflammatory and Immune Responses.” Clinical reviews in allergy & immunology vol. 54,2 (2018): 213-223. doi:10.1007/s12016-017-8600-0

-Hassan, Mohamed Ali Abol et al. “Mushroom lectins: specificity, structure and bioactivity relevant to human disease.” International journal of molecular sciences vol. 16,4 7802-38. 8 Apr. 2015, doi:10.3390/ijms16047802

-Jones, Mitchell et al. “Crab vs. Mushroom: A Review of Crustacean and Fungal Chitin in Wound Treatment.” Marine drugs vol. 18,1 64. 18 Jan. 2020, doi:10.3390/md18010064

- Kała, K., Kryczyk-Poprawa, A., Rzewińska, A. et al. Fruiting bodies of selected edible mushrooms as a potential source of lovastatin. Eur Food Res Technol 246, 713–722 (2020). https://doi.org/10.1007/s00217-020-03435-w

- Rangsinth, Panthakarn et al. “Potential Beneficial Effects and Pharmacological Properties of Ergosterol, a Common Bioactive Compound in Edible Mushrooms.” Foods (Basel, Switzerland) vol. 12,13 2529. 29 Jun. 2023, doi:10.3390/foods12132529

-Ríos, José-Luis. “Effects of triterpenes on the immune system.” Journal of ethnopharmacology vol. 128,1 (2010): 1-14. doi:10.1016/j.jep.2009.12.045

-Sizar O, Khare S, Jamil RT, et al. Statin Medications. [Updated 2023 Feb 5]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK430940/