Studies on Bioactive Substances and Medical Effects of REISHI, (Ganoderma Lucidum)
Takashi Mizuno, Shizuoka University, Japan
Reishi, the fruiting body of Mannentake, Ganoderma lucidum has been known in Japan, China, and other countries as a food and raw material for the development of drugs. recent studies have shown that that carcinostatic substance in Reishi is a polysaccharide, beta (1-3)- D – glucan. This polysaccharide seems to have promise as a new type of carcinostatic agent which might be useful in immunotherapy. Unlike chemicals used in chemotherapy, it has few toxic side effects because its effect is based on immunological enhancement in the host. Reishi also seems to contain other substances which reduce blood pressure, blood cholesterol, and blood sugar levels; and inhibit platelet aggregation, etc.
Recently, in vitro immunomodulating effects of Reishi extracts, and clinical study of micronized Reishi in Thai HIV and AIDS patients were attempted in Thailand. Some lanostane tri-terpenoids have been isolated from G. lucidum. These are highly oxidized compounds which show interesting biological activities.
1. Artificial Cultivation of Reishi
Artificial culture and cultivation of Mannentake, G. lucidum fungus were attempted initially by T. Henmi et al., in 1937. Its mass production was first achieved by Y. Naoi in 1971 by cultivating the spawn using pots containing sawdust. Since then use of bed logs or sawdust has become established practice. For some purposes a bagasse spawn bed method and bottle or bag cultivation may be used. Usually, for mass cultivation of high quality Reishi, either outdoors, bed logs of white oak, oak, Japanese chest-nut, Japanese apricot, etc., are used.
The 1995 production of Reishi in Japan was estimated to about 500 tons dry weight. Reishi cultivation has also prospered in China, Taiwan, Korea, Thailand and Vietnam. In addition, attempts are being made to obtain useful cellular materials or to produce effective substances from cultures mycelia.
2. Pharmacologically Active Components in reishi
2.1 General Chemical Components in Reishi
The major components and the free amino acids in Mannentake fruiting body (reishi) have been determines. Both qualitative and quantitative differences are found in the composition of naturally grown and artificially cultivated sampled of reishi, depending on the lines, places of the production, cultivation conditions, etc.
2.2. Medicinal Effects of reishi Extract with Hot Water
The hot water extract (ca. 10% dry matter) obtained from Reishi seems to have some properties. Little could be done to isolate the pure substances having these medicinal properties until recently, when the culture and cultivation of Mannentake became possible.
The results of this research are described below. Anti tumor substances whose properties have been studied in depth are described in detail in the article Anti tumor-Active Substances from Mushrooms.
2.3 Bitter Terpenoids
The fruiting body of Mannentake (Reishi) is extremely bitter, a characteristic not found in any other mushroom. The bitterness varies in degree depending on the place of production, cultivation conditions, its strain, etc. This bitterness is not found in cultures mycelia or substances produced in the culture medium, and Kokushi (black Reishi) does not contain the bitter substance. Though the relationship between bitterness and pharmacological effects is not fully understood, the bitterness serves as a marker for pharmacological evaluation and classification of Ganoderma sp.
The bitter components and related compounds, highly oxidized lanostane triterpenoids isolated from Mannentake have been studied for their anti allergy action, etc.
Ergosterol (pro vitamin D2) has been reported in concentrations of 0.3-0.4% in Reishi. However, further analysis has confirmed that the main component of the steroids is 24-methylcholesta-7, 22-dien-3-beta-ol. Ergosterol and 24-methylchesta-7-en-3-beta-ol are sub components. Recently, ganodesterone has also been isolated.
2,5. Nucleosides and Nucleotides
Like other mushrooms, reishi contains adenosine, 5-GMP, 5XMP, RNA, etc., components which contribute to umami. It has recently been found that nucleosides which contain adenosine and guanosine, found in the water/alcohol extract of Reishi, possess a platelet aggregation action (antithrotic activity).
2.6. Hypoglycemic Glycans and Proteoglycans.
High hypoglycemic activity both in normal mice and in alloxan-induced hyperglycemic mice has been induced by two polysaccharide-protein complexes, Ganoderans B and C, by their i.p. administration to male mice of Std:ddY strain. These complexes were obtained by adding ethanol to a hot water extract of Reishi and separating the precipitated polymer substances by column chromatography. We have isolated, from Reishi fractions of water-soluble polysaccharides, a 3% ammonium-oxalate-soluble heteropolysaccharide, and 5% NaOH-soluble peptidoglycan. These were further separated into several fractions by various chromatographic methods. Strong anti tumor activity and hypoglycemic activity were found in certain fractions of the heteropolysaccharides.
No correlation was found between the anti tumor activity of these active peptidoglycans and their antihyperpgycemic activity or between the ratio composition of polysaccharides and proteins in the complex. Further research is needed to determine the source of these two activities.
2.7 Blood Pressure Stabilizing Components
Reishi has been assumed to have both hypotensive and hypertensive properties (homeostasis). A peptidoglycan (molecular weight, 100,000) having a mild hypotensive effect on Wister rats and SHR rats (congenitally hypertensive) has been isolated from hot water extract of reishi. According to one report, the blood pressure of about half the patients with hypertension was reduced when a Reishi extract was administered. it has been reported that a hypertension-related angiotensin-I-converting enzyme was inhibited by ganoderic acids (B, D, F, H, R, S, and Y), ganoderal A, and ganoderol A and B.
2.8 Antithrombotic Compounds (Platelet Aggregation Inhibitors)
Some active compounds have been isolated from mushrooms as platelet aggregation inhibitor. We have also isolated and identified adenosin, guanosin, and their derivatives as potent inhibitors from 80% ethanol extract Reishi. A novel substance showing a higher activity than those of the nucleotides was also obtained. Its structure has been identified as both epimers of 5-deoxy-5-methylsulphinyl adenosine.
Investigation of lectins from G. lucidum are now being carried out at our laboratory. We have isolated lectins from the fruiting body and mycelium of this fungus. This myceliumlectin is the first isolated from other than the fruiting body of higher fungi.
3. Anti tumor Substances in Reishi
Mannentake (fruiting body and mycelium of G. lucidum fungus) contains various low molecular weight components. Free monosaccharides, sugar alcohols, oligosaccharrides, amino acids, organic acids, steroids, lipids, terpenoids, coumarin, tannin substances, etc., are among low molecular weight components extracted with various solvents of water/alcohol-water/acetone-water, etc.
3.1. Cytotoxic Terpenoids
It has been reported that some triterpenoids (ganoderic acid -R, -T, -U, -V, -W, -X, -Y, and -Z) isolated from cultures mycelia of G. lucidum, Mannentake showed a cytotoxicity-based carcinostatic effect on hepatoma cells in vitro.
3.2 Anti tumor Polysaccharides
Among polymer components in Reishi, many polysaccharides and their protein-complexes were extracted using hot water, ammonium oxalate solution, alkali solution, dimethyl sulfoxide (DMSO) solution, etc., and separated by various chromatographic methods.
These polysaccharide fraction were used for the screening of host-mediated Anti-tumor activities (BRM substances and immunotherapeutic agents) using Sarcoma 180 180/mice, i.p. or p.o. method. Strong anti-tumor activities were found in various hetero-beta-D-glycans having a beta(1-3)-D-glucan chain as the active site, such as beta-D-glucan, glucurono-beta-D-glucan, arabinoxylo-beta-D-glucan, xylo-beta-D-glucan, manno-beta-D-glucan and xylomanno-beta-D-glucan, as well as their protein complexes. These polysaccharides, especially in Reishi, will be examined for their possible use as new anti tumor agents.
In addition, polysaccharides having immunomodulated anti tumor activities or anti-inflammatory functions are contained not only in water soluble beta-D-glucans but also in hemicellulose (the so-called dietary fiber), which is water-insoluble. The polysaccharides present in hemicellulose can be extracted with alkali or DMSO in high yield.
In addition to these active polysaccharides, many other polysaccharides have been isolated or reported to exist, such as alpha-(1-6); alpha(1-4)-G-glucan (glycogen-like polysaccharide), fucogalactan, mannofucagalactan, fucoxylomannan and xylomannoarabinogalactan. None of these showed anti tumor activity.
3.3 Dietary Fibers
A high molecular component neither digested nor absorbed but excreted upon intake by human being is called the dietary fiber. Mushroom fungi contain dietary fibers belonging to beta-glucan, chitinus substances, hetero-polysaccharides (pectinous substances, hemicellulose, polyuronides, etc.) and others, as much as 10-50% in the dried matter.
Since beta-D-glucan and chitinous substance with carcinostatic activity are contained much in the dietary fiber of mushroom fungi, certain pharmacological effects can be expected, and further by physical actions, they absorb hazardous matters as carcinogenic substances to prevent their absorption in the intestine and to hasten their excretion (laxative action), thus it seems to work effectively to prevent cancer of the colon and rectus.
3.4 Germanium Components
Crude drugs obtained from ginseng, a polyporaceae, treasured as Oriental medicine have high germanium contents. The ability to concentrate Ge was confirmed in G. lucidum fungus. Correlation between the anti tumor activity (interferon-inducing activity) and Ge contents is also of interest because Ge is said to neutralize pain during the final stages of cancer.
4. Extracellular Polysaccharides of Ganoderma lucidum
Polysaccharides were produced extracellularly when G. lucidum mycelia were shaking cultured using a liquid medium containing monosaccharides or disaccharides as the carbon source.
Dried polysaccharides thus obtained were separated into water-insoluble (47%) and insoluble (53%) fractions. The water-insoluble polysaccharide fraction contained a beta (1-3)-D-glucan having beta-(1-6) branches. When this glucan was administered to mice (10 mg/kgX10, i.p.), it showed high anti tumor activity, with the suppression ratio percentage of tumor proliferation being 92% and the complete regression ratio being 4/6. The water-soluble fraction contained a heteroglucan composed of glucose, mannose and galactose having no anti tumor activity.
5. Clinical Study and Immunomodulating Effects of G. lucidum Mushroom in AIDS and HIV Patients.
5.1. In Vitro Immunomodulating Effects of Reishi Extracts
Our preliminary in vitro studies indicated that certain extracts of Reishi may function as immunorestorer in mild to moderately immunosupressed individuals. The effect may be mediated through changes T cells phenotypes or through enhancement of T cell function. Therefore, proper selection of the patients to be tested is essential to guarantee the favorable outcome of the clinical study.
5.2. Clinical Study of Micronized reishi Mushroom in Thai HIV Patients.
A fine-powdered Reishi from Japanese G. lucidum mushroom was administered to ten patients with advanced HIV infection in Thailand. Only one patient had already taken antiretrovirals for two or more months before enrolling into the study and the CD4 count still remained under 200 cell/cu mm. The same antiretroviral regiments were maintained throughout the 12-week study period. Patients were observed every 4 weeks for clinical, CD4 and HIV viral load changes. Results indicated that micronized Reishi mushroom was well tolerated. Nevertheless, the product did not show any appreciable benefits either for the clinical symptoms, the CD4 counts or HIV viral loads.
Therefore, it is desired to purify the active ingredients from the mushroom such as the terpenoids and polysaccharides including beta-D-glucan and its protein complex before additional clinical test in HIV patients is warranted.
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2) T. Mizuno: Chemistry and Biochemistry of Mushrooms, pp. 35-45, 211-221 (1992), Gakkai Shuppan Center, Tokyo
3) T. Mizuno: Reishi Mushroom, Recent Development of Physiologically Functional Food, pp. 319-330 (1996), CMC Co. Ltd., Tokyo.
4) T. Mizuno: Food Function and Medicinal Effects of Mushroom Fungi, pp. 1-170 (1994), Laboratory of Biochemistry, Faculty of Agriculture, Shizuoka University, Shizuoka.
5) T. Mizuno: Mushroom Science and Biotechnology, 1, 53-59 (1994)
6) T. Mizuno: Mushroom Science and Biotechnology, , 99-114 (1995)
7) T. Mizuno: Food and Food Ingredients Journal of Japan, No. 167, 69-85 (1996).
8) T. Mizuno: Food Reviews International, 11, 7-21, 23-61, 151-166 (1995).
9) T. Mizuno: Ganoderma lucidum, p. 253-279 (1996), IL-YANG Pharm. Co. Ltd., Seoul, Korea.
10) T. Mizuno: Mushroom Book No. 1, p. 60-65, p 106-112 (1995), Toyo Igakusha, Tokyo
11) T. Mizuno: Reishi book No. 1, p.88-92, p. 106-122 (1995), Toyo Igaku, Tokyo.
12) T. Mizuno: Unpublished data.