Inonotus obliquus
(from Medicinal Mushrooms – A Clinical Guide by Martin Powell)

Japanese name – Kabanoanatake
Chinese name – Bai Hua Rong
English name – Chaga

I. obliquus grows widely in the forests of eastern europe and Russia on several trees, including birch, alder and spruce where it appears as a sterile growth or conk on the trunk of the tree. The fruiting body is reported to be found growing nearby but is extremely rare in nature.

Traditionally only the I. obliquus growing on birch trees was used, as a tea in the treatment of cancers including inoperable breast cancer, hip, gastric, parotid, pulmonary, stomach, skin and rectal and Hodgkins disease1 and I. obliquus is recorded as a miraculous cure for cancer in Solzhenitzen’s semi-autobiographical 1967 novel, the ‘Cancer Ward’.

The wisdom of using birch grown I. obliquus is supported by the finding that one of its key components is the triterpene betulinic acid, which occurs naturally in a number of plants but primarily in the bark of the white birch (Betula pubescens – seen as the tree of life and fertility in many Eastern European and Siberian myths) from which it gets its name. I.obliquus growing on the birch trees takes up high concentrations of betulinic acid from the bark of the trees, making it and its derivatives available in an absorbable form.

Betulinic acid has been shown to induce mitochondrial apoptosis in different cancer cell lines and inhibit the enzyme topoisomerase2, which is essential for the unwinding and winding of the DNA strands in cell replication. In addition it possesses anti-retroviral, anti-parasitic and anti-inflammatory properties3. It is currently being developed as an anti-cancer agent through the Rapid Access to Intervention Development program of the US National Cancer Institute and is also major contributor to the anti-cancer action of mistletoe4.

Other important components of I.obliquus include polysaccharides and sterols. Its high phenolic content gives it exceptional anti-oxidant properties and a melanin complex has also been identified as having significant antioxidant and genoprotective properties5,6.

Cancer – Widely used in Poland and Russia as a folk remedy against cancer7, I. obliquus is now attracting increasing interest among practitioners with its combination of immune supporting polysaccharides and components with direct anti-cancer activity, especially betulinic acid.

In-vitro studies on betulinic acid have shown it to be highly effective against a wide variety of cancer cells: human melanoma, neuroectodermal (neuroblastoma, medulloblastoma, Ewing’s sarcoma) and malignant brain tumors, ovarian cancer, human leukemia HL-60 cells and malignant head and neck squamous cell cancers, including those derived from therapy-resistant and refractory tumors8,9. However, it was found to have no effect on epithelial tumors, such as breast cancer, colon cancer, small cell lung cancer and renal cell cancer, as well as T-cell leukemia cells. Its antitumor activity has been related to its direct effects on mitochondria and induction of apoptosis, irrespective of cells p53 status10.

Clinically betulinic acid’s action against brain tumor cells is particularly interesting and it is noteworthy that in one study it exerted cytotoxic activity against primary tumor cells cultured from patients in 4 of 4 medulloblastoma-tumor samples tested and in 20 of 24 glioblastoma-tumor samples11. It also shows great promise in combination with radiotherapy, exhiniting a strictly additive mode of growth inhibition in combination with radiation in human melanoma cells in one study and acting as a radiosensitizer in head and neck squamous cell cancers in another12,13.

In-vivo studies confirm its anti-cancer action as well as a complete absence of systemic toxicity in rodents8.

Anti-viral – I. obliquus has traditionally been used to treat a number of viral conditions and betulinic acid analogs have been shown to disrupt assembly and budding of the HIV-1 virus, viral fusion to the cell membrane9.

CLINICAL SUMMARY Main Therapeutic Applications – Cancer, Anti-viral, Anti-oxidant
Key Components – Polysaccharides, Betulinic acid derivatives
Dose – It is reported that only aqueous extracts prepared by boiling, as done traditionally, show anti-tumour activity14. Recommended dosage for aqueous extract as powder is 2-5g/day.

1. Plants used against cancer. Hartwell J.L. 1982. Quartermain Pubs: Lawrence, Mass. p.694
2. Betulinic acid, a potent inhibitor of eukaryotic topoisomerase I: identification of the inhibitory step, the major functional group responsible and development of more potent derivatives. Chowdhury A.R, Mandal S, Mittra B, Sharma S, Mukhopadhyay S, Majumder H.K. Medical Science Monitor. 2002;8(7):254–65.
3. Antimalarial activity of betulinic acid and derivatives in vitro against Plasmodium falciparum and in vivo in P. berghei-infected mice. de Sá M.S, Costa J.F, Krettli A.U, Zalis M.G, Maia G.L, Sette I.M, Câmara Cde A, Filho J.M, Giulietti-Harley A.M, Ribeiro Dos Santos R, Soares M.B. Parasitol Res. 2009;105(1):275-9.
4. Solubility studies of oleanolic acid and betulinic acid in aqueous solutions and plant extracts of Viscum album L. Jäger S, Winkler K, Pfüller U, Scheffler A. Planta Med. 2007;73(2):157-62.
5. Antioxidant small phenolic ingredients in Inonotus obliquus (persoon) Pilat (Chaga). Nakajima Y, Sato Y, Konishi T. Chem Pharm Bull (Tokyo). 2007;55(8):1222-6.
6. Melanin complex from medicinal mushroom Inonotus obliquus (Pers.: Fr.) Pilat (Chaga) (Aphyllophoromycetideae). Bisko N.A, Mitropolskaya N.Y, Ikonnikova N.V. Int J Med Mushr. 2002;4(2):139-145
7. Study of anticarcinogenic properties of Poria obliqua Patalog. Nazarewicz T, Konopa J. Pol. 1961;1:80-82
8. Betulinic acid, a natural compound with potent anticancer effects. Mullauer F.B, Kessler J.H, Medema J.P. Anticancer Drugs. 2010;21(3):215-27. 2010;24(1):90-114.
9. Betulinic acid induces apoptosis in human neuroblastoma cell lines. Schmidt M.L, Kuzmanoff K.L, Ling-Indeck L, Pezzuto J.M. European Journal of Cancer. 1997;33(12):2007–10.
10. Chemistry, biological activity, and chemotherapeutic potential of betulinic acid for the prevention and treatment of cancer and HIV infection. Cichewicz R.H, Kouzi S.A. Med Res Rev. 2004;24(1):90-114
11. Betulinic acid: a new cytotoxic agent against malignant brain-tumor cells. Fulda S, Jeremias I, Steiner H.H, Pietsch T, Debatin K.M. Int J Cancer. 1999;82(3):435-41.
12. Effects of betulinic acid alone and in combination with irradiation in human melanoma cells. Selzer E, Pimentel E, Wacheck V, et al. The Journal of Investigative Dermatology. 2000;114(5):935–40.
13. Betulinic acid – a radiosensitizer in head and neck Squamous cell carcinoma cell lines. Eder-Czembirek C, Erovic B.M, Czembirek C, Brunner M, Selzer E, Pötter R, Thurnher D. Strahlenther Onkol. 2010
14. Medicinal Mushrooms. Hobbs C. 1986. Botanica Press

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