Inonotus obliquus (Hymenochaetaceae family) has a long and storied history in both Eastern Europe and China as a potent folk medicine.  Referred to colloquially as Chaga (Russian) or Kabanoanatake (Japan), the tea of this medicinal mushroom was historically used to treat numerous diseases and disease states including tumors and cancerous growths, cardiovascular disease, liver disease, tuberculosis and various gastrointestinal diseases[i],[ii].

Found on birch trees (Betula spp.) in the Northern hemisphere,  Inonotus obliquus has a characteristic “burnt charcoal” appearance that is easy to spot.  The conch appearance includes a black outer shell or sclerotium and a brown-coloured fruiting body.  No stalk is evidenced on this fungus.  Often described as parasitic, some debate exists over whether the fungus is found on living or deceased trees[iii]^,[iv].  Having found this species numerous times, it appears that the fungus grows on  sick or injured plants with a distribution that includes both dead and living Betula species –more often occurring on the latter.

A recent review of the literature has demonstrated significant medicinal promise.  The following therapeutic benefits can at this time be attributed to the Inonotus obliquus species: anti-cancer benefits, hypoglycemic effects, anti-viral, immune-stimulating, anti-platelet aggregative effects, anti-inflammatory and anti-oxidant.[v]^,[vi],,[vii]

Inroads into the mechanism of action surrounding the numerous potential health benefits associated with Inonotus are being made, but as of yet, precise pharmacological activities have yet to fully surmised.  The chemical constituents associated with Inonotus obliquus’ medicinal actions are numerous and include polysaccharides, peptides, phenolics, terpenoids, b-glucan and inotodiol.[viii]^,[ix],[x]

The medicinal promise of Inonotus obliquus may be greatest in the treatment and/or prevention of human cancer.  Interestingly, studies isolating both the lanostane-type triterpenoids[xi] and the phenolic compounds[xii] have shown significant apoptotic ability and cancer cell toxicity.  For the purposes of this paper, I will focus on the latter phenolic compounds.

Seven anti-oxidant phenolics have been extracted and identified in the Inonotus spp.  These include 2,5 –hidydroxyterephthalic acid (DTA), protocatechuic acid (PCA), 3,4-dihydroxybenzaldehyde (DB), syringic acid (SA), caffeic acid (CA), 3,4-dihydroxybenzalacetone (DBL) and 4-hydroxy-3,5-dimethoxybenzoic acid 2-hydroxy-1-hydroxymethyl ethyl ester (BAEE) (See figure 1)[xiii].

In a study conducted by Nakajima et al (2009), the researchers examined the cytotoxicity of the above phenolic compounds as derived from both the outer sclerotium and the internal fruiting body against various human cancer lines.  Compounds extracted using both a decoction and MeOH extraction were also found to be cytotoxic to the studied cancer lines. The decoctions induced apoptosis while the extracted lines seemed to decrease cancer via cell necrosis.  Of particular interest was that in both the decoction and extraction samples, it was the sclerotium which demonstrated greater cytotoxic effects.  Also of note was that all phenolics tested non-toxic towards the normal cell lines.

---

[i] Zhong, XH et al. Progress of Research on Inonotus Obliquus (Review). Chin J Integr Med 2009 Apr;15(2):156-160.

 

 

 

[ii] Van Q et al. Anti-inflammatory effect of Inotus obliquus, Polygala senaga L., and Vibrunum trilobum in a cell screening assay.   J Ethnopharmacology 125 (2009) 487-493.

[iii] http://en.wikipedia.org/wiki/Chaga_mushroom

[iv] http://www.chagamushroom.com/

[v] Zhong, XH et al. Progress of Research on Inonotus Obliquus (Review). Chin J Integr Med 2009 Apr;15(2):156-160.

[vi] Van Q et al. Anti-inflammatory effect of Inotus obliquus, Polygala senaga L., and Vibrunum trilobum in a cell screening assay.   J Ethnopharmacology 125 (2009) 487-493.

[vii] Youn MJ et al. Chaga mushroom (Inontus obliquus) induces G0/G1 arrest and apoptosis in human hepatoma HepG2 cells.  World J Gastroenterol. 2008 Jan 28;14(4):511-7.

[viii] Nakajima Y et al. Cancer Cell Cytotoxicity of Extracts and Small Phenolic Compounds from Chaga[Inonotus obliquus (person) Pilat] J Med Food 12 93) 2009, 501-507.

[ix] Zhong, XH et al. Progress of Research on Inonotus Obliquus (Review). Chin J Integr Med 2009 Apr;15(2):156-160.

[x] Taji S et al. Lanostane-type triterpenoids from the sclerotia of Inonotus obliquus possessing anti-tumor promoting activity.  Eur J Med Chem 43(2008) 2373-2379

[xi] Taji S et al. Lanostane-type triterpenoids from the sclerotia of Inonotus obliquus possessing anti-tumor promoting activity.  Eur J Med Chem 43(2008) 2373-2379

[xii] Nakajima Y et al. Cancer Cell Cytotoxicity of Extracts and Small Phenolic Compounds from Chaga[Inonotus obliquus (person) Pilat] J Med Food 12 93) 2009, 501-507.

[xiii] Nakajima Y et al. Cancer Cell Cytotoxicity of Extracts and Small Phenolic Compounds from Chaga[Inonotus obliquus (person) Pilat] J Med Food 12 93) 2009, 501-507.