Chem. Pharm. Bull. 55(8) 1222—1226 (2007)

banoanatake or Chaga in Japan) is a fungus habiting as parasitism on birch in the cold latitudes of Europe, Japan and Korea. In Russia, the black shapeless overgrowth of fungus after 10—15 years of parasitism on trunks, mostly of birch, is usually called Chaga and has been used for medicinal preparations. Recently, many reports have been published concerning the health promoting functions of Chaga, for example, protection of DNA damage from oxidative stress, anti-inflammatory, anti-nociceptive and anti-tumor activities. However, no report has been published on the chemical structures of active ingredients from Chaga except some terpenoids until now. On the other hand, it is known oxidative stress is involved in variety of disorders such as cancer, hypertension, neurodegenerative (Alzheimer’s and Parkinson’s disease) and autoimmune diseases, and thus many antioxidant ingredients from foods or other natural sources are being challenged for diseases protection and treatment. In this context, antioxidant property of Chaga attracts much attention. Although it was reported that polyphenolic fraction of Chaga extract showed antioxidant activity, the structures of the antioxidant principle were left unclear. Chaga is comprised of two eye-distinguishable parts, black (mainly outside) and brown (mainly inside) that were previously classified as Sclerotium (ST) and Fruiting body (FB), respectively, by T. Mizuno et al., but most of Chaga products in Japan were processed without distinguish them. Therefore, in the present study, the antioxidant potential of hot water extract (decoction) of Chaga was compared first with those of other medicinal fungi (Agaricus blazei Mycelia, Ganoderma lucidum and Phellinus linteus). Then, ST and FB parts were separated and precisely examined their antioxidant property to identify the antioxidant ingredients.