Summary
The studies on antitumor activities of Basidiomycetes
have started at National Cancer Center Reserch Institute
of Japan since 1966. Nowadays, studies on mushrooms have
been world-widely developed. At that times when we started
the studies, it has been said in Japan that solid mushrooms
like Polyporaceae (Saruno-koshikake in Japanese)
were effective for cancer. So we tested such solid mushrooms
by a bioassay to measure the so-called "Host-mediated"
antitumor activities, but the result was not always satisfied,
including Coliolus versiclor (Kawaratake) or Phllinus
lintenus (Meshimakobu).
However, the aqueous extracts of edible mushrooms showed
high growth-inhibitory activity against solid sarcoma
180. Antitumor polysaccarides such as glucans were isolated
from Lentinus sdodes (Shiitake) was named Lentinan
and used clinically by a narrow adaptation in Japan.
Another popular edible mushroom, Flammulina velutipes
(Enokitake) have also high antitumor activity, and polysaccarides
and a low molecular weight protein-bound polysaccaride
(EA6) were isolated. It was demonstrated that EA6 was
active against tumors by oral administration, though not
so effective by i.p. injection. It is proved to be especially
useful by p.o. in combination with surgery and other antitumor
agents. By an antitumor screening test we isolated "proflamin"
from mycelia of F. velutipes, which was highly active
against allogenic and syngenic tumors by p.o. in mice.
It is indicated by an epidemiological study in Nagano
Prefecture, Japan that the cancer death-rate of farmers
producing F. velutipes as a main occupation was remarkably
lower than that of common people in the Prefecture. Detailed
epidemiological study is on-going.
Cancer prevention effect of Hypsizigus marmoreeus
(Bunashimeji), one of the most popular edible mushroom
was investigated. It has also high antitumor activity
and preventive effect for tumor metastasis. Cancer preventive
study of edible mushroom was performed. The control mice
were bred on an ordinary feed and the treated mice with
a feed containing 5% of dried fruit-body of H.marmoreus.
All mice were i.d. injected with strong carcinogen, methyl-cholanthrene,
and carcinogenesis of the mice was investigated. As a
result of the 76-weeks observation, 21 of 36 mice developed
tumors in the control mice, but only 3 of 36 mice in the
treated groups had tumors. The mechanism of cancer inhibitory
and preventive activities of edible mushroom was due to
be effective in cancer prevention and growth-inhibition.
It is said in Oriental traditional medicine from the ancient
times that Medicine and Food have the same origin (Isyoku
Dougen or Yakusyoku Dougen in Japanese).
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