Biological Effects Antitumor Activity
Edible Mushroom Maitake (Grifola frondosa)
Maitake is one of the most popular mushrooms used as a medicine, and is now
easily available in numerous stores throughout the year because of the artificial
cultivation. An American book recently outlined maitake’s medicinal effects, but it
stated that there has been no reliable research to determine whether any of these
ancient beliefs are really true or not and that formal safety studies have not been
performed [1]. We maintain that the safety of maitake does not need to be ques-
tioned because it has been taken daily by many people for generations and no cas-
es of medical problems have been reported to date.
In our laboratory, boiled water extracts of maitake showed anticancer activity
with a cure rate at 60% against Meth A tumor of BALB/c mice, using three intratu-
mor injections of 5 mg (Table 4.7). The ethanol precipitate (ET-pre) from the boiled
water extracts was stronger in therapeutic potency than that of the boiled water ex-
tracts, and its cure rate was 80%, using three intratumor injections of 1 mg [21]
(Table 4.8).
The ET-pre was further fractionated into the low (s-R) and high (r-R) molecular
RNA, and the water-soluble b-glucan (ASAS). The antitumor potencies of these
components were verified and are summarized in Table 4.9 [22].
Since the boiled water extracts did not show cytotoxicity against Meth A tumor
cells, maitake extracts probably strengthen the immune system in vivo to inhibit
the growth of tumors.
4.3 Mushroom 89
Table 4.7 Antitumor potency of boiled water extracts of maitake against Meth A
tumor of BALB/c mice.
Treatment Cure rate Tumor size in noncured mice (mm2)
Experiment 1
500 mg, 3 shots 0/5 534
5 mg, 3 shots 1/5 220
Control (no treatment) 0/5 527
Experiment 2
5 mg, 3 shots 1/5 116
Control 0/5 375
Experiment 3
5 mg, 3 shots 3/5 47
Control 0/5 457
Mice were treated with sample on days 2, 4 and 6 after tumor transplantation. Antitumor potency
was evaluated three weeks after tumor transplantation.
Table 4.8 Antitumor potency of ethanol precipitates of maitake against Meth A tumor.
Dosage Cure rate
ET-pre (1 mg, 3 shots) 4/5
Ether-washed ET-pre. (1 mg, 3 shots) 1/5
Control 0/5
ET-pre, ethanol precipitate.
Mice were treated with sample on days 2, 4 and 6 after tumor transplantation. Antitumor potency
was evaluated three weeks after tumor transplantation.
A principal constituent in maitake extracts with antitumor activity is considered
to be â-d-glucan, which might affect the human immune system in complex ways
[2]. However, our data showed that the RNA fraction in maitake extracts was more
effective in antitumor activity than that of â-glucan (Table 4.9), suggesting that the
RNA also contributes substantially to the antitumor activity of maitake, working to-
gether with â-glucan.
Effectiveness of Maitake’s extracts is suggested against the liver cancer, breast
cancer and leukemia, and stomach and brain cancer were less responsive to
Maitake’s treatment. Other proposed uses of Maitake are for diabetes, hyperten-
sion, high level of cholesterol, however, clinically definitive scientific evidences
should deserve further serious investigations that Maitake really functions in this
way [2].
Other proposed uses for maitake are for diabetes, hypertension, high levels of
cholesterol, but scientific evidence of these effects is lacking.
Edible Mushroom Maitake (Grifola frondosa)
Maitake is one of the most popular mushrooms used as a medicine, and is now
easily available in numerous stores throughout the year because of the artificial
cultivation. An American book recently outlined maitake’s medicinal effects, but it
stated that there has been no reliable research to determine whether any of these
ancient beliefs are really true or not and that formal safety studies have not been
performed [1]. We maintain that the safety of maitake does not need to be ques-
tioned because it has been taken daily by many people for generations and no cas-
es of medical problems have been reported to date.
In our laboratory, boiled water extracts of maitake showed anticancer activity
with a cure rate at 60% against Meth A tumor of BALB/c mice, using three intratu-
mor injections of 5 mg (Table 4.7). The ethanol precipitate (ET-pre) from the boiled
water extracts was stronger in therapeutic potency than that of the boiled water ex-
tracts, and its cure rate was 80%, using three intratumor injections of 1 mg [21]
(Table 4.8).
The ET-pre was further fractionated into the low (s-R) and high (r-R) molecular
RNA, and the water-soluble b-glucan (ASAS). The antitumor potencies of these
components were verified and are summarized in Table 4.9 [22].
Since the boiled water extracts did not show cytotoxicity against Meth A tumor
cells, maitake extracts probably strengthen the immune system in vivo to inhibit
the growth of tumors.
4.3 Mushroom 89
Table 4.7 Antitumor potency of boiled water extracts of maitake against Meth A
tumor of BALB/c mice.
Treatment Cure rate Tumor size in noncured mice (mm2)
Experiment 1
500 mg, 3 shots 0/5 534
5 mg, 3 shots 1/5 220
Control (no treatment) 0/5 527
Experiment 2
5 mg, 3 shots 1/5 116
Control 0/5 375
Experiment 3
5 mg, 3 shots 3/5 47
Control 0/5 457
Mice were treated with sample on days 2, 4 and 6 after tumor transplantation. Antitumor potency
was evaluated three weeks after tumor transplantation.
Table 4.8 Antitumor potency of ethanol precipitates of maitake against Meth A tumor.
Dosage Cure rate
ET-pre (1 mg, 3 shots) 4/5
Ether-washed ET-pre. (1 mg, 3 shots) 1/5
Control 0/5
ET-pre, ethanol precipitate.
Mice were treated with sample on days 2, 4 and 6 after tumor transplantation. Antitumor potency
was evaluated three weeks after tumor transplantation.
A principal constituent in maitake extracts with antitumor activity is considered
to be â-d-glucan, which might affect the human immune system in complex ways
[2]. However, our data showed that the RNA fraction in maitake extracts was more
effective in antitumor activity than that of â-glucan (Table 4.9), suggesting that the
RNA also contributes substantially to the antitumor activity of maitake, working to-
gether with â-glucan.
Effectiveness of Maitake’s extracts is suggested against the liver cancer, breast
cancer and leukemia, and stomach and brain cancer were less responsive to
Maitake’s treatment. Other proposed uses of Maitake are for diabetes, hyperten-
sion, high level of cholesterol, however, clinically definitive scientific evidences
should deserve further serious investigations that Maitake really functions in this
way [2].
Other proposed uses for maitake are for diabetes, hypertension, high levels of
cholesterol, but scientific evidence of these effects is lacking.
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