Antioxidant Properties of Fruiting Bodies, Mycelia, and Fermented Products of the Culinary-Medicinal King Oyster Mushroom, Pleurotus eryngii (Higher Basidiomycetes), with High Ergothioneine Content

Abstract

The culinary-medicinal king oyster mushroom Pleurotus eryngii is known to contain ergothioneine, and its products, including fruiting bodies, mycelia, and solid-state fermented products (adlay and buckwheat), were prepared to study their antioxidant properties. Fruiting bodies, regular and Hi-Ergo mycelia, and fermented products contained 2.05, 1.68, 5.76, 0.79-0.80 mg/g of ergothioneine, respectively. On the basis of the results obtained, P. eryngii products had effective antioxidant activity, reducing power, and scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions. Hi-Ergo mycelia was the most effective in the first 3 antioxidant properties in addition to its ergothioneine content. In addition, fruiting bodies were more effective in all antioxidant properties than regular mycelia. For ethanolic and hot water extracts from mycelia and fruiting bodies, the correlation coefficients between total phenol contents and each antioxidant attribute were 0.483-0.921. Overall, P. eryngii products with high amounts of ergothioneine could be used beneficially as a functional food.

Full text

International Journal of Medicinal Mushrooms, 15(3): 267–276 (2013)
267
1045-4403/13/$35.00 © 2013 Begell House, Inc. www.begellhouse.com
Antioxidant Properties of Fruiting Bodies, Mycelia,
and Fermented Products of the Culinary-Medicinal
King Oyster Mushroom, Pleurotus eryngii (Higher
Basidiomycetes), with High Ergothioneine Content
Chih-Hung Liang,1 Kung-Jui Ho,2 Ling-Yi Huang,2 Ching-Hsuan Tsai,2 Shin-Yi Lin,2,3
& Jeng-Leun Mau2,3,*
1Department of Food Science, Tunghai University, Taichung, Taiwan, Republic of China; 2Department of Food
Science and Biotechnology, National Chung-Hsing University, Taichung, Taiwan, Republic of China; 3NCHU-UCD
Plant and Food Biotechnology Program, Biotechnology Center, National Chung Hsing University, Taichung, Taiwan,
Republic of China
*Address all correspondence to: Jeng-Leun Mau, Department of Food Science and Biotechnology, National Chung-Hsing University, 250
Kuokuang Road, Taichung 40227, Taiwan, Republic of China; Tel.: +886-4-2285-4313; Fax: +886-4-2287-6211; jlmau@dragon.nchu.edu.tw.
ABSTRACT: The culinary-medicinal king oyster mushroom Pleurotus eryngii is known to contain ergothioneine,
and its products, including fruiting bodies, mycelia, and solid-state fermented products (adlay and buckwheat), were
prepared to study their antioxidant properties. Fruiting bodies, regular and Hi-Ergo mycelia, and fermented products
contained 2.05, 1.68, 5.76, 0.79–0.80 mg/g of ergothioneine, respectively. On the basis of the results obtained,
P. eryngii products had effective antioxidant activity, reducing power, and scavenging ability on 1,1-diphenyl-2-
picrylhydrazyl radicals and chelating ability on ferrous ions. Hi-Ergo mycelia was the most effective in the rst 3
antioxidant properties in addition to its ergothioneine content. In addition, fruiting bodies were more effective in all
antioxidant properties than regular mycelia. For ethanolic and hot water extracts from mycelia and fruiting bodies,
the correlation coefcients between total phenol contents and each antioxidant attribute were 0.483–0.921. Overall, P.
eryngii products with high amounts of ergothioneine could be used benecially as a functional food.
KEY WORDS: medicinal mushrooms, king oyster mushroom, ergothioneine, Pleurotus eryngii, mycelium, fruiting
body; antioxidant property
ABBREVIATIONS: BHA, butylated hydroxyanisole; DPPH, 1,1-diphenyl-2-picrylhydrazyl; EC50, 50% effective
concentration; Hi-Ergo, high ergothioneine; PFA, Pleurotus eryngii–fermented adlay; PFB, Pleurotus eryngii–
fermented buckwheat
I. INTRODUCTION
The culinary-medicinal king oyster mushroom
Pleurotus eryngii (DC: Fr.) Quél. (Pleurotaceae,
higher Basidiomycetes) is native to southern Europe
and the areas of central Asia and North Africa and is
commercially available in Taiwan. Its longer shelf
life and better consistency, pleasant aroma, and culi-
nary qualities make it preferable to other species of
Pleurotus.1 The proximate composition, volatile a-
vor compounds, and nonvolatile taste components
of this mushroom have been studied previously.2 P.
eryngii showed effective antioxidant activity, reduc-
ing power, scavenging ability on radicals, and che-
lating ability on ferrous ions.3 In addition, the acidic
glycosphingolipid from this mushroom has been
found to stimulate the immune system.4
P. eryngii has been found to contain high amount
of l-ergothioneine (2-mercaptohistidine trimethyl-
betaine), which is a precious amino acid and is asso-
ciated with autoimmune disorders such as rheuma-
toid arthritis and Crohn’s disease.5–7 The compound
also was to be an excellent antioxidant in vivo and a
cellular protector against oxidative damage.8–10 Er-
gothioneine was effective in intrinsic antihydroxyl,
antiperoxyl, and antiperoxynitrite radical antioxi-

International Journal of Medicinal Mushrooms
Liang et al.
268
dant activity.11
Solid-state fermentation was used to provide
the benecial effect of this mushroom in the form
of mycelia with a high amount of ergothioneine.
The mycelium of P. eryngii was inoculated into
cooked grains, and the fermented grain product
was formed after mycelial colonization.12 The grain
used was not only a substrate for the mycelium
but also a nutritional supplement. The mushroom-
fermented products were novel functional foods
that produce benecial effects on human health.
The chemical composition and taste components
of the fermented products were studied.12 In addi-
tion, mycelia with a high amount of ergothioneine
in submerged culture were prepared.13 However,
the antioxidant properties of Pleurotus-fermented
products and high-ergothioneine (Hi-Ergo) my-
celia are not available. Accordingly, our objective
was to prepare the ethanolic and hot water extracts
from Pleurotus-fermented products and Hi-Ergo
mycelia and to determine their antioxidant prop-
erties, including antioxidant activity, reducing
power, scavenging ability on radicals, and chelat-
ing ability on ferrous ions, compared with those of
regular mycelia and fruiting bodies.
II. MATERIALS AND METHODS
A. Fruiting Bodies, Mycelia, and Grains
Fruiting bodies and mycelia of P. eryngii were ob-
tained from Q-Yo Bio-Technology Farm (Pusin,
Chunghua, Taiwan), which is the major mushroom
farm producing the king oyster mushroom in Tai-
wan. Fresh mushrooms were pulled off the jar and
cut into fruiting bodies and the bases as described
elsewhere.2 The mycelia were maintained on pota-
to dextrose agar (Difco Laboratories, Sparks, MD)
at 25°C. For the production of regular mycelia, the
culture was inoculated at the rate of 10% into a
250-mL ask containing 100 mL of liquid medium
and incubated at 25°C and 125 rpm. The liquid
medium contained the following (per liter): 20 g
glucose, 5 g yeast extract, 2 g ammonium sulfate,
0.5 g monopotassium sulfate, 0.5 g dipotassium
phosphate, and 0.5 g magnesium sulfate. After 14
days of incubation, the mycelia were harvested and
washed 5 times with deionized water and freeze-
dried as regular mycelia.13
For mass production of mycelia, a fermentor
with a 10-L capacity (7-L working volume; MG-
1000SL, Micro-Giant Technology Co., Taichung,
Taiwan) was used. The fermentation conditions
were set at 25°C with an aeration rate of 1 vvm and
an agitation speed of 150 rpm. A 10% inoculum
rate was used and 4 mM histidine was added at day
7. After 20 days of fermentation, the mycelia in the
fermentor were harvested and washed 5 times with
deionized water then freeze dried as Hi-Ergo my-
celia.13 In addition, adlay (also called Job’s Tears
[Coix lacryma-jobi], coixseed, tear grass, adlay,
or adlai), a tall, grain-bearing tropical plant of the
family Poaceae that is native to Southeast Asia,
and buckwheat were purchased at a local market in
Taichung City, Taiwan, and were autoclaved and
freeze-dried as controls.
B. Fermented Grains
The fermented samples were prepared following
the optimal conditions described elsewhere.12 The
culture was homogenized in a Waring blender and
inoculated into autoclaved adlay or buckwheat
with 40% or 45% water (w/w) added, respectively.
P. eryngii–fermented adlay (PFA) or P. eryngii–
fermented buckwheat (PFB) then was produced
after the colonization of fungal mycelia for 17 days
at 30°C. For each of PFA, PFB, adlay, buckwheat,
regular mycelia, Hi-Ergo mycelia, fruiting bodies,
and the bases of fruiting bodies, 3 dried samples
(~50 g each) were selected randomly and ground
into a coarse powder (0.4 μm) using a RT-34 pul-
verizing machine (Rong Tsong Precision Technol-
ogy Co., Taichung, Taiwan).
C. Preparing Extracts
For ethanolic extraction, a subsample (10 g) from
8 types of products was extracted by stirring with
100 mL of 95% ethanol at 25°C at 100 rpm for 24
hours and ltering through Whatman No. 1 lter
paper. The residue then was extracted with 2 ad-

Volume 15, Number 3, 2013
Antioxidant properties of Pleurotus eryngii 269
ditional 100-mL portions of ethanol, as described
above. The combined ethanolic extracts were ro-
tary evaporated at 40°C to dryness. For hot water
extractions, a subsample (10 g) was extracted by
stirring with 100 mL of boiling water at 100°C at
100 rpm for 10 minutes, centrifuging at 5000 ×g
for 15 minutes, and ltering through Whatman No.
1 lter paper. The residue then was extracted with
2 additional 100-mL portions of boiling water, as
described above. The combined hot water extracts
were freeze-dried. The dried extract was used di-
rectly for analysis of antioxidant components or
was redissolved in water or ethanol to a concentra-
tion of 50 mg/mL and stored at 4°C for later use.
D. Ergothioneine Assay
Ergothioneine was determined according to meth-
ods described previously.9,12 Ergothioneine content
was quantied by the calibration curve of the au-
thentic compound.
E. Determining Antioxidant Properties
Antioxidant activity was determined using the
conjugated diene method.14 The antioxidant ac-
tivity assayed is the ability of the extracts from 8
types of products to inhibit the peroxidation of lin-
oleic acid, in which the double bond is converted
into conjugated diene. Reducing power was deter-
mined according to a method described previous-
ly. 15 The reducing power assayed is the ability of
the extracts to form a colored complex with ferri-
cyanide, which is an electron acceptor. Scavenging
ability on 1,1-diphenyl-2-picrylhydrazyl (DPPH)
radicals was determined using a method described
elsewhere.16 The scavenging ability assayed is the
ability of the extracts to react with DPPH radicals
and reduce most DPPH radical molecules. Ascor-
bic acid, butylated hydroxyanisole (BHA), and
α-tocopherol were used for comparison.
Chelating ability was determined according to
a method described previously.17 Ferrous ions play
an important role as catalysts in the oxidative pro-
cess, leading to the formation of hydroxyl radicals
and hydroperoxide decomposition by Fenton re-
action. The chelating ability assayed is the ability
of the extracts to inhibit the complex formation of
ferrozine with ferrous ions. Citric acid and ethyl-
enediaminetetraacetic acid were used for compari-
son. At a 50% effective concentration (EC50; the
concentration at which the antioxidant activity was
inhibited by 50%), the absorbance was 0.5 mg ex-
tract/mL for reducing power; DPPH radicals were
scavenged by 50%; and ferrous ions were chelated
by 50%, respectively. The EC50 value was obtained
by interpolation from linear regression analysis.
F. Determining Antioxidant Components
Total phenols and avonoids were determined ac-
cording to methods described previously.18,19 Con-
tent of components was calculated on the basis of
the calibration curve of the corresponding authen-
tic compounds, and gallic acid and quercetin were
used for total phenol and avonoids, respectively.
G. Statistical Analysis
For 1 of 8 types of products, 3 samples were pre-
pared for assays of every antioxidant attribute and
analyses of ergothioneine, total phenol, and a-
vonoid content. The experimental data were sub-
jected to a one-way analysis of variance for a clas-
sication design to determine the least signicant
difference using the SAS program (SAS Institute
Inc., Cary, NC) at a level of 0.05. Linear regres-
sion analysis was completed to obtain a correla-
tion coefcient (r) between the EC50 value of each
antioxidant attribute and total phenol or avonoid
contents.
III. RESULTS AND DISCUSSION
A. Contents of Ergothioneine
Adlay and buckwheat did not contain ergothione-
ine, whereas PFA and PFB contained substantial
amounts of ergothioneine (0.79–0.80 mg/g) as
a result of P. eryngii mycelial growth (Table 1).
Fruiting bodies contained higher amount of ergo-
thioneine than the base. It seems that as the mush-

International Journal of Medicinal Mushrooms
Liang et al.
270
rooms grew, the ergothioneine was synthesized and
accumulated more in the top part of the fruiting
bodies instead of in the base. In addition, regular
mycelia contained less ergothioneine than fruiting
bodies. However, through the optimal culture prac-
tice,13 Hi-Ergo mycelia contained higher (3.4-fold)
ergothioneine content than regular mycelia, as ex-
pected. Fruiting bodies, mycelia, and fermented
products of this king oyster mushroom seem to be
rich sources of ergothioneine.
B. Extraction Yield
Extraction yields were higher using hot water
(15.78–56.12%) instead of ethanol (1.55–20.54%)
as the extracting solvent (Table 2). The higher
yields of hot water extracts from 8 types of prod-
ucts might be because these products contained
more water-soluble substances. For both ethanolic
and hot water extracts, the yields from fermented
products and grains were lower than those from
fruiting bodies and mycelia, whereas those from
mycelia were lower than those from fruiting bod-
ies. For both ethanolic and hot water extracts, the
yields from fermented products were higher than
those from grains as a consequence of mycelial
growth. During the metabolic process of fermen-
tation on the grains, mycelia excreted hydrolyzing
enzymes such as cellulose and amylase, leading to
more extractable solids.20
C. EC50 Values in Antioxidant Properties
The antioxidant properties assayed herein are
summarized in Table 3, and the EC50 values (mil-
ligrams dry weight of various extracts per millili-
ter) were calculated for comparison. The effective-
ness of extracts in antioxidant properties inversely
correlated with their EC50 values. With regard to
the EC50 values of antioxidant activities, the etha-
nolic extract from adlay was more effective than
that from PFA, whereas the hot water extract from
adlay was less effective than that from PFA. Both
extracts from buckwheat were more effective than
those from PFB. In addition, both extracts from
regular mycelia were less effective than those from
fermented products, fruiting bodies, and the base.
Surprisingly, both extracts from Hi-Ergo myce-
lia showed higher antioxidant activity than those
from regular mycelia, fermented products, and
fruiting bodies. In general, grains showed better
antioxidant activity using the conjugated diene
method.14–16 After mycelial growth, the fermented
products showed higher antioxidant activity than
regular mycelia. It is obvious that grain substrate
was responsible for the effective antioxidant activ-
ity of its fermented product. However, EC50 values
of BHA and α-tocopherol were both <0.25 mg/mL,
TABLE 1. Ergothioneine Content of Adlay, Buckwheat, Fruiting
Bodies, Base of Fruiting Bodies, Regular Mycelia, High-Ergothioneine
Mycelia, Fermented Adlay, and Fermented Buckwheat of Pleurotus eryngii
Sample Content (mg/g dry weight)
Adlay ND
PFA 0.80 ± 0.05 D
Buckwheat ND
PFB 0.79 ± 0.05 D
Regular mycelium 1.68 ± 0.11 C
Hi-Ergo mycelium 5.76 ± 0.07 A
Fruiting body 2.05 ± 0.04 B
Base of fruiting body 1.74 ± 0.05 C
Each value is expressed as mean ± standard error (n = 3). Means with same
letter within a column are not signicantly different (P > 0.05).
Hi-Ergo mycelium, mycelium with high ergothioneine content; ND, not detected;
PFA, P. eryngii–fermented adlay; PFB, P. eryngii–fermented buckwheat.

Volume 15, Number 3, 2013
Antioxidant properties of Pleurotus eryngii 271
whereas that of ascorbic acid was 15.6 mg/mL.
With regard to the reducing power, EC50 values
of the ethanolic extracts from PFA and PFB were
higher than those from their corresponding grains,
but EC50 values of the hot water extracts showed
the reverse pattern. Both extracts from grains and
fermented products were less effective than those
from mycelia and fruiting bodies. The ethanolic
extract from regular mycelia was less effective
than those from fruiting bodies, whereas the hot
water extract from regular mycelia was more ef-
fective than those from fruiting bodies. Amazingly,
both extracts from Hi-Ergo mycelia showed the
most effective reducing power. However, EC50 val-
ues of ascorbic acid, BHA, and α-tocopherol were
0.13, 0.18, and 0.05 mg/mL, respectively.
With regard to the scavenging ability on DPPH
radicals, EC50 values of the ethanolic extracts from
8 types of products ranged from 0.66 to 5.17 mg/
mL, whereas those of the hot water extracts ranged
from 2.42 to 27.82 mg/mL. It seems that the etha-
nolic extracts were more effective than their cor-
responding hot water extracts. Both extracts from
PFA and PFB showed a similar effectiveness be-
tween grains and regular mycelia. Similarly, both
extracts from Hi-Ergo mycelia showed the most
effective scavenging ability. However, EC50 values
of BHA and α-tocopherol were both <0.27 mg/mL,
whereas that of ascorbic acid was 13.5 mg/mL.
With regard to the chelating ability on ferrous
ions, EC50 values of the ethanolic extracts from 8
types of products were divided into 4 groups (in
descending order): regular and Hi-Ergo mycelia
> PFA and PFB > adlay and buckwheat > fruit-
ing bodies and the base. For EC50 values of the hot
water extracts, 4 different groups were found (in
descending order): fruiting bodies, Hi-Ergo myce-
lia, and the bases > adlay > PFA, regular myce-
lia, and buckwheat > PFB. It was found that the
ethanolic extracts were more effective than the hot
water extracts. Both extracts from Hi-Ergo myce-
lia were not least effective in the chelating ability.
However, EC50 values of ethylenediaminetetraace-
tic acid and citric acid were 0.25 and 25.9 mg/mL,
respectively.
Overall, Hi-Ergo mycelia showed the most ef-
fective antioxidant activity, reducing power, and
scavenging ability, but the least effective chelating
ability, in addition to its high content of ergothio-
neine. All antioxidant properties assayed for fruit-
ing bodies and the bases were more effective than
those for regular mycelia. In addition, fermented
products seemed to retain the better antioxidant
properties of grains and regular mycelia. These
TABLE 2. Extraction Yield of the Extracts from Adlay, Buckwheat, Fruiting Bodies, Base of Fruiting
Bodies, Regular Mycelia, High-Ergothioneine Mycelia, Fermented Adlay, and Fermented Buckwheat of
Pleurotus eryngii
Sample
Extraction Yield (%, w/w)
Ethanolic Hot Water
Adlay b1.55 ± 0.13 F a20.26 ± 2.32 F
PFA b2.41 ± 0.13 E a27.57 ± 1.77 E
Buckwheat b5.12 ± 0.49 D a15.78 ± 1.40 G
PFB b5.33 ± 0.44 D a22.27 ± 0.96 F
Regular mycelium b10.01 ± 0.31 C a35.41 ± 0.20 D
Hi-Ergo mycelium b14.23 ± 0.18 B a46.49 ± 0.13 C
Fruiting body b14.82 ± 0.18 B a56.12 ± 0.13 A
Base of fruiting body b20.54 ± 0.32 A a50.88 ± 0.81 B
Each value is expressed as mean ± standard error (n = 3). Means with same lower case letter within a row
are not signicantly different (P > 0.05). Means with same capital letter within a column are not signicantly
different (P > 0.05).
Hi-Ergo mycelium, mycelium with high ergothioneine content; PFA, P. eryngii–fermented adlay; PFB, P. eryn-
gii–fermented buckwheat.

International Journal of Medicinal Mushrooms
Liang et al.
272
8 types of products showed effective antioxidant
properties.
D. Total Phenol and Flavonoid Content
The total phenol content was higher in ethanolic
and hot water extracts from regular and Hi-Ergo
mycelia than in those from fruiting bodies and the
bases (Table 4) and was higher in both extracts
from fermented products than in those from grains.
It is obvious that the higher total phenol contents
were the result of mycelial growth. With regard to
the avonoid contents of the hot water extracts,
buckwheat and Hi-Ergo mycelia had higher con-
tent than the rest of products, which were <2 mg/g.
However, avonoids were not detected in the etha-
TABLE 3. EC50 Values of Antioxidant Properties of the Extracts from Adlay, Buckwheat, Fruiting
Bodies, Base of Fruiting Bodies, Regular Mycelia, High-Eergothioneine Mycelia, Fermented Adlay, and
Fermented Buckwheat of Pleurotus eryngii
Extract
EC50 value a (mg extract/mL) of sample
Adlay PFA Buckwheat PFB
Regular
mycelium
Hi-Ergo
mycelium
Fruiting
body Base
Ethanolic
Antioxidant
activity
d4.21
±
0.19B
b35.76 ±
3.11A
d3.36 ±
0.25A
c17.71
±
0.22A
a51.40 ±
9.22Ac
d6.26 ±
0.36A
c17.06 ±
0.40A
c17.94
±
0.10A
Reducing
power
c18.25
±
0.11B
a22.70 ±
0.29A
d11.16 ±
0.08A
b21.73
±
0.15A
e9.18 ±
0.03A
h3.33 ±
0.03A
f7.01 ±
0.01B
g5.90
±
0.07B
Scavenging
ability
b3.69
±
0.12B
e2.31 ±
0.20B
f2.10 ±
0.09B
c2.66
±
0.08B
de2.47 ±
0.03B
g0.66 ±
0.01B
cd2.53 ±
0.01B
a5.17
±
0.09B
Chelating
ability
d3.83
±
0.10B
c9.18 ±
0.21B
de3.44 ±
0.12B
c9.60
±
0.62A
a18.50 ±
1.05A
b15.18 ±
0.07B
ef2.88 ±
0.01B
f2.48 ±
0.03B
Hot water
Antioxidant
activity
a20.26
±
0.06A
c13.51 ±
0.15B
f3.39 ±
0.03A
f4.24 ±
0.15B
b19.06 ±
1.64B
f3.87 ±
0.19B
e6.86 ±
0.11B
d11.18
±
0.38B
Reducing
power
a41.57
±
0.08A
b15.90 ±
0.24B
e5.72 ±
0.05B
e5.66
±
0.07B
f2.21 ±
0.02B
g2.00 ±
0.03B
c7.26 ±
0.01A
d6.80
±
0.09A
Scavenging
ability
a25.45
±
4.60A
b19.24 ±
3.07A
cd10.82 ±
1.07A
e5.63
±
0.64A
a27.82 ±
5.13A
e2.42 ±
0.25A
c13.47 ±
0.37A
de7.10
±
0.24A
Chelating
ability
d21.05
±
0.55A
e12.99 ±
1.78A
e11.10 ±
0.68A
f4.13
±0.12B
e11.42 ±
1.96B
b74.63 ±
3.64A
a80.47 ±
3.33A
c51.89
±
2.15A
a At EC50, the effective concentration at which the antioxidant activity was 50%, the absorbance was 0.5 for
reducing power, the 1,1-diphenyl-2-prcrylhydrazyl radicals were scavenged by 50%, and ferrous ions were
chelated by 50%. EC50 was obtained by interpolation from linear regression analysis (for bold values, EC50
was obtained by extrapolation from linear regression analysis). Each value is expressed as mean ± standard
error (n = 3). Means with the same lower case letter within a row are not signicantly different (P > 0.05).
Means with same capital letter within a column of the same antioxidant attribute are not signicantly different
(P > 0.05).
Hi-Ergo mycelium, mycelium with high ergothioneine content; PFA, P. eryngii–fermented adlay; PFB, P. eryn-
gii–fermented buckwheat.

Volume 15, Number 3, 2013
Antioxidant properties of Pleurotus eryngii 273
nolic extracts.
The comparable total phenol content in the
ethanolic extracts from adlay and buckwheat could
explain their comparable antioxidant properties
(shown in Table 3). Similarly, the comparable total
phenol content in the ethanolic extracts from PFA
and PFB could explain their comparable antioxi-
dant properties, except for antioxidant activity. The
higher total phenol and avonoid content in the hot
water extract from buckwheat than those from ad-
lay were consistent with their antioxidant proper-
ties. Again, the total phenol and avonoid content
was higher in the hot water extract from PFB than
that from PFA, which was consistent with their
antioxidant properties. However, the total phenol
content in both extracts of fruiting bodies and the
bases were not consistent with their antioxidant
properties. On the contrary, the lower contents in
both extracts from Hi-Ergo mycelia than those
from regular mycelia were inversely consistent
with their more effective antioxidant activity, re-
ducing power, and scavenging ability. However, a
moderate correlation between antioxidant capaci-
ties and ergothioneine was found (R = 0.60–71).9
It seems that some phenolic component in Hi-Ergo
mycelia might be responsible for these better anti-
oxidant properties.
Phenols include butylated hydroxytolune
and gallate, which are known to be effective an-
tioxidants.22 Tsai et al.23 found that contents of
total antioxidant components were moderately to
highly associated (r = 0.636–0.907) with antioxi-
dant properties. Furthermore, Dubost et al.9 found
a high correlation between oxygen radical absor-
bance capacity and polyphenols (R = 0.93). There-
fore, total phenols in extracts were responsible for
their effective antioxidant properties.
Because of wide variations found in the effec-
tiveness of antioxidant properties, the correlation
between total phenols and each antioxidant attri-
bute was not established for the 2 extracts from 8
types of products. However, these 8 types of prod-
TABLE 4. Total Phenol and Flavonoid Contents of the Extracts from Adlay, Buckwheat, Fruiting
Bodies, Base of Fruiting Bodies, Regular Mycelia, High-Ergothioneine Mycelia, Fermented Adlay, and
Fermented Buckwheat of Pleurotus eryngii
Extract Sample
Content (mg/g) of Sample
Total Phenols Flavonoids
Ethanolic Adlay 7.09 ± 0.47C ND
PFA 9.93 ± 0.56B ND
Buckwheat 7.76 ± 0.47C ND
PFB 9.53 ± 0.04B ND
Regular mycelium 12.65 ± 0.82A ND
Hi-Ergo mycelium 7.26 ± 0.08C ND
Fruiting body 4.47 ± 0.01D ND
Base of fruiting body 2.46 ± 0.07E ND
Hot water Adlay 2.61 ± 0.04H 0.35 ± 0.01F
PFA 5.96 ± 0.15E 0.58 ± 0.06E
Buckwheat 12.61 ± 0.13C 6.13 ± 0.07A
PFB 13.41 ± 0.14B 1.32 ± 0.07D
Regular mycelium 17.26 ± 0.66A 1.30 ± 0.09D
Hi-Ergo mycelium 6.87 ± 0.06D 4.61 ± 0.09B
Fruiting body 5.24 ± 0.02F 1.96 ± 0.04C
Base of fruiting body 3.79 ± 0.07G 1.97 ± 0.03C
Each value is expressed as mean ± standard error (n = 3). Means with same letter within a column of the
same extract are not signicantly different (P > 0.05).
Hi-Ergo mycelium, mycelium with high ergothioneine content; ND, not detected; PFA, P. eryngii–fermented
adlay; PFB, P. eryngii–fermented buckwheat.

International Journal of Medicinal Mushrooms
Liang et al.
274
ucts were not homologous in nature. When only 4
types of products—regular and Hi-Ergo mycelia,
fruiting bodies, and the bases—were considered,
the correlation coefcient (R) between total phe-
nol content and EC50 values of antioxidant activity,
reducing power, scavenging ability, and chelating
ability was 0.749, 0.483, 0.512, and 0.921 for the
ethanolic extracts and 0.779, 0.684, 0.854, and
0.840 for the hot water extracts, respectively. The
identication of individual phenolic compounds
responsible for the effective antioxidant properties
in these 4 types of products, particularly in Hi-Er-
go mycelia, will be another area of investigation.
IV. CONCLUSIONS
In this research, P. eryngii products, including
fruiting bodies, mycelia, and fermented products,
contained substantially high amounts of ergothi-
oneine. On the basis of EC50 values obtained, P.
eryngii products had effective antioxidant activ-
ity, reducing power, scavenging ability on DPPH
radicals, and chelating ability on ferrous ions. In
addition, adlay and buckwheat have more effective
antioxidant activity. Among P. eryngii products,
Hi-Ergo mycelia was shown to be the most effec-
tive of the rst 3 antioxidant properties in addition
to its high ergothioneine content. However, fruiting
bodies and the bases were more effective than reg-
ular mycelia in all antioxidant properties assayed.
For ethanolic and hot water extracts from mycelia
and fruiting bodies, the correlation coefcients be-
tween total phenol content and EC50 values of each
antioxidant attribute were 0.483–0.921. Overall,
these P. eryngii products with substantial amounts
of ergothioneine and alleged antioxidant properties
could be benecially used as food-avoring mate-
rials and food ingredients or as nutritional supple-
ments.
ACKNOWLEDGMENTS
This study was supported by the National Sci-
ence Council, Republic of China (Grant no. NSC
97-2313-B-005-028-MY3; NSC 101-2911-I-005-
301). We thank Mr. Shih-Wen Fang, Q-Yo Bio-
Technology Farm, for providing mushrooms.
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