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Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the medicinal fungus Wolfiporia cocos from China
Journal Pre-proof Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the medicinal fungus Wolfiporia cocos from China Jerzy Falandysz, Martyna Saba, Ji Zhang, Anetta Hanć PII:
S0045-6535(20)30120-X
DOI:
https://doi.org/10.1016/j.chemosphere.2020.125928
Reference:
CHEM 125928
To appear in:
ECSN
Received Date: 7 November 2019 Revised Date:
9 January 2020
Accepted Date: 13 January 2020
Please cite this article as: Falandysz, J., Saba, M., Zhang, J., Hanć, A., Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the medicinal fungus Wolfiporia cocos from China, Chemosphere (2020), doi: https://doi.org/10.1016/j.chemosphere.2020.125928. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Credit author statement
Jerzy Falandysz: Conceptualization, Formal analysis, Resources, Visualization Preparation, Writing - Original Draft Preparation, Review & Editing, Martyna Saba: Data Curation, Investigation, Ji Zhang: Conceptualization, Formal analysis, Resources, Visualization Preparation, Anetta Hanć: Data Curation, Investigation.
Hg > : < Se
Wolfiporia cocos sclerotia and raw products
1
Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the
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medicinal fungus Wolfiporia cocos from China
3 4
Jerzy Falandysz1,2,3*, Martyna Saba1, Ji Zhang3*, Anetta Hanć4
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1
University of Gdańsk, Environmental Chemistry and Ecotoxicology, Gdańsk, Poland
7
2
Environmental and Computational Chemistry Group, School of Pharmaceutical Sciences,
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Zaragocilla Campus, University of Cartagena, 130015 Cartagena, Colombia+
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3
Medicinal Plants Research Institute, Yunnan Academy of Agricultural Sciences, Kunming
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650200, China
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4
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Method, Umultowska 89b, PL 61-614 Poznań, Poland
Adam Mickiewicz University, Department of Trace Element Analysis by Spectroscopy
13 14 15
*Corresponding authors: Jerzy Falandysz (e-mail: [email protected]); Ji Zhang
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(email: [email protected]); +Visiting Professor
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1
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Highlights
27 28
●
The concentrations and intakes of Hg and Se from Wolfiporia cocos were measured
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●
Some positive correlations noted between Hg, Se and morphological parts
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●
Intake rates of Hg from sclerotia were considered as low; Se even lower
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
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Abstract
51 52
The contamination and distribution of mercury and selenium in the Chinese medicinal fungus
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Wolfiporia cocos was investigated. The sclerotial mercury concentrations ranged from 0.0043
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to 0.027 mg kg1 dry biomass (db) in the inner white part and 0.019 to 0.074 mg kg-1 db in the
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shell (outer part), while selenium concentrations ranged from < 0.00048 to 0.0040 mg kg-1 db
56
(white) and 0.0034 to 0.038 mg kg-1 db (shell). Positive correlations were found for mercury,
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as well as for mercury and selenium but they were not consistent for both morphological
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parts. Mercury concentrations exceeded selenium in 16 of 17 white part pools (molar quotient
59
0.53 to > 10) and in 11 of 17 shell pools (quotient 0.37 to 3.2). The estimated maximal
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exposure to mercury contained in sclerotial products based on 45 g per capita daily intake for
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a 60 kg individual over one week, was 0.000020 mg kg-1 body mass (bm; white) and
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0.000055 mg kg-1 bm (shell) on a daily basis, and 0.0014 mg kg-1 bm (white) and 0.00039 mg
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kg-1 bm (shell) on a weekly basis. Relative to mercury, the corresponding intake rates of
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selenium were considered very low, i.e., they averaged on a daily basis at 0.00075 µg kg-1 bm
65
(white) and 0.0097 µg kg-1 bm (shell) with maximum intake at 0.0030 µg kg-1 bm (white) and
66
0.028 µg kg-1 bm (shell).
67 68 69 70
Keywords: Traditional Herbal Medicine, Foods, Fungi, Organic Food, Wild Food, Wild
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Medicine
72 73 74
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75 76 77 78
1. Introduction
79 80
The distributions of mercury (Hg) and selenium (Se) are widespread occurring at ultra-trace
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concentrations in foods and in the environment. Alkyl mercury compounds are recognised as
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notorious toxicants for humans and wildlife. The Minamata Bay incident in Japan which
83
caused lethal intoxication, resulted from the consumption of seafood that was highly
84
contaminated with methyl mercury (MeHg+), a toxicologically and ecologically relevant
85
pollutant. Methyl mercury undergoes effective bioaccumulation and biomagnification in
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aquatic food webs (Bond et al., 2015) and subsequently causes disruption to the biochemistry
87
of the nutritionally important element, selenium, which can result in a deficit of vital
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selenoenzyme (Ralston and Raymond, 2010 and 2018). Wild mushrooms always contain
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inorganic mercury and MeHg+ at least in trace amounts, while some species can contain
90
mercury and also selenium at much greater concentration than other terrestrial foods or
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seafoods (Falandysz, 2010 and 2008; Saba et al., 2016a-c). Both mercury and selenium are
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considered as antagonistic elements in biological systems (McNear et al., 2012). The
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compound mercury(II) selenide precipitates are very hardly soluble in water (1.0 x 10-58 to 1.0
94
x 10-65 mol per dm3) (Nuttall, 1987). It has been identified recently in form of diselenol
95
mercury complex (Hg(Se-R)2) in mushrooms (Kavčič et al., 2019).
96
The south-western part of China including the province of Yunnan has areas with
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polymetallic soils that can be enriched in certain elements including mercury, arsenic (As) and
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low in selenium (Dinh et al., 2018; Shi et al., 2013; Wen and Chi, 2007; Zhang et al., 2019).
99
Apart from these soils, mushrooms growing in the wild in the Yunnan land can also
4
100
bioaccumulate mercury compounds (Falandysz et al., 2015a, 2015b, 2016; Kojta et al., 2015).
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Soils in the Yunnan province are considered to be marginal or rich in Se but there is limited
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available data for soils, environmental materials and foods (Blazina et al., 2014; Dinh et al.,
103
2018). For example, originally, 95% of the cereal products sampled from the Chuxiong region
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in Yunnan are Se-deficient which is reflected in the human deficiency of this element in the
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local people (based on concentration of Se in hair) (Dinh et al., 2018).
106
Mushrooms (macrofungi) are a type of vegetation with mycelia that are well adapted
107
to extract Hg from soils, bio-concentrating the element in their fruiting bodies. Many species
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will also bio-concentrate Se as well (Árvay et al., 2017; Chudzyński et al., 2009; Falandysz,
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2008, 2016, 2017; Gabriel et al., 2016; Kojta et al., 2012; Krasińska and Falandysz, 2016;
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Melgar et al., 2009; Nasr and Arp, 2011; Rzymski et al., 2016). In contrast to mercury, there
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are no published data on selenium in edible wild mushrooms from the SW China including
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Yunnan, thus far (Falandysz, 2008; 2013).
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China is the major producer, consumer and also exporter of mushrooms, both foraged
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from the wild as well as cultivated. The total production of edible mushrooms both cultivated
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and foraged in China reached 37,120 thousand tonnes in 2017 (China Edible Fungus
116
Association, 2018). Apart from edible species with gourmet value, hundreds of macrofungi
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species growing in the wild in China are considered to have a medicinal value (Dui et al.,
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2012; Mao, 2009; Wu et al., 2013, 2019). Wu et al. (2013) summarized 799 taxa of medicinal
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macrofungi. A recent study by Wu et al. (2019) summarized 1662 taxa including 1020 edible
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and 692 medicinal macrofungi and 277 that were simultaneously both of edible and medicinal
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quality.
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The Wolfiporia cocos [(Schwein.) Ryvarden & Gilb.], is a wood decaying fungus
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associated with pine trees, that produces sclerotia (a dense mass of mycelia) buried
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underground (Fig. 1). Morphologically, the sclerotia act as a store that is rich in energy and
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nutrients and it is widely used in Asian traditional medicine (Wang et al., 2013). The major 5
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constituents with pharmacological activity are considered to be triterpenes and
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polysaccharides contained in sclerotia (Wang et al., 2013). Sclerotia of W. cocos is used both
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in the traditional Chinese herbal medicine and also as a gourmet product (Wang et al., 2015).
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The authors Rios (2011), Wang et al. (2013) and Wu et al. (2019) reviewed data on the
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organic chemicals composition and medicinal properties, which shows that there is still very
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little data on mineral concentrations, including nutrients and possibly toxic inorganics in the
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sclerotia of W. cocos.
133
In the past, the white (inner part) of W. cocos sclerotia samples from Taiwan (Wang
134
et al., 1998) and province of Yunnan in China (Wang et al., 2015) showed a little
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contamination with radioactive caesium (137Cs). Mercury also has been found at small
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concentrations in the inner part of sclerotia from Yunnan (Wiejak et al., 2016). Studies on
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sclerotia have also investigated other mineral constituents such as Ba, Co, Cr, Cs, Cu, Li, Mn,
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Ni, Pb, Rb, Sr, V and Zn, and the more notorious contaminants such as Ag, As, Cd, Tl and U
139
that usually occurred at low levels or below the limit of detection (Falandysz et al., 2017).
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This report provides for the first time, data on the occurrence and distribution of mercury and
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selenium between the outer and inner part of a large number of sclerotia samples collected
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from the wild, as well as cultivars from Yunnan in 2013-2014, including retail commodity
143
samples.
144 145
2. Materials and methods
146 147
Sixteen composite samples of sclerotia (from 4 to 63 individual specimens per sample) were
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collected across Yunnan Province (the sites located from 1052 m to 2560 m above sea level),
149
one pooled sample was from a farm in Anhui Province (16 specimens; a site located at 617 m
150
above sea level) and two commodity samples in 2013-2014 (Fig. 2). Two commodity samples
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151
were bought from medicinal herb retail outlets in Yunnan and Guangxi provinces,
152
respectively. Fresh samples were cleaned with a soft brush. After brushing off soil and dust
153
from the surface, the bulk samples of the outer (shell) and inner (white) parts of sclerotia were
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prepared after taking six subsamples (each ca. 300 g) per layer from each individual
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specimen. The materials were thinly sliced, then air-dried separately in the shade, powdered
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using a ceramic mortar, screened using a 60-mesh stainless steel sieve, subsampled into ca.
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100 g portions in screw sealed plastic (low density polyethylene) bags and kept for analysis
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under dry conditions.
159
Determinations of mercury concentrations were carried out in 3-4 replicates of each
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sample using a fully validated method. In brief, the sclerotia samples were thermally
161
decomposed at 850 °C and the released mercury vapour were trapped in a gold wool trap.
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Following desorbtion, the absorbance was measured using a cold-vapour atomic absorption
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spectroscope (CV–AAS; Mercury analyzer type MA–2000 with an autosampler, Nippon
164
Instruments Corporation, Takatsuki, Japan) that was operated in “low mode” (Jarzyńska and
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Falandysz, 2011; Wiejak et al., 2016). The limit of detection for mercury was 0.001 mg kg-1
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dry biomass (db), and limit of quantification was 0.003 mg kg-1 db.
167
Determinations of selenium concentrations were carried out in 2 replicates using the
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ELAN DRC II ICP-MS Inductively Coupled Plasma Mass Spectrometer (PerkinElmer,
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SCIEX, Canada) equipped with a Meinhard concentric nebulizer, cyclonic spray chamber,
170
dynamic reaction cell, Pt cones and quadruple mass analyzer (Falandysz et al., 2017). Typical
171
instrument operating conditions for ICP-MS spectrometer were: RF power - 1100 W; plasma
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Ar flow rate - 15 L min-1; nebulizer Ar flow rate - 0.87 L min-1 and auxiliary Ar flow rate - 1.2
173
L min-1 and lens voltage – (7.5-9.0) V. For calibration curve construction, a mixed standard
174
solution with concentrations of 10 mg L-1 was used (Multielement Calibration Standard 3,
175
Atomic Spectroscopy Standard, PerkinElmer Pure). Moreover, the isotopes of
7
45
Sc,
74
Ge,
176
103
177
applied as internal standards in order to effectively correct temporal variations in signal
178
intensity (ICP Standard CertiPUR, Merck, Germany). Calibration curves for elements were
179
constructed in the range of 0.1 µg L-1 to 50 µg L-1. Argon with a purity of 99.999 % was used
180
as a nebulizer, auxiliary and plasma gas in ICP-MS (Messer, Chorzów, Poland). Reagent
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blank solutions (3 blanks) were prepared in the same way.
Rh and
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Tb prepared from individual solutions with concentrations of 1000 mg L-1 were
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The analytical procedure used was routinely subjected to analytical control and quality
183
assurance (AC/QA) using multiple blank samples and two herbal certified reference materials.
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These were produced by the Institute of Nuclear Chemistry and Technology (INCT) in
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Warsaw, Poland: Tea Leaves (INCT-TL-1 for Inorganic Trace Analysis: declared mercury at
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0.0050 ± 0.0007 mg kg-1 db) and Mixture Polish Herbs (INCT-MPH-2 for Inorganic Trace
187
Analysis: declared mercury at 0.018 ± 0.002 mg kg-1 db) with good results. The results
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determined in this study for mercury were 0.0050 ± 0.0007 mg kg-1 db (n = 6) in INCT-TL-1
189
and 0.019 ± 0.003 mg kg-1 db (n = 6) for INCT-MPH-2.
190 191
3. Results and discussion
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The mercury concentrations in the outer part of sclerotia samples were in the range of
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0.019 to 0.078 mg kg-1 db (median 0.027 mg kg-1 db, with mean and standard deviation (SD)
195
at 0.027 ± 0.016 mg kg-1 db). Corresponding concentrations in the inner part of sclerotia
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ranged from 0.0043 to 0.027 mg kg-1 db (median 0.0085 mg kg-1 db and mean±SD 0.0085 ±
197
0.0002 mg kg-1 db). The median value of the Hg concentration in the inner part of sclerotia in
198
this study was close to a value of 0.011 mg kg-1 db as was determined for a range of the white
199
sclerotia materials collected across Yunnan in 2012 (Wiejak et al., 2016). Selenium occurred
200
in the outer parts of sclerotia in the concentration range from 0.0034 to 0.038 mg kg-1 db 8
201
(median 0.011 mg kg-1 db and 0.013 ± 0.009 mg kg-1 db), with a range of < LOQ to 0.0040
202
mg kg-1 db (median < LOQ and mean 0.0010 ± 0.0009 mg kg-1 db) in the inner parts (Table
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1). There is no previous data on selenium concentration of sclerotia of fungi or in fruiting
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bodies of macrofungi from Yunnan province.
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The concentrations of mercury in the inner and outer parts of sclerotia correlated
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positively (y = 2.738322 x + 0.007582; r = 0.65; p < 0.05; Fig. 3), but there was no
207
correlation between the concentrations of selenium in the inner and outer parts (y = 2.861520
208
x + 0.009269; r = 0.009; p = 0.13). No correlation occurred between mercury and selenium
209
contained in the outer parts of sclerotia (y = 0.2053 x + 0.0057; r = 0.15; p = 0.073), while in
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the inner parts both elements correlated positively (y = 0.1520854 x - 0.0002692; r < 0.32; p
211
< 0.05) (Fig. 4).
212
Additionally the mercury and selenium concentrations in the sclerotia from the
213
Yunnan did not show any correlations or consistent tendencies, based on geographical
214
location of the sampling site or elevation above sea level. A pooled sample of sclerotia from
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the province of Anhui showed mercury concentration at 0.027 mg kg-1 db (outer layer) and
216
0.0082 mg kg-1 db (inner part), and both these results are close to the median concentration
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determined for a range of sclerotia materials collected across Yunnan (Table 1).
218
The quality of the W. cocos sclerotia products in this study in view of a low
219
contamination with mercury can be considered as good. Curiously, on a molecular basis, the
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outer sclerotial mercury concentrations in 11 of 17 pools were greater than the selenium
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concentrations (range of molar quotient 0.37 to 3.2), and in the case of the inner parts, the
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mercury concentration was in excess in 16 of 17 pools (range of molar quotient 0.53 to > 10)
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(Annex 1).
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Selenium is considered as protective against mercury toxicity when selenium
225
molecules exceed mercury molecules in foods (Kaneko and Ralston, 2007). A lack of
9
226
molecular balance between mercury – selenium in sclerotia of W. cocos may indicate a deficit
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of selenium in soils relative to an excess of geogenic mercury but no data were available on
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mercury and selenium in soils associated with fungi, in the present study. For this species, a
229
preferential accumulation of mercury over selenium may provide an explanation to the
230
observed results.
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The human exposure to mercury contained in these sclerotial products was
232
investigated. The estimation assumed a consumption mass of 45 g product per capita daily
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over a week at the maximal contamination levels determined in this study (0.027 mg kg-1 db
234
in the inner and 0.074 mg kg-1 db in the outer parts) for a 60 kg individual. The estimates
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showed intake from 0.020 µg kg-1 body mass (inner part) and 0.055 µg kg-1 body mass (outer
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part) on a daily basis, to 1.4 µg kg-1 body mass (inner part) and 0.39 µg kg-1 body mass (outer
237
part) on a weekly basis, which correspond to low intakes. These estimated doses are well
238
below published daily reference dose (RfD) for mercury at 0.3 µg kg-1 body mass or the
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provisionally tolerable weekly intake (PTWI) that is 4.0 µg kg-1 body mass (JECFA, 2010).
240
In view of mercury concentrations determined in the outer and inner parts of sclerotia
241
and estimated intakes of mercury, the estimated intake rates of selenium with 45 g of sclerotia
242
were considered negligible, i.e., they averaged on a daily basis at 0.00075 µg kg-1 bm (inner
243
part) and 0.0097 µg kg-1 bm (outer part) with maxima at 0.0030 µg kg-1 bm (inner part) and
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0.028 µg kg-1 bm (outer part). The processing of W. cocos sclerotia and the production of
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decocted preparations or other type of extracts, which are used in China, can affect the
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concentration of both mercury and selenium in the final product, but there is no data available.
247 248
4. Conclusion
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In Yunnan province in China, the mercury and selenium concentrations both of the outer
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(shell) and inner (white) parts of the sclerotia of W. cocos are low, and they vary between
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sampling sites, regardless of geographical location or elevation above the sea level.
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Statistically significant positive correlations were found for mercury and also for mercury and
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selenium. However these were not consistent for both morphological parts of sclerotia.
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Estimated intake rates of mercury from sclerotia were considered as low with even lower rates
256
for selenium.
257 258
Conflict of interest
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The authors declare that they have no conflict of interest.
260 261
Acknowledgements
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This study in part was supported by the National Natural Science Foundation of China (No.
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31860584).
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Nuttall KL., 1987. A model for metal selenide formation under biological conditions. Med Hypoth 24:217–21 R. Core Team., 2019. R; A language and environment to statistical computing. R Foundation for statistical Computing. Vienna, Austria. https;/www.R-project.org.pl Ralston NVC, Raymond LJ., 2010. Dietary selenium’s protective effects against methylmercury toxicity. Toxicology 278:112-123 Ralston NVC, Raymond LJ., 2018. Mercury's neurotoxicity is characterized by its disruption
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mercury accumulation in edible mushrooms cultivated on contaminated substrates. J Food
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Comp Anal 51:55-60
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Saba M, Falandysz J, Nnorom IC., 2016a. Accumulation and distribution of mercury in
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fruiting bodies by fungus Suillus luteus foraged in Poland, Belarus and Sweden. Environ
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Sci Pollut Res 23:2749–2757
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Saba M, Falandysz J, Nnnorom IC., 2016b. Evaluation of vulnerability of Suillus variegatus
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and Suillus granulatus mushrooms’ to sequester mercury in fruiting bodies. J Environ Sci
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Saba M, Falandysz J, Nnorom IC., 2016c. Mercury determination in Suillus bovinus
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mushroom: accumulation, distribution, probable dietary intake. Environ Sci Pollut Res
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23:14549–14559.
375 376
Shi J, Meng M, Shao M, Zhang Z, Zhang Q, Jiang G., 2013. Spatial distribution of mercury in topsoil from five regions of China. Environ Sci Pollut Res 20:1756-1761
377
Wang Y, Zhang J, Zhao Y, Tao L, Tao S, Li J, Li W, Liu H., 2013. Mycology, cultivation,
378
traditional uses, phytochemistry and pharmacology of Wolfiporia cocos (Schwein.)
379
Ryvarden et Gilb.: A review. J Ethnopharmacol 145:265-276
380 381
Wen X, Chi Q., 2007. Geochemical spatial distribution of mercury in China. Geochimica 36:633-637
382
Wiejak A, Wang Y, Zhang J, Falandysz J., 2014. Bioconcentration potential and
383
contamination with mercury of pantropical mushroom Macrocybe gigantea. J Environ Sci
384
Health Part B 49:811-814
385
Wiejak A, Wang Y-Z, Zhang J, Falandysz J., 2016. Mercury in sclerotia of Wolfiporia extensa
386
(Peck) Ginns fungus collected across of the Yunnan land. Spect Spectral Anal 36:3083-
387
3086
388 389 390 391 392 393 394 395 396
16
397 398 399 400 401 402 403 404 405 406 407 408
FIGURE CAPTIONS
409 410
Fig. 1. Sclerotia of Wolfiporia cocos and raw products.
411
Fig. 2. Locations of the sampling sites of W. cocos from China.
412
Fig. 3. Graphical image of relationship between Hg concentration in the inner and outer part
413 414 415
of sclerotia sampled (package in ”ggplot2” R.3.53) (R. Core Team, 2019). Fig. 4. Graphical image of relationship between Hg and Se concentrations in the inner part of sclerotia sampled (package in ”ggplot2” R.3.53) (R. Core Team, 2019).
416
17
Annex 1. Mercury and selenium (nM kg-1 dry biomass) and Hg to Se molar quotient values Outer part Hg Se Site Yongping, Dali (w) Lanping, Nujiang (w) Hongta, Yuxi (c) Changning, Baoshan (c) Zhenyuan, Pu'er (c) Shuangbai, Chuxiong (c) Baozhu, Wenshan (w) Lanping, Nujiang (w) Ninglang, Lijiang (c) Tengchong, Baoshan (c) Shuangjiang, Lincang(c) Yunlong, Dali (c) Jinggu, Pu'er (c) Shuangjiang, Lincang (c) Mojiang, Pu'er (c) Simao, Pu'er (c) Yuexi, Anhui Province (c) Guangxi Province (s) Simao, Pu'er (s)
130 140 120 390 140 190 180 370 95 150 110 110 150 120 200 140 130 WD WD
44 160 46 270 43 68 480 240 48 240 92 300 240 140 140 86 100 WD WD
Hg/Se quotient 2.9 0.87 2.6 1.4 3.2 2.8 0.37 1.5 2.0 0.62 1.2 0.37 0.62 0.86 1.4 1.6 1.3
Inner part Hg Se 42 42 36 130 50 42 39 60 28 49 31 27 50 40 75 41 41 21 41
14 <6 <6 61 12 <6 17 <6 12 12 <6 51 <6 16 23 <6 <6 <6 <6
Hg/Se quotient 3.0 >7 >6 2.1 4,2 >7 2.3 > 10 2.3 4.1 >5 0.53 >8 2.5 3.3 >6 >6 >3 >6
Notes: ¶(if < LOQ, a half of the value was used for calculation of mean content); c(cultivated); w(wild); co(commodity product from commodity samples were bought from a market of Chinese herbal medicine); WD (without data).
Table 1. The Hg and Se contents in sclerotia of Wolfiporia cocos from China
Region, sampling place and kind of sclerotia Lijiang, NinglangC Nujiang, LanpingW Nujiang, LanpingW Dali, YunlongW Chuxiong, ShuangbaiW Baoshan, ChangningC Pu'er, MojiangC Dali, YongpingW Pu'er, ZhenyuanC Yuxi, HongtaC Baoshan, TengchongC Wenshan, BaozhuW Lincang, ShuangjiangC Pu'er, SimaoC Pu'er, JingguC Shuangjiang, LincangC Yuexi, Anhui ProvinceC Guangxi ProvinceCO Pu'er, SimaoCO Mean SD Median## Minimal Maximal
Coordinates (North : East) 26°52'59.49" 100°55'39.13" 26°39'48.19" 99°11'23.84" 26°39'48.19" 99°11'23.84" 25°38'9.7512" 99°7'55.0811" 24°41'28.21" 101°38'57.42" 24°28'08.51" 99°30'11.47" 23°4'3.4824" 101°58'35.50” 25°32'09.82" 99°41'05.70" 23°49'12.04" 100°44'26.82" 24°25'54.7" 102°31'5.6" 25°25'20.32" 98°39'08.66" 23°28'29.99" 103°56'50.35" 23°20'55.478" 100°0'17.0856" 22°44'55.295" 101°3'22.6368" 23°25'13.454" 100°24'15.678" 23°28'40.537" E 99°50'16.134" N 31°4'8.584" 116°6'49.1472"
Hg (mg kg-1 db) Part Outer 0.019 ± 0.001 0.029 ± 0.001 0.074 ± 0.004 0.022 ± 0.001 0.039 ± 0.003 0,078 ± 0.003 0.041 ± 0.003 0.031 ± 0.002 0.027 ± 0.004 0.028 ± 0.002 0.025 ± 0.003 0.036 ± 0.002 0.023 ± 0.002 0.029 ± 0.001 0.031 ± 0.005 0.025 ± 0.003 0.027 ± 0.000 WD WD
Se (mg kg-1 db) Inner 0.0056 ± 0.0002 0.0084 ± 0.0005 0.012 ± 0.000 0.0054 ± 0.0003 0.0085 ± 0.0003 0.027 ± 0.001 0.015 ± 0.001 0.0098 ± 0.0004 0.0085 ± 0.0005 0.010 ± 0.000 0.0072 ± 0.0003 0.0078 ± 0.00 0.0064 ± 0.002 0.0083 ± 0.0005 0.010 ± 0.001 0.0081 ± 0.0003 0.0082 ± 0.0010 0.0043 ± 0.0002 0.0083 ± 0.0004
Outer 0.0038±0.0027 0.013±0.006 0.019±0.003 0.024±0.009 0.0054±0.0020 0.021±0.003 0.011±0.003 0.019±0.006 0.0035±0.0002 0.0034±0.0012 0.0036±0.0044 0.038±0.001 0.0073±0.0017 0.0068±0.0055 0.019±0.009 0.011±0.002 0.0080±0.0028 WD WD
Inner 0.00095±0.00023 < LOQ < LOQ 0.0040±0.0013 < LOQ < LOQ 0.0018±0.0012 0.00095±0.00015 0.0011±0.0002 0.00096±0.00032 < LOQ 0.0010±0.0005 < LOQ < LOQ < LOQ 0.0013±0.0004 < LOD < LOD < LOD
0.034 0.016 0.027 0.019 0.078
0.0085 0.0002 0.0085 0.0043 0.027
0.013 0.009 0.011 0.0034 0.038
0.0010 0.0009 < LOQ < LOQ 0.0040
Notes: ¶(if < LOQ, a half of the value was used for calculation of mean content); c(cultivated); w(wild); co(commodity product from commodity samples were bought from a market of Chinese herbal medicine); ##Without the commodity products; (1/2 LOQ = 0.00048 mg kg-1 db); WD (without data).
Highlights
The concentrations and intakes of Hg and Se from Wolfiporia cocos were measured Some positive correlations noted between Hg, Se and morphological parts Intake rates of Hg from sclerotia were considered as low; Se even lower
Authors declare no conflict of interest.
S0045-6535(20)30120-X
DOI:
https://doi.org/10.1016/j.chemosphere.2020.125928
Reference:
CHEM 125928
To appear in:
ECSN
Received Date: 7 November 2019 Revised Date:
9 January 2020
Accepted Date: 13 January 2020
Please cite this article as: Falandysz, J., Saba, M., Zhang, J., Hanć, A., Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the medicinal fungus Wolfiporia cocos from China, Chemosphere (2020), doi: https://doi.org/10.1016/j.chemosphere.2020.125928. This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. © 2020 Published by Elsevier Ltd.
Credit author statement
Jerzy Falandysz: Conceptualization, Formal analysis, Resources, Visualization Preparation, Writing - Original Draft Preparation, Review & Editing, Martyna Saba: Data Curation, Investigation, Ji Zhang: Conceptualization, Formal analysis, Resources, Visualization Preparation, Anetta Hanć: Data Curation, Investigation.
Hg > : < Se
Wolfiporia cocos sclerotia and raw products
1
Occurrence, distribution and estimated intake of mercury and selenium from sclerotia of the
2
medicinal fungus Wolfiporia cocos from China
3 4
Jerzy Falandysz1,2,3*, Martyna Saba1, Ji Zhang3*, Anetta Hanć4
5 6
1
University of Gdańsk, Environmental Chemistry and Ecotoxicology, Gdańsk, Poland
7
2
Environmental and Computational Chemistry Group, School of Pharmaceutical Sciences,
8
Zaragocilla Campus, University of Cartagena, 130015 Cartagena, Colombia+
9
3
Medicinal Plants Research Institute, Yunnan Academy of Agricultural Sciences, Kunming
10
650200, China
11
4
12
Method, Umultowska 89b, PL 61-614 Poznań, Poland
Adam Mickiewicz University, Department of Trace Element Analysis by Spectroscopy
13 14 15
*Corresponding authors: Jerzy Falandysz (e-mail: [email protected]); Ji Zhang
16
(email: [email protected]); +Visiting Professor
17 18 19 20 21 22 23 24 25
1
26
Highlights
27 28
●
The concentrations and intakes of Hg and Se from Wolfiporia cocos were measured
29
●
Some positive correlations noted between Hg, Se and morphological parts
30
●
Intake rates of Hg from sclerotia were considered as low; Se even lower
31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49
2
50
Abstract
51 52
The contamination and distribution of mercury and selenium in the Chinese medicinal fungus
53
Wolfiporia cocos was investigated. The sclerotial mercury concentrations ranged from 0.0043
54
to 0.027 mg kg1 dry biomass (db) in the inner white part and 0.019 to 0.074 mg kg-1 db in the
55
shell (outer part), while selenium concentrations ranged from < 0.00048 to 0.0040 mg kg-1 db
56
(white) and 0.0034 to 0.038 mg kg-1 db (shell). Positive correlations were found for mercury,
57
as well as for mercury and selenium but they were not consistent for both morphological
58
parts. Mercury concentrations exceeded selenium in 16 of 17 white part pools (molar quotient
59
0.53 to > 10) and in 11 of 17 shell pools (quotient 0.37 to 3.2). The estimated maximal
60
exposure to mercury contained in sclerotial products based on 45 g per capita daily intake for
61
a 60 kg individual over one week, was 0.000020 mg kg-1 body mass (bm; white) and
62
0.000055 mg kg-1 bm (shell) on a daily basis, and 0.0014 mg kg-1 bm (white) and 0.00039 mg
63
kg-1 bm (shell) on a weekly basis. Relative to mercury, the corresponding intake rates of
64
selenium were considered very low, i.e., they averaged on a daily basis at 0.00075 µg kg-1 bm
65
(white) and 0.0097 µg kg-1 bm (shell) with maximum intake at 0.0030 µg kg-1 bm (white) and
66
0.028 µg kg-1 bm (shell).
67 68 69 70
Keywords: Traditional Herbal Medicine, Foods, Fungi, Organic Food, Wild Food, Wild
71
Medicine
72 73 74
3
75 76 77 78
1. Introduction
79 80
The distributions of mercury (Hg) and selenium (Se) are widespread occurring at ultra-trace
81
concentrations in foods and in the environment. Alkyl mercury compounds are recognised as
82
notorious toxicants for humans and wildlife. The Minamata Bay incident in Japan which
83
caused lethal intoxication, resulted from the consumption of seafood that was highly
84
contaminated with methyl mercury (MeHg+), a toxicologically and ecologically relevant
85
pollutant. Methyl mercury undergoes effective bioaccumulation and biomagnification in
86
aquatic food webs (Bond et al., 2015) and subsequently causes disruption to the biochemistry
87
of the nutritionally important element, selenium, which can result in a deficit of vital
88
selenoenzyme (Ralston and Raymond, 2010 and 2018). Wild mushrooms always contain
89
inorganic mercury and MeHg+ at least in trace amounts, while some species can contain
90
mercury and also selenium at much greater concentration than other terrestrial foods or
91
seafoods (Falandysz, 2010 and 2008; Saba et al., 2016a-c). Both mercury and selenium are
92
considered as antagonistic elements in biological systems (McNear et al., 2012). The
93
compound mercury(II) selenide precipitates are very hardly soluble in water (1.0 x 10-58 to 1.0
94
x 10-65 mol per dm3) (Nuttall, 1987). It has been identified recently in form of diselenol
95
mercury complex (Hg(Se-R)2) in mushrooms (Kavčič et al., 2019).
96
The south-western part of China including the province of Yunnan has areas with
97
polymetallic soils that can be enriched in certain elements including mercury, arsenic (As) and
98
low in selenium (Dinh et al., 2018; Shi et al., 2013; Wen and Chi, 2007; Zhang et al., 2019).
99
Apart from these soils, mushrooms growing in the wild in the Yunnan land can also
4
100
bioaccumulate mercury compounds (Falandysz et al., 2015a, 2015b, 2016; Kojta et al., 2015).
101
Soils in the Yunnan province are considered to be marginal or rich in Se but there is limited
102
available data for soils, environmental materials and foods (Blazina et al., 2014; Dinh et al.,
103
2018). For example, originally, 95% of the cereal products sampled from the Chuxiong region
104
in Yunnan are Se-deficient which is reflected in the human deficiency of this element in the
105
local people (based on concentration of Se in hair) (Dinh et al., 2018).
106
Mushrooms (macrofungi) are a type of vegetation with mycelia that are well adapted
107
to extract Hg from soils, bio-concentrating the element in their fruiting bodies. Many species
108
will also bio-concentrate Se as well (Árvay et al., 2017; Chudzyński et al., 2009; Falandysz,
109
2008, 2016, 2017; Gabriel et al., 2016; Kojta et al., 2012; Krasińska and Falandysz, 2016;
110
Melgar et al., 2009; Nasr and Arp, 2011; Rzymski et al., 2016). In contrast to mercury, there
111
are no published data on selenium in edible wild mushrooms from the SW China including
112
Yunnan, thus far (Falandysz, 2008; 2013).
113
China is the major producer, consumer and also exporter of mushrooms, both foraged
114
from the wild as well as cultivated. The total production of edible mushrooms both cultivated
115
and foraged in China reached 37,120 thousand tonnes in 2017 (China Edible Fungus
116
Association, 2018). Apart from edible species with gourmet value, hundreds of macrofungi
117
species growing in the wild in China are considered to have a medicinal value (Dui et al.,
118
2012; Mao, 2009; Wu et al., 2013, 2019). Wu et al. (2013) summarized 799 taxa of medicinal
119
macrofungi. A recent study by Wu et al. (2019) summarized 1662 taxa including 1020 edible
120
and 692 medicinal macrofungi and 277 that were simultaneously both of edible and medicinal
121
quality.
122
The Wolfiporia cocos [(Schwein.) Ryvarden & Gilb.], is a wood decaying fungus
123
associated with pine trees, that produces sclerotia (a dense mass of mycelia) buried
124
underground (Fig. 1). Morphologically, the sclerotia act as a store that is rich in energy and
125
nutrients and it is widely used in Asian traditional medicine (Wang et al., 2013). The major 5
126
constituents with pharmacological activity are considered to be triterpenes and
127
polysaccharides contained in sclerotia (Wang et al., 2013). Sclerotia of W. cocos is used both
128
in the traditional Chinese herbal medicine and also as a gourmet product (Wang et al., 2015).
129
The authors Rios (2011), Wang et al. (2013) and Wu et al. (2019) reviewed data on the
130
organic chemicals composition and medicinal properties, which shows that there is still very
131
little data on mineral concentrations, including nutrients and possibly toxic inorganics in the
132
sclerotia of W. cocos.
133
In the past, the white (inner part) of W. cocos sclerotia samples from Taiwan (Wang
134
et al., 1998) and province of Yunnan in China (Wang et al., 2015) showed a little
135
contamination with radioactive caesium (137Cs). Mercury also has been found at small
136
concentrations in the inner part of sclerotia from Yunnan (Wiejak et al., 2016). Studies on
137
sclerotia have also investigated other mineral constituents such as Ba, Co, Cr, Cs, Cu, Li, Mn,
138
Ni, Pb, Rb, Sr, V and Zn, and the more notorious contaminants such as Ag, As, Cd, Tl and U
139
that usually occurred at low levels or below the limit of detection (Falandysz et al., 2017).
140
This report provides for the first time, data on the occurrence and distribution of mercury and
141
selenium between the outer and inner part of a large number of sclerotia samples collected
142
from the wild, as well as cultivars from Yunnan in 2013-2014, including retail commodity
143
samples.
144 145
2. Materials and methods
146 147
Sixteen composite samples of sclerotia (from 4 to 63 individual specimens per sample) were
148
collected across Yunnan Province (the sites located from 1052 m to 2560 m above sea level),
149
one pooled sample was from a farm in Anhui Province (16 specimens; a site located at 617 m
150
above sea level) and two commodity samples in 2013-2014 (Fig. 2). Two commodity samples
6
151
were bought from medicinal herb retail outlets in Yunnan and Guangxi provinces,
152
respectively. Fresh samples were cleaned with a soft brush. After brushing off soil and dust
153
from the surface, the bulk samples of the outer (shell) and inner (white) parts of sclerotia were
154
prepared after taking six subsamples (each ca. 300 g) per layer from each individual
155
specimen. The materials were thinly sliced, then air-dried separately in the shade, powdered
156
using a ceramic mortar, screened using a 60-mesh stainless steel sieve, subsampled into ca.
157
100 g portions in screw sealed plastic (low density polyethylene) bags and kept for analysis
158
under dry conditions.
159
Determinations of mercury concentrations were carried out in 3-4 replicates of each
160
sample using a fully validated method. In brief, the sclerotia samples were thermally
161
decomposed at 850 °C and the released mercury vapour were trapped in a gold wool trap.
162
Following desorbtion, the absorbance was measured using a cold-vapour atomic absorption
163
spectroscope (CV–AAS; Mercury analyzer type MA–2000 with an autosampler, Nippon
164
Instruments Corporation, Takatsuki, Japan) that was operated in “low mode” (Jarzyńska and
165
Falandysz, 2011; Wiejak et al., 2016). The limit of detection for mercury was 0.001 mg kg-1
166
dry biomass (db), and limit of quantification was 0.003 mg kg-1 db.
167
Determinations of selenium concentrations were carried out in 2 replicates using the
168
ELAN DRC II ICP-MS Inductively Coupled Plasma Mass Spectrometer (PerkinElmer,
169
SCIEX, Canada) equipped with a Meinhard concentric nebulizer, cyclonic spray chamber,
170
dynamic reaction cell, Pt cones and quadruple mass analyzer (Falandysz et al., 2017). Typical
171
instrument operating conditions for ICP-MS spectrometer were: RF power - 1100 W; plasma
172
Ar flow rate - 15 L min-1; nebulizer Ar flow rate - 0.87 L min-1 and auxiliary Ar flow rate - 1.2
173
L min-1 and lens voltage – (7.5-9.0) V. For calibration curve construction, a mixed standard
174
solution with concentrations of 10 mg L-1 was used (Multielement Calibration Standard 3,
175
Atomic Spectroscopy Standard, PerkinElmer Pure). Moreover, the isotopes of
7
45
Sc,
74
Ge,
176
103
177
applied as internal standards in order to effectively correct temporal variations in signal
178
intensity (ICP Standard CertiPUR, Merck, Germany). Calibration curves for elements were
179
constructed in the range of 0.1 µg L-1 to 50 µg L-1. Argon with a purity of 99.999 % was used
180
as a nebulizer, auxiliary and plasma gas in ICP-MS (Messer, Chorzów, Poland). Reagent
181
blank solutions (3 blanks) were prepared in the same way.
Rh and
159
Tb prepared from individual solutions with concentrations of 1000 mg L-1 were
182
The analytical procedure used was routinely subjected to analytical control and quality
183
assurance (AC/QA) using multiple blank samples and two herbal certified reference materials.
184
These were produced by the Institute of Nuclear Chemistry and Technology (INCT) in
185
Warsaw, Poland: Tea Leaves (INCT-TL-1 for Inorganic Trace Analysis: declared mercury at
186
0.0050 ± 0.0007 mg kg-1 db) and Mixture Polish Herbs (INCT-MPH-2 for Inorganic Trace
187
Analysis: declared mercury at 0.018 ± 0.002 mg kg-1 db) with good results. The results
188
determined in this study for mercury were 0.0050 ± 0.0007 mg kg-1 db (n = 6) in INCT-TL-1
189
and 0.019 ± 0.003 mg kg-1 db (n = 6) for INCT-MPH-2.
190 191
3. Results and discussion
192 193
The mercury concentrations in the outer part of sclerotia samples were in the range of
194
0.019 to 0.078 mg kg-1 db (median 0.027 mg kg-1 db, with mean and standard deviation (SD)
195
at 0.027 ± 0.016 mg kg-1 db). Corresponding concentrations in the inner part of sclerotia
196
ranged from 0.0043 to 0.027 mg kg-1 db (median 0.0085 mg kg-1 db and mean±SD 0.0085 ±
197
0.0002 mg kg-1 db). The median value of the Hg concentration in the inner part of sclerotia in
198
this study was close to a value of 0.011 mg kg-1 db as was determined for a range of the white
199
sclerotia materials collected across Yunnan in 2012 (Wiejak et al., 2016). Selenium occurred
200
in the outer parts of sclerotia in the concentration range from 0.0034 to 0.038 mg kg-1 db 8
201
(median 0.011 mg kg-1 db and 0.013 ± 0.009 mg kg-1 db), with a range of < LOQ to 0.0040
202
mg kg-1 db (median < LOQ and mean 0.0010 ± 0.0009 mg kg-1 db) in the inner parts (Table
203
1). There is no previous data on selenium concentration of sclerotia of fungi or in fruiting
204
bodies of macrofungi from Yunnan province.
205
The concentrations of mercury in the inner and outer parts of sclerotia correlated
206
positively (y = 2.738322 x + 0.007582; r = 0.65; p < 0.05; Fig. 3), but there was no
207
correlation between the concentrations of selenium in the inner and outer parts (y = 2.861520
208
x + 0.009269; r = 0.009; p = 0.13). No correlation occurred between mercury and selenium
209
contained in the outer parts of sclerotia (y = 0.2053 x + 0.0057; r = 0.15; p = 0.073), while in
210
the inner parts both elements correlated positively (y = 0.1520854 x - 0.0002692; r < 0.32; p
211
< 0.05) (Fig. 4).
212
Additionally the mercury and selenium concentrations in the sclerotia from the
213
Yunnan did not show any correlations or consistent tendencies, based on geographical
214
location of the sampling site or elevation above sea level. A pooled sample of sclerotia from
215
the province of Anhui showed mercury concentration at 0.027 mg kg-1 db (outer layer) and
216
0.0082 mg kg-1 db (inner part), and both these results are close to the median concentration
217
determined for a range of sclerotia materials collected across Yunnan (Table 1).
218
The quality of the W. cocos sclerotia products in this study in view of a low
219
contamination with mercury can be considered as good. Curiously, on a molecular basis, the
220
outer sclerotial mercury concentrations in 11 of 17 pools were greater than the selenium
221
concentrations (range of molar quotient 0.37 to 3.2), and in the case of the inner parts, the
222
mercury concentration was in excess in 16 of 17 pools (range of molar quotient 0.53 to > 10)
223
(Annex 1).
224
Selenium is considered as protective against mercury toxicity when selenium
225
molecules exceed mercury molecules in foods (Kaneko and Ralston, 2007). A lack of
9
226
molecular balance between mercury – selenium in sclerotia of W. cocos may indicate a deficit
227
of selenium in soils relative to an excess of geogenic mercury but no data were available on
228
mercury and selenium in soils associated with fungi, in the present study. For this species, a
229
preferential accumulation of mercury over selenium may provide an explanation to the
230
observed results.
231
The human exposure to mercury contained in these sclerotial products was
232
investigated. The estimation assumed a consumption mass of 45 g product per capita daily
233
over a week at the maximal contamination levels determined in this study (0.027 mg kg-1 db
234
in the inner and 0.074 mg kg-1 db in the outer parts) for a 60 kg individual. The estimates
235
showed intake from 0.020 µg kg-1 body mass (inner part) and 0.055 µg kg-1 body mass (outer
236
part) on a daily basis, to 1.4 µg kg-1 body mass (inner part) and 0.39 µg kg-1 body mass (outer
237
part) on a weekly basis, which correspond to low intakes. These estimated doses are well
238
below published daily reference dose (RfD) for mercury at 0.3 µg kg-1 body mass or the
239
provisionally tolerable weekly intake (PTWI) that is 4.0 µg kg-1 body mass (JECFA, 2010).
240
In view of mercury concentrations determined in the outer and inner parts of sclerotia
241
and estimated intakes of mercury, the estimated intake rates of selenium with 45 g of sclerotia
242
were considered negligible, i.e., they averaged on a daily basis at 0.00075 µg kg-1 bm (inner
243
part) and 0.0097 µg kg-1 bm (outer part) with maxima at 0.0030 µg kg-1 bm (inner part) and
244
0.028 µg kg-1 bm (outer part). The processing of W. cocos sclerotia and the production of
245
decocted preparations or other type of extracts, which are used in China, can affect the
246
concentration of both mercury and selenium in the final product, but there is no data available.
247 248
4. Conclusion
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10
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In Yunnan province in China, the mercury and selenium concentrations both of the outer
251
(shell) and inner (white) parts of the sclerotia of W. cocos are low, and they vary between
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sampling sites, regardless of geographical location or elevation above the sea level.
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Statistically significant positive correlations were found for mercury and also for mercury and
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selenium. However these were not consistent for both morphological parts of sclerotia.
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Estimated intake rates of mercury from sclerotia were considered as low with even lower rates
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for selenium.
257 258
Conflict of interest
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The authors declare that they have no conflict of interest.
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Acknowledgements
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This study in part was supported by the National Natural Science Foundation of China (No.
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31860584).
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FIGURE CAPTIONS
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Fig. 1. Sclerotia of Wolfiporia cocos and raw products.
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Fig. 2. Locations of the sampling sites of W. cocos from China.
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Fig. 3. Graphical image of relationship between Hg concentration in the inner and outer part
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of sclerotia sampled (package in ”ggplot2” R.3.53) (R. Core Team, 2019). Fig. 4. Graphical image of relationship between Hg and Se concentrations in the inner part of sclerotia sampled (package in ”ggplot2” R.3.53) (R. Core Team, 2019).
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Annex 1. Mercury and selenium (nM kg-1 dry biomass) and Hg to Se molar quotient values Outer part Hg Se Site Yongping, Dali (w) Lanping, Nujiang (w) Hongta, Yuxi (c) Changning, Baoshan (c) Zhenyuan, Pu'er (c) Shuangbai, Chuxiong (c) Baozhu, Wenshan (w) Lanping, Nujiang (w) Ninglang, Lijiang (c) Tengchong, Baoshan (c) Shuangjiang, Lincang(c) Yunlong, Dali (c) Jinggu, Pu'er (c) Shuangjiang, Lincang (c) Mojiang, Pu'er (c) Simao, Pu'er (c) Yuexi, Anhui Province (c) Guangxi Province (s) Simao, Pu'er (s)
130 140 120 390 140 190 180 370 95 150 110 110 150 120 200 140 130 WD WD
44 160 46 270 43 68 480 240 48 240 92 300 240 140 140 86 100 WD WD
Hg/Se quotient 2.9 0.87 2.6 1.4 3.2 2.8 0.37 1.5 2.0 0.62 1.2 0.37 0.62 0.86 1.4 1.6 1.3
Inner part Hg Se 42 42 36 130 50 42 39 60 28 49 31 27 50 40 75 41 41 21 41
14 <6 <6 61 12 <6 17 <6 12 12 <6 51 <6 16 23 <6 <6 <6 <6
Hg/Se quotient 3.0 >7 >6 2.1 4,2 >7 2.3 > 10 2.3 4.1 >5 0.53 >8 2.5 3.3 >6 >6 >3 >6
Notes: ¶(if < LOQ, a half of the value was used for calculation of mean content); c(cultivated); w(wild); co(commodity product from commodity samples were bought from a market of Chinese herbal medicine); WD (without data).
Table 1. The Hg and Se contents in sclerotia of Wolfiporia cocos from China
Region, sampling place and kind of sclerotia Lijiang, NinglangC Nujiang, LanpingW Nujiang, LanpingW Dali, YunlongW Chuxiong, ShuangbaiW Baoshan, ChangningC Pu'er, MojiangC Dali, YongpingW Pu'er, ZhenyuanC Yuxi, HongtaC Baoshan, TengchongC Wenshan, BaozhuW Lincang, ShuangjiangC Pu'er, SimaoC Pu'er, JingguC Shuangjiang, LincangC Yuexi, Anhui ProvinceC Guangxi ProvinceCO Pu'er, SimaoCO Mean SD Median## Minimal Maximal
Coordinates (North : East) 26°52'59.49" 100°55'39.13" 26°39'48.19" 99°11'23.84" 26°39'48.19" 99°11'23.84" 25°38'9.7512" 99°7'55.0811" 24°41'28.21" 101°38'57.42" 24°28'08.51" 99°30'11.47" 23°4'3.4824" 101°58'35.50” 25°32'09.82" 99°41'05.70" 23°49'12.04" 100°44'26.82" 24°25'54.7" 102°31'5.6" 25°25'20.32" 98°39'08.66" 23°28'29.99" 103°56'50.35" 23°20'55.478" 100°0'17.0856" 22°44'55.295" 101°3'22.6368" 23°25'13.454" 100°24'15.678" 23°28'40.537" E 99°50'16.134" N 31°4'8.584" 116°6'49.1472"
Hg (mg kg-1 db) Part Outer 0.019 ± 0.001 0.029 ± 0.001 0.074 ± 0.004 0.022 ± 0.001 0.039 ± 0.003 0,078 ± 0.003 0.041 ± 0.003 0.031 ± 0.002 0.027 ± 0.004 0.028 ± 0.002 0.025 ± 0.003 0.036 ± 0.002 0.023 ± 0.002 0.029 ± 0.001 0.031 ± 0.005 0.025 ± 0.003 0.027 ± 0.000 WD WD
Se (mg kg-1 db) Inner 0.0056 ± 0.0002 0.0084 ± 0.0005 0.012 ± 0.000 0.0054 ± 0.0003 0.0085 ± 0.0003 0.027 ± 0.001 0.015 ± 0.001 0.0098 ± 0.0004 0.0085 ± 0.0005 0.010 ± 0.000 0.0072 ± 0.0003 0.0078 ± 0.00 0.0064 ± 0.002 0.0083 ± 0.0005 0.010 ± 0.001 0.0081 ± 0.0003 0.0082 ± 0.0010 0.0043 ± 0.0002 0.0083 ± 0.0004
Outer 0.0038±0.0027 0.013±0.006 0.019±0.003 0.024±0.009 0.0054±0.0020 0.021±0.003 0.011±0.003 0.019±0.006 0.0035±0.0002 0.0034±0.0012 0.0036±0.0044 0.038±0.001 0.0073±0.0017 0.0068±0.0055 0.019±0.009 0.011±0.002 0.0080±0.0028 WD WD
Inner 0.00095±0.00023 < LOQ < LOQ 0.0040±0.0013 < LOQ < LOQ 0.0018±0.0012 0.00095±0.00015 0.0011±0.0002 0.00096±0.00032 < LOQ 0.0010±0.0005 < LOQ < LOQ < LOQ 0.0013±0.0004 < LOD < LOD < LOD
0.034 0.016 0.027 0.019 0.078
0.0085 0.0002 0.0085 0.0043 0.027
0.013 0.009 0.011 0.0034 0.038
0.0010 0.0009 < LOQ < LOQ 0.0040
Notes: ¶(if < LOQ, a half of the value was used for calculation of mean content); c(cultivated); w(wild); co(commodity product from commodity samples were bought from a market of Chinese herbal medicine); ##Without the commodity products; (1/2 LOQ = 0.00048 mg kg-1 db); WD (without data).
Highlights
The concentrations and intakes of Hg and Se from Wolfiporia cocos were measured Some positive correlations noted between Hg, Se and morphological parts Intake rates of Hg from sclerotia were considered as low; Se even lower
Authors declare no conflict of interest.