The two faces of Coprinus comatus—Functional properties and potential hazards

Abstract Mushrooms have been used for centuries not only as food but also in traditional medicine as a source of components with pro‐health activity. One of them is Coprinus comatus (O.F.Müll.) Pers. also called shaggy mane, chicken drumstick mushroom, or lawyer's wig. In Asian countries, C. comatus (CC) is approved as edible mushroom and often cultivated for consumption, whereas in many other countries, although it is widespread, it is unrecognized and not used. In this review, for the first time, we discussed about the composition related to functional properties as well as the potential risks associated with consumption of CC by reviewing scientific literature. The information has been collected in order to get to know this species thoroughly. Various studies show many of the physiological activities, such as antioxidant, anticancer, antiandrogenic, hepatoprotective, acetylcholinesterase inhibitory, antiinflammatory, antidiabetic, antiobesity, antibacterial, antifungal, antinematode, and antiviral. Besides positive physiological properties, CC has also negative features, for example, skin reactions in patients with dermatitis and atopic predisposition, risk of confusion with poisonous mushrooms, quick autolysis after collection, and contamination of toxic elements.

woods, meadows, and verges of roads. Many physiological effects of CC have been reported, for example, antioxidant, anticancer, antiandrogenic, hepatoprotective, acetylcholinesterase inhibitory, antiinflammatory, antidiabetic, antiobesity, antimicrobial, antiviral, antifungal, and antinematode activity (Dotan, Wasser, & Mahajna, 2011;Li, Lu, Suo, Nan, & Li, 2010;Park et al., 2014;Sabo et al., 2010;Stojkovi c et al., 2013;Zaidman, Wasser, Nevo, & Mahajna, 2008;Zhang et al., 2017;S. Zhao et al., 2014;Zhou & Han, 2008). CC is valued for its taste as well as for nutritional properties;therefore, in 2006, in China, 382,000 tons of this mushroom have been consumed (Bailey, Turner, Jakeman, & Hayes, 1984;Fan et al., 2006). CC is cultivated as an edible mushroom in Japan, China, and other Asian countries, but in some countries in Europe, for example, and in Poland, it is not legally classified as an edible mushroom (Polish Journal of Laws, 2018). The aim of the presented work is to discuss the composition related to functional properties as well as the potential risks associated with consumption of CC by reviewing scientific literature.

| NUTRITIONAL VALUE AND CHEMICAL COMPOSITION OF CC
Mushrooms are appreciated for their taste but also for nutritional value. Nutritional value of CC was examined by various researchers.
The assays show that 100 g dry weight (d.w.) of CC provided energy in amount of 368.1-525 kcal. The main compounds of mushrooms were carbohydrates. The content of carbohydrates in CC was 49.2-76.3 g/100 g d.w. It is worth emphasizing that CC was a good source of dietary fiber because dried CC contained 32.8 ± 4.2% water-insoluble and 1.79 ± 1.1% water-soluble fiber. CC has been reported to have 11.8-29.5 g of protein and 1.1-5.4 g of fat in 100 g d.w. (Akata, Ergonul, & Kalyoncu, 2012;Cheung, 2013;Stojkovi c et al., 2013;Vaz et al., 2011). Nutritional value of protein from mushrooms is related to ratio of various protein fractions. The analyses detected six different protein fractions: albumins, globulins, prolamines, prolamines-like fraction soluble in alcohol after reduced with 2-mercaptoethanol, glutelin-like fraction soluble in alkali, and true glutelin. Protein fractions were presented as percentage of total protein in CC and reached value 14.75 ± 0.72%, 27.36 ± 0.65%, 5.48 ± 0.18%, 5.27 ± 0.26%, 4.48 ± 0.14%, and 6.97 ± 0.17%, respectively. Moreover, the total protein content in mushroom was higher than in other foods mentioned by Petrovska, such as barley, amaranth grain, maize, rice, wild rice, wheat, and sorghum (Petrovska, 2001). It is worth emphasizing that protein from mushroom like CC is also highly digestible, and usually it is in a range 71-90%. It was found that 2 g protein from mushroom is equal to 1 g meat protein. Therefore, in Eastern Europe mushrooms were sometimes called 'forest meat' or 'meat for poverty' (Kalač, 2016;Mukerji & Manoharachary, 2010).
The chemical composition of CC fruiting body depends on origin, environmental condition, and so forth. Mushrooms are rich in various types of biologically active substances and their metabolites with many different properties (Tang, Yin, Zhang, Jia, & Gao, 2015). Some of these compounds were found only in cultivated mushrooms, whereas others only in wild ones (Table 1) (Li, Dobruchowska, Gerwig, Dijkhuizen, & Kamerling, 2013 The lower concentrations were measured in the fatty acids with small number of carbon and none of double bonds (Pedneault et al., 2008).
The reducing power of CC extracts was also tested with spectrophotometric method, which measures the force to reduce ferricyanide to ferrocyanide. The reducing power of ethanol solution extract of cap and stipe at 10 mg/mL concentration was 1.653 and 0.364, while water extracts reached 0.998 and 1.122, respectively (Li et al., 2010). The reducing power of CC ethanol solution extract in a different studies was 0.50 at 10 mg/mL concentration and in water extract was 0.48 at 5 mg/mL (Tsai et al., 2009). However, reference substance, which was L-ascorbic acid, showed reducing power of 2.087 at 1.0 mg/mL (Li et al., 2010). Naturally occurring antioxidant components, such as ascorbic acid, β-Carotene, lycopene, and various phenolic compounds were found in the CC extracts (Sánchez, 2016).
Ethanol solution extracts contained more flavonoids and tocopherols but less polysaccharides than hot water extracts. The authors showed differences in the chemical composition and the antioxidant activity The content of phenolic compounds in C. comatus aqueous extract (Tešanovi c et al., 2017)   plate test (usually used to assess analgesic effect of narcotic and other drugs) (Calcagni & Elenkov, 2006;Ren et al., 2012). Polysaccharides from CC significant attenuated level of interleukin 6 (IL-6), inducible nitric oxide synthase (iNOS), and cyclooxygenase 2 (COX-2) indicated that CC reduce inflammatory response caused by alcohol (Zhao et al., 2019). The writhing test that evaluates analgesic property showed that extracts from fermented CC at 1 and 5 mg/kg concentration inhibited analgesic activity by 19 and 21%, respectively. Antinociceptive effect was tested by the formalin test and reaches inhibition value 3% at first phase and 6% at second phase at 10 mg/kg concentration (Han, 2009

| Hepatoprotective activity
Polysaccharides from CC have been reported as biologically active which may induce liver recovery after damage caused by alcohol consumption. This health and social problems are correlated with liver illness, for example, hepatitis, cirrhosis, and fatty liver (Yuan, Gong, Li, & Li, 2007

| Acetylcholinesterase inhibitory property
Extract from CC was also screened for acetylcholinesterase (AChE) inhibitory potential. AChE takes a part in a synthesis of acetylcholine neurotransmitter (Basiri et al., 2013;Giacobini, 2004). Progressive cognitive impairment in Alzheimer's disease is connected with neurotransmitter acetylcholine deficiency and synaptic failure (Bartus, 2000). Inhibitors
Zhou and Han tested the potential influence of combination of CC and vanadium on glycemic metabolism. In this study, homogenized fermented CC fruiting body was used in culture medium containing sodium metavanadate-NaVO3 (CCRV). The level of hepatic glycogen was increased by the use of aforementioned combination. In mice fed on CCRV, glycogen level was at 27.6 ± 5.2 mg/g, and it was higher com- The inhibition of α-amylase causes reduced level of glucose and also reduced postprandial glucose (Ng & Rosman, 2019 (Gregoire, Smas, & Sul, 1998). The phosphatidylinositol 3-kinase/Akt signaling pathway is a second path of adipogenesis regulation and adipocyte differentiation (Magun et al., 1996;Sakaue et al., 1998). The MTT assay showed that After 5 weeks of treatment with CC extract, the body weight was substantially reduced by 25% at 60 mg CC extract/kg b.w. and 36% at 200 mg/kg b.w., compared with the control group. Therapy using 200 mg/kg b.w. CC extract reduced total triglycerides and total cholesterol level in serum by 32 and 46%, respectively. Moreover, the high-density lipoprotein level was significantly increased in the group treated with CC compared with the control. Expression of adipogenesis genes was also inhibited by the extract in high fat diet (HF-diet) induced obese rats (Park et al., 2014).

| Antimicrobial activity
The antimicrobial compound (3R,4S)-2-methylene-3,4-dihydroxypentanoic acid 1,4-lactone was isolated from CC by De Carvalho et al. The CC lactone disrupted with quorum sensing and distracted biofilms of Pseudomonas aeruginosa, which also limited the formation of rhamnolipid B and pyocyanin pathogenicity factors (De Carvalho et al., 2016). Bacterial biofilm is thin sheet coating bacteria responsible for resistance to antibiotics and phagocytosis (Magun et al., 1996). Additionally, that compound also works against Staphy-
Coprine causes inhibition of the dehydrogenase in the liver, which increases the level of acetaldehyde in the blood after alcohol consumption. However, in opposite to disulfiram-like reaction, coprine does not inhibit dopamine-beta hydroxylase. Disulfiram-like reaction ensues if ethanol is consumed in time of 30 min to 3 days after the mushroom ingestion. It can happen within several minutes after consuming alcohol (Haberl, Pfab, Berndt, Greifenhagen, & Zilker, 2011;Köppel, 1993).
During alcohol metabolism, coprine blocks conversion of acetaldehyde into acetate and causes aldehyde accumulation in the liver and then in the blood (Tottmar & Lindberg, 1977). Usually, accumulation of acetaldehyde causes unpleasant effect, such as flushing, vomiting, nausea, tachycardia, headache, dizziness, hypotension, palpitations, and dyspnea (Haberl et al., 2011). Therapy of this reaction is supportive and consists of fluid and electrolyte replacement. Normally, the symptoms resolve after 6 hr from the time of alcohol ingestion and there is a risk that this reaction may recur after repeated alcohol consumption indicates that CC does not contain coprine (Berger & Guss, 2005;Berger & Guss, 2005a;Carisson et al., 1978;Diaz, 2005;Michelot, 1992;Peredy, 2014).

| Only the young CC fruit body are edible
The majority of edible mushrooms can be eaten in all stages of their growth. However, CC is edible only when it is young, the old mushroom becomes inedible. At maturity, spores and hymenia transform through the process of autodigestion into inky, black fluid which makes CC darker (Figure 1b). The process of CC autodigestion reduces its culinary properties and nutritional values (Saiz-Jimenez,-1983). CC fruiting bodies are highly perishable and must be consumed, processed, or iced within 4-6 hr of collection. Within 2 days, they undergo autolysis when they are stored after collection (Sas-Golak, Siwulski, Sobieralski, & Lisiec, 2012).  (Byrne, Ravnik, & Kosta, 1976;Fischer, Rapsomanikis, Andreae, & Baldi, 1995;Laaksovirta & Lodenius, 1979;Quinche & Dvorak, 1975). The content of Hg in CC from some sites in Poland was also high and reached median value 9.2 mg/kg d.w. in caps and 5.2 mg/kg d.w. in stipes (Falandysz, 2016). Eating contaminated mushrooms can expose consumer to relatively high dose of Hg. Based on the WHO norms, Provisional Tolerable Weekly Intake (PTWI = 4 μg/kg b.w.) and the Hg content in CC, the toxicity dose can be determined. It is estimated that the value that will exceed PTWI was from 20 g to 1.6 kg CC depending on the mushroom habitat (FAO, 2011). Mercury is definitely one of the most toxic elements to humans. All its forms alter physiological cellular function because it changes the structure of protein by binding with selenohydryl and sulfhydryl groups. The main target of Hg is the brain and also immune, endocrine, nerve, renal, and muscle functions (Berlin, 2003).

| Pollution of CC
Mushrooms not only absorb Hg but they can also accumulate other toxic metals. Cen et al. presented accumulation of different metal, for example cadmium (Cd) in cap and stipe of CC. Amount of Cd in CC increased with the increasing metal level in soil. After CC cultivation on soil with Cd concentration of 0.5 mg/kg, metal accumulation in stipe was 0.27 mg/kg d.w. and in cap was 0.35 mg/kg d.w. (Cen, Hu, & Xu, 2012).
Nickel (Ni) is considered as the one of the largest heavy pollutants (Tang et al., 2016). Accumulation of Ni in the food chain could cause health problem in a human body, such as eczema, respiratory problems, and allergic contact dermatitis (Yeganeh et al., 2013). Tang et al. tested Ni concentration in CC depending on bacterial inoculation, and it was from 5.22 to 15.90 mg/kg. Bioconcentration factor which is content of Ni in CC/Ni concentration in soil was 0.07-0.21 and depended on bacterial inoculation (Tang et al., 2018). Kalač indicated that CC harvested on unpolluted areas may also accumulate aluminum, barium, and vanadium (Kalač, 2016).
There is only little information about toxicity dose of CC in published papers. Ren et al. determined lethal dose LD 50 (dose which killed half of the subjects) by injection of triglycerides extracted from fermented CC to mice. LD 50 was estimated as 400 mg/kg b.w. (Ren et al., 2012). Different assay on mice showed that oral administration of alkalic-extractable polysaccharides from CC in 1,000-6,000 mg/kg b.w. dose was without any toxicity symptoms ( Zhao et al., 2019). Ma et al. evaluated toxicity effect of vanadium (IV and V) absorbed by CC and fermented mushroom of CC on mice. The study consisted of measured body weight and masses organs such as the liver, kidney, and heart. In this test, vanadium (IV and V) absorbed by CC reduced body weight (28.6 ± 2.1 and 20.2 ± 2.6 g), liver weight (1.36 ± 0.06 and 1.23 ± 0.07 g), kidney weight (0.41 ± 0.03 and 0.32 ± 0.05 g), and heart weight (0.16 ± 0.02 and 0.10 ± 0.01 g) compared with control value of body weight (36.9 ± 1.9 g), liver weight (1.40 ± 0.07 g), kidney weight (0.47 ± 0.03 g), and heart weight (0.18 ± 0.01 g). On the contrary, fermented mushroom of CC did not decrease significantly body weight (36.0 ± 1.7 g), liver weight (1.38 ± 0.05 g), kidney weight (0.44 ± 0.02 g), and heart weight (0.18 ± 0.02 g; Ma & Fu, 2009).

| CONCLUSIONS
In this review, for the first time, all information about composition, bioactivity, as well as potential hazards related to the consumption of CC has been collected in order to get to know this species thoroughly. Indepth study is required to investigate bioactive compounds of CC and its influence on health as well as to ensure its acceptance among consumers. In this connection, it is also relevant to confirm health benefits and safety of CC. In addition to its basic nutritional value, CC could provide pro-health benefits, which is the characteristic of functional food.
Given these points, CC should be considered for use as nutraceuticals, functional foods, and raw materials for medical preparations.

ACKNOWLEDGMENTS
The authors are grateful to Anna Pu scion-Jakubik PhD for opportunity of using the picture of Coprinus comatus. This work was supported by grants from Medical University of Bialystok N/ST/MN/18/001/2216 and SUB/2/DN/19/002/2216.

CONFLICTS OF INTEREST
The authors declare no potential conflict of interest.