The authors declare that there are no conflicts of interest present.
Ergothioneine is a widespread thiol metabolite present in fungal and bacterial species. Ergothioneine has been demonstrated to increase the lifespan of the model laboratory species C. elegans and M. musculus through increased protein crosslinking. It is rapidly gaining popularity as a fungal derived nutraceutical compound, however the complete mushrooms species distribution and ecological role of ergothioneine is unknown. We show ergothioneine concentrations appear to be highest in mushroom species that are capable of cellulose degradation. We also show that ergothioneine is a thermally stable compound and does not appear to degrade but rather increases in concentration in cooked mushrooms.
Figure 1.
Table 1: Histidine and Ergothioneine concentrations in diverse fungal samples.
| Species | Phylum; Family; Common Name | Sample Type | Histidine mg/g Average(±SE) | Sample Type | Ergothioneine mg/g Average(±SE) |
|---|---|---|---|---|---|
| Agaricus bisporus | Basidiomycete | Fresh: | 0.024 (±0.008)t | Fresh: | 0.0002 (±0.00003) t |
| Agaricaceae | Dried: | 0.17 (±0.027) t | Dried: | 0.019(±0.004) t | |
| Button Mushroom | Canned: | 0.002 (±0.0001) t | Canned: | 0.007 (±0.0004) t | |
| Boletus edulis | Basidiomycete | Dried: | 0.094(±0.025) t | Dried: | 0.904 (±0.071) t |
| Boletaceae | |||||
| Porcini | |||||
| Cantharellus cibarius | Basidiomycete | Dried: | 0.003 (±0.001) t | Dried: | 0.002 – (one replicate detection) |
| Cantharellaceae | |||||
| Golden Chanterelle | |||||
| Hericium erinaceus | Basidiomycete | Dried Powder: | 0.178 (±0.042)s | Dried Powder: | 0.143(±0.01) s |
| Hericiaceae | Capsule Powder: | 0.051 (±0.021) t | Capsule Powder: | BLQ t | |
| Lions Mane | |||||
| Hypomyces lactifluorumΔ | Ascomycete | Dried: | 0.025 (±0.004) s | Dried: | 0.039 (±0.012) s |
| Hypocreaceae | |||||
| Lobster Mushroom | |||||
| Lentinula edodes | Basidiomycete | Fresh: | 0.026 (±0.001) t | Fresh: | 0.024 (±0.002) t |
| Omphalotaceae | Dried: | 0.048 (±0.0145) s | Dried: | 0.171 (±0.037) s | |
| Shiitake | |||||
| Morchella esculenta | Ascomycete | Dried: | 0.051 (±0.003) s | Dried: | 0.207 (±0.041) s |
| Morchellaceae | |||||
| Yellow Morel | |||||
| Pleurotus ostreatus | Basidiomycete | Fresh: | 0.012 (±0.001) t | Fresh: | 0.025 (±0.004) t |
| Pleurotaceae | Dried: | 0.363 (±0.055) s | Dried: | 0.511(±0.117) s | |
| Oyster Mushroom | |||||
| Tricholoma matsutake | Basidiomycete | Dried: | 0.035(±0.002) t | Dried: | BLQ t |
| Tricholomataceae | |||||
| Matsutake |
Many fungal and bacterial species produce a histidine derived small sulphur containing metabolite called Ergothioneine (Beelman et al., 2020). Ergothioneine has potential nutraceutical properties as an antioxidant and an anti-aging compound (Wijeskara and Xu, 2024). Concentrated ergothioneine applications to
Ergothioneine in Aspergillus is synthesized from the The
We assessed the distribution of ergothioneine in commercial mushroom and mushroom products from a broad assortment of mushroom species, we also monitored the concentration of histidine to determine if cooking impacts histidine as it does ergothioneine (Table 1). The tested mushrooms were predominantly dry, however some of which were fresh, canned, or further processed into powders and capsules. Fresh mushroom samples were processed in-house under defined procedures, however commercial drying, canning, and powdering conditions were unknown. These commercial processing conditions may impact ergothioneine or histidine concentrations (Lee et al., 2019). Mushroom products were quantified using liquid chromatography / tandem mass spectrometry for histidine and ergothioneine concentrations. Our results expand the species distribution examined by Dubost et al. (2006), while supporting their original findings. Dubost et al. (2006) identified the lowest concentration of ergothioneine in in
Several studies indicate that ergothioneine is remarkably stable to heat and pH, yet its measured concentration in mushrooms may decrease depending on the cooking method and extent of leaching into water (Lo et al., 2020). For example, a study on shiitake mushrooms found that boiling mushrooms reduces ergothioneine content while roasting resulted in a slight increase (Lee et al., 2019). Our analysis found that both frying and autoclaving fresh weight Shiitake and Oyster mushrooms increased the concentration of ergothioneine significantly, supporting the claim the compound is exceptionally stable with cooking. Interestingly, the concentration of ergothioneine increased at a greater rate than the relative water loss due to frying.
Mushrooms are widely consumed by humans for nutritional and nutraceutical properties. The mushrooms themselves and the fungi they grow from occupy diverse and essential ecological roles. Ergothioneine is a small sulphur containing metabolite present in a variety of mushroom species, and may be associated with their ecological niche, as high concentrations are not ubiquitous across fungal families. Further research into the growth rates of a model mushrooms species, such as oyster mushrooms with varieties lacking ergothioneine may provide further insight into the ecological role of this molecule. Furthermore, ergothioneine is a thermally stable small molecule, with detectable concentrations increasing in thermally processed shiitake and oyster mushrooms. Therefore, individuals seeking to maximize ergothioneine consumption for presumed nutraceutical properties should fry or pressure cook their mushrooms. Highly processed and products containing dilute mushroom extracts such as Lions Mane tablets (Table 1) may contain less ergothioneine than whole mushrooms.
Mushroom and mushroom products were selected from a range of commercially available sources: Lions Mane powder blend, OM, lot: 417710B192 ; Lions Mane capsules, Supplier: Purica, lot: P04900; 417710B192; Chantarelles (dried), Supplier: Ponderosa Mushrooms, lot: 2204904; Morel (dried), Supplier: W.C. wild foods, lot: 2825043833; Wild Porcini (dried), Supplier: Untamed Feast, lot: 00662109; Pine (dried), Supplier: W. C wild foods, lot: 2304102; Lobster (dried), Supplier: W.C. wild foods, lot: 2203108;Oyster mushrooms (Fresh, dried in house), Supplier: Compliments organic, lot: unidentified; Shiitake (fresh and dried in house), Supplier: Choices Market, lot: unidentified; Button (fresh and dried in house), Supplier: Choices Market, lot: unidentified; Button (canned), Money’s, lot: not recorded. Samples dried in-house for metabolite analysis were cut into 2 cm strips and dried for 25 h at 50º C. For metabolite extraction approximately 10 mg of mushroom sample was macerated with a pestle in 1 mL of 50% H 2 O:50% Methanol and 0.1% Formic acid. Samples were vortexed for 30 s and sonicated in a bath sonicator for two minutes. Samples were then centrifuged for 2 min at 10,000 rcf. The supernatant was removed and filtered with a 0.22 µm PTFE filter and stored in a glass vial at -20º C prior to analysis. Standards and processing chemicals were purchased from Millipore-Sigma (MilliporeSigma Canada Ltd, Oakville, ON, Canada). To simulate a pressure-cooking process and examine the impact on ergothioneine, fresh frozen Oyster and shiitake mushroom samples were autoclaved for 20 minutes at 15 PSI and 120º C. For fried samples, fresh frozen mushrooms were added to a hot pan containing a small volume of avocado oil. Samples were fried for 10 - 12 minutes until they browned and appeared cooked. Fried samples were blotted to remove excess oil and processed for metabolite extraction. Moisture loss was determined by weight loss in samples following 16 h drying at 50ºC.
Histidine and ergothioneine were quantified on a 1290 infinity ii LC system coupled to an Ultivo triple quadrupole mass spectrometer (LC-MS/MS) (Agilent Technologies Inc, Santa Clara, CA, USA). 10 µL of filtered extract was injected and separated on a Zorbax SB-C18 (3.0 mm x 0.5 mm x 1.8 µm) guard column and separated with a Zorbax SB-C18 (2.1 mm x 50 mm x 1.8 µm) column at 40ºC. The solvent flow rate was constant at 0.3 mL/min. The solvents used were A: deionized water with 0.1% Formic acid, and B: acetonitrile. Solvent gradients were 0.0– 1.0 min, hold 95% A; 1.0 – 5.0 min gradient 95% A to 5% A and 95% B; 5.0– 7.0 min hold 95% B; 7.0 – 8.0 min gradient 5% A to 95% A; 8.0-9.0 min hold 95% A. Samples were ionized using an Agilent AJS electrospray ionization source in positive mode. The source parameters were gas temperature 300 ºC, gas flow 8.0 L/min, nebulizer pressure 35 psi, sheath gas temperature 180 ºC, sheath gas flow 10 L/min, capillary voltage 4000 V, and nozzle voltage 1500 V. The quantitative ion transition for ergothioneine was 230>127 at a collision energy (CE) of 20 V, the qualitative ion was 230>60 at CE 15 V. For histidine the quantitative ion transition was 156>110 at CE 17 V and the qualifying ion transition was 156>83 at CE 25 V. Samples were quantified by comparison to regression of known concentrations, and with matching qualifying ion ratios in Agilent Quantitative QQQ software (Agilent Technologies Inc). Standard concentrations ranged from 10 µg/mL to 1 ng/mL. Statistical comparisons of cooked samples were students t-tests conducted in Graphpad Prism.