Botanical Adulterants Monitor: Issue 20, September 2020
HPTLC
Method to Authenticate Reishi Dietary Supplements
Reviewed: Frommenwiler
DA, Trefzer D, Schmid M, Cañigueral S, Reich E. Comprehensive HPTLC
fingerprinting: A novel economic approach to evaluating the quality of Ganoderma lucidum fruiting body. J Liq Chromatogr Rel Techn. 2020;43(11-12);414-423.
Keywords:
Adulteration, fruiting body, Ganoderma
lucidum, Ganoderma
spp., HPTLC
Dietary
supplements made from various fungal parts (fruiting body, mycelium) have seen
a rapid increase in sales in the United States over the past few years. For
many of the popular mushrooms, quality parameters are not well-established, and
proper authentication remains challenging. For reishi (Ganoderma lucidum, Ganodermataceae) mushrooms,
the situation is complicated since the taxonomy is a matter of debate; some
authors believe that the lumping of all Ganoderma
species which are morphologically similar into G.
lucidum is appropriate, while others propose that the scientific
name Ganoderma lingzhi should be
used for reishi originating from Eastern Asia and G. lucidum should be restricted to reishi from Europe.1-3
This taxonomic debate is not yet settled. Furthermore, two additional species, G. japonicum and G. tsugae, are listed with the common name
“reishi” in the American Herbal Products Association’s Herbs of Commerce, 2nd edition.4 This means that these two species
can also be sold as reishi in the United States. In Asia, reishi fruiting
bodies are mostly differentiated with G.
lucidum assigned to red forms of reishi and other species (e.g., G. japonicum) assigned to black forms.5
The authors of this investigation developed a high-performance
thin-layer chromatography (HPTLC) method for the authentication of ingredients
claiming to be made from G. lucidum
fruiting body. The method evaluates the fingerprint of triterpenoic acids
(ganoderic acids A, B, C2, D, and G) and ergosterol. In addition, the amount of
total triterpenoic acids was determined by quantitative HPTLC, and samples
evaluated using acceptance criteria (not less than 0.3% by weight of
triterpenoic acids) established in the USP monograph.6 Plates were
assessed under white light, UV at 254 nm and 366 nm, or after derivatization
with 10% sulfuric acid in methanol.
A total of 50 commercial reishi samples were obtained from or
provided by different companies and institutions from USA, France, Switzerland,
and Canada. Commercial samples originated from Canada (n = 5), China (n = 9), France
(n = 1), Germany (n = 3), Korea (n = 1), the United States (n = 21), or were of
unknown origin (n = 10). The label description indicated G. lucidum fruiting body (n = 43), Ganoderma spp. (n = 4), or reishi mushroom
(n = 3). A reference sample provided by USP, and authenticated samples of 13
other fungal species, including G.
applanatum and G. sinensis,
were also included in the analysis.
According to the authors’ assessment, 22 samples complied with USP
specifications, five were of questionable quality, and the remaining 23 samples
had some deficiencies, mainly the lack of characteristic bands for one or
several of the ganoderic acids. Ganoderic acid contents ranged between
0.05-0.64%; 21 samples were below the 0.3% specification for ganoderic acid
listed in the USP monograph. However, it is not clear if any of these samples
actually claimed to comply with USP specifications.
Comment: Authentication of reishi based on chemical fingerprints is
challenging, since the triterpenoic acid pattern is reportedly variable
depending on the origin of the sample.1,7,8 However, the published
data consistently report the presence of ganoderic and other acids in reishi
fruiting bodies and even in mycelium obtained from submerged cultures of the
fungus.9 It is unclear if any of the commercial products analyzed by
Frommenwiler et al. was adulterated, although some supplements lacked zones for
triterpenoic acids. Nevertheless, the paper represents the largest investigation
of commercial reishi fruiting body to date and provides a valuable insight into
the variability of marketed products. For industry members who manufacture or
sell reishi products, the proposed HPTLC method is a helpful tool to evaluate
the quality of their material, and to determine compliance with specifications
set forth by the USP.
References
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and East Asia on the basis of morphology, molecular phylogeny, and triterpenic acid
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- McGuffin M, Kartesz JT, Leung AY, Tucker AO. American Herbal Products Association’s Herbs
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