Usnic acid: Difference between revisions

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	{{chembox		{{chembox
	\| ~~Watchedfields~~ = changed		\| Verifiedfields = changed
			\| Watchedfields = changed
	\| verifiedrevid = 452888826
			\| verifiedrevid = 477867469
	\| Name = Usnic acid
	\| ~~ImageFile~~ = Usnic acid~~.svg~~		\| Name = Usnic acid
			\| ImageFile = Usnic acid.svg
	<!-- \| ImageSize = 200px -->
	\| ~~ImageName~~ = Chemical structure of usnic acid		\| ImageName = Chemical structure of usnic acid
	\| ~~IUPACName~~ = 2,6-Diacetyl-7,9-dihydroxy-8,9b-~~dimethyl~~-1,3(2H,~~9bh~~)~~<br />~~-~~dibenzofurandione~~		\| IUPACName = 2,6-Diacetyl-7,9-dihydroxy-8,9b-dimethyldibenzofuran-1,3(2''H'',9b''H'')-dione
			\| OtherNames = {{bulletedlist\|Usneine\|Usninic acid\|Usniacin}}
	\| OtherNames = usneine, usninic acid, usniacin
	\| Section1 = {{Chembox Identifiers		\| Section1 = {{Chembox Identifiers
	\| CASNo_Ref = {{cascite\|correct\|??}}		\| CASNo_Ref = {{cascite\|correct\|CAS}}
	\| CASNo = 125-46-2~~<ref name="AshAsh2004">{{cite book~~		\| CASNo = 125-46-2
			\| CASNo_Comment = ]
	\|author1=Michael Ash
			\| CASNo1_Ref = {{cascite\|correct\|CAS}}
	\|author2=Irene Ash
			\| CASNo1 = 7562-61-0
	\|title=Handbook of preservatives
			\| CASNo1_Comment = (''R'')-(+)
	\|url=http://books.google.com/books?id=XZ2QB7bu5LwC&pg=PA670
			\| CASNo2_Ref = {{cascite\|correct\|CAS}}
	\|accessdate=5 August 2010
			\| CASNo2 = 6159-66-6
	\|year=2004
			\| CASNo2_Comment = (''S'')-(–)
	\|publisher=Synapse Info Resources
			\| ChEMBL_Ref = {{ebicite\|changed\|EBI}}
	\|isbn=9781890595661
	\|page=5856}}</ref>
	\| ChEMBL_Ref = {{ebicite\|correct\|EBI}}
	\| ChEMBL = 242022		\| ChEMBL = 242022
			\| ChEBI_Ref = {{ebicite\|changed\|EBI}}
	\| SMILES = CC1=C(C(=C2C(=C1O)C3(C(=CC(=O)C(C3=O)C(=O)C)O2)C)C(=O)C)O
	\| ~~PubChem~~ = ~~5646~~		\| ChEBI = 38319
			\| SMILES = CC1=C(C(=C2C(=C1O)C3(C(=CC(=O)C(C3=O)C(=O)C)O2)C)C(=O)C)O
	\| ChemSpiderID_Ref = {{chemspidercite\|correct\|chemspider}}
			\| PubChem = 5646
			\| ChemSpiderID_Ref = {{chemspidercite\|correct\|chemspider}}
	\| ChemSpiderID = 5444		\| ChemSpiderID = 5444
			\| UNII_Ref = {{fdacite\|correct\|FDA}}
	\| InChI = 1/C18H16O7/c1-6-14(22)12(8(3)20)16-13(15(6)23)18(4)10(25-16)5-9(21)11(7(2)19)17(18)24/h5,11,22-23H,1-4H3
			\| UNII = 0W584PFJ77
	\| InChIKey = CUCUKLJLRRAKFN-UHFFFAOYAS
	\| ~~StdInChI_Ref~~ = {{~~stdinchicite~~\|correct\|~~chemspider~~}}		\| UNII1_Ref = {{fdacite\|correct\|FDA}}
			\| UNII1 = 663456969I
			\| UNII1_Comment = (''R'')-(+)
			\| UNII2_Ref = {{fdacite\|correct\|FDA}}
			\| UNII2 = 5HYW08F205
			\| UNII2_Comment = (''S'')-(–)
			\| InChI = 1/C18H16O7/c1-6-14(22)12(8(3)20)16-13(15(6)23)18(4)10(25-16)5-9(21)11(7(2)19)17(18)24/h5,11,22-23H,1-4H3
			\| InChIKey = CUCUKLJLRRAKFN-UHFFFAOYAS
			\| StdInChI_Ref = {{stdinchicite\|correct\|chemspider}}
	\| StdInChI = 1S/C18H16O7/c1-6-14(22)12(8(3)20)16-13(15(6)23)18(4)10(25-16)5-9(21)11(7(2)19)17(18)24/h5,11,22-23H,1-4H3		\| StdInChI = 1S/C18H16O7/c1-6-14(22)12(8(3)20)16-13(15(6)23)18(4)10(25-16)5-9(21)11(7(2)19)17(18)24/h5,11,22-23H,1-4H3
	\| StdInChIKey_Ref = {{stdinchicite\|correct\|chemspider}}		\| StdInChIKey_Ref = {{stdinchicite\|correct\|chemspider}}
	\| StdInChIKey = CUCUKLJLRRAKFN-UHFFFAOYSA-N		\| StdInChIKey = CUCUKLJLRRAKFN-UHFFFAOYSA-N
	}}		}}
	\| Section2 = {{Chembox Properties		\| Section2 = {{Chembox Properties
			\| C=18 \| H=16 \| O=7
	\| Formula = C<sub>18</sub>H<sub>16</sub>O<sub>7</sub>
			\| Density =
	\| MolarMass = 344.315 g/mol
			\| MeltingPtC = 204
	\| Density =
			\| BoilingPt =
	\| MeltingPt = 204 °C
			\|Solubility = <0.001 g/L (25°C)<ref name="Merck">{{Cite book \|title=The Merck index: an encyclopedia of chemicals, drugs, and biologicals \|date=2001 \|publisher=Merck \|year=2001 \|isbn=978-0-911910-13-1 \|editor-last=O'Neil \|editor-first=Maryadele J. \|edition=13th \|location=Whitehouse Station, NJ \|page=1762 \|language=English \|editor-last2=Merck Sharp and Dohme Research Laboratories}}</ref>
	\| BoilingPt =
			\|Solvent1 = acetone
	}}
			\|Solubility1 = 0.077 g/L<ref name="Merck"/>
			\|Solvent2 = ethyl acetate
			\|Solubility2 = 0.088 g/L<ref name="Merck"/>
			\|Solvent3 = furfural
			\|Solubility3 = 0.732 g/L<ref name="Merck"/>
			\|Solvent4 = furfuryl alcohol
			\|Solubility4 = 0.121 g/L<ref name="Merck"/>
			}}
	}}		}}

			'''Usnic acid''' is a naturally occurring ] derivative found in several ] species with the formula C<sub>18</sub>H<sub>16</sub>O<sub>7</sub>. It was first isolated by German scientist W. Knop in 1844<ref>{{cite journal \| last1 = Knop \| first1 = W \| year = 1844 \| title = Chemisch-physiologische Untersuchung uber die Flechten \| url = https://zenodo.org/record/1426980\| journal = Annalen der Chemie und Pharmacie\| volume = 49 \| issue = 2\| pages = 103–124 \| doi=10.1002/jlac.18440490202}}</ref> and first synthesized between 1933 and 1937 by Curd and Robertson.<ref>{{cite journal \| last1 = Robertson \| first1 = A. \| last2 = Curd \| first2 = F. H. \| year = 1933 \| title = 277. Usnic acid. Part III. Usnetol, usnetic acid, and pyrousnic acid\| journal = Journal of the Chemical Society (Resumed)\| page = 1173 \| doi = 10.1039/jr9330001173 }}</ref> Usnic acid was identified in many genera of lichens including '']'', '']'', '']'', '']'', '']'', '']'', '']'' and '']''. Although it is generally believed that usnic acid is exclusively restricted to lichens, in a few unconfirmed isolated cases the compound was found in ] tea and non-lichenized ].<ref name="CocchiettoSkert2002">{{cite journal\|last1=Cocchietto\|first1=Moreno\|last2=Skert\|first2=Nicola\|last3=Nimis\|first3=Pier\|last4=Sava\|first4=Gianni\|title=A review on usnic acid, an interesting natural compound\|journal=Naturwissenschaften\|volume=89\|issue=4\|year=2002\|pages=137–146\|issn=0028-1042\|doi=10.1007/s00114-002-0305-3\|pmid=12061397\|bibcode=2002NW.....89..137C\|s2cid=11481018}}</ref><ref name="Blanc1996">{{cite journal\|last1=Blanc\|first1=Philippe J.\|title=Characterization of the tea fungus metabolites\|journal=Biotechnology Letters\|volume=18\|issue=2\|year=1996\|pages=139–142\|issn=0141-5492\|doi=10.1007/BF00128667\|s2cid=34822312}}</ref>
	'''Usnic acid''' is a naturally occurring ] derivative found in several ] species. It was first isolated by German scientist W. Knop in 1844<ref>Knop W. (1844) Chemisch-physiologische Untersuchung uber die Flechten. ''Justus Lieb. Ann. Chern'' 49: 103-124.
	</ref> and first synthesized between 1933-1937 by Curd and Robertson.<ref>A. Robertson and F. H. Curd. ''J. Chem. Soc.'' 1173 (1933)</ref> Usnic acid was identified in many genera of lichens including '']'', '']'', '']'', '']'', '']'', '']'' and '']''. Although it is generally believed that usnic acid is exclusively restricted to lichens, in a few unconfirmed isolated cases the compound was found in ] tea and non-lichenized ].

	At normal conditions, usnic acid is a bitter, yellow, solid substance.<ref name="AshAsh2004"/> ~~It is known to occur in nature in both the d- and l-forms as well as a racemic mixture.~~		At normal conditions, usnic acid is a bitter, yellow, solid substance.<ref name="AshAsh2004">{{cite book
			\| author1 =Michael Ash
			\| author2 =Irene Ash
			\| title =Handbook of preservatives
			\| url =https://books.google.com/books?id=XZ2QB7bu5LwC&pg=PA670
			\| access-date =5 August 2010
			\| year =2004
			\| publisher =Synapse Info Resources
			\| isbn =978-1-890595-66-1
			\| page =5856}}</ref> It is known to occur in nature in both the d- and l-forms as well as a ] mixture. Salts of usnic acid are called usnates (e.g. ]).

	==Biological role in lichens==		==Biological role in lichens==

	Usnic acid is a secondary metabolite in lichens whose role has not been completely elucidated. It is believed that usnic acid protects the lichen from adverse effects of sunlight exposure and deters grazing animals with its bitter taste.		Usnic acid is a secondary metabolite in lichens whose role has not been completely elucidated. It is believed that usnic acid protects the lichen from adverse effects of sunlight exposure and deters grazing animals with its bitter taste.

			==Biosynthesis==
	]
			Usnic acid is a ] biosynthesized via methylphloroacetophenone as an intermediate.<ref>{{Cite journal \| doi = 10.1248/cpb.17.2054 \| pmid = 5353559 \| title = Biosynthesis of Natural Products. VI. Biosynthesis of Usnic Acid in Lichens. (1). A General Scheme of Biosynthesis of Usnic Acid \| journal = Chemical & Pharmaceutical Bulletin \| volume = 17 \| issue = 10 \| pages = 2054–2060 \| year = 1969 \| last1 = Taguchi \| first1 = Heihachiro \| last2 = Sankawa \| first2 = Ushio \| last3 = Shibata \| first3 = Shoji \| doi-access = free }}
			</ref>
			]{{clear-left}}

			==Safety==
	==Uses and properties==
			Usnic acid and its salts are idiosyncratically associated with severe ] and ].<ref>{{cite journal \| doi = 10.1111/j.1440-1746.2008.05310.x \| pmid = 18318821 \| title = Hepatotoxic slimming aids and other herbal hepatotoxins \| journal = Journal of Gastroenterology and Hepatology \| volume = 23 \| issue = 3 \| pages = 366–373 \| year = 2008 \| last1 = Chitturi \| first1 = Shivakumar \| last2 = Farrell \| first2 = Geoffrey C. \| s2cid = 23840983 }}
			</ref><ref>{{cite journal
			\| vauthors = Yellapu RK, Mittal V, Grewal P, Fiel M, Schiano T
			\| title = Acute liver failure caused by 'fat burners' and dietary supplements: a case report and literature review
			\| journal = Canadian Journal of Gastroenterology\| volume = 25
			\| issue = 3
			\| pages = 157–60
			\| year = 2011
			\| pmid = 21499580
			\| pmc = 3076034
			\| doi = 10.1155/2011/174978
			\| doi-access = free
			}}</ref> Daily oral intake of 300–1350 mg over a period of weeks has led to severe hepatotoxicity in a number of persons.<ref>{{cite journal \| last1 = Hsu \| first1 = LM \| last2 = Huang \| first2 = YS \| last3 = Chang \| first3 = FY \| last4 = Lee \| first4 = SD \| date = Jul 2005 \| title = 'Fat burner' herb, usnic acid, induced acute hepatitis in a family \| journal = Journal of Gastroenterology and Hepatology\| volume = 20 \| issue = 7\| pages = 1138–9 \| doi=10.1111/j.1440-1746.2005.03855.x\| pmid = 15955234 \| s2cid = 6717430 }}</ref><ref>{{cite journal \| doi = 10.4065/81.4.541 \| pmid = 16610575 \| title = Severe Hepatotoxicity Associated with Use of a Dietary Supplement Containing Usnic Acid \| journal = Mayo Clinic Proceedings \| volume = 81 \| issue = 4 \| pages = 541–544 \| year = 2006 \| last1 = Sanchez \| first1 = William \| last2 = Maple \| first2 = John T. \| last3 = Burgart \| first3 = Lawrence J. \| last4 = Kamath \| first4 = Patrick S. \| doi-access = }}</ref>

			Sodium usnate was one ingredient in a product called "Lipokinetix" that was claimed to induce weight loss via an increase in metabolic rate. Lipokinetix has been the topic of an FDA warning in the USA<ref>{{cite web\|title=Safety Alerts for Human Medical Products > Lipokinetix\|url=https://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm172824.htm\|work=MedWatch: The FDA Safety Information and Adverse Event Reporting Program\|publisher=U.S. Food and Drug Administration\|access-date=5 December 2012\|date=November 20, 2001\|quote=FDA has received multiple reports of persons who developed liver injury or liver failure while using Lipokinetix. The product contains norephedrine (also known as phenylpropanolamine or PPA), caffeine, yohimbine, diiodothyronine, and sodium usniate.}}</ref> due to potential hepatotoxicity, although it is unclear yet if any toxicity would be attributable to the aforementioned salt. Lipokinetix also contained ] (PPA), ], ] and ].
	Lichen extracts containing usnic acid have been utilized in medicine, perfumery, cosmetics, and ecology.

			==Pharmacology==
	Usnic acid possess a wide range of interesting biological properties. It is a potent antibiotic effective against gram positive bacteria, including '']'', '']'', '']'', and '']'', as well as some pathogenic ]. It also exhibits antiviral, antiprotozoal, antimitotic, anti-inflammatory and analgesic activity. Other characteristics, like ultraviolet absorption, preserving properties, antigrowth, antiherbivore and anti-insect properties, have also been demonstrated.
			Usnic acid has been found to have ] in both frog and earthworm nerve junction models in preliminary research.<ref>Harris N. J. (1961), Honors Thesis, Clark University, Worcester, Massachusetts</ref>

			==Analytics==
	Usnic acid has been included as an ingredient in creams, powders, toothpastes, mouthwash, deodorants, hair shampoos and sunscreen products. In some of these preparations, usnic acid is employed as an active principle, in others as a preservative.
			It is possible to determine the content of usnic acid in ] ] using reversed-polarity ] or ] analysis.<ref>{{cite journal \| doi = 10.1002/1522-2683(200108)22:13<2755::AID-ELPS2755>3.0.CO;2-6 \| title = Reversed-polarity capillary zone electrophoretic analysis of usnic acid \| journal = Electrophoresis \| volume = 22 \| issue = 13 \| pages = 2755–2757 \| year = 2001 \| last1 = Kreft \| first1 = Samo \| last2 = Štrukelj \| first2 = Borut \| pmid = 11545403 \| s2cid = 24341350 }}

			</ref>
	Usnic acid and its salt form, sodium usniate, have been marketed in the US as an ingredient in food supplements for use in weight reduction, although unsupported by solid scientific proof. These supplements, if taken according to label instructions, can supply daily oral doses of 10–1350 mg for adults. Daily oral intake of 300–1350 mg over a period of weeks has led to severe hepatotoxicity in a number of persons.<ref>Hsu LM, Huang YS, Chang FY, Lee SD. 'Fat burner' herb, usnic acid, induced acute hepatitis in a family. J Gastroenterol Hepatol. 2005 Jul;20(7):1138-9.</ref><ref>Sanchez W, Maple JT, Burgart LJ, Kamath PS. Severe hepatotoxicity associated with use of a dietary supplement containing usnic acid. Mayo Clin Proc. 2006 Apr;81(4):541-4.</ref>
	Usnea was one ingredient in a product called Lipokinetix, promoted to induce weight loss via increase in metabolic rate. Lipokinetix has been the topic of an FDA warning in the USA,<ref>http://www.cfsan.fda.gov/~dms/ds-lipo.html</ref> due to potential hepatotoxicity, although it is unclear yet if any toxicity would be attributable to the Usnea. Lipokinetix also contained PPA, caffeine, yohimbine and diiodothyronine. There is reason to believe that usnic acid, in high concentrations, could possess some toxicity. The National Toxicology Program is currently evaluating the issue.

	==Pharmacolgy==

	Usnic acid has been found to have adrenergic activity in both frog and earthworm nerve junction models in preliminary research.<ref>Harris N. J.(1961), Honors Thesis, Clark University, Worcester, Massachusetts</ref>

	==References==		==References==
Line 72:		Line 107:

	==External links==		==External links==
			* , ''New York Times'', March 4, 2003
	* http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=search&db=pcsubstance&term=usnic%20acid
	* http://bioweb.ucr.edu/ChemMine/view.php?TYPE=1&i_id=996789
	* http://ntp.niehs.nih.gov/index.cfm?objectid=E87D09E6-BDB5-82F8-FF11A36F2EEA025F
	* http://query.nytimes.com/gst/fullpage.html?res=9802E2DD163FF937A35750C0A9659C8B63

	{{DEFAULTSORT:Usnic Acid}}		{{DEFAULTSORT:Usnic Acid}}
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Latest revision as of 13:49, 19 July 2024

Usnic acid
Names

IUPAC name 2,6-Diacetyl-7,9-dihydroxy-8,9b-dimethyldibenzofuran-1,3(2H,9bH)-dione
Other names Usneine Usninic acid Usniacin
Identifiers
CAS Number	125-46-2 racemic 7562-61-0 (R)-(+) 6159-66-6 (S)-(–)
3D model (JSmol)	Interactive image
ChEBI	CHEBI:38319
ChEMBL	ChEMBL242022
ChemSpider	5444
ECHA InfoCard	100.004.310
PubChem CID	5646
UNII	0W584PFJ77 663456969I (R)-(+) 5HYW08F205 (S)-(–)
CompTox Dashboard (EPA)	DTXSID0040123
InChI InChI=1S/C18H16O7/c1-6-14(22)12(8(3)20)16-13(15(6)23)18(4)10(25-16)5-9(21)11(7(2)19)17(18)24/h5,11,22-23H,1-4H3Key: CUCUKLJLRRAKFN-UHFFFAOYSA-N InChI=1/C18H16O7/c1-6-14(22)12(8(3)20)16-13(15(6)23)18(4)10(25-16)5-9(21)11(7(2)19)17(18)24/h5,11,22-23H,1-4H3Key: CUCUKLJLRRAKFN-UHFFFAOYAS
SMILES CC1=C(C(=C2C(=C1O)C3(C(=CC(=O)C(C3=O)C(=O)C)O2)C)C(=O)C)O
Properties
Chemical formula	C₁₈H₁₆O₇
Molar mass	344.319 g·mol
Melting point	204 °C (399 °F; 477 K)
Solubility in water	<0.001 g/L (25°C)
Solubility in acetone	0.077 g/L
Solubility in ethyl acetate	0.088 g/L
Solubility in furfural	0.732 g/L
Solubility in furfuryl alcohol	0.121 g/L
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). N verify (what is ?) Infobox references

Chemical compound

Usnic acid is a naturally occurring dibenzofuran derivative found in several lichen species with the formula C₁₈H₁₆O₇. It was first isolated by German scientist W. Knop in 1844 and first synthesized between 1933 and 1937 by Curd and Robertson. Usnic acid was identified in many genera of lichens including Usnea, Cladonia, Hypotrachyna, Lecanora, Ramalina, Evernia, Parmelia and Alectoria. Although it is generally believed that usnic acid is exclusively restricted to lichens, in a few unconfirmed isolated cases the compound was found in kombucha tea and non-lichenized ascomycetes.

At normal conditions, usnic acid is a bitter, yellow, solid substance. It is known to occur in nature in both the d- and l-forms as well as a racemic mixture. Salts of usnic acid are called usnates (e.g. copper usnate).

Biological role in lichens

Usnic acid is a secondary metabolite in lichens whose role has not been completely elucidated. It is believed that usnic acid protects the lichen from adverse effects of sunlight exposure and deters grazing animals with its bitter taste.

Biosynthesis

Usnic acid is a polyketide biosynthesized via methylphloroacetophenone as an intermediate.

Safety

Usnic acid and its salts are idiosyncratically associated with severe hepatotoxicity and liver failure. Daily oral intake of 300–1350 mg over a period of weeks has led to severe hepatotoxicity in a number of persons.

Sodium usnate was one ingredient in a product called "Lipokinetix" that was claimed to induce weight loss via an increase in metabolic rate. Lipokinetix has been the topic of an FDA warning in the USA due to potential hepatotoxicity, although it is unclear yet if any toxicity would be attributable to the aforementioned salt. Lipokinetix also contained norephedrine (PPA), caffeine, yohimbine and 3,5-diiodothyronine.

Pharmacology

Usnic acid has been found to have adrenergic activity in both frog and earthworm nerve junction models in preliminary research.

Analytics

It is possible to determine the content of usnic acid in lichen extract using reversed-polarity capillary zone electrophoresis or high performance liquid chromatography analysis.

References

^ O'Neil, Maryadele J.; Merck Sharp and Dohme Research Laboratories, eds. (2001). The Merck index: an encyclopedia of chemicals, drugs, and biologicals (13th ed.). Whitehouse Station, NJ: Merck. p. 1762. ISBN 978-0-911910-13-1.{{cite book}}: CS1 maint: date and year (link)
Knop, W (1844). "Chemisch-physiologische Untersuchung uber die Flechten". Annalen der Chemie und Pharmacie. 49 (2): 103–124. doi:10.1002/jlac.18440490202.
Robertson, A.; Curd, F. H. (1933). "277. Usnic acid. Part III. Usnetol, usnetic acid, and pyrousnic acid". Journal of the Chemical Society (Resumed): 1173. doi:10.1039/jr9330001173.
Cocchietto, Moreno; Skert, Nicola; Nimis, Pier; Sava, Gianni (2002). "A review on usnic acid, an interesting natural compound". Naturwissenschaften. 89 (4): 137–146. Bibcode:2002NW.....89..137C. doi:10.1007/s00114-002-0305-3. ISSN 0028-1042. PMID 12061397. S2CID 11481018.
Blanc, Philippe J. (1996). "Characterization of the tea fungus metabolites". Biotechnology Letters. 18 (2): 139–142. doi:10.1007/BF00128667. ISSN 0141-5492. S2CID 34822312.
Michael Ash; Irene Ash (2004). Handbook of preservatives. Synapse Info Resources. p. 5856. ISBN 978-1-890595-66-1. Retrieved 5 August 2010.
Taguchi, Heihachiro; Sankawa, Ushio; Shibata, Shoji (1969). "Biosynthesis of Natural Products. VI. Biosynthesis of Usnic Acid in Lichens. (1). A General Scheme of Biosynthesis of Usnic Acid". Chemical & Pharmaceutical Bulletin. 17 (10): 2054–2060. doi:10.1248/cpb.17.2054. PMID 5353559.
Chitturi, Shivakumar; Farrell, Geoffrey C. (2008). "Hepatotoxic slimming aids and other herbal hepatotoxins". Journal of Gastroenterology and Hepatology. 23 (3): 366–373. doi:10.1111/j.1440-1746.2008.05310.x. PMID 18318821. S2CID 23840983.
Yellapu RK, Mittal V, Grewal P, Fiel M, Schiano T (2011). "Acute liver failure caused by 'fat burners' and dietary supplements: a case report and literature review". Canadian Journal of Gastroenterology. 25 (3): 157–60. doi:10.1155/2011/174978. PMC 3076034. PMID 21499580.
Hsu, LM; Huang, YS; Chang, FY; Lee, SD (Jul 2005). "'Fat burner' herb, usnic acid, induced acute hepatitis in a family". Journal of Gastroenterology and Hepatology. 20 (7): 1138–9. doi:10.1111/j.1440-1746.2005.03855.x. PMID 15955234. S2CID 6717430.
Sanchez, William; Maple, John T.; Burgart, Lawrence J.; Kamath, Patrick S. (2006). "Severe Hepatotoxicity Associated with Use of a Dietary Supplement Containing Usnic Acid". Mayo Clinic Proceedings. 81 (4): 541–544. doi:10.4065/81.4.541. PMID 16610575.
"Safety Alerts for Human Medical Products > Lipokinetix". MedWatch: The FDA Safety Information and Adverse Event Reporting Program. U.S. Food and Drug Administration. November 20, 2001. Retrieved 5 December 2012. FDA has received multiple reports of persons who developed liver injury or liver failure while using Lipokinetix. The product contains norephedrine (also known as phenylpropanolamine or PPA), caffeine, yohimbine, diiodothyronine, and sodium usniate.
Harris N. J. (1961), Honors Thesis, Clark University, Worcester, Massachusetts
Kreft, Samo; Štrukelj, Borut (2001). "Reversed-polarity capillary zone electrophoretic analysis of usnic acid". Electrophoresis. 22 (13): 2755–2757. doi:10.1002/1522-2683(200108)22:13<2755::AID-ELPS2755>3.0.CO;2-6. PMID 11545403. S2CID 24341350.

External links

Seeking to Fight Fat, She Lost Her Liver, New York Times, March 4, 2003

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