Review of usnic acid and Usnea barbata toxicity.
Usnic acid is a prominent secondary lichen metabolite that has been used for various purposes worldwide. Crude extracts of usnic acid or pure usnic acid have been marketed in the United States as dietary supplements to aid in weight loss. The US Food and Drug Administration (FDA) received 21 reports of liver toxicity related to the ingestion of dietary supplements that contain usnic acid. This prompted the FDA to issue a warning about one such supplement, LipoKinetix, in 2001 (http://www.cfsan.fda.gov/~dms/ds-lipo.html). Subsequently, usnic acid and Usnea barbata lichen were nominated by the National Toxicology Program (NTP) for toxicity evaluations. At present, a toxicological evaluation of usnic acid is being conducted by the NTP. This review focuses on the recent findings of usnic acid-induced toxicities and their underlying mechanisms of action.
Guo
Lei
L
National Center for Toxicological Research, Food and Drug Administration, Jefferson, Arkansas 72079, USA. lei.guo@fda.hhs.gov
Shi
Qiang
Q
Fang
Jia-Long
JL
Mei
Nan
N
Ali
A Afshan
AA
Lewis
Sherry M
SM
Leakey
Julian E A
JE
Frankos
Vasilios H
VH
D000818:Animals; D001572:Benzofurans / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology / Q000633:toxicity*; D006801:Humans; D008099:Liver / Q000187:drug effects; D009152:Mutagenicity Tests; D010936:Plant Extracts / Q000493:pharmacokinetics / Q000494:pharmacology / Q000633:toxicity*; D020949:Usnea / Q000737:chemistry*; D015431:Weight Loss
D001572:Benzofurans; D010936:Plant Extracts; C073339:usnic acid