Research for the lichen Usnea barbata metabolites.
Bazarnova Y, Politaeva N, Lyskova N.
Z Naturforsch C. 2018 Jul 26;73(7-8):291-296. doi: 10.1515/znc-2017-0177.

Secondary Metabolite Profiling of Species of the Genus Usnea by UHPLC-ESI-OT-MS-MS.
Salgado F, Albornoz L, Cortéz C, Stashenko E, Urrea-Vallejo K, Nagles E, Galicia-Virviescas C, Cornejo A, Ardiles A, Simirgiotis M, García-Beltrán O, Areche C.
Molecules. 2017 Dec 27;23(1). pii: E54. doi: 10.3390/molecules23010054.

Protective effects of lichen metabolites evernic and usnic acids against redox impairment-mediated cytotoxicity in central nervous system-like cells.
Fernández-Moriano C, Divakar PK, Crespo A, Gómez-Serranillos MP.
Food Chem Toxicol. 2017 Jul;105:262-277. doi: 10.1016/j.fct.2017.04.030.

Detection of herbaceous-plant pararetrovirus in lichen herbarium samples.
Petrzik K, Koloniuk I, Sarkisová T, Číhal L.
Acta Virol. 2016 Jun;60(2):196-200.

Evaluation of Anticancer and Antioxidant Activity of a Commercially Available CO2 Supercritical Extract of Old Man's Beard (Usnea barbata).
Zugic A, Jeremic I, Isakovic A, Arsic I, Savic S, Tadic V.
PLoS One. 2016 Jan 8;11(1):e0146342. doi: 10.1371/journal.pone.0146342

Metabolites of Toxigenic Fungi in Lichens of Genera Alectoria, Bryoria, Evernia, Pseudevernia, and Usnea.  
Burkin AA, Kononenko GP.
Izv Akad Nauk Ser Biol. 2015 Jul-Aug;(4):361-7

Usnea barbata CO2-supercritical extract in alkyl polyglucoside-based emulsion system: contribution of Confocal Raman imaging to the formulation development of a natural product.
Zugic A, Lunter DJ, Daniels R, Pantelic I, Tasic Kostov M, Tadic V, Misic D, Arsic I, Savic S.
Pharm Dev Technol. 2016 Aug;21(5):563-75. doi: 10.3109/10837450.2015.1026606.

Application of molecular markers to detect DNA damage caused by environmental pollutants in lichen species.
Cansaran-Duman D, Altunkaynak E, Aslan A, Büyük I, Aras S.
Genet Mol Res. 2015 May 4;14(2):4637-50. doi: 10.4238/2015.May.4.23.

Genotoxic and antigenotoxic potentials of two Usnea species.
Ceker S, Orhan F, Kizil HE, Alpsoy L, Gulluce M, Aslan A, Agar G.
Toxicol Ind Health. 2015 Nov;31(11):990-9. doi: 10.1177/0748233713485889.

Usnea barbata beard lichen is a washed green or grey lichen found in both Europe and North America.

It has antibiotic properties and is very bitter. It is used against bronchitis, flu, colds, digestive disorders.

Used in the treatment of cancer, it currently has no authoritative medical evidence to confirm its effectiveness.

Among its components, the usnic acid, a component that can also induce toxicity (1), is used in supplements for weight loss, dandruff and more.

The aqueous methanolic extract of Usnea barbata has been successfully used as an antibiotic therapeutic agent against infections caused by Lactococcus garvieae on rainbow trout (2).

The extract has demonstrated antifungal properties at concentrations of 10mg ml^-1 against Alternaria alternaria, a parasite ascomycetes fungus that attacks the leaves and damages the crops of about 350 plant species and can induce allergies in humans (3).

Usnea barbata studies

References_________________________________

(1) Activation of the Nrf2 signaling pathway in usnic acid-induced toxicity in HepG2 cells.  Chen S, Zhang Z, Qing T, Ren Z, Yu D, Couch L, Ning B, Mei N, Shi L, Tolleson WH, Guo L.  Arch Toxicol. 2017 Mar;91(3):1293-1307. doi: 10.1007/s00204-016-1775-y.

The role of autophagy in usnic acid-induced toxicity in hepatic cells.  Chen S, Dobrovolsky VN, Liu F, Wu Y, Zhang Z, Mei N, Guo L.  Toxicol Sci. 2014 Nov;142(1):33-44. doi: 10.1093/toxsci/kfu154.

(2) Therapeutic effects of beard lichen, Usnea barbata extract against Lactococcus garvieae infection in rainbow trout (Oncorhynchus mykiss).  Bilen S, Sirtiyah AMA, Terzi E.  Fish Shellfish Immunol. 2019 Apr;87:401-409. doi: 10.1016/j.fsi.2019.01.046.

(3) In vitro antifungal activity of some South African medicinal plants AJ Afolayan, DS Grierson, L Kambizi, I Madamombe and PJ Masika  South African Journal of Botany 2002, 68: 72–76