Editing Lichenology (section)

==Lichens in pharmacology==
Although several species of lichen have been used in [[traditional medicine]] it was not until the early 20th century that modern science became interested in them. The discovery of various substances with [[antibacterial]] action in lichen thalli was essential for scientists to become aware of the possible importance of these organisms to [[medicine]].<ref>http://lichens.science.oregonstate.edu/antibiotics/lichen_antibiotics.htm Mike Crockett, Stacie Kageyama, Delfina Homen, Carrie Lewis, Jane Osborn, Logan Sander (2003). "Antibacterial Properties of four Pacific North West Lichens".</ref> From the 1940s there appeared various works by the noted [[microbiologist]] [[Rufus Paul Burkholder]] who demonstrated antibacterial action of lichens of the genus ''[[Usnea]]'' against ''[[Bacillus subtilis]]'' and ''[[Sarcina lutea]]''.<ref>{{cite web | url=http://modmedmicrobes.wikispaces.com/Sarcina+Lutea | title=Wikispaces}}</ref> Studies showed that the substance that inhibited growth of bacteria was [[usnic acid]]. Something similar occurred with the substance [[Ramelina]] synthesised by the lichen ''[[Ramalina reticulata]]'',<ref>{{Cite journal | doi=10.1126/science.106.2756.394| pmid=17750561| title=Antibiotic Compound Isolated from the Lichen Ramalina reticulata| journal=Science| volume=106| issue=2756| pages=394–395| year=1947| last1=Marshak| first1=A.| last2=Barry| first2=G. T.| last3=Craig| first3=L. C.| bibcode=1947Sci...106..394M}}</ref> nevertheless, these substances proved ineffective against [[Gram negative bacteria]] such as ''[[Escherichia coli]]'' and ''[[Pseudomonas]]''. With these investigations the number of antibacterial substances and possible drug targets known to be produced by lichens increased [[ergosterol]], [[usnic acid]] etc.<ref>Bustinza, Francisco (1948) "Contribution to the Study of Antibiotics Produced by Lichens". ''Annals of the Botanical Garden of Madrid'' (7) ISSN pp. 511–548.</ref>

Interest in the potential of substances synthesised by lichens increased with the end of [[World War II]] along with the growing interest in all [[antibiotic]] substances. In 1947 antibacterial action was identified in extracts of ''[[Cetraria islandica]]'' and the compounds identified as responsible for bacterial inhibition were shown to be [[d-protolichosteric acid]] and [[d-1-usnic acid]].<ref>Bustinza, Francisco (1951) "Contribution to the Study of Antibacterial Activity in ''Cetraria islandica''". ''Annals of the Botanical Garden of Madrid'' (10) ISSN pp. 144–149.</ref> Further investigations have identified novel antibacterial substances, [[Alectosarmentin]]<ref>{{Cite journal
 | pmid = 7964789
| year = 1994
| last1 = Gollapudi
| first1 = S. R.
| title = Alectosarmentin, a new antimicrobial dibenzofuranoid lactol from the lichen, Alectoria sarmentosa
| journal = Journal of Natural Products
| volume = 57
| issue = 7
| pages = 934–8
| last2 = Telikepalli
| first2 = H
| last3 = Jampani
| first3 = H. B.
| last4 = Mirhom
| first4 = Y. W.
| last5 = Drake
| first5 = S. D.
| last6 = Bhattiprolu
| first6 = K. R.
| last7 = Vander Velde
| first7 = D
| last8 = Mitscher
| first8 = L. A.
 | doi=10.1021/np50109a009
}}</ref> or [[Atranorin]].<ref>{{Cite journal | url=http://nora.nerc.ac.uk/17588/ | doi=10.1016/S0022-2860(02)00626-9| title=Molecular structural studies of lichen substances II: Atranorin, gyrophoric acid, fumarprotocetraric acid, rhizocarpic acid, calycin, pulvinic dilactone and usnic acid| journal=Journal of Molecular Structure| volume=651-653| pages=27–37| year=2003| last1=Edwards| first1=Howell G.M.| last2=Newton| first2=Emma M.| last3=Wynn-Williams| first3=David D.| bibcode=2003JMoSt.651...27E}}</ref>

Antibacterial action of substances produced by lichens is related to their ability to disrupt bacterial [[proteins]] with a subsequent loss of bacterial [[metabolic]] capacity. This is possible due to the action of lichen [[Natural phenol|phenol]]ics such as [[usnic acid]] derivatives.<ref>Neli Kika Honda & Wagner Vilegas (1998) "The Chemistry of Lichens" (Port)[http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40421999000100018&lng=in&nrm=iso&tlng=in] Química Nova 22(1) ISSN 0100-4042</ref>

From the 1950s the lichen product [[usnic acid]] was the object of most [[antitumour]] research. These studies revealed some [[in vitro]] antitumour activity by substances identified in two common lichens ''[[Peltigera leucophlebia]]'' and ''[[Collema flaccidum]]''.<ref>{{cite web | url=http://www.ebi.ac.uk/ebisearch/search.ebi?db=allebi&t=%22Collema+flaccidum%22 | title=EBI Search}}</ref>

Recent work in the field of applied [[biochemistry]] has shown some antiviral activity with some lichen substances. In 1989 K Hirabayashi<ref>{{Cite journal
 | pmid = 2575016
| year = 1989
| last1 = Hirabayashi
| first1 = K
| title = Inhibitory effect of a lichen polysaccharide sulfate, GE-3-S, on the replication of human immunodeficiency virus (HIV) in vitro
| journal = Chemical & Pharmaceutical Bulletin
| volume = 37
| issue = 9
| pages = 2410–2
| last2 = Iwata
| first2 = S
| last3 = Ito
| first3 = M
| last4 = Shigeta
| first4 = S
| last5 = Narui
| first5 = T
| last6 = Mori
| first6 = T
| last7 = Shibata
| first7 = S
 | doi=10.1248/cpb.37.2410
| doi-access = free
}}</ref> presented his investigations on inhibitory lichen polysaccharides in [[HIV]] infection.<ref>Francisco Javier Toledo Marante, Ana Garcia Costellano, Francisco Leon Oyola and Jaime Bermejo Barrera "Ecologia Quimica en Hongos y Liquenes" (Spa) ''Columbian Academy of Science'' 28 ISSN 0370-3908 pp. 509–528 [http://www.accefyn.org.co/revista/Vol_28/109/06_509_528.pdf]</ref>