Antibacterial Activity of the Chloroform, Acetone, Methanol and queous Extracts of Algerian Lichens

Brakni Rafika, Ali Monia

Abstract


In the current study, we investigated the antibacterial activity of chloroform, acetone, methanol and aqueous
extracts of the following lichens: Evernia prunastri (L.) Ach., Ramalina fastigiata (Pers.) Ach. and Cladonia
rangiformis Hoffm. The phytochemical analyses of extracts of each species were determined by thin layer
chromatography (TLC) and microcrystallization. These extracts were tested in vitro against Escherichia coli,
Klebsiella pneumonia, Staphylococcus aureus, Proteus mirabilis and Pseudomonas aeruginosa by the disc
diffusion method.
The sensitivity of the bacteria to the different lichen extracts is as follows: Staphylococcus aureus is highly
sensitive to all extracts and more precisely to the methanolic extract of Evernia prunastri (with a 43 mm inhibition
zone), Escherichia coli particularly sensitive to the chloroformic and acetonic extracts of E prunastri and R
fastigiata and to the methanolic and aqueous extracts of C rangiformis, Klebsiella pneumonia is insensitive to all
lichen extracts, Proteus mirabilis and Pseudomonas aeruginosa are slightly sensitive to certain extracts of R
fastigiata.
The activity of the lichenic extracts was certainly due to predominant compounds such as lichenic acids (Usnic
acid, Evernic acid, Fumarprotocetraric acid and Atranorin), some of which have already proved their antibacterial
efficacy. Therefore, these lichens may be used to discover bioactive products that may serve as new sources of
natural antimicrobial agents.

Keywords


Lichens, Extract, Secondary metabolites, TLC, Microcrystallization, Antimicrobial activity.

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