Antioxidant, antimicrobial and anticancer activity of the lichens Cladonia furcata, Lecanora atra and Lecanora muralis

<p>Abstract</p> <p>Background</p> <p>The aim of this study is to investigate in vitro antioxidant, antimicrobial and anticancer activity of the acetone extracts of the lichens <it>Cladonia furcata, Lecanora atra </it>and <it>Lecanora muralis</it>.</p> <p>Methods</p> <p>Antioxidant activity was evaluated by five separate methods: free radical scavenging, superoxide anion radical scavenging, reducing power, determination of total phenolic compounds and determination of total flavonoid content. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration by the broth microdilution method against six species of bacteria and ten species of fungi. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using MTT method.</p> <p>Results</p> <p>Of the lichens tested, <it>Lecanora atra </it>had largest free radical scavenging activity (94.7% inhibition), which was greater than the standard antioxidants. Moreover, the tested extracts had effective reducing power and superoxide anion radical scavenging. The strong relationships between total phenolic and flavonoid contents and the antioxidant effect of tested extracts were observed. Extract of <it>Cladonia furcata </it>was the most active antimicrobial agent with minimum inhibitory concentration values ranging from 0.78 to 25 mg/mL. All extracts were found to be strong anticancer activity toward both cell lines with IC₅₀values ranging from 8.51 to 40.22 μg/mL.</p> <p>Conclusions</p> <p>The present study shows that tested lichen extracts demonstrated a strong antioxidant, antimicrobial and anticancer effects. That suggest that lichens may be used as as possible natural antioxidant, antimicrobial and anticancer agents to control various human, animal and plant diseases.</p

Antimicrobial activity of selected corticolous macrolichens

The present study was conducted to screen antimicrobial activity of three foliose macrolichens viz., Parmotrema reticulatum (Taylor) M. Choisy (Parmeliaceae), Heterodermia  obscurata (Nyl.) Trevis (Physciaceae) and Dirinaria consimilis (Stirt.) D.D. Awasthi (Physciaceae) and two fruticose macrolichens viz., Ramalina pacifica Asahina (Ramalinaceae), and Ramalina hossei H. Magn &amp; G. Awasthi (Ramalinaceae) growing on barks of areca trees. The lichens were identified on the basis of morphological, anatomical and color tests and the secondary metabolites (lichen substances) were identified by thin layer chromatography. Antibacterial activity of lichen extracts was evaluated against three Gram positive and five Gram negative bacteria by Agar well diffusion assay. The lichen extracts were effective in inhibiting all test bacteria. Overall, extract of D. consimilis and P. reticulatum displayed marked and least antibacterial efficacy. Marked inhibitory activity was observed against Klebsiella pneumoniae. Antifungal effect of lichen extracts was determined against four molds by Poisoned food technique. Among fungi, the growth of Colletrotrichum capsici was suppressed to higher extent by lichen extracts. The observed inhibitory activity of lichens could be ascribed to the presence of lichen substances.Keywords: Lichens, Antimicrobial, Agar well diffusion, Poisoned food technique