Abstract

Lichens are complex symbiotic associations between a fungus (mycobiont) and photobiont, which can be either an alga or cyanobacteria. They are proven as the earliest colonizers of terrestrial habitats on the earth with a worldwide distribution from the Poles to tropical regions and from the plains to the highest mountains. In this study, the antartic lichen Usnea aurantiaco-atra has been characterized morphologically as well as structurally. A phytochemical study has been carried out, aiming to explore the most important metabolites. Moreover, the cytotoxic, antioxidant and insecticidal activity of their extracts has been determined. Citotoxicity studies have found that the hexanic extract that contains usnic acid as its main metabolite, linoleic acid and terpenes proved to have an interesting citotoxic activity when compared to melanoma and queratinocites. Testing the extract’s insecticidal activity in Ceratitis Capitata has demonstrated that usnic acid is linked to flies’ mortality. However, the results obtained with different extracts cannot be considered significant. On another note, we have analyzed the presence of total phenols in the extracts and we have seen that they do not have a significant influence in their antioxidant activity.

Highlights

  • Lichens have a large variety of uses and for some of them ethnopharmacological properties are reported

  • The F3 stood out, which presented a lower percentage of usnic acid than in the hexane extract, Ergosta -4,6,8 (14), 22-tetraen-3-one and a low percentage of unidentified terpene and acids fatty

  • The antioxidant activity was determined on the methanolic extract by means of a DPPH solution following the method previously published by (Fukumoto and Mazza, 2000), using BHT (2,6-di-t-butyl-4-methylphenol) as a reference

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Summary

INTRODUCTION

Lichens have a large variety of uses and for some of them ethnopharmacological properties are reported. These organisms are a source of original compounds (e.g. depsides and depsidones) that have been poorly investigated for their biological activities (Muller, 2001). These studies reported a variety of very interesting properties e.g. antibiotic (Lauterwein et al 1995), antiproliferative (Ogmundsdottir et al 1998), antioxidant (Hidalgo et al 1994), anti-HIV (Zhao, H et al 1997). As the lichen flora from the Antarctic region, remarkable for its variety and development, represents a potential source of new bioactive compounds, we have undertaken a biological screening to detect cytotoxic activity and antioxidant activity of the lichen extracts of the Usnea Aurantiaco-Atra

Plant materials
Extraction procedure
The extract identification
Cell lines
Cytotoxicity assay
Determination of Total Phenols on the methanolic extract
Findings
Conclusions
Full Text
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