Fractionated Lichen Parmelia vagansExtract Exhibits Two distinct Antiproliferative Activities Against Human Cancer Cells

Abstract

IntroductionApproximately one quarter of all prescription drugs contain active ingredients of plant origins. Lichens have been historically used to treat a multitude of ailments, ranging from headaches during the Middle Ages to dressing wounds before colonial times and much of the potency of lichen relies on the secondary metabolites they produce. The purpose of this project is to analyze antiproliferative properties of the secondary metabolites of lichen Parmelia vagans.MethodsLichen extracts were prepared using different organic solvents and further fractionated either by preparative TLC or by reverse‐phase chromatography. We assessed the antiproliferative activity of the fraction using human cancer cell lines. The same number of cells of different cell lines were plated into a 96‐well plate and allowed to adhere overnight. Next day, different dilutions of the enriched fractions were added to the adhered cells and the plate was placed in CO2 incubator for 24 hours. By the end of the incubation time a picture of each well was taken to assess cell confluency and morphology followed by Resazurin assay to analyze the effect of the lichen extract on cell growth and proliferation. After Resazurin assay, the cells in each well were treated with trypsin, suspended in growth medium and counted using Bio‐Rad cell counter to evaluate a percent of live cells.ResultsAssessment of antiproliferative activity of the TLC and reverse‐phase chromatography fractions revealed two separate peaks of inhibitory activity against cancer cell. The fraction obtained from P.vagans extract significantly suppress (30% ‐ 80%) the growth of human lung carcinoma A549. We also found that cancer cells treated by the lichen extracts results in their morphological changes that resemble an activation of apoptosis.DiscussionOur findings indicate that from P.vagans produces secondary metabolites that slow cancer cells growth and proliferation. Future experiments will be focused on isolation and identification of the compounds from P.vagans that are responsible for the inhibition of cancer cells growth. Another important aspect of the future research is to identify the cellular target(s) of the antiproliferative compound(s) and its molecular mechanism of action. I summary, the lichen’s secondary metabolites may hold a vast medicinal potential and could be a viable source of a novel of anticancer drugs.