norstictic-acid and usnic-acid

Cancer is the second leading cause of human deaths in the USA. Despite continuous efforts to treat cancer over the past 50 years, human mortality rates have not decreased significantly. Natural products, such as lichens, have been good sources of anticancer drugs. This study reports the cytotoxic activity of crude extracts of 17 lichen species against Burkitt's lymphoma (Raji) cells. Out of the 17 lichen species, extracts from 14 species showed cytotoxicity against Raji cells. On the basis of IC50 values, we selected Xanthoparmelia chlorochroa and Tuckermannopsis ciliaris to study the mechanism of cell death. Viability of normal lymphocytes was not affected by the extracts of X. chlorochroa and T. ciliaris. We found that extracts from both lichens decreased proliferation, accumulated cells at the G0 /G1 stage, and caused apoptosis in a dose-dependent manner. Both lichen extracts also caused upregulation of p53. The T. ciliaris extract upregulated the expression of TK1 but X. chlorochroa did not. We also found that usnic, salazinic, constictic, and norstictic acids were present in the extract of X. chlorochroa, whereas protolichesterinic acid in T. ciliaris extracts. Our data demonstrate that lichen extracts merit further research as a potential source of anticancer drugs.

Topics: 4-Butyrolactone; Antineoplastic Agents; Apoptosis; Benzofurans; Cell Line, Tumor; Cell Survival; Humans; Inhibitory Concentration 50; Lactones; Lichens; Lymphocytes; Molecular Structure; Salicylates; Thymidine Kinase; Tumor Suppressor Protein p53; United States

The aim of this study was to investigate the chemical composition of acetone extracts of the lichens Toninia candida and Usnea barbata and in vitro antioxidant, antimicrobial, and anticancer activities of these extracts together with some of their major metabolites. The chemical composition of T. candida and U. barbata extracts was determined using HPLC-UV analysis. The major phenolic compounds in these extracts were norstictic acid (T. candida) and usnic acid (U. barbata). Antioxidant activity was evaluated by free radical scavenging, superoxide anion radical scavenging, reducing power and determination of total phenolic compounds. Results of the study proved that norstictic acid had the largest antioxidant activity. The total content of phenols in the extracts was determined as the pyrocatechol equivalent. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration using the broth microdilution method. The most active was usnic acid with minimum inhibitory concentration values ranging from 0.0008 to 0.5 mg/mL. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using the microculture tetrazolium test. Usnic acid was found to have the strongest anticancer activity towards both cell lines with IC(50) values of 12.72 and 15.66 μg/mL.

Topics: Anti-Infective Agents; Antioxidants; Ascomycota; Bacteria; Benzofurans; Biphenyl Compounds; Cell Cycle; Cell Line, Tumor; Cell Survival; Fungi; Humans; Inhibitory Concentration 50; Lactones; Lichens; Microbial Sensitivity Tests; Molecular Structure; Phenols; Picrates; Salicylates; Usnea

Usnea undulata Stirton (Usneaaceae) is a fruticose lichen used locally in ethnoveterinary medicine to treat mammary infections in cattle while human beings use it for the treatment of wounds in Eastern Cape, South Africa. Bioactivity-guided fractionation of its extracts led to the isolation and characterization of a new depsidone, 2'-O-methylhypostictic acid (8), together with seven known compounds, i.e. methyl β-orsellinate, norstictic acid, menegazziaic acid, (+) usnic acid, hypoconstictic acid, salazinic acid, and galbinic acid. The structures of the compounds were elucidated on the basis of their spectral analysis including homo- and hetero-nuclear correlation NMR experiments (COSY, NOESY, HMQC, and HMBC) and mass spectra as well as by comparison with available data in the literature. The minimum inhibitory concentrations (MICs) values of the compounds against six bacteria were determined. Compound 8 showed inhibitory activity against Bacillus cereus, Bacillus subtilis, and Staphylococcus epidermidis with MICs of 31, 62.5, 62.5 μg/ml, respectively. (+) Usnic acid was most active against B. subtilis, B. cereus, Staphylococcus aureus, and Escherichia coli with MICs of 8, 8, 31, and 31 μg/ml, respectively, while other compounds exhibited moderate activity.

Topics: Animals; Anti-Bacterial Agents; Bacillus cereus; Bacillus subtilis; Benzofurans; Cattle; Depsides; Escherichia coli; Humans; Lactones; Microbial Sensitivity Tests; Salicylates; South Africa; Staphylococcus aureus; Usnea