Clastogenic Effect of Atranorin, Evernic acid, and Usnic Acid on Human Lymphocytes

Three lichen secondary metabolites atranorin (1), evernic acid (2), and usnic acid (3), were evaluated for their in vitro clastogenic and antiproliferative effects on human lymphocytes using the cytochalasin-B blocked micronucleus (CBMN) assay at concentrations of 2 microg/mL, 4 microg/mL and 6 microg/mL of final culture solution. The frequency of micronucleus (MN) was scored in binucleated cells, and cytokinesis-block proliferation index (CBPI) was calculated. Among the tested compounds, 3 exhibited the most prominent effect decreasing the frequency of MN in the range of 42.5% - 48.9%, that is about double of the positive control amifostin WR-2721 that reduces MN frequency for 22.0%. The effect of evernic acid was approximately equal to action of amifostin (23.2% -32.9%). Atranorin at concentrations of 2 microg/mL and 4 microg/mL decreasing the frequency of MN only for 11.1% and 1.8%, while in concentration of 6 microg/mL increases the frequency of MN for 9.6 %. The comparable CBPI values of the investigated compounds and control suggested that they did not show a statistically significant inhibitory effect on lymphocyte cell proliferation at applied concentrations.