The aim of this study is to investigate in vitro the anticancer, antioxidant, and antibacterial activities of three low molecular weight subfractions I, II and III isolated from secondary metabolites produced by the wood degrading fungus Cerrena unicolor. The present study demonstrated that the low molecular weight subfractions III exhibited the strongest inhibitory activity towards breast carcinoma cells MDA-MB-231, prostatic carcinoma cells PC3, and breast cancer cells MCF7 with the half-maximal inhibitory concentration (IC₅₀) value of 52,25 μg/mL, 60,66 μg/mL, and 54,92 μg/mL, respectively. The highest percentage of inhibition was noted at a concentration of 300 μg/mL in all the examined tumor lines. A significant percentage (59.08%) of ex-LMSIII inhibition of the MDA-MB-231 tumor line was reached at a concentration of 15 μg/ml, while the concentration applied did not affect normal human fibroblast cells. The low molecular weight subfraction III was the most effective and additionally showed the highest free radical 1,1-diphenyl-2-picryl-hydrazyl scavenging activity (IC₅₀ 20.39 μg/mL) followed by the low molecular weight subfraction I (IC₅₀ 64.14 μg/mL) and II (IC₅₀ 49.22 μg/mL). The antibacterial activity of the tested preparations was evaluated against three microorganisms: Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. The MIC minimal inhibitory concentration (MIC) values for the low molecular weight subfraction I, II, and III showed a stronger inhibition effect on S. aureus than on B. subtilis and E. coli cells. The MIC values for the low molecular weight subfraction II against S. aureus, B. subtilis, and E. coli were 6.25, 12.5, and 100 mg/mL, respectively.

Three bioactive fractions, extracellular laccase (ex-LAC), crude endopolysaccharides (c-EPL), and a low molecular subfraction of secondary metabolites (ex-LMS), were isolated from the idiophasic cultures of the white rot fungusCerrena unicolor. For the first time, we determined the antioxidant properties of these samples by chemiluminometric measurement (a) and assessment of the scavenging effect on ABTS (b) and the DPPH reduction rate (c). The highest reducing capability was found for the ex-LMS fraction: 39–90% for (a), 20–90% for (b), and 10–59% for (c) at the concentration of 6.25–800 µg/mL. The scavenging abilities of theC. unicolorc-EPL were between 36 and 70% for (a), 2 and 60% for (b), and 28 and 32% for (c) at the concentration of 6.25–800 µg/mL. A very high prooxidative potential was observed for the ex-LAC probes. The preliminary toxicity tests were done using the Microtox system and revealed the following percentage of the toxic effect againstVibrio fischeri: 85.37% for c-EPL, 50.67% for ex-LAC, and 99.8% for ex-LMS, respectively. The ex-LAC sample showed the antibacterial activity againstEscherichia coli, c-EPL againstStaphylococcus aureus, and ex-LMS against both bacterial strains, respectively, but the stronger inhibitory effect was exerted onS. aureus.

Chronic lymphocytic leukemia (CLL) is the most commonly observed adult hematological malignancy in Western countries. Despite the fact that recent improvements in CLL treatment have led to an increased percentage of complete remissions, CLL remains an incurable disease. Cerrena unicolor is a novel fungal source of highly active extracellular laccase (ex-LAC) that is currently used in industry. However, to the best of our knowledge, no reports regarding its anti-leukemic activity have been published thus far. In the present study, it was hypothesized that C. unicolor ex-LAC may possess cytotoxic activity against leukemic cell lines and CLL primary cells. C. unicolor ex-LAC was separated using anion exchange chromatography on diethylaminoethyl cellulose-Sepharose and Sephadex G-50 columns. The cytotoxic effects of ex-LAC upon 24- and 48-h treatment on HL-60, Jurkat, RPMI 8226 and K562 cell lines, as well as CLL primary cells of nine patients with CLL, were evaluated using 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. Annexin V/propidium iodide staining of Jurkat cells treated with ex-LAC was used to investigate apoptosis via flow cytometry. Ex-LAC induced changes in Jurkat and RPMI 8226 cells, as visualized by fluorescence and scanning electron microscopy (SEM). The XTT assay revealed high cytotoxic rates following treatment with various concentrations of ex-LAC on all the cell lines and CLL primary cells analyzed, with a half maximal inhibitory concentration ranging from 0.4 to 1.1 µg/ml. Fluorescence microscopy and SEM observations additionally revealed apoptotic changes in Jurkat and RPMI 8226 cells treated with ex-LAC, compared with control cells. These results were in agreement with the apoptosis analysis of Jurkat cells on flow cytometry. In conclusion, C. unicolor ex-LAC was able to significantly induce cell apoptosis, and may represent a novel therapeutic agent for the treatment of various hematological neoplasms.