Aims: The objective of this study was to explore the diversity of endolichenic fungi from Nephroma laevigatum and to investigate their antiproliferative and antibiofilm potential.
Methods and results: Forty-six isolates were obtained and identified by DNA barcoding. They belonged to genera Nemania, Daldinia, Peziza and Coniochaeta. Six strains belonging to the most represented species were selected and tested for their antiproliferative and antibiofilm activities. Extracts were analysed by reversed-phase HPLC. Activities against fungal and bacterial biofilm were evaluated using tetrazolium salt (XTT) assay and crystal violet assay respectively. Antiproliferative responses of extracts were determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Apoptosis induction by two extracts was observed in two cell lines (HT-29 and PC-3) via morphological changes, pro-apoptotic and anti-apoptotic proteins analysis (Western blotting) and DNA fragmentation. Four extracts displayed activities against Candida albicans biofilm with IC50 values ranging from 25 to 200 μg ml-1 . All extracts were inactive against Staphylococcus aureus and Pseudomonas aeruginosa biofilms. The most active isolates against human colorectal (HT-29 and HCT116) and prostate (PC-3 and DU145) cancer cell lines were Nemania serpens (NL08) and Nemania aenea var. aureolatum (NL38) with IC50 values ranging from 13 to 39 μg ml-1 . These extracts induced an apoptotic process through activation of caspases 8 and 3, poly(ADP-ribose) polymerase cleavage and DNA fragmentation.
Conclusions: Selected crude fungal extracts have antiproliferative and antibiofilm activities. Data suggest that this antipoliferative effect is due to apoptosis process. This is the first report showing the effects of endolichenic fungi from N. laevigatum.
Significance and impact of the study: This study highlights the therapeutic potential of endolichenic fungi metabolites as sources for drug discovery programmes.
Keywords: Candida albicans; DNA barcoding; Nemania sp.; Sordariomycetes; apoptosis; cancer cell lines.
© 2018 The Society for Applied Microbiology.