Context: Lichens produce specific secondary metabolites with different biological activity.
Objective: This study investigated the cytotoxic effects of physodic acid, in addition to the total phenolic content and cytotoxic and antioxidant activity of acetone extract from Hypogymnia physodes (L.) Nyl. (Parmeliaceae).
Materials and methods: Cytotoxicity of physodic acid (0.1-100 μM) was assessed in MDA-MB-231, MCF-7 and T-47D breast cancer cell lines and a nontumorigenic MCF-10A cell line using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, neutral red uptake and crystal violet assays during 72 h of incubation. An MTT assay was also used to assess the cytotoxic effects of the acetone extract (0.1-100 μg/mL) in the MDA-MB-231, MCF-7, T-47D breast cancer cell lines after 72 h. The total phenolic content of the acetone extract, expressed as the gallic acid equivalent, was investigated using Folin-Ciocalteu reagent. The antioxidant activity of the extract was assessed by 2,2-diphenyl-1-picrylhydrazyl and ferric-reducing antioxidant power assays.
Results: The cytotoxic activity of physodic acid appeared to be strong in the tumorigenic cell lines (IC50 46.0-93.9 μM). The compound was inactive against the nontumorigenic MCF-10A cell line (IC50 >100 μM). The acetone extract showed cytotoxicity in the breast cancer cell lines (IC50 46.2-110.4 μg/mL). The acetone extract was characterized by a high content of polyphenols, and it had significant antioxidant activity.
Discussion and conclusion: Physodic acid and acetone extract from H. physodes displayed cytotoxic effects in the breast cancer cell lines. Furthermore, acetone extract from H. physodes possessed significant antioxidant properties.
Keywords: Anticancer; antioxidant; depsidone; lichen; polyphenols.