*4.5. Metabolic Activity Measurement*

Survival rate and cytoprotection were determined using an MTT assay according to the method described by Mosmann [43] with some modifications. After treatments, a solution of MTT (2 mg/mL, 100 μL) was added to wells, and plates were incubated for 1 h. Then, the medium was removed, and formazan crystals were dissolved with DMSO (100 μL). Absorbance was measured at 550 nm with a Spectrostar BMG microplate reader.

#### *4.6. Intracellular ROS Production*

Intracellular ROS production was determined using a DCFH-DA assay as described by LeBel et al. (1992) [44]. Briefly, DCFH-DA dissolved in DMEM medium (1%) without phenol red was added to 96-well plates for 30 min. This solution was then removed, and cells were treated with non-cytotoxic lichen concentrations for 24 h before hydrogen peroxide (250 μM). Fluorescence was measured with a microplate reader (FLUOstar OPTIMA, BMG Labtech, Ortenberg, Germany) at excitation/emission wavelength 485/528 nm.

#### *4.7. BCA Assay*

The protein concentration was calculated using a bicinchoninic acid (BCA) assay. The colorimetric reaction was measured at 550 nm in a Spectrostar microplate reader (BMG Labtech, Ortenberg, Germany). Samples of total cellular extracts were mixed with a reaction solution [bicinchoninic acid and copper (II) sulfate]. The purple color proportionally increased with the amount of protein. A bovine serum albumin (BSA) curve was used to normalize protein [45].
