Cytotoxicity and ROS production
The cytotoxicity of the extracts was determined via MTT assay, and intercellular ROS production was evaluated by DCFH-DA probe after PA explosion (Dai, Jiang, Lu, et al., 2020). Two cells in the PA group were added with 0.1, 0.2, 0.3, 0.4 and 0.5 mM PA to screen for the appropriate stimulating dose. The cells were seeded at a density of 1×106 cells/mL in a 96-well plate for 24 h and treated with the indicated concentrations of PA. The untreated cells were regarded as blank. After 24 h incubation, 50 μL of 2 mg/mL MTT solution was added to the cells. After another 3 h, the supernatant was discarded, and 200 μL of dimethyl sulfoxide was added to each well. The absorbance at 540 nm was determined by enzyme-linked immunosorbent assay to calculate the cell viability. Similarly, the cytotoxicity and ROS production of samples in PA-induced cells were determined by MTT and DCFH-DA assays, respectively.