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Figure 7: The cell toxicity of pine pollen was evaluated by the cell proliferation detected by the MTT assay. In brief, the 2BS cells were seeded in flat-bottomed 96-well microplates at the density of 3000 cells in 0.2 mL per well. After 20 h, the cells were incubated in the culture medium containing various concentrations of pine pollen (PP) for 48 h.Then 20 μL MTT [3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-diphenlytetrazoliumbromide] of 10 mg/mL was added to each well. After incubation for 4 h, 0.2 mL DMSO was added to stop reactions. The absorbance values of each well were determined spectrophotometrically at 570 nm using the microplate reader (BIOTEK, Rockville, MA, USA). A stimulatory rather than inhibitory effect of pine pollen under 0.5–5 mg/mL on 2BS cell proliferation was observed, which indicated its biosafety under such dosages.