3.6. Cytoprotective Effect of ZSP

Once heavy metals enter the human body, they are difficult to eliminate and are mainly metabolized by the liver. Excessive accumulation of heavy metals will damage the liver. Therefore, HepG2 cell was selected and preprotected with ZSP to evaluate the ability of polysaccharide to bind heavy metal ions in vitro. The method of Li et al. was referenced and slightly modified [38]. The cells were cultured in DMEM medium containing 10% fetal bovine serum, penicillin and streptomycin at 37 °C and 5% CO₂. When the cells grew to about 80% of the coverage rate, they were cultured with trypsin enzyme digesting until the cells grew to logarithmic phase and then the cells were transferred to 96-well plates (cell suspension is 100 µL/hole). The ZSP solutions (10 µL/hole) were added to the cells for preprotection and subsequent experiments were conducted after the cells grew for 3 h. The metal ion solutions (10 µL each; 20 mM) were added to the sample holes of cell culture plate respectively and the protective effect of ZSP on cells was observed after 24 h. The cellular activity was determined by CKK-8 assay.