Preliminary study of the toxicity and radioprotective effects of zymosan in vitro and in vivo
Abstract Background: This study aimed to confirm the cytotoxicity of zymosan in AHH-1 cells and HIECs and to determine the treatment time and dose of zymosan at which it exerts radioprotective effects.Methods: AHH-1 cells and HIECs were administered 0, 20, 40, 80 or 160 μg/mL zymosan. The CCK-8 assay and flow cytometry were used to evaluate cell viability and apoptosis 24 h, 48 h, and 72 h after administration. Furthermore, 12 h before irradiation, the cells were treated with 0, 5, 10, or 20 μg/mL zymosan and then irradiated with 4 Gy X-rays. Cell viability and apoptosis were measured by the CCK-8 assay and flow cytometry at 24 h. In addition, the protective effect of zymosan against radiation in vitro was compared to that of 20 μg/mL LPS as a positive control. In vivo, weight, the spleen index and the thymus index were measured to evaluate the toxicity of 0, 5, 10, 20 and 10 mg/kg zymosan. In addition, rats were treated with 0, 2, 4, 8 or 10 mg/kg zymosan and then irradiated with 7 Gy X-rays. The survival rate, spleen index and thymus index were evaluated. The protective effect of zymosan against radiation in vivo was compared to that of 10 mg/kg LPS a positive control. Results: The viability and apoptosis of cells treated with different doses of zymosan for different treatment times were not different from those of control cells (p<0.05). Furthermore, cell viability and apoptosis were clearly improved after zymosan preadministration (p<0.05). The radioprotective effect of zymosan was dose-dependent. In addition, the viability of cells pretreated with zymosan was higher than that of cells pretreated with LPS, and the apoptosis rate of zymosan-treated cells was lower than that of cells pretreated with LPS (p<0.05). In vivo, weight, the spleen index and the thymus index were significantly decreased by zymosan at a concentration of 20 mg/kg (p<0.05). Further experiments showed that the concentration at which zymosan exerted radioprotective effects was 10 mg/kg. The radioprotective effect of zymosan was better than that of LPS pretreatment (p<0.05). Conclusion: Zymosan is nontoxic to cells and exerts a better radioprotective effect than LPS.