**3. Results and Discussion**

### *3.1. Effect of Dimethomorph on Cell Viability*

The action mechanism of DMM is to destroy the cell wall membrane, causing the decomposition of the sporangium wall and inducing pathogen death [33]. However, the immunotoxicity of DMM on the human body and its mechanism has not received much attention. In the process of in vitro cytotoxicity evaluation, cell proliferation is an important marker for the evaluation of cytotoxicity [34]. The assessment of cellular activity was based on the ability of these cells to metabolize water-soluble tetrazole-8 (WST-8) of CCK-8 and convert it to orange formazan via mitochondrial dehydrogenase. Cell viability was determined by the extent of WST-8 cleavage by mitochondrial dehydrogenases in DMMexposed cells and controls [35]. Figure 1A shows the viability of Jurkat cells after exposure to different concentrations of DMM. Compared to the control group (with 0.1% acetone but without DMM addition), the cell activity decreased with an increasing DMM concentration, showing a concentration-dependent trend. In the EC50, EC25, and EC10 treatment groups, the Jurkat cells calculated by nonlinear curve fitting were 126.01 mg/L (0.32 mM), 21.37 mg/L (0.06 mM), and 4.12 mg/L (0.01 mM), respectively (Figure 1B). When the cells were exposed to the EC50, EC25, and EC10 treatment groups, the cell activities were consistent with the expected results (97.8%, 81.8%, and 53.4%, respectively) (Figure 1C), which could be used in subsequent apoptosis experiments.

**Figure 1.** Effect of dimethomorph on Jurkat T cells viability. (**A**) Jurkat cells exposed for 36 h at different DMM concentrations or controls. (**B**) Nonlinear curve fitting results of different effective concentration (EC) using the results of (**A**). (**C**) Jurkat T cells exposed for 36 h to EC50, EC25, EC10 DMM, or controls. Cell viability is presented as a percentage compared to the control. The results shown are the mean ± SD from triplicate exposures.
