2.4.1. The Content of Ergosterol in Mycelia Plasma Membrane

The content of ergosterol in an A. flavus mycelia plasma membrane was determined as Tian et al. [13] described. A. flavus spores (100 μL, 2 × 10⁸ spores/mL) were inoculated into 50-mL liquid sabourand medium with different concentrations of CV (0, 50, 100 and 200 µg/mL) and cultured at 28 °C with a speed of 200 r/min for 2 days. Then, A. flavus mycelia were filtered and collected. Five milliliters of 25% alcoholic potassium hydroxide solution were added to each sample, vortex-mixed for 2 min and then incubated at 85 °C for 4 h. Two milliliters of sterile distilled water and 5-mL n-heptane were then added, followed by vortex mixing for 2 min. The n-heptane layer (upper layer) was collected and scanned in the range of 230–300 nm by UV spectrophotometry. The presence of ergosterol (at 282 nm) and 24(28) dehydroergosterol (at 230 and 282 nm) in mycelium led to a characteristic curve. The ergosterol amount was calculated as a percentage of the wet weight of the cells and was based on the absorbance and wet weight of the initial pellet. Samples without CV treatment were considered as the control group. The ergosterol amount was calculated by a formula as follows:

where A282 and A230 are the absorbance of the n-heptane layer in 282 nm and 230 nm, respectively. The E-values are 290 and 518 (in percentages per cm) determined for crystalline ergosterol and 24 (28) dehydroergosterol, respectively.