The toxicity EC50 of GA on HEp-2 cells in MEM supplemented with 1% fetal bovine serum (FBS) was 27.63 ± 2.21 μM (Fig. S1A) or 63.5 ± 3.2 μM (Fig. S1B) on cells supplemented with 5% FBS. In cells infected with HCMV strain CH19 and supplemented with 1% FBS, the 50% inhibitory concentration (IC50) was 6.83 ± 1.08 μM, and with 10% bovine serum, the IC50 of GA was 41 μM (Fig. 1A). The toxicity EC50 of GA on HFF cells was 14.00 μM ± 0.1 in MEM medium supplemented with 1% FBS (Fig. S1C), and 137.04 μM ± 10.44 (Fig. S1D) in MEM medium supplemented with 10% FBS. The results indicated that the activity and toxicity of GA is affected by the serum concentration in the medium (see discussion).
Figure 1 Ginkgolic Acids (C13:0, C15:1, C17:1) inhibit HCMV in a dose-dependent manner and prevents plaque formation. (A) Monolayers of human foreskin fibroblasts (HFF) were inoculated with 50–100 cells infected with one of two cell-associated clinical isolates of HCMV (CH19 and BI-6) in a total of 4 wells per drug concentration followed by treatment with medium containing 0–10 µM GA. Viral infection was allowed to progress for 7 days when the mean number of HCMV plaques per concentration was counted, and the IC50 was determined. The effects of different concentrations of FBS and time delay on the IC50 are also shown. (B) Dose-dependent inhibitory effect of GA on infection by the cell-free virus strain PT30CMV-GFP. (C) Inhibitory effect of 10 µM GA C15:1 compared to 16 µM GCV on HCMV-GFP cell-free infection. (D) Inhibitory effect of 10 µM GA C13:0 on HCMV-GFP infection, and (E) Inhibitory effect of 10 µM GA C17:1 on cell-free HCMV-GFP infection. (B–E) representing average of 20 scanned fields.