Fig. 6
The inhibition mechanism of dieckol. a The inhibitory activity of dieckol in the FRET assay. Mpro (0.4 µM) was preincubated with the indicated concentrations of dieckol at RT for 35 min in the presence of 1 mM DTT in FP assay buffer. After addition of FRET substrate, the RFU value was separately measured every second for 3 min by a microplate reader (BioTek). The VI was calculated by the slope of a linear regression in the first 30 s. DMSO and GC-376 (1 µM) was used as the negative and positive control, respectively. The RFU value was notably quenched by dieckol in a dose-dependent manner. b The inhibitory activity of dieckol in the absence or present of DTT. The IC50 values were separately obtained from dose-response curves by plotting the VI against various concentrations of dieckol in GraphPad Prmis 5.0. c The Lineweaver–Burk plots for analysis the inhibition mechanism of dieckol on Mpro using a FRET assay. d The secondary plots for a Ki value of dieckol in the FRET substrate