Figure 2.

PhytoQuin potently inactivates human coronaviruses 229E and OC43. (A) HCoV-229E was combined with 0.5% DMSO or PhytoQuin (0.5, 1, 2, or 4 µg/mL) prior to exposure to LED light in black tubes (“Dark”, black dots/lines) or clear tubes (“Light”, blue dots/lines) at 49 J/cm². The treated inocula were serially diluted and used to infect Huh7.5 cells and titered using TCID₅₀ assays. (B) HCoV-OC43 was combined with 0.5% DMSO or PhytoQuin (0.5, 1, 2, or 4 µg/mL) prior to exposure to light as indicated for panel A. The treated inocula were serially diluted and used to infect BHK-21 cells and titered using TCID₅₀ assays. The resulting TCID₅₀/mL values are plotted showing the individual data points with each bar graph (DMSO, grey; PhytoQuin, white) representing the average ± SEM from four or six independent experiments. The LOD for the TCID50 assays is indicated by the horizontal dotted line. * p = 0.01–0.05, ** p = 0.001–0.01, using unpaired t-tests comparing to DMSO/+Light. Abbreviations: DMSO, dimethyl sulfoxide; LED, light-emitting diode; LOD, limit of detection; SEM, standard error of the mean; TCID₅₀, median tissue culture infectious dose.