Table 1.

Antiviral activity of MB and Radachlorin in Vero E6 cells without laser irradiation.

Compounds	PS added to cells along with SARS-CoV-2 (IC50 μg/mL)	PS added to cells 3.5 h post infection with SARS-CoV-2 (IC50 μg/mL)	CC50 μg/mL
MB	0.22 ± 0.07	0.66 ± 0.23	100 ± 24.0
Radachlorin	0.33 ± 0.09	2.0 ± 0.60	50 ± 15.0
T-705 and T-1105	≥ 60	NT	> 250*

Note: Data are the mean ± SEM of 3 independent tests (3 replicates for one test per concentration; the ranges of concentrations tested were 150−0.06 μg/mL for MB and Radachlorin and 60−0.02 μg/mL for T-705 and T-1105). Antiviral activity is expressed as the IC₅₀, defined as the compound concentration producing 50 % inhibition of virus replication, as estimated by microscopic scoring of the CPE and by measuring cell viability in the formazan-based MTT assay. Cytotoxicity is expressed as the CC₅₀, the compound concentration producing 50 % cytotoxic effect estimated by the MTT cell viability assay.

The T-705 and T-1105 compounds were kindly provided by Prof. Tikhonov A.Y. (N.N. Vorozhtsov Novosibirsk Institute of Organic Chemistry of the SB RAS) as potential inhibitors for viral RNA-dependent RNA polymerase of influenza virus. *the CC₅₀ value [17]. NT - not tested.