Table 1.

Antiviral activity of compounds 1–23 against influenza A and B viruses and RSV in MDCK^a and HeLa cells, respectively.

Compound	Influenzab assay in MDCK cells				RSV assay in HeLa cells
	EC50c (μM)		Cytotoxicity (μM)		EC50d (μM)	Cytotoxicity
	Influenza A	Influenza B	MCCe	CC50f		MCCe (μM)
1	>100	>100	>100	>100	>100	>100
2	11	24	≥20	>100	>100	>100
3	35	7.7	≥20	>100	>100	>100
4	>100	0.29	≥0.8	18	0.40	≥100
5	28	4.0	≥4	>100	>100	≥100
6	>100	0.19	≥0.16	51	1.8	≥100
7	>100	>100	>100	>100	>100	>100
8	87	39	≥100	>100	>100	>100
9	>100	28	≥100	>100	>100	>100
10	>100	>100	>100	>100	>100	>100
11	>100	>100	>100	>100	>100	>100
12	>100	>100	>100	>100	>100	>100
13	>100	>100	>100	>100	>100	>100
14	>100	>100	>100	>100	>100	>100
15	>100	>100	>100	>100	>100	>100
16	>100	>100	>100	>100	>100	>100
17	>100	>100	>100	>100	>100	>100
18	>100	>100	>100	>100	>100	>100
19	>100	>100	>100	>100	>100	>100
20	>100	3.0	>100	>100	>100	>100
21	>100	>100	>100	>100	>100	>100
22	>100	>100	>100	>100	>100	>100
23	>100	>100	100	45	>100	100
Zanamivir	1.3	0.14	>100	>100	–	–
Amantadine	26	>500	>500	>500	–	–
Rimantadine	28	>500	≥500	>500	–	–
Ribavirin	11	3.2	≥20	>100	5.8	>250
DS-10,000g	–	–	–	–	0.80	>100

^aMDCK: Madin-Darby canine kidney cells.

^bInfluenza virus strains: A/PR/8/34 (A/H1N1) and B/Ned/537/05.

^cEC₅₀: 50% effective concentration giving 50% protection against virus-induced reduction in cell viability, as determined by colorimetric formazan-based MTS assay.

^dEC₅₀: 50% effective concentration producing 50% inhibition of virus-induced cytopathic effect (CPE), as determined by microscopy.

^eMCC: minimum compound concentration producing a microscopically detectable alteration in normal cell morphology.

^fCC₅₀: 50% cytotoxic concentration, as determined by measuring the cell viability with the MTS assay.

^gFor DS-10,000 (dextran sulphate of MW 10,000) concentrations are in μg/mL. Values shown are the mean of two or three independent experiments.