Table 3. Anti-RSV Activity, Cytotoxicity for HEp-2 Cells, and Selectivity Indices (SI) of Compounds Isolated from Milletia oblata.
| anti-RSV activity | cytotoxicity |
SIb | ||
|---|---|---|---|---|
| compound/extract | IC50 (μM) | CC50 (μM) | cytostatic activitya | (CC50/IC50) |
| 1 | >100.0 | >100.0 | 1.0 | |
| 2 | >100.0 | >100.0 | 1.0 | |
| 3 | 22.0 | 90.0 | 4.1 | |
| 4 | >100.0 | >100.0 | 1.0 | |
| 5 | 53 | >100.0 | >1.9 | |
| 6 | 1.4 | 50.0 | PCS (20.0 μM) | 35.7 |
| 7 | 1.8 | 6.7 | 3.8 | |
| 8 | 1.5 | 42.0 | PCS (20.0 μM) | 28.0 |
| 9 | 0.8 | 12.5 | PCS (0.8 and 4.0 μM) | 15.6 |
| 10 | 0.4 | 26.5 | PCS (4.0 μM) | 61.6 |
| 11 | 8.0 | 91.0 | PCS (20.0 μM) | 11.4 |
| 12 | >100.0 | >100 | 1.0 | |
| 13 | 2.1 | >100.0 | PCS (4.0, 20.0, and 100.0 μM) | >47.6 |
| 14 | 10.0 | >100.0 | PCS (100.0 μM) | >10 |
| 15 | 10.0 | 65.0 | PCS (20.0 μM) | 6.5 |
| 16 | >100.0 | >100.0 | 1.0 | |
| 17 | >100.0 | >100.0 | 1.0 | |
| 18 | NDc | NDc | NDc | NDc |
| 19 | >0.8 | 2.0 | <2.5 | |
| ribavirin | 10.6 | >100 | PCP (100 μM) | >9.4 |
| DMSO | >100 | >100 | 1 | |
a
The CC50 assay was complemented by microscopic recording of possible cytostatic activity of test compounds manifested as poor cell proliferation (PCP), altered cell shape (ACS), or poor cell staining (PCS).
b
SI of 1 indicates lack of antiviral activity, i.e., lack of cell protection against RSV; SI of 2–10 suggests that antiviral activity may at least in some compounds be unspecific due to cytostatic activity (poor cell proliferation/altered cell shape) that occurs at concentrations just below the CC50 and may not be detectable by the cell toxicity assay used; SI > 10 suggests specific antiviral activity for most compounds tested.
c
ND, not determined