Table 1.
Antimicrobial activities* of machaeridiol based synthetic analogs 1–3, 5, 7–11, 13–15, and 17.
| Compounds | IC50 / MIC (μg/mL) * | ||
|---|---|---|---|
| Methicillin-Resistant S. aureus (MRSA ATCC 1708) | Vancomycin-Resistant E. faecium (VRE ATCC 700221) |
Cryptococcus neoformans (ATCC 90113) |
|
| 1 | 3.24/NT | 2.49/NT | NA |
| 2 | 3.69/NT | 18.37/NT | 16.74/NT |
| 3 | 8.15/NT | 3.38/NT | NA |
| 5 | 1.18/2.50 ** | 2.27/2.50 | 2.15/2.50 |
| 7 | 8.04/NT | NA | NA |
| 8 | 16.51/NT | 18.1/NT | NA |
| 11 | 0.95/1.25 | 2.28/2.50 | 0.95/2.50 |
| 13 | 2.3/10.0 | 3.2/10.0 | 4.3/NT |
| 14 | 3.0/5.0 | 2.3/5.0 | 1.5/NT |
| 15 | 17.0/NT | 17.8/NT | >20/NT |
| 17 | 0.91/1.25 | 1.17/2.50 | 1.92/5 |
| Machaeriol C # | 0.69/1.25 | 1.16/2.5 | NA |
| Machaeridiol A # | 1.03/2.5 | 0.72/2.5 | 15/NT |
| Machaeridiol C # | 0.38/1.25 | 0.72/1.25 | 25/NT |
| Methicillin | 2.2/50 | >20/20 | NT |
| Meropenem | 7.03/12.50 | NA | NA |
| Amphotericin B | NT | NT | 0.88/1.56 |
* The primary (IC50) and secondary (MIC) assays were run separately and each was executed in duplicate. ** Compounds 5, 11, 13, 14, and 17 were selected for MIC determination based on their IC50 cut-off values of 3.0 μg/mL or < 3.0 μg/mL against MRSA. Compounds 4, 6, 9+10, 12, and 16 were inactive in the primary assay (IC50 > 20 μg/mL). NA: not active. NT: not tested. All compounds were inactive against VERO cells. MRSA: methicillin-resistant S. aureus, VRE: vancomycin-resistant Enterococci. # Literature values [7,8,9] are included for comparison with the synthetic analogs.