Table 4.
Determination of acid stability of artemisinin and its five potent derivativesa
| Sample | MIC (μg/ml) |
MBC (μg/ml) |
% Decomposition during acidic exposure for: |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Normal |
Acid treated |
Normal |
Acid treated |
|||||||||
| 80A | 43504 | 80A | 43504 | 80A | 43504 | 80A | 43504 | 0 h | 1 h | 2 h | 24 h | |
| GRB-1 | 2 | 0.5 | 2 | 1 | 2 | 1 | 4 | 1 | 8 | 5 | 5 | 18 |
| GRB-2 | 1 | 0.5 | 1 | 0.5 | 2 | 0.5 | 4 | 0.5 | 5 | 24 | 25 | 77 |
| GRB-3 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 4 | 6 | 5 | 2 |
| GRB-4 | 1 | 0.5 | 2 | 1 | 1 | 1 | 2 | 1 | 2 | 1 | 1 | 18 |
| GRB-5 | 2 | 2 | 4 | 4 | 8 | 4 | 8 | 4 | 6 | 0 | 4 | 31 |
| GRB-17 | 2 | 2 | 4 | 4 | 8 | 4 | 8 | 4 | 4 | 5 | 0 | 6 |
a
Acid treatment (pH 2.0) of the compounds was carried out for 24 h at 25°C. For MIC/MBC determination by broth microdilution assay, acid-treated (2 h) and untreated samples were serially diluted (2-fold) in 96-well microtiter plates in duplicate containing a total volume of 0.1 ml of Mueller-Hinton broth supplemented with 5% FCS and 0.0025% Dent. The chemical decomposition was assessed using HPLC by estimating the reduction in peak areas at the indicated time points (“0 h” means just upon addition of HCl) with respect to untreated controls.