Table 3. Isomerization Study in PBS at pH 7.4 via HPLC–MSa.
| 0 h |
24 h |
|||
|---|---|---|---|---|
| compd | % isomer 1 | % isomer 2 | % isomer 1 | % isomer 2 |
| Triapine | 100 (7.7)b | 100 | ||
| H2NNHMe | 100 (10.0) | 100 | ||
| H2NNMe2 | 100 (10.2) | 100 | ||
| MeHNNH2 | 100 (10.5) | 100 | ||
| MeHNNHMe | 99 (11.3) | 1 (9.8)b | 99 | 1 |
| MeHNNMe2 | 98 (11.3) | 2 (10.3) | 98 | 2 |
| (E)-Me2NNH2 | 100 (10.3) | 8 | 92 | |
| (Z)-Me2NNH2 | 94 (13.9) | 6 (10.3) | 6 | 94 |
| (E)-Me2NNHMe | 4 (16.3) | 96 (11.1) | 15 | 85 |
| (Z)-Me2NNHMe | 93 (16.3) | 7 (11.1) | 13 | 87 |
| Me2NNMe2 | c | c | c | c |
a
DMSO stock solutions of all compounds were diluted with PBS (pH 7.4) to a final concentration of 50 μM (1% DMSO) and immediately measured by HPLC–MS. All measured values are ±2%.
b
The numbers in brackets correspond to the HPLC–MS retention time (min) of the compounds.
c
In the case of Me2NNMe2, only one very broad peak was obtained, which could not be separated into the two isomers, presumably due to the fast interconversion on the column.