Table 1.
In vitro pharmacological data for various QDs, dendrons (D5), and their complexes with nucleosides and solubilizing moieties.
| Compd. | Kiapp at hA2AAR, μM or % inhibitiona | Solubility |
|---|---|---|
| 1a | 0.015 | +++ |
| 1b | 0.010 | +++ |
| 2a | NT | - |
| 2b | NEe | +++ |
| 3 | NEe | ++ |
| 4 | < 20%e | + |
| 5 | < 20%e | - |
| 6 | < 20%e | + |
| 7 | < 20%e | + |
| 8b | < 20%e | ++(72.3 nM in DMSO)d |
| 9 | < 20%e | ++ |
| 10 | 9.8 ± 7.4% (at 1.0 μM) | +++ |
| 11 | 1.02 ± 0.15 | +++ |
| 12 | 2.2 ± 1.1% (at 1.0 μM) | +++ |
| 13c | 0.118 ± 0.054 | +++ (66.1 μM in DMSO)d |
a All experiments were done on HEK-293 cells stably expressing the human A2AAR. The binding affinity (n = 3-5) and was determined by using agonist radioligands [3H]CGS21680. The concentrations of the ligand complexes were measured by the concentration of the macromolecule, not the attached nucleoside. Therefore, binding Ki values calculated from the IC50 using the Cheng-Prusoff equation[37] of large conjugates are expressed as Kiapp values.
b 8, MRS5252.
c 13, MRS5303.
d In order to determine more exactly the solubility of the compounds in two cases we plotted a standard curve graph. We measured the fluorescence intensity of the underivatized QDs (2a and 2b) in DMSO at different concentrations; then, we measured the fluorescence intensity of each conjugate, 8 and 13, in DMSO to determine its maximal solubility, based on comparison to the standard curve of the chemical precursor 2a or 2b.
e NE, no effect, or less than 20% inhibition at the maximal concentration tested. This concentration was intended to be 1 μM, however in most cases this was not reached due to precipitation.
NT, not tested.