TABLE 3.
In vitro agonist biases of novel G protein-biased KOR agonists which were investigated in vivo for analgesic or anti-scratch effects.
| Compound (Reference) | G protein signaling; cells used |
β-arrestin signaling; cells used |
Agonist bias (Reference compound) |
| Triazole 1.1 (Zhou et al., 2013) |
1. Membrane [35S]GTPγS binding (mG); CHO-hKOR cells 2. Whole Cell [35S]GTPγS binding (wcG); CHO-hKOR cells 3. Cellular Impedance; CHO-hKOR cells |
β-Arrestin2 recruitment; DiscoverX PathHunter U2OS EFC cell line expressing β-arrestin2 and hKOR β-Arrestin2 Imaging; U2OS cell line stably expressing hKOR and β-arrestin2-eGFP |
(U69,593) mG/β-arr2 EFC, 61.2 mG/β-arr2 imaging, 20.0 wcG/β-arr2 EFC, 8.6 wcG/β-arr2 imaging, 2.8 imped/β-arr2 EFC, 6.9 imped/β-arr2 imaging, 2.3 |
| Isoquinolinone 2.1 (Zhou et al., 2013) |
(U69,593) mG/β-arr2 EFC, 31.4 mG/β-arr2 imaging, 7.2 wcG/β-arr2 EFC, 17.3 wcG/β-arr2 imaging, 4.0 imped/β-arr2 EFC, 66.7 imped/β-arr2 imaging, 3.0 |
||
| Triazole 1.1 (Brust et al., 2016) |
Membrane [35S]GTPγS binding (mG); CHO-hKOR cells | β-Arrestin2 recruitment (DiscoveRx PathHunter) U2OS EFC cell line expressing β-arrestin2 and hKOR | (U50,488H) G protein-biased, 28 |
| RB-64 (White et al., 2014) |
cAMP, inhibition of isoproterenol-stimulated adenylate cyclase (GloSensor); HEK293T cells transiently transfected with 3 × HA-hKOR and pGloSensor-22F cAMP biosensor |
β-arrestin2 recruitment (Tango luciferase-based assay); HTLA cells transiently transfected with human KOR-V2-TEV-tTA |
G protein-biased, 35 (Salvinorin A) |
| HS665, HS666 (Spetea et al., 2017) | [35S]GTPγS binding; CHO cells stably expressing the hKOR | β-arrestin2 recruitment assay (DiscoveRx PathHunter); U2OS cells stably co-expressing the hKOR and the enzyme acceptor-taggedβ-arrestin2 fusion protein | HS665, G protein-biased, 389 HS666, G protein-biased, 62 (U69,593) |
| 16-Bromo SalA (Paton et al., 2020) | Inhibition of forskolin-stimulated adenylate cyclase (DiscoveRx HitHunter) | β-arrestin2 recruitment assay (DiscoveRx PathHunter) | G protein-biased, 7.7 (U50,488H) |
| LOR17 (c[Phe-Gly-(b-Ala)-DTrp]) (Bedini et al., 2020) |
Inhibition of forskolin-stimulated adenylate cyclase (cAMP ELISA assay), HEK-293 cells expressing the human KOR, U87-MG cells and normal human astrocytes | β-arrestin2 recruitment assay (DiscoveRx PathHunter) with U2OS cells co-expressing the human KOR and the enzyme acceptor tagged β-arrestin 2 fusion protein |
G protein-biased, 853 (U50,488H) |
| LOR17 (c[Phe-Gly-(b-Ala)-DTrp]) (Bedini et al., 2020) |
Early-phase ERK1/2 phosphorylation | p38MAPK phosphorylation; p38MAPK-mediated cell proliferation in astrocytes |
No bias calculation |