Bentley analogues: In vitro competition binding experiments all derivatives showed low subnanomolar affinity to MOR. For DOR the ligands showed comparable binding affinities than the selective DOR agonist Ile5,6-deltorphin II peptide ligand except 8 (Ki > 3000 nM). In the KOR binding assays the analogues still displayed nanomolar affinities. In G-protein activity measurements compound 1f, 2a, 2b had antagonistic; 1e, 2c, 8 had partial agonistic and 2d, 4, 5, 7 had full agonistic effects. Ligands were examined in G-protein activation tests in rat brain membranes, the selectivity could not be observed as the receptor selective antagonists such as Cyp, NTI, nor-BNI and the selective agonists such as DAMGO, Ile5,6-deltorphine II, U-69,593 are not able to inhibit the effects of the extremely potent Bentley analogues. In vivo tests in osteoarthritis inflammatory model the thevinol derivatives showed a significant antiallodynic effect, while orvinol derivatives, except for 2c, did not display this effect. Oligopeptides: In competition binding assays the KYNA‐containing peptide, KA1 bound selectively to the MOR with a low Ki value and a high selectivity ratio, the other oligopeptides also showed selectivity to MOR, except K3, which bound to MOR and DOR with similar affinity. In the G-protein activition tests the EM-2 containing compounds, K2 and K3 stimulated G-protein with low efficacy, compound KA1, K4, K5 behaved as full agonists, while K6 had efficacy and potency higher than those of the reference compound DAMGO. In functional binding assays all oligopetides were inhibited by Cyp (MOR) and NTI (DOR) in rat brain membrane. In guinea pig brain membrane K4 and K6 stimulated G-protein, the efficacy of K4 was inhibited by nor-BNI, while the effect of K6 was not. K6 exhibited a strong antinociceptive effect in formalin test.
Phosphorylation-dependent interaction of the synaptic vesicle proteins cysteine string protein and synaptotagmin I