Table 3: Functional bioactivities of opioid ligands 1, 2, and 19–50.

GPIMVD

Nos.CompoundsIC50 (nM)apA2bIC50 (nM)pA2Reference

1H-Tyr-Pro-Trp-Phe-NH2(EM-1)4.03c283[10]
2H-Tyr-Pro-Phe-Phe-NH2(EM-2)6.88344[10]
19H-Dmt-Pro-Trp-Phe-NH20.27>10,0008.6[10]
20H-Dmt-Pro-Phe-Phe-NH20.071.87[9]
21H-Dmt-Pro-Phe-NH22.33113[9]
22H-Dmt-Pro-Phe-NH-C2H4-Ph5.03>10,0007.05[9]
23H-Dmt-Pro-Phe-NH-Bzl22>10,0007.18[11]
24H-Dmt-Pro-Phe-NH-Ph37.7>10,0006.94[11]
25H-Dmt-Pro-Phe-NH-4-Pyr11.8>10,0006.52[11]
26H-Dmt-Pro-Phe-NH-3-Pyr72.8>10,0006.33[11]
27H-Dmt-Pro-Phe-NH-2-Pyr15>10,0006.7[11]
28H-Dmt-Pro-Phe-NH-1-Nph0.495.47[11]
29H-Dmt-Pro-Phe-NH-3-Qln9.14>10,0005.93[11]
30H-Dmt-Pro-Phe-NH-5-Qln0.260.6165.88[11]
31H-Dmt-Pro-Phe-NH-6-Qln6.21>10,0005.41[11]
32H-Dmt-Pro-Phe-NH-8-Qln4452,9816.14[11]
33H-Dmt-Pro-Phe-NH-5-Isq0.94>10,0006.12[11]
34H-Mmt-Pro-Phe-Phe-NH20.92428.7++d[12]
35H-Emt-Pro-Phe-Phe-NH20.6231.08+e[12]
36H-Imt-Pro-Phe-Phe-NH210.6601+[12]
37H-Det-Pro-Phe-Phe-NH20.90347.1+[12]
38H-Dit-Pro-Phe-Phe-NH2299>10,000NDf[12]
39H-Tmt-Pro-Phe-Phe-NH22.3146.4++[12]
40H-Dmt-Pro-Mmp-Phe-NH20.16>10,0006.59[13]
41H-Dmt-Pro-3,5Dmp-Phe-NH214.4>10,0006.77[13]
42H-Dmt-Pro-Dmp-Phe-NH20.12>10,0008.15[13]
43H-Dmt-Pro-Dmt-Phe-NH21.94>10,0007.06[13]
44H-Dmt-Pro-Tmp-Phe-NH20.21>10,0009.05[13]
45H-Dmt-Pro-Emp-Phe-NH20.170.51[13]
46H-Dmt-Pro-Imp-Phe-NH20.25.56[13]
47[N-allyl-Dmt1]EM-1>10,0008.18>10,0007.32[10]
48[N-allyl-Dmt1]EM-2>10,0008.59>10,0006.32[10]
491,6-bis[N-allyl-Dmt-NH]hexane>10,0007.23>10,0006.83[10]
503,6-bis[N-allyl-Dmt-NH-propyl]-5-methyl-2(1H)-pyrazinone>10,0007.17>10,0006.38[10]

aIC50 value is the concentration required to 50% inhibition of the electrically induced contraction in a muscle. bpA2 is the negative log of the molar concentration required to double the agonist IC50 value in order to achieve the original response. cNot tested. d,eAntagonism by CTAP (200 nM) with the percent recovery of electrically evoked contraction: ++, >50%; +, <50%. fNot detected.