Abstract
Dimeric opioid analogues linked to a pyrazinone platform, 3-[Tyr/Dmt-NH(CH2)m]-6-[Tyr/Dmt-NH(CH2)n]-2(1H)-pyrazinone (m, n=3 or 4), were synthesized. The Tyr-containing compound (m=4, n=3) exhibited mu-receptor affinity (K(i)mu; 7.58 nM) comparable to that of morphine, while the Dmt derivatives exhibited considerably higher affinity (K(i)mu; 0.021-0.051 nM) with corresponding agonism (IC50=1.79-4.93 nM). Interestingly one compound (m=4, n=3) revealed modest delta-opioid agonism; the converse analogue (m=3, n=4), however, was inactive in MVD assay.