DADLE, opioid ligand

The concept of bridging has also been applied to antagonists bivalent ligands containing /3-naltrexamine pharmacophores (p. 67) linked by an oligoethylene glycol spanner have been described that differentially block /x, k, and S-opioid receptors.(198) Thus, 10a (with a six-ethylene-units spanner) most effectively blocks S-receptors (DADL on MVD), while 10b (with shorter spanner) acts preferentially at k-sites (ethylketazocine on GPI). 

Adequate modifications and alterations in the amino-acid sequence and composition of the enkephalins (pentapeptides produced in the brain) give rise to sueh eompoimds that signifieantly demonstrate both high poteney and distinet selectivity for the delta opioid receptors. James et. al. (1984) introdueed [D-Ala, D-Leu ] enkephalin, also termed as DADLE whereas, Mosberg et al. (1983) introdueed the eyelie peptide [D-Pen, D-Pen ] enkephalin, also known as DPDPE, whieh enjoyed the reputation of being the peptides invariably and frequently employed as selective delta receptor ligands. 

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