Biological active analogues of the opioid peptide biphalin: mixed α/ß(3)-peptides.

ABSTRACT

Natural residues of the dimeric opioid peptide Biphalin were replaced by the corresponding homo-ß(3) amino acids. The derivative 1 containing hß(3) Phe in place of Phe showed good µ- and δ-receptor affinities (Ki(δ) = 0.72 nM; Ki(µ) = 1.1 nM) and antinociceptive activity in vivo together with an increased enzymatic stability in human plasma.