deltorphin II

Deltorphin II (also known as deltorphin B) is a naturally occurring heptapeptide originally isolated from the skin secretions of South American tree frogs of the genus *Phyllomedusa* (such as *Phyllomedusa bicolor*). It is one of the most potent and highly selective agonists of the delta-opioid receptor (DOR) known, exhibiting several orders of magnitude higher selectivity for delta-opioid receptors over mu- and kappa-opioid receptors. Structurally, it features a D-alanine residue at position 2, which confers resistance to enzymatic degradation and enhances its biostability. Deltorphin II is widely utilized as a pharmacological research tool to study the physiological roles of delta-opioid receptors, including their involvement in antinociception, neuropathic pain, cardiovascular regulation, and metabolic homeostasis.

Other names

[D-Ala2, Glu4]deltorphin II[D-Ala2]-deltorphin IIDADELT IITyr-D-Ala-Phe-Glu-Val-Val-Gly-NH2Tyr-D-Ala-Phe-Glu-Val-Val-Gly-NH-2Tyr-D-Ala-Phe-Glu-Val-Val-Gly-NH 2deltorphin B