2^′, 6^′-Dimethylphenylalanine : A Useful Aromatic Amino Acid Surrogate for Tyr or Phe Residue in Opioid Peptides

Table 3

Antinociceptive activities of Dmp-containing YRFB analogs after subcutaneous injection in the formalin test.

Peptides		ED50 (95% C. L.)^a, nmol/kg
	First phase		Second phase
[Dmp^3]YRFB (22)	98.6	(26.7–364)	113	(48.6–264 )
[Dmp^1]YRFB (24)	1946	( 1026–3691 )	1529	( 1199–1950)
YRFB	628	(364–1280)	514	(378–700)
Morphine	3811	(2921–4973 )	7319	(4058–13198)

^aED₅₀ values and 95% confidence limits.