IC50: 1.3 nM for opiate activity
Bovine adrenal medulla 22 peptide (BAM22P) is a peptide with 22 amino acids which is one of the cleavage products of proenkephalin A, the precursor of Leu- and Met-enkephalin, in the adrenal medulla, with very potent opiate activity.
In vitro: In the guinea-pig ileum assay, BAM-22P has been shown to have typical and extraordinarily potent opioid activities antagonized by naloxone. The potency of BAM-22P is 26 times that of Met-enkephalin and 22 times that of B hendorphin. IC50 value of BAM-22P in this tissue, 1.3 nM, makes it the most potent Met-enkephalin relatives that discoveried so far. [1].
In vivo: Intrathecal (i.t.) administration of BAM22 decreased nocifensive behavior scores, which measured as the sum of flinching and lifting/licking, in the first and second phases of the formalin test. Such decrease was partially attenuated by systemic injection of naloxone. [2].
Clinical trial: Up to now, BAM 22P is still in the preclinical development stage.
Reference:
[1] Mizuno K, Minamino N, Kangawa K, Matsuo H. A new family of endogenous "big" Met-enkephalins from bovine adrenal medulla: purification and structure of docosa- (BAM-22P) and eicosapeptide (BAM-20P) with very potent opiate activity. Biochem Biophys Res Commun. 1980 Dec 31;97(4):1283-90.
[2] Hong Y, Dai P, Jiang J, Zeng X. Dual effects of intrathecal BAM22 on nociceptive responses in acute and persistent pain--potential function of a novel receptor. Br J Pharmacol. 2004 Feb;141(3):423-30.