Hemopressin (Hp) is an alpha hemoglobin fragment with the sequence PVNFKFLSH, originally identified in extracts of rat brain using an enzyme capture technique.

[2] Longer forms of hemopressin containing 2-3 additional amino acids on the N-terminus have been identified in extracts of mouse brain.

These longer hemopressin peptides, named RVD-Hpα and VD-Hpα, bind to CB1 receptors and were originally reported to be agonists.

[4][5] RVD-hemopressin (pepcan-12) is generated from a pro-peptide called pepcan-23 and these peptides are exclusively found in noradrenergic neurons in the brain and in the adrenal medulla.

[9] Scientists at the University of Manchester have discovered that hemopressin could be used as an appetite suppressant without having the side effects of many other drugs that are used for this purpose.