Orexin A (CAS 205640-90-0), also known as Hypocretin-1, is a synthetic 33-amino acid neuropeptide with a molecular weight of 3561.97 g/mol. Its structure features an N-terminal pyroglutamyl residue and two intramolecular disulfide bridges between Cys6-Cys12 and Cys7-Cys14, a structural arrangement that confers a compact, folded conformation considered central to its receptor binding characteristics. The amino acid sequence is fully conserved across human, bovine, mouse, and rat species. Produced via solid-phase peptide synthesis, Hypocretin-1 acts as an endogenous agonist at both orexin receptors, OX1R and OX2R.

Orexin A has been investigated in preclinical sleep neuroscience and neuroendocrine research. The orexinergic projection system, originating in the lateral hypothalamus, has been found to be implicated in the regulation of arousal state transitions, and the loss of orexin-producing neurons has been documented as a central feature of narcolepsy type 1 research models. In vitro receptor pharmacology studies have characterised Orexin A binding affinity at OX1R and OX2R, documenting Ki values in the low nanomolar range and characterising downstream Gq-coupled intracellular calcium signalling as a primary readout of orexin receptor activation in cell-based pharmacological preparations [1]. In vivo rodent studies have investigated Orexin A’s interaction with sleep-wake circuitry, documenting that central administration of Hypocretin-1 activates locus coeruleus cell firing and increases arousal under controlled experimental conditions, characterising orexin receptor-mediated activation of noradrenergic wakefulness circuitry as a primary in vivo pharmacological property of the compound [2], making Orexin A a key reference compound in neuropeptide research examining orexin receptor pharmacology and the neuroendocrine regulation of arousal state transitions.

Orexin A is manufactured in a cGMP compliant laboratory to a guaranteed purity of 98% or above. Every batch is independently tested using HPLC and MS-UPLC analysis before dispatch. Vials are vacuum sealed and stored in a temperature controlled, monitored cold storage system. Certificates of Analysis are available on request.

Sold strictly for in vitro research purposes only. Not for human consumption. Intended for use by qualified researchers in laboratory settings only.

Editorial Team

Dr. Martina Rossi, PhD

Scientific Contributor and Reviewer

Reviewed and approved 14 June 2026

View credentials →