Hupehenine is a steriodal alkaloid extracted from the bulbs of Fritillaria Hupehensis, with the potential for inhibiting acetylcholine, antagonism for muscarinic receptors and cholinesterase inhibition.

Histamine, an organic nitrogen compound, works on target cells in the mammalian brain by stimulating of Histamine 1/2.

Dynorphin A (1-8) is the predominant opioid peptide identified in placental tissue extracts. Dynorphin A (1-8) is the most likely natural ligand of the kappa receptor. The binding of 3H-Bremazocine to the purified kappa receptor is inhibited by Dynorphin A (1-8) (IC50=303 nM).