β-Endorphin, an endogenous opioid neuropeptide, is an opioid receptor agonist. β-Endorphin binds preferentially to μ-opioid receptors and is produced in certain neurons of the central and peripheral nervous system and is one of three endorphins produced in humans. β-Endorphin can be used to reduce stress and maintain homeostasis in the body and is involved in neurological pain perception regulation.

1H-Pyrazole-3-carboxylic acid is a chemical compound.

Pimonidazole hydrochloride accumulates in hypoxic cells via covalent binding with macromolecules or by forming reductive metabolites after the reduction of its nitro group.