4-methylcatechol is a metabolite of homoprotocatechuic acid. It is both a substrate and a suicide inhibitor of Catechol 23-dioxygenase. 4-methylcatechol is known to induce the production of brain-derived neurotrophic factor (BDNF). Recent studies have suggested that a lack of brain-derived neurotrophic factor (BDNF) in the limbic system may cause neuropathic pain.

IRBP (1-20), human is the 1-20 fragment of interphotoreceptor retinoid binding protein (IRBP).This peptide is a 1 to 20 amino acid fragment of the interphotoreceptor retinoid binding protein (IRBP). IRBP is a 140-kDa glycolipoprotein residing in the interphotoreceptor matrix between the neural retina and the retinal pigment epithelium.

Auraptene is a coumarin derived from citrus plants that bears a geranyloxyl moiety at its C-7.