2-Hydroxyphenethylamine has been found in human testicle tissue, and has also been primarily detected in blood. 2-Hydroxyphenethylamine can be converted into 2-(hydroxymethyl)-4-(1-hydroxy-2-{[6-(4-phenylbutoxy)hexyl]amino}ethyl)phenol.

N-Acetylhistamine acetate is a histamine metabolite. It can be used as a potential biomarker of histidine metabolism for anaphylactoid reactions.

Stachydrine (N,N-Dimethyl-L-proline) is a major constituent of Chinese herb leonurus heterophyllus sweet used to promote blood circulation and dispel blood stasis. Stachydrine (N,N-Dimethyl-L-proline) can inhibit the NF-κB signal pathway. Stachydrine (N,N-Dimethyl-L-proline) is a biomarker for the consumption of citrus fruits.

Dimethyl sulfone exists in all living organisms, ranging from bacteria to humans. It derives from dietary sources, from intestinal bacterial metabolism and from human endogenous methanethiol metabolism. Dimethyl sulfone is a metabolite occurring in plasma and CSF of normal human.

γ-Aminobutyric acid (4-Aminobutyric acid) is the most common inhibitory neurotransmitter in the central nervous system.