Quinolinic acid (QUIN) is an endogenous N-methyl-D-aspartate (NMDA) receptor agonist synthesized from L-tryptophan via the kynurenine pathway.

4-Pyridoxic Acid (4-Pyridoxinsaeure), a catabolite of vitamin B6, is a water-soluble B-group vitamin that can be used as a urinary diagnostic biomarker for determining the nutritional status of these vitamins.

6-Hydroxynicotinic acid (6-Hydroxypyridine-3-carboxylic acid) is exploited in the use of NMR spectroscopy or gas chromatography--mass spectrometry for the diagnosis of Pseudomonas aeruginosa in urinary tract infection. Among the common bacteria causing urinary infection, only P. aeruginosa produces 6-hydroxynicotinic acid from nicotinic acid.

Pyridoxylamine dihydrochloride (Pyridorin) is a hydrochloride salt of one form of vitamin B6.

TRIA-662 (Nicotinamide Chloromethylate) is a niacin metabolite excreted via the urinary system.

PCL 016 (2-Picolinic acid) is a topical antiviral agent, which inhibits adenovirus replication in rabbit.

N-Methylnicotinamide is one of the endogenous metabolites that ameliorates endothelial dysfunction.

The 4-carboxyaldehyde form of vitamin B6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid.

α-Pyridone (2-Hydroxypyridine)e is the catalyst for generating β-oxopropyl carbonates from cyclic carbonates and alcohols and in the aminolysis of a polyglutamate.