Lanthionine and Other Relevant Sulfur Amino Acid Metabolites: Detection of Prospective Uremic Toxins in Serum by Multiple Reaction Monitoring Tandem Mass Spectrometry.

In the context of the vascular effects of hydrogen sulfide (H2S), it is known that this gaseous endogenous biological modulator of inflammation, oxidative stress, etc. is a potent vasodilator. Chronic renal failure, a common disease affecting the aging population, is characterized by low levels of H2S in plasma and tissues, which could mediate their typical hypertensive pattern, along with other abnormalities. Lanthionine and homolanthionine, natural non-proteinogenic amino acids, are formed as side products of H2S production. Also in consideration of the intrinsic difficulties in H2S measuring, these compounds have been proposed as reliable and stable markers of H2S synthesis. However, in the setting of chronic renal failure patients on hemodialysis, they represent typical retention products (without ruling out the possibility of an increased intestinal synthesis) and prospective novel uremic toxins. Here, a method utilizing liquid chromatography-electrospray tandem mass spectrometry (LC-MS/MS) in multiple reaction monitoring ion mode has been developed and evaluated for the determination of these key H2S metabolites in plasma, by using a triple quadrupole mass spectrometer.