Profiling histidine‐containing dipeptides in rat tissues by liquid chromatography/electrospray ionization tandem mass spectrometry

Abstract

The histidine-containing dipeptides carnosine (CAR) and structurally related anserine (ANS) and homocarnosine (HCAR), widely distributed in vertebrate organisms, have recently been proposed as endogenous quenchers for highly cytotoxic a,b-unsaturated aldehydes generated by peroxidation. A sensitive, selective, specific and rapid liquid chromatographic/electrospray ionization tandem mass spectrometric assay was developed and validated for the simultaneous determination of these peptides in biological matrices in order to establish their plasma/tissue distribution. Samples (plasma or tissue homogenates from male rats) were prepared by protein precipitation with HClO The intra-and inter-day precisions were <10% (≤17.47% at the LOQ) and the intra-and inter-assay accuracies were within ±10% for all concentrations. The mapping profile in rat tissue gave the following results: the highest concentrations of CAR and ANS were found in skeletal muscles (soleus, gastrocnemius, tibialis), followed by the heart, cerebellum and brain (ANS below the LOQ). HCAR was found only in the brain and cerebellum. No histidine-containing dipeptides were detectable in plasma, liver, kidney and lung.

Lipoxidation‐Derived Reactive Carbonyl Species as Potential Drug Targets in Preventing Protein Carbonylation and Related Cellular Dysfunction

“…[87,88] In particular, we demonstrated the CAR scavenging effect towards cytotoxic aldehydes in biological matrices by using a peptidomic approach; with the aim of identifying the main detoxification pathways of unsaturated aldehydes in skeletal muscle, rat gastrocnemius homogenate was spiked with HNE and, after 1 h incubation, peptides and peptide adducts were identified by LC-ESIMS-MS analysis. [87,89] Figure 5 shows the two-dimensional plot of native (upper panel) and HNE spiked (lower panel) sample, the latter characterised by the presence of two adducts at m/z 383 and 397, which were identified by MS-MS analysis as Michael adducts of HNE with CAR, and anserine (ANS), respectively. In addition, CAR-HNE has been shown to be an early, stable, and specific biomarker of oxidative stress in rat skeletal muscle exposed to oxidative damage.…”

Role of Aldose Reductase in the Metabolism and Detoxification of Carnosine-Acrolein Conjugates

“…Individual samples were separated by HPLC and analyzed by high precision mass spectrometry using methods optimized for the collection and identification of the aldehyde conjugates of carnosine. Because carnosine could be hydrolyzed to histidine and ␤-alanine, some of the aldehyde-carnosine conjugates could be excreted as histidyl conjugates (40). Therefore, histidine conjugates of HNE and acrolein were measured as well.…”

Carnosine and Related Peptides: Therapeutic Potential in Age-Related Disorders

“…No ID were detectable in plasma, liver, kidney and lung [3]. The homocarnosine biosynthesis from L-histidine and γ-aminobutyric acid (GABA) is favored by a ligase enzyme namely carnosine synthase (EC 6.3.2.11) [2].…”