Carnosine and carnosine-related antioxidants: a review

Mutual influence of non-covalent interactions formed by imidazole: A systematic quantum-chemical study

Imidazole is a five-membered heterocycle that is part of a number of biologically important molecules such as the amino acid histidine and the hormone histamine. Imidazole has a unique ability to participate in a variety of non-covalent interactions involving the NH group, the pyridine-like nitrogen atom or the π-system. For many biologically active compounds containing the imidazole moiety, its participation in formation of hydrogen bond NH⋯O/N and following proton transfer is the key step of mechanism of their action. In this work a systematic study of the mutual influence of various paired combinations of non-covalent interactions (e.g., hydrogen bonds and π-interactions) involving the imidazole moiety was performed by means of quantum chemistry (PW6B95-GD3/def2-QZVPD) for a series of model systems constructed based on analysis of available x-ray data. It is shown that for considered complexes formation of additional non-covalent interactions can only enhance the proton-donating ability of imidazole. At the same time, its proton-accepting ability can be both enhanced and weakened, depending on what additional interactions are added to a given system. The mutual influence of non-covalent interactions involving imidazole can be classified as weak geometric and strong energetic cooperativity-a small change in the length of non-covalent interaction formed by imidazole can strongly influence its strength. The latter can be used to develop methods for controlling the rate and selectivity of chemical reactions involving the imidazole fragment in larger systems. It is shown that the strong mutual influence of non-covalent interactions involving imidazole is due to the unique ability of the imidazole ring to effectively redistribute electron density in non-covalently bound systems with its participation.

Histidine-Bound Dinitrosyl Iron Complexes: Antioxidant and Antiradical Properties

Dinitrosyl iron complexes (DNICs) are important physiological derivatives of nitric oxide. These complexes have a wide range of biological activities, with antioxidant and antiradical ones being of particular interest and importance. We studied the interaction between DNICs associated with the dipeptide L-carnosine or serum albumin and prooxidants under conditions mimicking oxidative stress. The ligands of these DNICs were histidine residues of carnosine or His39 and Cys34 in bovine serum albumin. Carnosine-bound DNICs reduced the level of piperazine free radicals in the reaction system containing tert-butyl hydroperoxide (t-BOOH), bivalent iron ions, a nitroxyl anion donor (Angeli's salt), and HEPES buffer. The ability of carnosine DNICs to intercept organic free radicals produced from t-BOOH decay could lead to this effect. In addition, carnosine DNICs reacted with the superoxide anion radical (O2•-) formed in the xanthine/xanthine oxidase enzymatic system. They also reduced the oxoferryl form of the heme group formed in the reaction of myoglobin with t-BOOH. DNICs associated with serum albumin were found to be rapidly destroyed in a model system containing metmyoglobin and t-BOOH. At the same time, these protein DNICs inhibited the t-BOOH-induced oxidative degradation of coenzymes Q9 and Q10 in rat myocardial homogenate. The possible mechanisms of the antioxidant and antiradical action of the DNICs studied and their role in the metabolism of reactive oxygen and nitrogen species are discussed.

High-Resolution Magic Angle Spinning (HRMAS) NMR Identifies Oxidative Stress and Impairment of Energy Metabolism by Zearalenone in Embryonic Stages of Zebrafish (Danio rerio), Olive Flounder (Paralichthys olivaceus) and Yellowtail Snapper (Ocyurus chrysurus)

Zearalenone (ZEA) is a mycotoxin, commonly found in agricultural products, linked to adverse health impacts in humans and livestock. However, less is known regarding effects on fish as both ecological receptors and economically relevant "receptors" through contamination of aquaculture feeds. In the present study, a metabolomics approach utilizing high-resolution magic angle spinning nuclear magnetic resonance (HRMAS NMR) was applied to intact embryos of zebrafish (Danio rerio), and two marine fish species, olive flounder (Paralichthys olivaceus) and yellowtail snapper (Ocyurus chrysurus), to investigate the biochemical pathways altered by ZEA exposure. Following the assessment of embryotoxicity, metabolic profiling of embryos exposed to sub-lethal concentrations showed significant overlap between the three species and, specifically, identified metabolites linked to hepatocytes, oxidative stress, membrane disruption, mitochondrial dysfunction, and impaired energy metabolism. These findings were further supported by analyses of tissue-specific production of reactive oxygen species (ROS) and lipidomics profiling and enabled an integrated model of ZEA toxicity in the early life stages of marine and freshwater fish species. The metabolic pathways and targets identified may, furthermore, serve as potential biomarkers for monitoring ZEA exposure and effects in fish in relation to ecotoxicology and aquaculture.

Neuroprotective effects of carnosine in a mice stroke model concerning oxidative stress and inflammatory response

Carnosine (β-alanyl-L-histidine) is a natural dipeptide with multiple neuroprotective properties. Previous studies have advertised that carnosine scavenges free radicals and displays anti-inflammatory activity. However, the underlying mechanism and the efficacies of its pleiotropic effect on prevention remained obscure. In this study, we aimed to investigate the anti-oxidative, anti-inflammative, and anti-pyroptotic effects of carnosine in the transient middle cerebral artery occlusion (tMCAO) mouse model. After a daily pre-treatment of saline or carnosine (1000 mg / kg / day) for 14 days, mice (n = 24) were subjected to tMCAO for 60 min and continuously treated with saline or carnosine for additional 1 and 5 days after reperfusion. The administration of carnosine significantly decreased infarct volume 5 days after the tMCAO (*p < 0.05) and effectively suppressed the expression of 4-HNE, 8-OHdG, Nitrotyrosine 5 days, and RAGE 5 days after tMCAO. Moreover, the expression of IL-1β was also significantly suppressed 5 days after tMCAO. Our present findings demonstrated that carnosine effectively relieves oxidative stress caused by ischemic stroke and significantly attenuates neuroinflammatory responses related to IL-1β, suggesting that carnosine can be a promising therapeutic strategy for ischemic stroke.

Pulmonary inflammation, oxidative stress, and fibrosis in a mouse model of cholestasis: the potential protective properties of the dipeptide carnosine

Cholestasis is a clinical complication that primarily influences the liver. However, it is well known that many other organs could be affected by cholestasis. Lung tissue is a major organ influenced during cholestasis. Cholestasis-induced lung injury could induce severe complications such as respiratory distress, serious pulmonary infections, and tissue fibrosis. Unfortunately, there is no specific pharmacological intervention against this complication. Several studies revealed that oxidative stress and inflammatory response play a role in cholestasis-induced lung injury. Carnosine (CARN) is a dipeptide found at high concentrations in different tissues of humans. CARN's antioxidant and antiinflammatory properties are repeatedly mentioned in various experimental models. This study aimed to assess the role of CARN on cholestasis-induced lung injury. Rats underwent bile duct ligation (BDL) to induce cholestasis. Broncho-alveolar lavage fluid (BALF) levels of inflammatory cells, pro-inflammatory cytokines, and immunoglobulin were monitored at scheduled intervals (7, 14, and 28 days after BDL). Moreover, lung tissue histopathological alterations and biomarkers of oxidative stress were evaluated. A significant increase in BALF inflammatory cells, TNF-α, IL-1β, IL-6, and immunoglobulin-G (IgG) was detected in the BALF of BDL rats. Moreover, lung tissue histopathological changes, collagen deposition, increased TGF-β, and elevated levels of oxidative stress biomarkers were evident in cholestatic animals. It was found that CARN (100 and 500 mg/kg, i.p.) significantly alleviated lung oxidative stress biomarkers, inflammatory response, tissue fibrosis, and histopathological alterations. These data indicate the potential protective properties of CARN in the management of cholestasis-induced pulmonary damage. The effects of CARN on inflammatory response and oxidative stress biomarkers seems to play a crucial role in its protective properties in the lung of cholestatic animals.

Immunomodulatory Effects of Chicken Broth and Histidine Dipeptides on the Cyclophosphamide-Induced Immunosuppression Mouse Model

The carnosine and anserine, which represent histidine dipeptides (HD), are abundant in chicken broth (CB). HD are endogenous dipeptide that has excellent antioxidant and immunomodulatory effects. The immunomodulatory effect of CB hydrolysate (CBH) and HD in cyclophosphamide (CTX)-induced immunosuppressed mice was examined in this study. CBH and HD were given to mice via oral gavage for 15 days, accompanied by intraperitoneal CTX administration to induce immunosuppression. CBH and HD treatment were observed to reduce immune organ atrophy (p < 0.05) and stimulate the proliferation of splenic lymphocytes (p < 0.05) while improving white blood cell, immunoglobulin M (IgM), IgG, and IgA levels (p < 0.05). Moreover, CBH and HD strongly stimulated interleukin-2 (IL-2) and interferon-gamma (IFN-γ) production by up-regulating IL-2 and IFN-γ mRNA expression (p < 0.05) while inhibiting interleukin-10 (IL-10) overproduction and IL-10 mRNA expression (p < 0.05). In addition, CBH and HD prevented the inhibition of the nitric oxide (NP)/cyclic guanosine monophosphate-cyclic adenosine monophosphate (cGMP-cAMP)/protein kinase A (PKA) signaling pathway (p < 0.05). These results indicate that CBH and HD have the potential to prevent immunosuppression induced by CTX. Our data demonstrate that CBH can effectively improve the immune capacity of immunosuppressed mice similar to the same amount of purified HD, which indicates that CBH plays its role through its own HD.

Impact of a High-Fat Diet on the Metabolomics Profile of 129S6 and C57BL6 Mouse Strains

Different inbred mouse strains vary substantially in their behavior and metabolic phenotype under physiological and pathological conditions. The purpose of this study was to extend the knowledge of distinct coping strategies under challenging events in two differently adapting mouse strains: C57BL/6NTac (Bl6) and 129S6/SvEvTac (129Sv). Thus, we aimed to investigate possible similarities and differences in the body weight change, behavior, and several metabolic variables in Bl6 and 129Sv strains in response to high-fat diet (HFD) using the AbsoluteIDQ p180 kit. We found that 9 weeks of HFD induced a significant body weight gain in 129Sv, but not in Bl6 mice. Besides that, 129Sv mice displayed anxiety-like behavior in the open-field test. Metabolite profiling revealed that 129Sv mice had higher levels of circulating branched-chain amino acids, which were even more amplified by HFD. HFD also induced a decrease in glycine, spermidine, and t4-OH-proline levels in 129Sv mice. Although acylcarnitines (ACs) dominated in baseline conditions in 129Sv strain, this strain had a significantly stronger AC-reducing effect of HFD. Moreover, 129Sv mice had higher levels of lipids in baseline conditions, but HFD caused more pronounced alterations in lipid profile in Bl6 mice. Taken together, our results show that the Bl6 line is better adapted to abundant fat intake.

Using 2D qNMR analysis to distinguish between frozen and frozen/thawed chicken meat and evaluate freshness

We identified key metabolites reflecting microbial spoilage and differentiated unfrozen meat from frozen/thawed (FT) using 2D qNMR analysis. Unfrozen and FT chicken breasts were prepared, individually aerobically packaged, and stored for 16 days at 2 °C. Only volatile basic nitrogen (VBN) was significantly changed after 6 log CFU/g of total aerobic bacteria (p < 0.05). Extended storage resulted in an increase in organic acids, free amino acids, biogenic amines, and hypoxanthine and a decrease in N,N-dimethylglycine, inosine 5'-monophosphate, and proline. Acetic acid demonstrated the highest correlation with VBN (r = 0.97). Unfrozen and FT breast meat can be differentiated by uniform concentration of carnosine, β-alanine, and histidine levels, consistent changes in nucleotides by storage time, and changes in microbial metabolism patterns that are reflected by some free amino acids. Thus, NMR-based metabolomics can be used to evaluate chicken breast meat freshness and distinguish between unfrozen and FT meat.

Effect of Beta-Alanine Supplementation on Exercise-Induced Cell Damage and Lactate Accumulation in Female Basketball Players: A Randomized, Double-Blind Study

Beta-alanine (BA) is a supplement that has received attention for its buffering potential among athletes. The aim of this study was to investigate the effects of BA supplementation on exercise performance and exercise-induced cell damage in female basketball players. Twenty-two female basketball players participated in a randomized, double-blind study. They ingested 6.4 g·day^-1 of BA or an isocaloric placebo (dextrose) over 4 weeks. Exercise performance including aerobic (Bruce test), anaerobic (Wingate test), intermittent (Yo-Yo test) and basketball performance (countermovement jump and free throw shots) was measured before and following the intervention. Exercise measures were performed at the lab and free throw shots were undertaken on a wooden indoor basketball court. Blood samples were also collected before and after the exhaustive exercise to assess lactate concentration, creatine kinase (CK), lactate dehydrogenase (LDH) and malondialdehyde (MDA) activity. The exhaustive exercise test induced an increase in lactate concentration and MDA, CK and LDH activity (all p < 0.05). BA supplementation significantly reduced the lactate response to exhaustive exercise (p = 0.001); however, it had no significant effect on exercise-induced MDA, CK and LDH activity (all p > 0.05). Furthermore, exercise performance measures improved from pre- to post-test regardless of supplement/placebo ingestion (all p < 0.05). BA consumption over 4 weeks significantly reduced lactate accumulation following exhaustive exercise, but had no ergogenic effect in female basketball players. Usual dosing of BA does not seem to exhibit protective effect against oxidative damage.

Neuroprotective Effect of Carnosine Is Mediated by Insulin-Degrading Enzyme

l-Carnosine is an endogenous dipeptide that has high potential for therapeutic purposes, being an antioxidant with metal chelating, anti-aggregating, anti-inflammatory, and neuroprotective properties. Despite its potential therapeutic values, the biomolecular mechanisms involved in neuroprotection are not fully understood. Here, we demonstrate, at chemical and biochemical levels, that insulin-degrading enzyme plays a pivotal role in carnosine neuroprotection.

Small Intestine Microbiome and Metabolome of High and Low Residual Feed Intake Angus Heifers

The gastrointestinal tract (GIT) contains complex microbial communities and plays an essential role in the overall health of the host. Previous studies of beef cattle feed efficiency have primarily concentrated on the ruminal microbiota because it plays a key role in energy production and nutrient supply in the host. Although the small intestine is the important site of post-ruminal digestion and absorption of nutrients, only a few studies have explored the relationship between the microbial populations in the small intestine and feed efficiency. Moreover, variations in GIT metabolites contribute to differences in feed efficiency. The objective of this study was to investigate relationships among bacterial populations of duodenum, jejunum, ileum; microbial metabolites; and RFI phenotype of beef cattle. We carried out by using Illumina MiSeq sequencing of the 16S rRNA V3-V4 region and liquid chromatography-mass spectrometry (LC–MS). In the duodenum, the relative abundances of Firmicutes ( p < 0.01), Lachnospiraceae, Ruminococcaceae, Family_XIII, Christensenellaceae, Christensenellaceae_R-7_group ( p < 0.05), and Lachnospiraceae_NK3A20_group ( p < 0.05) were higher in the low residual feed intake (LRFI) group compared with the high residual feed intake (HRFI) group, whereas the HRFI group had higher abundances of Proteobacteria and Acinetobacter ( p < 0.01). In the jejunum, the relative abundances of Lachnospiraceae and Lachnospiraceae_NK3A20_group were higher in the LRFI group ( p < 0.05). In the ileum, the relative abundances of Ruminococcaceae ( p < 0.01), Christensenellaceae, Christensenellaceae_R-7_group, and Ruminococcus_2 were also higher in the LRFI group ( p < 0.05). Moreover, the genera Lachnospiraceae_NK3A20_group, Christensenellaceae_R-7_group, and Ruminococcus_2 were negatively associated with RFI, while the genus Acinetobacter was positively associated with RFI. The metabolomics analysis revealed that the LRFI group significantly improved protein digestion and absorption, as well as glycerophospholipid metabolism in the duodenum, jejunum, ileum. The correlation between intestinal microorganisms and metabolites revealed that some microorganisms play an important role in amino acid metabolism, glycerophospholipid metabolism, nutrient digestion and absorption, and antioxidant enhancement. The present study provides a better understanding of the small intestinal microbiota and metabolites of beef cattle with different RFI phenotypes and the relationships among them, which are potentially important for the improvement of beef cattle feed efficiency.

Functional Properties of Meat in Athletes’ Performance and Recovery

Physical activity (PA) and sport play an essential role in promoting body development and maintaining optimal health status both in the short and long term. Despite the benefits, a long-lasting heavy training can promote several detrimental physiological changes, including transitory immune system malfunction, increased inflammation, and oxidative stress, which manifest as exercise-induced muscle damages (EIMDs). Meat and derived products represent a very good source of bioactive molecules such as proteins, lipids, amino acids, vitamins, and minerals. Bioactive molecules represent dietary compounds that can interact with one or more components of live tissue, resulting in a wide range of possible health consequences such as immune-modulating, antihypertensive, antimicrobial, and antioxidative activities. The health benefits of meat have been well established and have been extensively reviewed elsewhere, although a growing number of studies found a significant positive effect of meat molecules on exercise performance and recovery of muscle function. Based on the limited research, meat could be an effective post-exercise food that results in favorable muscle protein synthesis and metabolic performance.

An investigation on the structure and group vibrations of balenine molecule by matrix isolation IR spectroscopy, DFT and MP2 based calculations

Stable conformers of neutral balenine were scanned through molecular dynamics simulations and energy minimizations using Allinger's MM2 force field. For each of the found minimum-energy conformers, geometry optimization and thermochemistry calculations were performed by using B3LYP, MP2, G3MP2B3 methods, 6-31G(d), 6-311++G(d,p) and aug-cc-pvTZ basis sets. The calculation results have indicated that balenine has about twenty stable conformers whose relative energies are in the range of 0-9.5 kcal/mol. Three of these are thought to provide the major contribution to matrix isolation IR spectra of the molecule. Our solvent calculations using the polarized continuum model revealed the stable zwitterion structures which are predicted to dominate IR spectra of balenine in water and heavy water (D₂O) solvents. Pulay's SQM-FF method was used in scaling of the harmonic force constants and vibrational spectral data calculated for the neutral and zwitterion structures. These refined calculation data together with those obtained from anharmonic frequency calculations enabled us to correctly interpret the matrix isolation IR spectrum of balenine and the tautomerism-based changes observed in its KBr IR and solution (D₂O) IR spectra. The results revealed the crucial role of conformation and zwitterionic tautomerism on the structure and vibrational spectral data of the molecule.

Clinical Efficacy and Safety of Non-Cross-Linked Hyaluronic Acid Combined with L-carnosine for Horizontal Neck Wrinkles Treatment

Background Horizontal neck wrinkle formation is gaining more attention among cosmetic practitioners and clients. To date, hyaluronic acid products are one of the most common treatment options for this aesthetic concern. However, different therapeutic strategies should be given to solve the problem due to multiple etiological reasons. Given that oxidative damage plays a critical role in neck wrinkle formation, anti-oxidative compounds are now considered by physicians when making a treatment plan. Aims To evaluate the efficacy and safety of a non-cross-linked hyaluronic acid filler in combination with L-carnosine in treating horizontal neck wrinkles. Methods Thirteen patients with a Wrinkle Assessment Scale (WAS) of 2–5 for horizontal neck wrinkles were treated with L-carnosine-containing non-cross-linked hyaluronic acid. Participants were followed-up for 3 months after treatment. The post-treated WAS scores evaluated by physicians were collected when patient satisfaction was surveyed. Any post-treatment adverse events were recorded. Results With a single injection of the above filler, the physician-evaluated WAS scores improved by at least one score at one month and the improvement kept consistent as far as three months after injection. According to the last follow-up visit, 11/13 patients were satisfied with the treatment effect of their neck wrinkle. Moreover, adverse events were rare after filler injection, except for local complications that were considered common reactions to the filler injection procedure. Conclusion The non-cross-linked hyaluronic acid filler containing L-carnosine is safe and effective for treating horizontal neck wrinkles.

Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.

Nutrition and Healthy Aging: Prevention and Treatment of Gastrointestinal Diseases

Nutritional well-being is a fundamental aspect for the health, autonomy and, therefore, the quality of life of all people, but especially of the elderly. It is estimated that at least half of non-institutionalized elderly people need nutritional intervention to improve their health and that 85% have one or more chronic diseases that could improve with correct nutrition. Although prevalence estimates are highly variable, depending on the population considered and the tool used for its assessment, malnutrition in the elderly has been reported up to 50%. Older patients are particularly at risk of malnutrition, due to multiple etiopathogenetic factors which can lead to a reduction or utilization in the intake of nutrients, a progressive loss of functional autonomy with dependence on food, and psychological problems related to economic or social isolation, e.g., linked to poverty or loneliness. Changes in the aging gut involve the mechanical disintegration of food, gastrointestinal motor function, food transit, intestinal wall function, and chemical digestion of food. These alterations progressively lead to the reduced ability to supply the body with adequate levels of nutrients, with the consequent development of malnutrition. Furthermore, studies have shown that the quality of life is impaired both in gastrointestinal diseases, but especially in malnutrition. A better understanding of the pathophysiology of malnutrition in elderly people is necessary to promote the knowledge of age-related changes in appetite, food intake, homeostasis, and body composition in order to better develop effective prevention and intervention strategies to achieve healthy aging.

Increased Bioavailability of β-Alanine by a Novel Controlled-Release Powder Blend Compared to a Slow-Release Tablet

BACKGROUND

β-Alanine is a sport supplement with increasing popularity due to its consistent ability to improve physical performance, with the downside of requiring several weeks of supplementation as imposed to the maximum daily and single dose tolerated without side effects (i.e., paresthesia). To date, the only alternative to overcome this problem has been use of a sustained-release tablet, while powders are the most commonly used format to deliver several grams of amino acids in a single dose. In this study we assessed the bioavailability, pharmacokinetics and paresthesia effect of β-alanine after administration in a novel controlled-released powder blend (test) versus a sustained-release tablet (reference).

METHODS

Twelve subjects (25.6 ± 3.2 y, 50% female) participated in a randomized, single-blind, crossover study. Each participant was administered orally the test (β-alanine 8 g, l-histidine 300 mg, carnosine 100 mg) or the reference product (10 tablets to reach β-alanine 8 g, Zinc 20 mg) with a 1-week washout period. β-Alanine plasma concentrations (0-8 h) were determined by LC-MS/MS and model-independent pharmacokinetic analysis was carried out. Paresthesia intensity was evaluated using a Visual Analog Score (VAS) and the categorical Intensity Sensory Score (ISS).

RESULTS

The CMAX and AUC0→∞ increased 1.6- and 2.1-fold (both p < 0.001) in the test product, respectively, which yielded 2.1-fold higher bioavailability; Ka decreased in the test (0.0199 ± 0.0107 min-1) versus the reference (0.0299 ± 0.0121 min-1) product (p = 0.0834) as well as V/F and Cl/F (both p < 0.001); MRT0→last increased in the test (143 ± 19 min) versus reference (128 ± 16 min) formulation (p = 0.0449); t1/2 remained similar (test: 63.5 ± 8.7 min, reference: 68.9 ± 9.8 min). Paresthesia EMAX increased 1.7-fold using the VAS (p = 0.086) and the ISS (p = 0.009). AUEC increased 1.9-fold with the VAS (p = 0.107) and the ISS (p = 0.019) reflecting scale intrinsic differences. Pharmacokinetic-pharmacodynamic analysis showed a clockwise hysteresis loop without prediction ability between CMAX, AUC0→∞ and EMAX or AUEC. No side effects were reported (except paresthesia).

CONCLUSIONS

The novel controlled-release powder blend shows 100% higher bioavailability of β-alanine, opening a new paradigm that shifts from chronic to short or mid-term supplementation strategies to increase carnosine stores in sports nutrition.

Combined Untargeted and Targeted Metabolomics Approaches Reveal Urinary Changes of Amino Acids and Energy Metabolism in Canine Babesiosis With Different Levels of Kidney Function

Canine babesiosis is a tick-borne disease with a worldwide distribution, caused by the haemoprotozoan parasites of the genus Babesia. One of the most prevalent complication is acute kidney injury, and an early diagnosis of altered kidney function remains a challenge for veterinary practice. The aim of this study was to assess the urine metabolic profile from dogs with babesiosis and different degree of kidney function using untargeted and targeted MS-based metabolomics approaches. In this study, 22 dogs naturally infected with Babesia canis and 12 healthy dogs were included. Untargeted metabolomics approach identified 601 features with a differential abundance between the healthy group and groups of dogs with babesiosis and different level of kidney function, with 27 of them identified as a match to known standards; while targeted approach identified 17 metabolites with significantly different concentrations between the groups. A pattern of significantly altered metabolites referring to the inflammatory host response, oxidative stress, and energy metabolism modulation in babesiosis was presented. Our findings have demonstrated that kidney dysfunction accompanying canine babesiosis was associated with changes in amino acid metabolism, energy metabolism, fatty acid metabolism, and biochemical pathways such as urea cycle and ammonia detoxication. These findings will enable the inclusion of urinary markers for the detection and monitoring of renal damage in babesiosis, as well as in other similar diseases.

Alterations in Urine Metabolomics Following Sport-Related Concussion: A 1H NMR-Based Analysis

Objective: Millions of sport-related concussions (SRC) occur annually in North America, and current diagnosis of concussion is based largely on clinical evaluations. The objective of this study was to determine whether urinary metabolites are significantly altered post-SRC compared to pre-injury.

Setting: Outpatient sports medicine clinic.

Participants: Twenty-six male youth sport participants.

Methods: Urine was analyzed pre-injury and after SRC by ¹H NMR spectroscopy. Data were analyzed using multivariate statistics, pairwise t-test, and metabolic pathway analysis. Variable importance analysis based on random variable combination (VIAVC) was applied to the entire data set and resulted in a panel of 18 features. Partial least square discriminant analysis was performed exploring the separation between pre-injury and post-SRC groups. Pathway topography analysis was completed to identify biological pathway involvement. Spearman correlations provide support for the relationships between symptom burden and length of return to play and quantifiable metabolic changes in the human urinary metabolome.

Results: Phenylalanine and 3-indoxysulfate were upregulated, while citrate, propylene glycol, 1-methylhistidine, 3-methylhistidine, anserine, and carnosine were downregulated following SRC. A receiver operator curve (ROC) tool constructed using the 18-feature classifier had an area under the curve (AUC) of 0.887. A pairwise t-test found an additional 19 altered features, 7 of which overlapped with the VIAVC analysis. Pathway topology analysis indicated that aminoacyl-tRNA biosynthesis and beta-alanine metabolism were the two pathways most significantly changed. There was a significant positive correlation between post-SRC 2-hydroxybutyrate and the length of return to play (ρ = 0.482, p = 0.02) as well as the number of symptoms and post-SRC lactose (ρ = 0.422, p = 0.036).

Conclusion: We found that ¹H NMR metabolomic urinary analysis can identify a set of metabolites that can correctly classify SRC with an accuracy of 81.6%, suggesting potential for a more objective method of characterizing SRC. Correlations to both the number of symptoms and length of return to play indicated that 2-hydroxybutyrate and lactose may have potential applications as biomarkers for sport-related concussion.

Influences of Beta-Alanine and l-Histidine Supplementation on Growth Performance, Meat Quality, Carnosine Content, and mRNA Expression of Carnosine-Related Enzymes in Broilers

Simple Summary

In recent years, much attention has been paid to developing functional meat, which contains more functional peptides to impart health benefits. Poultry meat is a good source of imidazole dipeptides (carnosine and its derivative anserine), which are active endogenous constituents and may convey versatile physiological functions to promote health conditions. Carnosine is synthesized from l-histidine and beta-alanine. Dietary addition of histidine and/or beta-alanine may elevate the carnosine content in broiler meat. The current study further investigated the interaction of l-histidine and beta-alanine supplementation on carnosine content, meat quality, and gene expression of carnosine-related enzymes in broilers, which can facilitate a better understanding of the relationship between l-histidine and beta-alanine in carnosine synthesis.

Abstract

The current study investigated the effect of dietary l-histidine and beta-alanine supplementation on growth performance, meat quality, carnosine content, and gene expression of carnosine-related enzymes in broilers. A two-factor design was adopted in this study. A total of 640 1-day-old male broilers were assigned to eight treatments with factorial arrangement containing four levels of l-histidine (0, 650, 1300, or 1950 mg/kg) and two levels of beta-alanine (0 or 1200 mg/kg) supplementation; 0 mg/kg histidine and/or 0 mg/kg were treated as control groups. Each treatment including eight replicates with 10 birds each and the feeding trial lasted for 42 days. Dietary supplementation with l-histidine and beta-alanine did not affect average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) of broilers during the grower (22–42 days) and the entire phase (1–42 days), compared with the control group (p > 0.05). The only exception was a significantly reduced ADG in the 1950 mg/kg l-histidine group in the starter period (1–21 days, p < 0.05). l-Histidine at 1950 mg/kg significantly decreased redness (a*) and yellowness (b*) values of the meat at 45 min postmortem (p < 0.05), whereas it increased b* value and pH in breast muscle at 24 h postmortem. Moreover, dietary supplementation with beta-alanine alone or combination with l-histidine significantly increased ΔpH in breast muscle (p < 0.01). Dietary l-histidine markedly increased total superoxide dismutase activity and total antioxidant capacity (T-AOC) both in breast muscle (p < 0.01) and in plasma (p < 0.01), and it decreased malondialdehyde (MDA) concentration in breast muscle (p < 0.01). Dietary addition of beta-alanine, alone or combination, significantly increased T-AOC in breast muscle (p < 0.01) and markedly decreased MDA content both in breast muscle and in plasma (p < 0.01). Addition of l-histidine and beta-alanine significantly increased muscle peptide (carnosine and anserine) content (p < 0.05) and upregulated the expression of carnosine synthase, transporter of carnosine/ l-histidine, and l-histidine decarboxylase genes (p < 0.05), with greater change occurring in the combination group of 1300 mg/kg l-histidine and 1200 mg/kg beta-alanine. Overall, dietary l-histidine and beta-alanine could improve meat quality and antioxidant capacity, enhance the carnosine and anserine content, and upregulate the gene expression of carnosine synthesis-related enzymes in broilers.

Carnosine, Small but Mighty-Prospect of Use as Functional Ingredient for Functional Food Formulation

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine's biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

Isolation of balenine from opah (Lampris megalopsis) muscle and comparison of antioxidant and iron-chelating activities with other major imidazole dipeptides

Balenine (Bal) in opah muscle was extracted using hot water and purified by ion-exchange chromatography and recrystallization to provide 41 g of over 95% pure Bal from 1 kg of opah muscle. The structure of purified Bal was identical to that of an authentic Bal standard by NMR analysis. The antioxidant (ORAC and HORAC values) and Fe(II) ion-chelating abilities of purified Bal were examined by comparison with two major imidazole dipeptides, carnosine (Car) and anserine (Ans). Opah-derived Bal showed significantly higher ORAC and HORAC values and Fe(II) ion-chelating ability at 0.3 mM. In silico molecular simulation revealed that Bal and Car formed hydrogen bonds between the hydrogen atom of the imidazole imino group and the carboxyl carbonyl oxygen, whereas Ans did not. The proposed method for extracting and purifying Bal from opah muscle suggests that opah can be utilized as a functional food or Bal resource.

Carnosine Protects Macrophages against the Toxicity of Aβ1-42 Oligomers by Decreasing Oxidative Stress

Carnosine (β-alanyl-L-histidine) is a naturally occurring endogenous peptide widely distributed in excitable tissues such as the brain. This dipeptide has well-known antioxidant, anti-inflammatory, and anti-aggregation activities, and it may be useful for treatment of neurodegenerative disorders such as Alzheimer’s disease (AD). In this disease, peripheral infiltrating macrophages play a substantial role in the clearance of amyloid beta (Aβ) peptides from the brain. Correspondingly, in patients suffering from AD, defects in the capacity of peripheral macrophages to engulf Aβ have been reported. The effects of carnosine on macrophages and oxidative stress associated with AD are consequently of substantial interest for drug discovery in this field. In the present work, a model of stress induced by Aβ1-42 oligomers was investigated using a combination of methods including trypan blue exclusion, microchip electrophoresis with laser-induced fluorescence, flow cytometry, fluorescence microscopy, and high-throughput quantitative real-time PCR. These assays were used to assess the ability of carnosine to protect macrophage cells, modulate oxidative stress, and profile the expression of genes related to inflammation and pro- and antioxidant systems. We found that pre-treatment of RAW 264.7 macrophages with carnosine counteracted cell death and apoptosis induced by Aβ1-42 oligomers by decreasing oxidative stress as measured by levels of intracellular nitric oxide (NO)/reactive oxygen species (ROS) and production of peroxynitrite. This protective activity of carnosine was not mediated by modulation of the canonical inflammatory pathway but instead can be explained by the well-known antioxidant and free-radical scavenging activities of carnosine, enhanced macrophage phagocytic activity, and the rescue of fractalkine receptor CX3CR1. These new findings obtained with macrophages challenged with Aβ1-42 oligomers, along with the well-known multimodal mechanism of action of carnosine in vitro and in vivo, substantiate the therapeutic potential of this dipeptide in the context of AD pathology.

Interaction pattern of histidine, carnosine and histamine with methylglyoxal and other carbonyl compounds

The ability of histidine to scavenge sugar-derived 1,2-dicarbonyl compounds was investigated using aqueous methanolic model systems containing histidine or histamine in the presence of glucose, methylglyoxal, or glyoxal. The samples were prepared either at room temperature (RT) or at 150 °C and analyzed using ESI-qTOF-MS/MS and isotope labeling technique. Replacing glucose with [U-¹³C₆]glucose allowed the identification of glucose carbon atoms incorporated in the products. Various sugar-generated carbonyl compounds ranging in size from C1 to C6 were captured by histidine or histamine. The majority of the fragments incorporated were either C3 or C2 units originating from glyoxal (C2) or methylglyoxal (C3). The ESI-qTOF-MS/MS analysis indicated that histamine could react with either of the two carbonyl carbons of methylglyoxal utilizing the α-amino group and/or the imidazolium moiety. Furthermore, when histidine was added to 2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine (PhIP) generating model system, it completely suppressed the formation of PhIP due to scavenging of phenylacetaldehyde.

Nonviral gene delivery using PAMAM dendrimer conjugated with the nuclear localization signal peptide derived from human papillomavirus type 11 E2 protein

Polyamidoamine (PAMAM) dendrimers are biocompatible polymers utilized in multiple biomedical applications including tissue engineering, medical diagnosis, drug and gene delivery systems, and biosensors. Normally, high-generation PAMAM dendrimers are advantageous for use in gene therapy research because they have a relatively high transfection efficiency. A high-generation PAMAM dendrimer has a high charge density, which induces greater damage to the membranous organelles than that induced by a low-generation PAMAM dendrimer. In this study, we added NLS sequences derived from the human papillomavirus (HPV) type 11 E2 protein to the low-generation PAMAM generation 2 (PAMAM G2) dendrimer and simultaneously introduced histidine residues to reduce cytotoxicity. RKRARH-PAMAM G2 showed similar and high transfection efficiencies in Neuro-2A and NIH3T3 cell lines and relatively low cytotoxicities relative to that of polyethylenimine 25 kDa (PEI 25 kDa).

A Meretrix meretrix visceral mass derived peptide inhibits lipopolysaccharide-stimulated responses in RAW264.7 cells and adult zebrafish model

The Meretrix meretrix is abundantly present in the Indian coastal areas which can be used as an important useful bioactive source for industrial applications. The M. meretrix visceral mass (MMV) was hydrolysed with four different enzymes and verified for anti-inflammatory activity with the help of HRBC membrane stabilization (HMS) and albumin denaturation (AD) assay. Among the hydrolysates, the tryptic 6th hour hydrolysate was selected for purification using ultrafiltration and size-exclusion chromatography (SEC). Further, the purified peptide was identified to have six amino acid sequence (HKGQCC, 675.582 Da). However, to confirm the anti-inflammatory effects of the purified peptide, it was investigated for nitric oxide synthase (iNOS), pro-inflammatory cytokines production as well as cyclooxygenase-2 (COX-2) activation in lipopolysaccharide (LPS)-stimulated RAW264.7 cells and also evaluated for its functional properties. The in-vitro gastrointestinal digestion was performed on the peptide which cleaved the peptide into two i.e. MMV1 (HK, 284.1 Da) and MMV2 (GQCC, 410.1 Da). The data suggested that the MMV2 peptide have maximum activity and was found to be stable at high temperatures. The MMV2 peptide demonstrated abrupt localization throughout the adult zebrafish body and successfully downregulated the mRNA levels of inflammation-related genes in LPS-induced adult zebrafish. This study indicates that the peptide MMV2 possesses anti-inflammatory activity by suppressing the induced inflammation and can be a strong competitor against non-steroidal anti-inflammatory drugs (NSAIDs).

The dynamic process of dietary soybean β-conglycinin in digestion, absorption, and metabolism among different intestinal segments in grass carp (Ctenopharyngodon idella)

The present study aimed to investigate the dynamic process of soybean β-conglycinin in digestion, absorption, and metabolism in the intestine of grass carp (Ctenopharyngodon idella). Fish fed with 80 g β-conglycinin/kg diet for 7 weeks, the intestinal digestive enzyme was extracted to hydrolyze β-conglycinin in vitro, the free amino acid and its metabolism product contents in intestinal segments were analyzed. The present study first found that β-conglycinin cannot be thoroughly digested by fish intestine digestive enzyme and produces new products (about 60- and 55-kDa polypeptides). The indigestible β-conglycinin further caused the free amino acid imbalance, especially caused free essential amino acid deficiency in the proximal intestine but excess in the distal intestine. Moreover, these results might be partly associated with the effect of β-conglycinin in amino acid transporters and tight junction-regulated paracellular pathway. Finally, dietary β-conglycinin increased the content of amino acid catabolism by-product ammonia while decreased the amino acid anabolism product carnosine content in the proximal intestine and distal intestine. Thus, the current study first and systemically explored the dynamic process of β-conglycinin in digestion, absorption, and metabolism, which further supported our previous study that dietary β-conglycinin suppressed fish growth and caused intestine injure.

Sleeping without Prescription: Management of Sleep Disorders in Children with Autism with Non-Pharmacological Interventions and Over-the-Counter Treatments

Autism Spectrum Disorders (ASD) are lifelong neurodevelopmental conditions characterized by abnormal social interaction, communication, and behavior. Sleep disturbances represent a common comorbidity in children and adolescents with ASD, with prevalence ranging from 50 to 80%. It has been proved that sleep disruption worsens the symptoms of autism and results in challenging behaviors. Improving sleep should therefore be a primary therapeutic goal. Treatment options range from lifestyle modifications to pharmacological therapy. Several reviews have been written on pharmacological treatments, but very few on the beneficial effects of non-pharmacological interventions, over-the-counter drugs, and nutritional supplements. This study consists of a narrative review of the literature, presenting the available evidence on the following treatments: sleep education, behavioral interventions, complementary and alternative medicine (special mattresses and blankets, massage, aromatherapy, yoga, physical activity), and commonly used over-the-counter medications and supplements (antihistamines, melatonin, tryptophan, carnosine, iron, vitamins, and herbal remedies). For some treatments—such as melatonin and behavioral interventions—effectiveness in ASD is well established in the literature, while other interventions appear of benefit in clinical practice, even if specific studies in children and adolescents with ASD are lacking. Conversely, other treatments only seem to show anecdotal evidence supporting their use.

Mechanisms of Neuroprotective Action of Hesperetin and Carnosine in Focal Ischemia of the Brain in Rats

We compared the direct neuroprotective effect of minor food components, antioxidants hesperetin and carnosine, and analyzed their influence on the parameters of the oxidative status of the penumbra zones in the cerebral cortex during focal ischemia (1 h) of with reperfusion in Wistar rats. The animals received hesperetin and carnosine included in the diet in daily doses of 50 and 150 mg/kg, respectively, for 7 days before ischemia induction. The neuroprotective effect of hesperetin manifested in reduction of the ischemic lesion size by 30%, which was comparable with the effect of carnosine. Both hesperetin and carnosine reduced the level of MDA in the penumbra zone of the cerebral cortex and increased the total antioxidant activity of the brain tissue. Hesperetin also increased SOD activity to a level observed in the sham-operated control group.

Carnosine and Kidney Diseases: What We Currently Know?

Carnosine (beta-alanyl-L-histidine) is an endogenously synthesised dipeptide which is present in different human tissues e.g. in the kidney. Carnosine is degraded by enzyme serum carnosinase, encoding by CNDP1 gene. Carnosine is engaged in different metabolic pathways in the kidney. It reduces the level of proinflammatory and profibrotic cytokines, inhibits advanced glycation end products' formation, moreover, it also decreases the mesangial cell proliferation. Carnosine may also serve as a scavenger of peroxyl and hydroxyl radicals and a natural angiotensin-converting enzyme inhibitor. This review summarizes the results of experimental and human studies concerning the role of carnosine in kidney diseases, particularly in chronic kidney disease, ischemia/reperfusion-induced acute renal failure, diabetic nephropathy and also drug-induced nephrotoxicity. The interplay between serum carnosine concentration and serum carnosinase activity and polymorphism in the CNDP1 gene is discussed. Carnosine has renoprotective properties. It has a promising potential for the treatment and prevention of different kidney diseases, particularly chronic kidney disease which is a global public health issue. Further studies of the role of carnosine in the kidney may offer innovative and effective strategies for the management of kidney diseases.

Comparative Cerebroprotective Potential of d- and l-Carnosine Following Ischemic Stroke in Mice

l-carnosine is an attractive therapeutic agent for acute ischemic stroke based on its robust preclinical cerebroprotective properties and wide therapeutic time window. However, large doses are needed for efficacy because carnosine is rapidly degraded in serum by carnosinases. The need for large doses could be particularly problematic when translating to human studies, as humans have much higher levels of serum carnosinases. We hypothesized that d-carnosine, which is not a substrate for carnosinases, may have a better pharmacological profile and may be more efficacious at lower doses than l-carnosine. To test our hypothesis, we explored the comparative pharmacokinetics and neuroprotective properties of d- and L-carnosine in acute ischaemic stroke in mice. We initially investigated the pharmacokinetics of d- and L-carnosine in serum and brain after intravenous (IV) injection in mice. We then investigated the comparative efficacy of d- and l-carnosine in a mouse model of transient focal cerebral ischemia followed by in vitro testing against excitotoxicity and free radical generation using primary neuronal cultures. The pharmacokinetics of d- and l-carnosine were similar in serum and brain after IV injection in mice. Both d- and l-carnosine exhibited similar efficacy against mouse focal cerebral ischemia. In vitro studies in neurons showed protection against excitotoxicity and the accumulation of free radicals. d- and l-carnosine exhibit similar pharmacokinetics and have similar efficacy against experimental stroke in mice. Since humans have far higher levels of carnosinases, d-carnosine may have more favorable pharmacokinetics in future human studies.

Protective effects of phenelzine administration on synaptic and non-synaptic cortical mitochondrial function and lipid peroxidation-mediated oxidative damage following TBI in young adult male rats

Traumatic brain injury (TBI) results in mitochondrial dysfunction and induction of lipid peroxidation (LP). Lipid peroxidation-derived neurotoxic aldehydes such as 4-HNE and acrolein bind to mitochondrial proteins, inducing additional oxidative damage and further exacerbating mitochondrial dysfunction and LP. Mitochondria are heterogeneous, consisting of both synaptic and non-synaptic populations, with synaptic mitochondria being more vulnerable to injury-dependent consequences. The goal of these studies was to explore the hypothesis that interrupting secondary oxidative damage following TBI using phenelzine (PZ), an aldehyde scavenger, would preferentially protect synaptic mitochondria against LP-mediated damage in a dose- and time-dependent manner. Male Sprague-Dawley rats received a severe (2.2 mm) controlled cortical impact (CCI)-TBI. PZ (3-30 mg/kg) was administered subcutaneously (subQ) at different times post-injury. We found PZ treatment preserves both synaptic and non-synaptic mitochondrial bioenergetics at 24 h and that this protection is partially maintained out to 72 h post-injury using various dosing regimens. The results from these studies indicate that the therapeutic window for the first dose of PZ is likely within the first hour after injury, and the window for administration of the second dose seems to fall between 12 and 24 h. Administration of PZ was able to significantly improve mitochondrial respiration compared to vehicle-treated animals across various states of respiration for both the non-synaptic and synaptic mitochondria. The synaptic mitochondria appear to respond more robustly to PZ treatment than the non-synaptic, and further experimentation will need to be done to further understand these effects in the context of TBI.

Histidine-containing dipeptides reduce central obesity and improve glycaemic outcomes: A systematic review and meta-analysis of randomized controlled trials

Supplementation with histidine-containing dipeptides has been shown to improve obesity and glycaemic outcomes in animal and human studies. We conducted a systematic review and meta-analysis of randomized controlled trials to examine these effects. Electronic databases were searched investigating the effects of histidine-containing dipeptides supplementation on anthropometric and glycaemic outcomes. Meta-analyses were performed using random-effects models to calculate the weighted mean difference and 95% confidence interval. There were 30 studies for the systematic review and 23 studies pooled for meta-analysis. Histidine-containing dipeptide groups had a lower waist circumference (WMD [95% CI] = -3.53 cm [-5.65, -1.41], p = 0.001) and HbA1c level (WMD [95% CI] = -0.76% (8.5 mmol/mol) [-1.29% (14.3 mmol/mol), -0.24% (2.8 mmol/mol)], p = 0.004) at follow-up compared with controls. In sensitivity analyses of studies with low risk of bias, waist circumference, HbA1c, and fasting glucose levels (WMD [95% CI] = -0.63 mmol/L [-1.09, -0.18], p = 0.006) were significantly lower in intervention groups versus controls. There was also a trend toward lower fat mass (p = 0.09), insulin resistance (p = 0.07), and higher insulin secretion (p = 0.06) in intervention versus control groups. Supplementation with histidine-containing dipeptides may reduce central obesity and improve glycaemic outcomes. Further studies exploring histidine-containing dipeptide use in obesity and diabetes prevention and treatment are warranted.

Decreased Formation of Advanced Glycation End-Products in Peritoneal Fluid by Carnosine and Related Peptides

Background

Formation of advanced glycation end-products (AGEs) is a major problem in uremic patients treated with peritoneal dialysis (PD). Application of additives with known anti-glycosylation properties to PD fluid may be beneficial in minimizing the formation of AGEs. This study aimed to evaluate the effect of carnosine and its related peptides homocarnosine and anserine against the formation of AGEs in PD fluid.

Methods

PD solutions (1.5% dextrose) were incubated with human serum albumin (HSA) or collagen (type IV) with or without 10 mmol/L of each of carnosine, anserine, homo-carnosine, histidine, and aminoguanidine. The formation of AGEs was followed by fluorescence spectrophotometry at weekly intervals for 7 weeks. For the determination of the acute effect of carnosine and related compounds, HSA and collagen were incubated with 4.25% dextrose PD solutions for 24 hours, followed by incubation with 20 mmol/L of carnosine and related compounds for another 24 hours. The rate of AGE formation was monitored by fluorescence spectrophotometry.

Results

Carnosine and related compounds showed effective regression in AGE formation in both types of proteins in both long- and short-term exposure to PD fluids at a rate of effectiveness of the order of carnosine > homocarnosine > anserine, aminoguanidine > histidine in long-term exposure, and homocarnosine > carnosine > aminoguanidine > anserine > histidine in short-term exposure.

Conclusion

Carnosine and related peptides could suppress the formation of AGEs initiated by PD fluid. This observation may provide a new therapeutic approach for the prevention and treatment of the AGE-related complications in PD patients.

Development of multiple reaction monitoring assay for quantification of carnosine in human plasma

Carnosine, a histidine containing dipeptide, exerts beneficial effects by scavenging reactive carbonyl compounds (RCCs) that are implicated in pathogenesis of diabetes. However, the reduced carnosine levels may aggravate the severity of diabetes. The precise quantification of carnosine levels may serve as an indicator of pathophysiological state of diabetes. Therefore, we have developed a highly sensitive targeted multiple reaction monitoring (MRM) method for quantification of carnosine in human plasma samples. Various mass spectrometry parameters such as ionization of precursor, fragment abundance and stability, collision energy, tube lens offset voltage were optimized to develop a sensitive and robust assay. Using the optimized MRM assay, the lower limit of detection (LOD) and limit of quantification (LOQ) for carnosine were found to be 0.4 nM and 1.0 nM respectively. Standard curves were constructed ranging from 1.0 nM to 15.0 μM and the levels of carnosine in mice and human plasma were determined. Further, the MRM assay was extended to study carnosine hydrolyzing activity of human carnosinases, the serum carnosinase (CN1) and the cytosolic carnosinase (CN2). CN1 showed three folds higher activity than CN2. The MRM assay developed in this study is highly sensitive and can be used for basal plasma carnosine quantification, which can be developed as a novel marker for scavenging of RCCs in diabetes.

Human plasma carnosine quantification by developing a sensitive multiple reaction monitoring method.

A Review on Free Radicals and Antioxidants

Free radicals are generated in our body by several systems. A balance among free radicals and antioxidants is an important matter for appropriate physiological function. If free radicals become greater than the ability of the body to control them, a case known as oxidative stress appears, as a result of that, a number of human diseases spread in the body. Antioxidants can contribute to facingthis oxidative stress. The present review provides a brief overview of free radicals, oxidative stress, some natural antioxidants and the relationship between them.

Antioxidant activities and protective effects of duck embryo peptides against H2 O2-induced oxidative damage in HepG2 cells

Previous work showed that peptides from duck eggs incubated for 15 D presented high total antioxidant activities. Here, this work explore the antioxidant activities of different segments, ZT1 (≤3 KD), ZT2 (≤10 KD), and ZT3 (≤30 KD), derived from duck embryo peptides and their protective effects against H₂ O₂-induced oxidative damage in HepG2 cells. Peptides present no cytotoxicity to HepG2 cells. Moreover, ZT1 exhibits a higher ability to scavenge several radicals as well as stronger inhibition of H₂ O₂-induced oxidative stress than ZT2 and ZT3. The activities of catalase and glutathione peroxidase as well as total superoxide dismutase increase in a concentration-dependent manner. Peptides are isolated from ZT1 and then subjected to LC-MS/MS to identify their sequences, followed by functional annotation, bioinformatics prediction, and hot-spot motif recognition. As a result, 413 potential functional peptides are identified, with some compounds exhibiting more than 1 function. This work will help for exploring bioactive substances in duck embryo eggs and enhance the utilization value of duck or other poultry eggs.

Synthesis of radioiodinated carnosine for hepatotoxicity imaging induced by carbon tetrachloride and its biological assessment in rats

The imaging of organs is very important in the field of diagnosis especially in case of liver diseases. In the present work, carnosine was successfully labeled with iodine-131 at room temperature in acidic medium using chloramine-T (Ch-T) as moderate oxidizing agent. The parameters affecting labeling of carnosine such as amount of oxidizing agent, amount of substrate, pH value of the reaction mixture, reaction temperature and reaction time, were investigated. The best conditions for formation of 131I-carnosine (131I-CAR) complex were 40 μg of chloramine-T (Ch-T), 75 μg of carnosine, pH 4 and 45 min reaction time at room temperature. The radiochemical yield for 131I-CAR complex was (91 ± 0.11) % at optimum conditions and the labeled complex was stable for 2 h after labeling process. Biodistribution study was achieved using three groups of rats (normal, treated by inactive carnosine and hepatotoxicity rats induced by CCl4). Hepatotoxicity of liver was evaluated using different biochemical markers such as ALT, AST and ALK.P. The 131I-CAR complex showed selective bio-localization in stomach and liver and its selectivity increases in acquired hepatotoxicity. The biological distribution indicates that the suitability of 131I-CAR as a potential hepatotoxicity imaging to detect hepatitis and medical prognosis.

A Comprehensive Review on Lipid Oxidation in Meat and Meat Products

Meat and meat products are a fundamental part of the human diet. The protein and vitamin content, as well as essential fatty acids, gives them an appropriate composition to complete the nutritional requirements. However, meat constituents are susceptible to degradation processes. Among them, the most important, after microbial deterioration, are oxidative processes, which affect lipids, pigments, proteins and vitamins. During these reactions a sensory degradation of the product occurs, causing consumer rejection. In addition, there is a nutritional loss that leads to the formation of toxic substances, so the control of oxidative processes is of vital importance for the meat industry. Nonetheless, despite lipid oxidation being widely investigated for decades, the complex reactions involved in the process, as well as the different pathways and factors that influenced them, make that lipid oxidation mechanisms have not yet been completely understood. Thus, this article reviews the fundamental mechanisms of lipid oxidation, the most important oxidative reactions, the main factors that influence lipid oxidation, and the routine methods to measure compounds derived from lipid oxidation in meat.