Further evidence for the rejuvenating effects of the dipeptide L-carnosine on cultured human diploid fibroblasts

Biosynthesis of Zinc Oxide Nanoparticles on l-Carnosine Biofunctionalized Polyacrylonitrile Nanofibers; a Biomimetic Wound Healing Material

Multifunctional biohybrid nanofibers (NFs) that can simultaneously drive various cellular activities and confer antibacterial properties are considered desirable in producing advanced wound healing materials. In this study, a bionanohybrid formulation was processed as a NF wound dressing to stimulate the adhesion and proliferation of fibroblast and endothelial cells that play a major role in wound healing. Polyacrylonitrile (PAN) electrospun NFs were hydrolyzed using NaOH and biofunctionalized with l-carnosine (CAR), a dipeptide which could later biosynthesize zinc oxide (ZnO) nanoparticles (NPs) on the NFs surface. The morphological study verified that ZnO NPs are uniformly distributed on the surface of CAR/PAN NFs. Through EDX and XRD analysis, it was validated that the NPs are composed of ZnO and/or ZnO/Zn(OH)2. The presence of CAR and ZnO NPs brought about a superhydrophilicity effect and notably raised the elastic modulus and tensile strength of Zn-CAR/PAN NFs. While CAR ligands were shown to improve the viability of fibroblast (L929) and endothelial (HUVEC) cells, ZnO NPs lowered the positive impact of CAR, most likely due to their repulsive negative surface charge. A scratch assay verified that CAR/PAN NFs and Zn-CAR/PAN NFs aided HUVEC migration more than PAN NFs. Also, an antibacterial assay implied that CAR/PAN NFs and Zn-CAR/PAN NFs are significantly more effective in inhibiting Staphylococcus aureus (S. aureus) than neat PAN NFs are (1000 and 500%, respectively). Taken together, compared to the neat PAN NFs, CAR/PAN NFs with and without the biosynthesized ZnO NPs can support the cellular activities of relevance for wound healing and inactivate bacteria.

Metabolomics Characterize the Differential Metabolic Markers between Bama Xiang Pig and Debao Pig to Identify Pork

The Bama Xiang pig (BM) is a unique pig species in Guangxi Province, China. Compared to other breeds of domestic pig, such as the Debao pig (DB), it is smaller in size, better in meat quality, resistant to rough feeding and strong in stress resistance. These unique advantages of Bama Xiang pigs make them of great edible value and scientific research value. However, the differences in muscle metabolites between Bama Xiang pigs (BM) and Debao pigs (DB) are largely unexplored. Here, we identified 214 differential metabolites between these two pig breeds by LC-MS. Forty-one such metabolites are enriched into metabolic pathways, and these metabolites correspond to 11 metabolic pathways with significant differences. In Bama pigs, the abundance of various metabolites such as creatine, citric acid, L-valine and hypoxanthine is significantly higher than in Debao pigs, while the abundance of other metabolites, such as carnosine, is significantly lower. Among these, we propose six differential metabolites: L-proline, citric acid, ribose 1-phosphate, L-valine, creatine, and L-arginine, as well as four potential differential metabolites (without the KEGG pathway), alanyl-histidine, inosine 2'-phosphate, oleoylcarnitine, and histidinyl hydroxyproline, as features for evaluating the meat quality of Bama pigs and for differentiating pork from Bama pigs and Debao pigs. This study provides a proof-of-concept example of distinguishing pork from different pig breeds at the metabolite level and sheds light on elucidating the biological processes underlying meat quality differences. Our pork metabolites data are also of great value to the genomics breeding community in meat quality improvement.

Whole-cell biotransformation for large scale production of carcinine in Escherichia coli

Carcinine is a natural imidazole-containing peptide derivative. It is widely used in the cosmetics industry as anti-aging supplement with antioxidant, anti-glycation and glycation reversal functions, and it also has a notable pharmacological effect as anti-tumor drug and in protection against retinopathy. However, a technological method for synthesis and production of carcinine has not been established. In this study, a whole-cell transformation system converting β-alanine and histamine to carcinine by the enzymes Ebony and phosphopantetheine transferase (Sfp) has been developed. The results revealed that the catalytic efficiency of the strain containing the fusion protein of Ebony and Sfp (Sfp-glycine-serine-glycine-Ebony, SGE) in Escherichia coli W3110 (WSGE strain) is significantly higher (7.45 mM) than the combinatorial strain of pET28a-ebony and pACYCDuet-sfp in E. coli BL21(DE3) (BSE strain) (2.17 mM). Under the optimal reaction conditions (25 ℃, pH 7.0, 12.5 g/L wet cells, 20 mM β-alanine and 40 mM histamine), the carcinine can be quickly synthesized within 24 h up to a concentration of 22.63 mM. To achieve a continuous and efficient conversion of the precursors, a batch-feeding catalysis was designed. With this system, β-alanine (40 mM) and histamine (40 mM) could be completely transformed to carcinine (40.34 mM) in 36 h with a productivity of 0.204 g/L h reaching a titer of 7.34 g/L. Hence, the batch-feeding whole-cell biocatalysis is a promising technology for the high yield production of carcinine which can promote the industrial production of carcinine.

Carnosine research in relation to aging brain and neurodegeneration: A blessing for geriatrics and their neuronal disorders

Carnosine, an endogenous dipeptide (β-Ala-l-His), is enriched in prefrontal cortex and olfactory bulb of the brain, blood and also in muscle. It has mainly antioxidant and antiglycating properties which makes this molecule unique. Its content reduces during aging and aging-induced neurodegenerative diseases. Aging is a progressive biological process that leads to develop the risk factors of diseases and death. During aging the morphological, biochemical, cellular and molecular changes occur in brain and blood including other tissues. The objective of this review is to combine the updated information from the existing literature about the aging-induced neurodegeneration and carnosine research to meet the lacuna of mechanism of carnosine. The grey matter and white matter loses its normal ratio in aging, and hence the brain volume and weight. Different aging related neurodegenerative disorders arise due to loss of neurons, and synapses as a result of proteinopathies in some cases. Carnosine, being an endogenous biomolecule and having antioxidant, antiglycating properties has shown its potency to counteract erroneous protein biosynthesis, stress, activated microglial and astrocyte activity, and different neurodegenerative disorders. It (carnosine) can also inhibit the metal ion-induced degeneration by acting as a metal chelator. In this review the trends in carnosine research in relation to aging brain and neurodegeneration have been discussed with a view to its (carnosine) eligibility (including its mechanism of action) to be used as a promising neurotherapeutic for the betterment of elderly populations of our society at the national and international levels in near future.

Inflammation as the Common Biological Link Between Depression and Cardiovascular Diseases: Can Carnosine Exert a Protective Role?

Several epidemiological studies have clearly shown the high co-morbidity between depression and Cardiovascular Diseases (CVD). Different studies have been conducted to identify the common pathophysiological events of these diseases such as the overactivation of the hypothalamic- pituitary-adrenal axis and, most importantly, the dysregulation of immune system which causes a chronic pro-inflammatory status. The biological link between depression, inflammation, and CVD can be related to high levels of pro-inflammatory cytokines, such as IL-1β, TNF-α, and IL-6, released by macrophages which play a central role in the pathophysiology of both depression and CVD. Pro-inflammatory cytokines interfere with many of the pathophysiological mechanisms relevant to depression by upregulating the rate-limiting enzymes in the metabolic pathway of tryptophan and altering serotonin metabolism. These cytokines also increase the risk to develop CVD, because activation of macrophages under this pro-inflammatory status is closely associated with endothelial dysfunction and oxidative stress, a preamble to atherosclerosis and atherothrombosis. Carnosine (β-alanyl-L-histidine) is an endogenous dipeptide which exerts a strong antiinflammatory activity on macrophages by suppressing reactive species and pro-inflammatory cytokines production and altering pro-inflammatory/anti-inflammatory macrophage polarization. This dipeptide exhibits antioxidant properties scavenging reactive species and preventing oxidative stress-induced pathologies such as CVD. In the present review we will discuss the role of oxidative stress and chronic inflammation as common pathophysiological events both in depression and CVD and the preclinical and clinical evidence on the protective effect of carnosine in both diseases as well as the therapeutic potential of this dipeptide in depressed patients with a high co-morbidity of cardiovascular diseases.

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.

Carnosine treatment during human semen processing by discontinuous density gradient

The aim of this article was to evaluate the effects of different concentrations of carnosine added during human semen processing. Semen samples from 34 patients were submitted to processing by discontinuous density gradient centrifugation without (control) or with different concentrations of carnosine supplementation as follows: (a) 20 mM of carnosine supplementation on the layers of Percoll; and (b) 50 mM carnosine supplementation. Sperm samples were then washed with human tubal fluid medium and evaluated according to sperm kinetics and functional assessment. For statistical analysis, data were evaluated by a general linear model or a Friedman test, whenever appropriate. The 50 mM carnosine supplementation led to improved sperm mitochondrial activity when compared to untreated samples. Motility variables, such as percentage of motile and progressively motile spermatozoa, average path velocity, straight line velocity, curvilinear velocity and linearity, showed an improvement after semen processing irrespective of carnosine supplementation. Both concentrations of carnosine increased the beat-cross frequency (BCF) when compared to samples before processing. We conclude that carnosine supplementation in semen samples benefits sperm mitochondrial activity and BCF.

In vitro effect of low-level laser therapy on the proliferative, apoptosis modulation, and oxi-inflammatory markers of premature-senescent hydrogen peroxide-induced dermal fibroblasts

Skin aging is a complex biological process induced by intrinsic and extrinsic factors which is characterized by clinical and cellular changes, especially dermal fibroblasts. It is possible that, some procedures, such as low-level laser therapy (LLLT), could decelerate this process. To test this hypothesis, this study evaluated the in vitro LLLT on dermal fibroblast cell line (HFF-1) with premature senescence H2O2-induced. HFF-1 cells were cultured in standardized conditions, and initially H2O2 exposed at different concentrations. Fibroblasts were also just exposed at different LLLT (660 nm) doses. From these curves, the lowest H2O2 concentration that induced indicators of premature senescence and the lowest LLLT doses that triggered fibroblast proliferation were used in all assays. Cellular mortality, proliferation, and the levels of oxidative, inflammatory cytokines, apoptotic markers, and of two growth signaling molecules (FGF-1 and KGF) were compared among treatments. The H2O2 at 50 μM concentration induced some fibroblast senescence markers and for LLLT, the best dose for treatment was 4 J (p < 0.001). The interaction between H2O2 at 50 μM and LLLT at 4 J showed partially reversion of the higher levels of DNA oxidation, CASP 3, CASP 8, IL-1B, IL-6, and INFy induced by H2O2 exposure. LLLT also trigger increase of IL-10 anti-inflammatory cytokine, FGF-1 and KGF levels. Cellular proliferation was also improved when fibroblasts treated with H2O2 were exposed to LLLT (p < 0.001). These results suggest that in fibroblast with some senescence characteristics H2O2-induced, the LLLT presented an important protective and proliferative action, reverting partially or totally negative effects triggering by H2O2.

A carnosine analog with therapeutic potentials in the treatment of disorders related to oxidative stress

Interactive relationships among metabolism, mitochondrial dysfunction and inflammation at skeletal muscle level play a key role in the pathogenesis of disorders related to oxidative stress. Mitochondrial dysfunction and oxidative stress result in cellular energy deficiency, inflammation and cell death inducing a vicious cycle that promotes muscle wasting. The histidine-containing dipeptides, carnosine and anserine, are carbonyl scavengers whose cytoprotective contributions extend beyond the antioxidant defence, but the physiological meaning of these capacities is actually limited. In the present study, we compared and investigated the potential protective effects of three different histidine-containing dipeptides: carnosine, anserine and carnosinol, a carnosine-mimetic new compound, against oxidative stress induction in rat L6 skeletal muscle cells. The hydrogen peroxide induced-oxidative stress significantly altered cell morphology, induced apoptosis, oxidative stress and inflammation, decreased mitochondrial peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α)/sirtuin3 pathway and the antioxidant system. Notably, all three investigated dipeptides in the present study, with a different extent and in a concentration-dependent manner, reduced myotube oxidative stress, apoptosis and inflammation. The present study underlined that carnosinol, maintaining the safety condition of carnosine and anserine, was the more efficient studied dipeptide in the preservation of mitochondrial environment mediated by PGC-1α and sirtuin3 expression and thereby in the reduction of oxidative stress-related alterations in this in vitro skeletal muscle model. Furthermore, we observed that carnosinol's antioxidant effects are not blocked inhibiting sirtuin3, but are maintained with almost the same extend, indicating its multiple capacities of reactive carbonyl species-scavenging and of mitochondrial modulation through PGC-1α. In conclusion, carnosinol retained and surpassed the efficacy of the well-known investigated histidine-containing dipeptides improving oxidative stress, inflammation and also cell metabolism and so becoming a greatly promising therapeutic carnosine derivate.

Carnosine selectively inhibits migration of IDH-wildtype glioblastoma cells in a co-culture model with fibroblasts

Background

Glioblastoma (GBM) is a tumor of the central nervous system. After surgical removal and standard therapy, recurrence of tumors is observed within 6–9 months because of the high migratory behavior and the infiltrative growth of cells. Here, we investigated whether carnosine (β-alanine-l-histidine), which has an inhibitory effect on glioblastoma proliferation, may on the opposite promote invasion as proposed by the so-called “go-or-grow concept”.

Methods

Cell viability of nine patient derived primary (isocitrate dehydrogenase wildtype; IDH1R132H non mutant) glioblastoma cell cultures and of eleven patient derived fibroblast cultures was determined by measuring ATP in cell lysates and dehydrogenase activity after incubation with 0, 50 or 75 mM carnosine for 48 h. Using the glioblastoma cell line T98G, patient derived glioblastoma cells and fibroblasts, a co-culture model was developed using 12 well plates and cloning rings, placing glioblastoma cells inside and fibroblasts outside the ring. After cultivation in the presence of carnosine, the number of colonies and the size of the tumor cell occupied area were determined.

Results

In 48 h single cultures of fibroblasts and tumor cells, 50 and 75 mM carnosine reduced ATP in cell lysates and dehydrogenase activity when compared to the corresponding untreated control cells. Co-culture experiments revealed that after 4 week exposure to carnosine the number of T98G tumor cell colonies within the fibroblast layer and the area occupied by tumor cells was reduced with increasing concentrations of carnosine. Although primary cultured tumor cells did not form colonies in the absence of carnosine, they were eliminated from the co-culture by cell death and did not build colonies under the influence of carnosine, whereas fibroblasts survived and were healthy.

Conclusions

Our results demonstrate that the anti-proliferative effect of carnosine is not accompanied by an induction of cell migration. Instead, the dipeptide is able to prevent colony formation and selectively eliminates tumor cells in a co-culture with fibroblasts.

Electronic supplementary material

The online version of this article (10.1186/s12935-018-0611-2) contains supplementary material, which is available to authorized users.

Effects of collagen-derived bioactive peptides and natural antioxidant compounds on proliferation and matrix protein synthesis by cultured normal human dermal fibroblasts

Nutraceuticals containing collagen peptides, vitamins, minerals and antioxidants are innovative functional food supplements that have been clinically shown to have positive effects on skin hydration and elasticity in vivo. In this study, we investigated the interactions between collagen peptides (0.3-8 kDa) and other constituents present in liquid collagen-based nutraceuticals on normal primary dermal fibroblast function in a novel, physiologically relevant, cell culture model crowded with macromolecular dextran sulphate. Collagen peptides significantly increased fibroblast elastin synthesis, while significantly inhibiting release of MMP-1 and MMP-3 and elastin degradation. The positive effects of the collagen peptides on these responses and on fibroblast proliferation were enhanced in the presence of the antioxidant constituents of the products. These data provide a scientific, cell-based, rationale for the positive effects of these collagen-based nutraceutical supplements on skin properties, suggesting that enhanced formation of stable dermal fibroblast-derived extracellular matrices may follow their oral consumption.

Biopolymeric agents for skin wrinkle treatment

Skin aging is caused by several factors capable of deteriorating dermal matrix and is visibly noticed in skin color and skin contour deformities. In addition to the prevention of skin aging by application of antioxidants and sunscreens, treatment of skin wrinkles with those of dermal fillers is also recommended. Dermal filler products with enhanced injectability and longer duration are being developed continuously. Biodegradable polymers such as skin elastic fibers and dermal matrix mimetic used for treatment of skin wrinkle are summarized in this article. Additionally, the importance of amino acids, enzymes, and proteins in aesthetic of skin is addressed. Thus, elective agents are proposed for the dermatologists, cosmetic formulators, and the individuals facing skin aging problems. The candidate natural peptides from marine sources are additionally presented for widening the choice of actives application for treating aging.

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

Imidazole dipeptides (ID), such as carnosine (β-alanyl-L-histidine), are compounds widely distributed in excitable tissues of vertebrates. ID are also endowed of several biochemical properties in biological tissues, including antioxidant, bivalent metal ion chelating, proton buffering, and carbonyl scavenger activities. Furthermore, remarkable biological effects have been assigned to such compounds in age-related human disorders and in patients whose activity of serum carnosinase is deficient or undetectable. Nevertheless, the precise biological role of ID is still to be unraveled. In the present review we shall discuss some evidences from clinical and basic studies for the utilization of ID as a drug therapy for age-related human disorders.

Amino acids and derivatives, a new treatment of chronic heart failure?

Amino acids play a key role in multiple cellular processes. Amino acids availability is reduced in patients with heart failure (HF) with deleterious consequences on cardiac and whole-body metabolism. Several metabolic abnormalities have been identified in the failing heart, and many of them lead to an increased need of amino acids. Recently, several clinical trials have been conducted to demonstrate the benefits of amino acids supplementation in patients with HF. Although they have shown an improvement of exercise tolerance and, in some cases, of left ventricular function, they have many limitations, namely small sample size, differences in patients' characteristics and nutritional supplementations, and lack of data regarding outcomes. Moreover recent data suggest that a multi-nutritional approach, including also antioxidants, vitamins, and metals, may be more effective. Larger trials are needed to ascertain safety, efficacy, and impact on prognosis of such an approach in HF.

Fragmentation pathways analysis for the gas phase dissociation of protonated carnosine-oxaliplatin complexes

Collision-induced dissociation (CID) experiments on the protonated carnosine-oxaliplatin complex were shown to yield nine different fragment ions. Density functional calculations were employed to probe the fragmentation mechanisms that account for all experimental data.

Hormone-brain-aging relationships, broadly reactive with imidazole-containing dipeptides: targeting of telomere attrition as an aging biomarker and dynamic telomerase activity flirting

It has been documented that telomere-associated cellular senescence may contribute to certain age-related disorders, and telomere length (TL) may be an informative biomarker of healthy aging. Hormone-brain-aging behavior-modulated telomere dynamics and changes in telomerase activity are consistent elements of cellular alterations associated with changes in proliferative state, and these processes are consequently considered as the new therapeutic drug targets for physiological control with advanced drug delivery and nutritional formulations. We raise and support a therapeutic concept of using nonhydrolyzed forms of naturally occurring neuron-specific imidazole dipeptide-based compounds carnosine and carcinine, making it clinically possible that slowing down the rate of telomere shortening could slow down the human aging process in specific tissues where proliferative senescence is known to occur, with the demonstrated evidence of telomere shortening that appeared to be a hallmark of oxidative stress and disease. Carnosine released from skeletal muscle during exercise may be transported into the hypothalamic tuberomammillary nucleus (TMN) histamine neurons and hydrolyzed. The resulting L-histidine may subsequently be converted into histamine, which could be responsible for the effects of carnosine on neurotransmission and hormone-like antiaging physiological function. The preliminary longitudinal studies of elderly individuals suggest that longer telomeres are associated with better survival, and an advanced oral nutritional support with nonhydrolyzed carnosine (or carcinine and patented compositions thereof) is a useful therapeutic tool for a critical TL maintenance that may fundamentally be applied in the treatment of age-related sight-threatening eye disorders, prolonged life expectancy, increased survival and chronological age of an organism in health control, smoking behavior, and disease. "Our pleasures were simple-they included survival." -Dwight D. Eisenhower, 34th President of the United States, 1953-1961.

Effects of oral administration of orodispersible levo-carnosine on quality of life and exercise performance in patients with chronic heart failure

OBJECTIVE

Chronic heart failure (CHF) is characterized by several micronutrient deficits. Amino acid supplementation may have a positive effect on nutritional and metabolic status in patients with CHF. Levo-carnosine (β-alanyl-L-histidine) is expressed at a high concentration in myocardium and muscle. Preliminary studies with L-carnosine in healthy individuals have suggested a potential role in improving exercise performance. To our knowledge, no study has been conducted in patients with heart failure. The aim of this study was to test the oral supplementation of L-carnosine and its effects on quality of life and exercise performance in patients with stable CHF.

METHODS

Fifty patients with stable CHF and severe left-ventricular systolic dysfunction on optimal medical therapy were randomized 1:1 to receive oral orodispersible L-carnosine (500 mg OD) or standard treatment. Left-ventricular ejection fraction (LVEF) was measured by echocardiography. Cardiopulmonary stress test, 6-minute walking test (6 MWT) and quality-of-life (visual analog scale score and the EuroQOL five dimensions questionnaire [EQ-5D]) were performed at baseline and after 6 mo.

RESULTS

Patients receiving orodispersible L-carnosine had an improvement in 6 MWT distance (P = 0.014) and in quality-of-life (VAS score) (P = 0.039) between baseline and follow-up. Compared with controls, diet supplementation with orodispersible L-carnosine was associated with an improvement in peakVO2 (P < 0.0001), VO2 at anaerobic threshold, peak exercise workload, 6 MWT and quality-of-life assessed by the EQ-5D test and the VAS score.

CONCLUSION

This study suggests that L-carnosine, added to conventional therapy, has beneficial effects on exercise performance and quality of life in stable CHF. More data are necessary to evaluate its effects on left-ventricular ejection fraction and prognosis in CHF.

Physiology and pathophysiology of carnosine

Carnosine (β-alanyl-l-histidine) was discovered in 1900 as an abundant non-protein nitrogen-containing compound of meat. The dipeptide is not only found in skeletal muscle, but also in other excitable tissues. Most animals, except humans, also possess a methylated variant of carnosine, either anserine or ophidine/balenine, collectively called the histidine-containing dipeptides. This review aims to decipher the physiological roles of carnosine, based on its biochemical properties. The latter include pH-buffering, metal-ion chelation, and antioxidant capacity as well as the capacity to protect against formation of advanced glycation and lipoxidation end-products. For these reasons, the therapeutic potential of carnosine supplementation has been tested in numerous diseases in which ischemic or oxidative stress are involved. For several pathologies, such as diabetes and its complications, ocular disease, aging, and neurological disorders, promising preclinical and clinical results have been obtained. Also the pathophysiological relevance of serum carnosinase, the enzyme actively degrading carnosine into l-histidine and β-alanine, is discussed. The carnosine system has evolved as a pluripotent solution to a number of homeostatic challenges. l-Histidine, and more specifically its imidazole moiety, appears to be the prime bioactive component, whereas β-alanine is mainly regulating the synthesis of the dipeptide. This paper summarizes a century of scientific exploration on the (patho)physiological role of carnosine and related compounds. However, far more experiments in the fields of physiology and related disciplines (biology, pharmacology, genetics, molecular biology, etc.) are required to gain a full understanding of the function and applications of this intriguing molecule.

Carnosine's effect on amyloid fibril formation and induced cytotoxicity of lysozyme

Carnosine, a common dipeptide in mammals, has previously been shown to dissemble alpha-crystallin amyloid fibrils. To date, the dipeptide's anti-fibrillogensis effect has not been thoroughly characterized in other proteins. For a more complete understanding of carnosine's mechanism of action in amyloid fibril inhibition, we have investigated the effect of the dipeptide on lysozyme fibril formation and induced cytotoxicity in human neuroblastoma SH-SY5Y cells. Our study demonstrates a positive correlation between the concentration and inhibitory effect of carnosine against lysozyme fibril formation. Molecular docking results show carnosine's mechanism of fibrillogenesis inhibition may be initiated by binding with the aggregation-prone region of the protein. The dipeptide attenuates the amyloid fibril-induced cytotoxicity of human neuronal cells by reducing both apoptotic and necrotic cell deaths. Our study provides solid support for carnosine's amyloid fibril inhibitory property and its effect against fibril-induced cytotoxicity in SH-SY5Y cells. The additional insights gained herein may pave way to the discovery of other small molecules that may exert similar effects against amyloid fibril formation and its associated neurodegenerative diseases.

Inhibition of tumour cell growth by carnosine: some possible mechanisms

The naturally occurring dipeptide carnosine (β-alanyl-L-histidine) has been shown to inhibit, selectively, growth of transformed cells mediated, at least in part, by depleting glycolytic ATP levels. The mechanism(s) responsible has/have yet to be determined. Here, we discuss a number of probable and/or possible processes which could, theoretically, suppress glycolytic activity which would decrease ATP supply and generation of metabolic intermediates required for continued cell reproduction. Possibilities include effects on (i) glycolytic enzymes, (ii) metabolic regulatory activities, (iii) redox biology, (iv) protein glycation, (v) glyoxalase activity, (vi) apoptosis, (vii) gene expression and (viii) metastasis. It is possible, by acting at various sites that this pluripotent dipeptide may be an example of an endogenous "smart drug".

Effect of carnosine and related compounds on proliferation of cultured rat pheochromocytoma PC-12 cells

The study was undertaken to determine the mechanism of carnosine effect on cell proliferation. We studied the effect of carnosine and its derivatives on cell cycle progression in cultured rat pheochromocytoma cells (PC-12). It was found that 48-h incubation of PC-12 cells with carnosine in concentrations of 10-50 mM led to deceleration of cell proliferation, reduction of G0/G1 peak, and accumulation of S- and G2/M-phase cells. Methylation of the carnosine molecule by 1N-position of the imidazole ring potentiated its effect on cell proliferation. Acetylation of the carnosine molecule by free β-amino group attenuated its effect.

Anti-stress effects of carnosine on restraint-evoked immunocompromise in mice through spleen lymphocyte number maintenance

Carnosine (β-alanyl-L-histidine), a naturally occurring dipeptide, has been characterized as a putative neurotransmitter and serves as a reservoir for brain histamine, which could act on histaminergic neurons system to relieve stress-induced damages. However, understanding of the role of carnosine in stress-evoked immunocompromise is limited. In this study, results showed that when mice were subjected to restraint stress, spleen index and the number of spleen lymphocytes including Natural Killer (NK) cells were obviously decreased. Results also demonstrated that restraint stress decreased the cytotoxic activity of NK cells per spleen (LU₁₀/spleen) while the activity of a single NK cell (LU₁₀/10⁶ cells) was not changed. However, oral administration of carnosine (150 and 300 mg/kg) increased spleen index and number of spleen lymphocytes (including NK cells), and elevated the cytotoxic activity of NK cells per spleen in restraint-stressed mice. These results indicated that carnosine ameliorated stress-evoked immunocompromise through spleen lymphocyte number maintenance. Carnosine was further found to reduce stress-induced elevation of plasma corticosterone level. On the other hand, results showed that carnosine and RU486 (a glucocorticoids receptor antagonist) treatment prevented the reduction in mitochondrion membrane potential and the release of mitochondrial cytochrome c into cytoplasm, increased Bcl-2/Bax mRNA ratio, as well as decreased terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL)-positive cells in spleen lymphocytes of stressed mice. The results above suggested that the maintenance of spleen lymphocyte number by carnosine was related with the inhibition of lymphocytes apoptosis caused by glucocorticoids overflow. The stimulation of lymphocyte proliferation by carnosine also contributed to the maintenance of spleen lymphocyte number in stressed mice. In view of the elevated histamine level, the anti-stress effects of carnosine on restraint-evoked immunocompromise might be via carnosine-histamine metabolic pathway. Taken together, carnosine maintained spleen lymphocyte number by inhibiting lymphocyte apoptosis and stimulating lymphocyte proliferation, thus prevented immunocompromise in restraint-stressed mice.

Carnosine and cancer: a perspective

The application of carnosine in medicine has been discussed since several years, but many claims of therapeutic effects have not been substantiated by rigorous experimental examination. In the present perspective, a possible use of carnosine as an anti-neoplastic therapeutic, especially for the treatment of malignant brain tumours such as glioblastoma is discussed. Possible mechanisms by which carnosine may perform its anti-tumourigenic effects are outlined and its expected bioavailability and possible negative and positive side effects are considered. Finally, alternative strategies are examined such as treatment with other dipeptides or β-alanine.

Cellular stress responses, hormetic phytochemicals and vitagenes in aging and longevity

Modulation of endogenous cellular defense mechanisms represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. This paper introduces the emerging role of exogenous molecules in hormetic-based neuroprotection and the mitochondrial redox signaling concept of hormesis and its applications to the field of neuroprotection and longevity. Maintenance of optimal long-term health conditions is accomplished by a complex network of longevity assurance processes that are controlled by vitagenes, a group of genes involved in preserving cellular homeostasis during stressful conditions. Vitagenes encode for heat shock proteins (Hsp) Hsp32, Hsp70, the thioredoxin and the sirtuin protein systems. Dietary antioxidants, such as polyphenols and L-carnitine/acetyl-L-carnitine, have recently been demonstrated to be neuroprotective through the activation of hormetic pathways, including vitagenes. Hormesis provides the central underpinning of neuroprotective responses, providing a framework for explaining the common quantitative features of their dose response relationships, their mechanistic foundations, their relationship to the concept of biological plasticity as well as providing a key insight for improving the accuracy of the therapeutic dose of pharmaceutical agents within the highly heterogeneous human population. This paper describes in mechanistic detail how hormetic dose responses are mediated for endogenous cellular defense pathways including sirtuin, Nrfs and related pathways that integrate adaptive stress responses in the prevention of neurodegenerative diseases. This article is part of a Special Issue entitled: Antioxidants and Antioxidant Treatment in Disease.

Telomere length is a biomarker of cumulative oxidative stress, biologic age, and an independent predictor of survival and therapeutic treatment requirement associated with smoking behavior

Globally, tobacco use is associated with 5 million deaths per annum and is regarded as one of the leading causes of premature death. Major chronic disorders associated with smoking include cardiovascular diseases, several types of cancer, and chronic obstructive pulmonary disease (lung problems). Cigarette smoking (CS) generates a cumulative oxidative stress, which may contribute to the pathogenesis of chronic diseases. Mainstream and side stream gas-phase smoke each have about the same concentration of reactive free radical species, about 1 × 10(16) radicals per cigarette (or 5 × 10(14) per puff). This effect is critical in understanding the biologic effects of smoke. Several lines of evidence suggest that cigarette smoke constituents can directly activate vascular reactive oxygen species production. In this work we present multiple evidence that CS provide the important risk factors in many age-related diseases, and is associated with increased cumulative and systemic oxidative stress and inflammation. The cited processes are marked by increased white blood cell (leucocytes, WBCs) turnover. The data suggest an alteration of the circulating WBCs by CS, resulting in increased adherence to endothelial cells. Telomeres are complex DNA-protein structures located at the end of eukaryotic chromosomes. Telomere length shortens with biologic age in all replicating somatic cells. It has been shown that tobacco smoking enhances telomere shortening in circulating human WBCs. Telomere attrition (expressed in WBCs) can serve as a biomarker of the cumulative oxidative stress and inflammation induced by smoking and, consequently, show the pace of biologic aging. We originally propose that patented specific oral formulations of nonhydrolized carnosine and carcinine provide a powerful tool for targeted therapeutic inhibition of cumulative oxidative stress and inflammation and protection of telomere attrition associated with smoking. The longitudinal studies of the clinical population groups described in this study including elderly support the hypothesis that telomere length is a predictor of survival and therapeutic treatment requirement associated with smoking behavior.

Modulation of PARP-1 and PARP-2 expression by L-carnosine and trehalose after LPS and INFγ-induced oxidative stress

Poly(ADP-ribose) polymerases (PARPs) play a crucial role in DNA damage surveillance through their nick sensor functions. Since PARPs' over activation leads to an excessive consumption of NAD(+) and ATP depletion, these enzymes also are involved in the early events of programmed cell death as well as in necrosis. In order to verify the protective action of L: -carnosine and trehalose against NO induced cell death, in the present study we examined their effects on the expression of PARP-1, PARP-2 and iNOS in primary rat astrocyte and oligodendrocyte cells, treated with lipopolysaccharide (LPS) and interferon gamma (INFγ), through semi-quantitative PCR and western analysis. To further characterize the molecular mechanisms underlying L-carnosine and trehalose action, we measured cell viability, nitrite production and LDH release. The data obtained clearly demonstrate that in the stress model employed L-carnosine and trehalose down regulate PARP-1 and PARP-2 expression in both cell phenotypes, thus suggesting their possible application in clinical trials.

Lower frequency of the 5/5 homozygous CNDP1 genotype in South Asian Surinamese

We investigated the frequency of the 5/5 homozygous CNDP1 (carnosinase) genotype, which was found to be associated with a reduced risk of developing diabetic nephropathy, in three ethnic groups in The Netherlands. Particularly interesting were the South Asian Surinamese, who have a high prevalence of diabetic nephropathy. Furthermore, we investigated the association between this gene and carnosinase activity in South Asian Surinamese and whether carnosinase was expressed in the kidney. We genotyped 290 South Asian Surinamese, 532 African Surinamese, and 472 White Dutch in a cross-sectional population study. Furthermore, an independent cohort of South Asian Surinamese was genotyped. In this population, carnosinase activity was measured in serum. Immunostaining and in situ hybridization for CNDP1 were performed on kidney tissue. Both South Asian populations had lower frequencies of the 5/5 homozygous genotype than African Surinamese and White Dutch (23.0%, 27.2%, 38.2%, and 41.3%, respectively; chi-square, p<0.001). This genotype showed a lower carnosinase activity in South Asian Surinamese (Wilcoxon rank-sum, p=0.03). CNDP1 was expressed in the kidney. South Asian Surinamese have a lower frequency of the 5/5 homozygous genotype, which was associated with lower carnosinase activity. Our study provides an indication that South Asian Surinamese are genetically at risk for developing diabetic nephropathy.

Carnosine and its possible roles in nutrition and health

The dipeptide carnosine has been observed to exert antiaging activity at cellular and whole animal levels. This review discusses the possible mechanisms by which carnosine may exert antiaging action and considers whether the dipeptide could be beneficial to humans. Carnosine's possible biological activities include scavenger of reactive oxygen species (ROS) and reactive nitrogen species (RNS), chelator of zinc and copper ions, and antiglycating and anticross-linking activities. Carnosine's ability to react with deleterious aldehydes such as malondialdehyde, methylglyoxal, hydroxynonenal, and acetaldehyde may also contribute to its protective functions. Physiologically carnosine may help to suppress some secondary complications of diabetes, and the deleterious consequences of ischemic-reperfusion injury, most likely due to antioxidation and carbonyl-scavenging functions. Other, and much more speculative, possible functions of carnosine considered include transglutaminase inhibition, stimulation of proteolysis mediated via effects on proteasome activity or induction of protease and stress-protein gene expression, upregulation of corticosteroid synthesis, stimulation of protein repair, and effects on ADP-ribose metabolism associated with sirtuin and poly-ADP-ribose polymerase (PARP) activities. Evidence for carnosine's possible protective action against secondary diabetic complications, neurodegeneration, cancer, and other age-related pathologies is briefly discussed.

Antiglycation and antioxidant effect of carnosine against glucose degradation products in peritoneal mesothelial cells

BACKGROUND/AIM

Toxicity with advanced glycation end products (AGEs) is a major problem in uremic patients. Treatment with peritoneal dialysis (PD) exacerbates AGE formation as a result of bioincompatibility of the conventional peritoneal dialysis fluid (PDF). The presence of glucose degradation products (GDPs) in PDF is the main cause of its bioincompatibility. Carnosine is an endogenous dipeptide with a powerful antiglycation/antioxidant activity. In an attempt to improve PDF biocompatibility, we evaluated the effect of carnosine in human peritoneal mesothelial cells (HPMC) incubated with PDF or GDPs in vitro.

METHODS

HPMC were incubated for short or prolonged time with PDF in the presence or absence of carnosine. Similarly, HPMC were incubated in the same condition but with a combination of GDPs. Following the incubation, cells were tested for their viability, protein carbonyl content and reactive oxygen species (ROS) production.

RESULTS

Results demonstrated a significant protective effect of carnosine to HPMC in both acute and chronic conditions with PDF or GDPs as judged by the enhancement of cell viability, preserved protein from modification and decreased ROS production.

CONCLUSION

Carnosine enhanced HPMC viability against the toxic effect of GDPs probably through protection of cellular protein from modification and from ROS-mediated oxidative damage. The salutary effect of carnosine may render it a desirable candidate for improving PDF biocompatibility and reducing AGE complications in PD patients.

Biological activities of the natural imidazole-containing peptidomimetics n-acetylcarnosine, carcinine and L-carnosine in ophthalmic and skin care products

Apart from genetically programmed cell aging, different external aggressors related to oxidative stress and lipid peroxidation (LPO) can accelerate the skin aging phenomenon. Oxidative stress associated with the formation of lipid peroxides is suggested to contribute to pathological processes in aging and systemic diseases known as the risk factors for cataract. Despite the fact that L-carnosine-related peptidomimetics N-acetylcarnosine (N-acetyl-beta-alanyl-L-histidine) (NAC) and carcinine (beta-alanylhistamine) are metabolically related to L-carnosine and have been demonstrated to occur in tissues of many vertebrates, including humans, these compounds were shown resistant toward enzymatic hydrolysis. A series of related biocompatible imidazole-containing peptidomimetics were synthesized in order to confer resistance to enzymatic hydrolysis and ex vivo improvement of protective antioxidative properties related to L-carnosine. The included findings revealed a greater role of N-acetylcarnosine (NAC) and carcinine ex vivo in the prolongation and potentiation of physiological responses to the therapeutical and cosmetics treatments with L-carnosine as antioxidant. 3-D molecular conformation studies proposed the antioxidant activity of peptidomimetics (carcinine, L-prolylhistamine, N-acetylcarnosine, L-carnosine) for metal ion binding, quenching of a number free radicals, and binding of hydroperoxide or aldehyde (including dialdehyde LPO products) in an imidazole-peroxide adducts. NAC can act as a time release (carrier) stable version of L-carnosine during application in ophthalmic pharmaceutical and cosmetics formulations which include lubricants. Carcinine, L-prolylhistamine show efficient deactivation of lipid hydroperoxides monitored by HPLC and protection of membrane phospholipids and water soluble proteins from the lipid peroxides-induced damages. This activity is superior over the lipophilic antioxidant vitamin E. The biologically significant applications of carnosine mimetics were patented by Dr. Babizhayev and the alliance Groups (WO 2004/028536 A1; WO 94/19325; WO 95/12581; WO 2004/064866 A1).

The concept of telomeric non-reciprocal recombination (TENOR) applied to human fibroblasts grown in serial cultures: concordance with genealogical data

Since the discovery of the limited life span of human fibroblasts some 50 years ago, many genealogical studies have been undertaken to describe growth kinetics of fibroblasts in serial cultures by their individual division behavior. It is now accepted that proliferation capacities of human fibroblasts strongly depend on their telomere lengths and integrity. Telomeres shorten with each replication round, and there is a direct correlation between cell division capacity and telomere lengths; that is, the consumption of disposable telomeric DNA repeats during cell divisions progresses until critically short telomeres determining the replicative senescence of the cells are present. Recently, we have suggested that telomeres in fibroblasts can also become elongated during DNA replication by telomeric non-reciprocal recombination (TENOR). Here we discuss genealogical data collected over the last decades as well as more recent findings on the telomere-driven replicative senescence process, and we summarize both to give an integrated picture.

Glycation, ageing and carnosine: Are carnivorous diets beneficial?

Non-enzymic protein glycosylation (glycation) plays important roles in ageing and in diabetes and its secondary complications. Dietary constituents may play important roles in accelerating or suppressing glycation. It is suggested that carnivorous diets contain a potential anti-glycating agent, carnosine (beta-alanyl-histidine), whilst vegetarians may lack intake of the dipeptide. The possible beneficial effects of carnosine and related structures on protein carbonyl stress, AGE formation, secondary diabetic complications and age-related neuropathology are discussed.