Biological Activity of Novel Synthetic Derivatives of Carnosine

The Therapeutic Potential of Novel Carnosine Formulations: Perspectives for Drug Development

Carnosine (beta-alanyl-L-histidine) is an endogenous dipeptide synthesized via the activity of the ATP-dependent enzyme carnosine synthetase 1 and can be found at a very high concentration in tissues with a high metabolic rate, including muscles (up to 20 mM) and brain (up to 5 mM). Because of its well-demonstrated multimodal pharmacodynamic profile, which includes anti-aggregant, antioxidant, and anti-inflammatory activities, as well as its ability to modulate the energy metabolism status in immune cells, this dipeptide has been investigated in numerous experimental models of diseases, including Alzheimer's disease, and at a clinical level. The main limit for the therapeutic use of carnosine is related to its rapid hydrolysis exerted by carnosinases, especially at the plasma level, reason why the development of new strategies, including the chemical modification of carnosine or its vehiculation into innovative drug delivery systems (DDS), aiming at increasing its bioavailability and/or at facilitating the site-specific transport to different tissues, is of utmost importance. In the present review, after a description of carnosine structure, biological activities, administration routes, and metabolism, we focused on different DDS, including vesicular systems and metallic nanoparticles, as well as on possible chemical derivatization strategies related to carnosine. In particular, a basic description of the DDS employed or the derivatization/conjugation applied to obtain carnosine formulations, followed by the possible mechanism of action, is given. To the best of our knowledge, this is the first review that includes all the new formulations of carnosine (DDS and derivatives), allowing a decrease or complete prevention of the hydrolysis of this dipeptide exerted by carnosinases, the simultaneous blood-brain barrier crossing, the maintenance or enhancement of carnosine biological activity, and the site-specific transport to different tissues, which then offers perspectives for the development of new drugs.

2-Oxo-imidazole dipeptides in meat

2-Oxo-imidazole dipeptides (2-oxo-IDPs) are highly functional, but it is unclear whether 2-oxo-IDPs exist in meat. Here, we measured 2-oxo-IDPs levels in meat and observed that it varied according to animal species and body parts. In addition, 2-oxo-IDPs in chicken breast extract increased after aeration in the presence of CuSO4/ascorbate, suggesting the potential of elevated 2-oxo-IDPs in effective usage of meat.

Synergistic Effect of L-Carnosine and Hyaluronic Acid in Their Covalent Conjugates on the Antioxidant Abilities and the Mutual Defense against Enzymatic Degradation

Hyaluronic acid (Hy) is a natural linear polymer that is widely distributed in different organisms, especially in the articular cartilage and the synovial fluid. During tissue injury due to oxidative stress, Hy plays an important protective role. All the beneficial properties of Hy make the polymer attractive for many biomedical uses; however, the low stability and short biological half-life limit Hy application. To overcome these problems, the addition of small antioxidant molecules to Hy solution has been employed to protect the molecular integrity of Hy or delay its degradation. Carnosine (β-alanyl-L-histidine, Car) protects cells from the damage due to the reactive species derived from oxygen (ROS), nitrogen (RNS) or carbonyl groups (RCS). Car inhibits the degradation of hyaluronan induced by free radical processes in vitro but, like Hy, the potential protective action of Car is drastically hampered by the enzymatic hydrolysis in vivo. Recently, we conjugated Hy to Car and the derivatives (HyCar) showed protective effects in experimental models of osteoarthritis and rheumatoid arthritis in vivo. Here we report the antioxidant activity exerted by HyCar against ROS, RNS and RCS. Moreover, we tested if the covalent conjugation between Hy and Car inhibits the enzymatic hydrolysis of the polymer and the dipeptide backbone. We found that the antioxidant properties and the resistance to the enzymatic hydrolysis of Hy and Car are greatly improved by the conjugation.

Ionophore Ability of Carnosine and Its Trehalose Conjugate Assists Copper Signal in Triggering Brain-Derived Neurotrophic Factor and Vascular Endothelial Growth Factor Activation In Vitro

l-carnosine (β-alanyl-l-histidine) (Car hereafter) is a natural dipeptide widely distributed in mammalian tissues and reaching high concentrations (0.7-2.0 mM) in the brain. The molecular features of the dipeptide underlie the antioxidant, anti-aggregating and metal chelating ability showed in a large number of physiological effects, while the biological mechanisms involved in the protective role found against several diseases cannot be explained on the basis of the above-mentioned properties alone, requiring further research efforts. It has been reported that l-carnosine increases the secretion and expression of various neurotrophic factors and affects copper homeostasis in nervous cells inducing Cu cellular uptake in keeping with the key metal-sensing system. Having in mind this l-carnosine ability, here we report the copper-binding and ionophore ability of l-carnosine to activate tyrosine kinase cascade pathways in PC12 cells and stimulate the expression of BDNF. Furthermore, the study was extended to verify the ability of the dipeptide to favor copper signaling inducing the expression of VEGF. Being aware that the potential protective action of l-carnosine is drastically hampered by its hydrolysis, we also report on the behavior of a conjugate of l-carnosine with trehalose that blocks the carnosinase degradative activity. Overall, our findings describe a copper tuning effect on the ability of l-carnosine and, particularly its conjugate, to activate tyrosine kinase cascade pathways.

Hyaluronan-carnosine conjugates inhibit Aβ aggregation and toxicity

Alzheimer’s disease is the most common neurodegenerative disorder. Finding a pharmacological approach that cures and/or prevents the onset of this devastating disease represents an important challenge for researchers. According to the amyloid cascade hypothesis, increases in extracellular amyloid-β (Aβ) levels give rise to different aggregated species, such as protofibrils, fibrils and oligomers, with oligomers being the more toxic species for cells. Many efforts have recently been focused on multi-target ligands to address the multiple events that occur concurrently with toxic aggregation at the onset of the disease. Moreover, investigating the effect of endogenous compounds or a combination thereof is a promising approach to prevent the side effects of entirely synthetic drugs. In this work, we report the synthesis, structural characterization and Aβ antiaggregant ability of new derivatives of hyaluronic acid (Hy, 200 and 700 kDa) functionalized with carnosine (Car), a multi-functional natural dipeptide. The bioactive substances (HyCar) inhibit the formation of amyloid-type aggregates of Aβ₄₂ more than the parent compounds; this effect is proportional to Car loading. Furthermore, the HyCar derivatives are able to dissolve the amyloid fibrils and to reduce Aβ-induced toxicity in vitro. The enzymatic degradation of Aβ is also affected by the interaction with HyCar.

[Neuroprotective mechanisms of the ubiquinol action in experimental focal ischemia]

Ischemic stroke is one of the most socially important diseases characterized by impaired cerebral circulation with focal damage of the brain tissue and decreased functionality. Despite the successes of modern pharmacology, possibilities of pharmacotherapy for stroke remain limited, and the research for new drugs with neuroprotective effects that can prevent brain cell death is still relevant. In this study we have investigated the neuroprotective activity of ubiquinol as a part of an innovative form on a rat model of irreversible 24 h-cerebral ischemia with evaluation of the mechanisms of its neuroprotective effect. Ubiquinol (30 mg/kg), administered intravenously in the acute period of irreversible 24 h focal cerebral ischemia, had a direct neuroprotective effect, characterized by a decrease in the volume of brain tissue necrosis. The protective effect of ubiquinol is due to its ability to inhibit the development of oxidative stress by the direct anti-radical action, preventing the increase in the lipid hydroperoxide content in the brain tissue adjacent to the focus of necrosis, lowering the lipid oxidation rate in plasma against under conditions of increased total antioxidant activity in the brain and blood of experimental animals. In vitro experiments have shown the ability of ubiquinol to prevent cell death in primary culture of cerebral neurons of rat brain under 4 h oxygen/glucose deprivation followed by 20 h reoxygenation.

A new derivative of acetylsalicylic acid and carnosine: synthesis, physical and chemical properties, biological activity

PURPOSE

The aim of this study was to create and assess biological activity of a new compound based on carnosine and acetylsalicylic acid (ASA) that will comprise antioxidant effect with antiplatelet activity, while simultaneously preventing side effects on the gastrointestinal tract.

METHODS

Salicyl-carnosine (SC) was synthesized by condensation of ASA and carnosine. Antioxidant activity was determined by spectrophotometric and chemiluminescence methods. Antiplatelet activity was carried out by the light transmission-aggregometry method using the inductor ADP. Chronic gastric ulcer in rats was modeled using glacial acetic acid.

RESULTS

Using SOD-like activity, iron-induced chemiluminescence, BaSO4-activated respiratory burst, and evaluation of red blood cell structure stabilization during oxidative damage induced by sodium hypochlorite, it was shown that SC possesses antioxidant activity analogous, or better, than that of carnosine. Antiplatelet activity of SC was evaluated in the blood of healthy individuals, and was also shown to be comparable to, or exceeding that of ASA. Also SC demonstrates high resistance to hydrolysis by tissue and serum carnosinases. Most importantly, it was shown that SC has protected the gastric mucosa against the formation of stomach ulcerative lesions and promoted their epithelization, therefore overcoming the undesirable inherent side effects of ASA.

CONCLUSIONS

SC preserves pharmacologically significant properties of ASA and carnosine while retaining an anti-ulcer activity and resistance to the carnosinase hydrolysis at the same time. These properties are particularly promising for the potential development of new anti-inflammatory and antithrombotic drugs. Graphical abstract .

Carnosine exerts antitumor activity against bladder cancers in vitro and in vivo via suppression of angiogenesis

Carnosine, a naturally occurring dipeptide, was recently reported to exhibit anticancer activity; however, the molecular mechanisms and regulators underlying its activity against tumor-associated angiogenesis remain unidentified. In this study, we evaluated the in vitro and in vivo antitumor effects of carnosine in EJ bladder cancer cells and EJ-xenografted BALB/c nude mice, respectively. In addition, in vitro capillary tube formation of HUVECs, ex vivo aortic ring and in vivo Matrigel plug assays were employed to examine the antiangiogenic potential of carnosine. Carnosine significantly inhibited EJ cell proliferation. Flow cytometric and immunoblot analyses indicated that carnosine modulated regulators of the G1 cell cycle phase, including cyclin D1, CDK4 and p21WAF1. The mitogen-activated protein kinases, ERK and p38, but not JNK or AKT, responded to carnosine. Carnosine inhibited the migratory and invasive potential of EJ cells by inhibiting MMP-9 activity, which was associated with suppression of binding activity of NF-κB, SP-1 and AP-1. In xenograft tumors, carnosine exhibited antitumor activity equivalent to cisplatin, but no weight loss occurred in carnosine-treated mice. In HUVECs, carnosine inhibited VEGF-mediated proliferation, colony tube formation, migration and invasion. The antiangiogenic activity of carnosine was partially due to the suppression of VEGFR-2-mediated ERK/AKT/eNOS signaling and MMP-2. Furthermore, using aortic ring and Matrigel plug assays, we confirmed the antiangiogenic activity of carnosine. Given that targeting tumor-associated angiogenesis is a proven effective therapeutic strategy, our results may provide valuable information for the development of preventive or therapeutic agents for bladder cancer patients.

A carnosine analog mitigates metabolic disorders of obesity by reducing carbonyl stress

Sugar- and lipid-derived aldehydes are reactive carbonyl species (RCS) frequently used as surrogate markers of oxidative stress in obesity. A pathogenic role for RCS in metabolic diseases of obesity remains controversial, however, partly because of their highly diffuse and broad reactivity and the lack of specific RCS-scavenging therapies. Naturally occurring histidine dipeptides (e.g., anserine and carnosine) show RCS reactivity, but their therapeutic potential in humans is limited by serum carnosinases. Here, we present the rational design, characterization, and pharmacological evaluation of carnosinol, i.e., (2S)-2-(3-amino propanoylamino)-3-(1H-imidazol-5-yl)propanol, a derivative of carnosine with high oral bioavailability that is resistant to carnosinases. Carnosinol displayed a suitable ADMET (absorption, distribution, metabolism, excretion, and toxicity) profile and was determined to have the greatest potency and selectivity toward α,β-unsaturated aldehydes (e.g., 4-hydroxynonenal, HNE, ACR) among all others reported thus far. In rodent models of diet-induced obesity and metabolic syndrome, carnosinol dose-dependently attenuated HNE adduct formation in liver and skeletal muscle, while simultaneously mitigating inflammation, dyslipidemia, insulin resistance, and steatohepatitis. These improvements in metabolic parameters with carnosinol were not due to changes in energy expenditure, physical activity, adiposity, or body weight. Collectively, our findings illustrate a pathogenic role for RCS in obesity-related metabolic disorders and provide validation for a promising new class of carbonyl-scavenging therapeutic compounds rationally derived from carnosine.

[Lipoilcarnosine: synthesis, study of physico-chemical and antioxidant properties, biological activity]

Synthesis of lipoilcarnosine (LipC) - a conjugated molecule based on two natural antioxidants, carnosine and a-lipoic acid, is described. Its physico-chemical, antioxidant properties and biological activity are characterized. According to reversed-phase HPLC with a UV detector, purity of the final product was 89.3%. The individuality of the obtained sodium salt of LipC was confirmed by tandem HPLC-mass spectrometry. High resistance of LipC to hydrolysis with serum carnosinase was demonstrated. The antioxidant activity of LipC measured by reaction with the formation of thiobarbituric acid reacting substances and kinetic parameters of iron-induced chemiluminescence was higher than that of carnosine and lipoic acid. LipC did not affect viability of SH-SY5Y human neuroblastoma culture cells, differentiated towards the dopaminergic type, at concentrations not exceeding 5 mM. At the concentration range of 0.1-0.25 mM LipC protected neuronal cells against 1-methyl-4-phenylpyridinium (MPP + )-induced toxicity.

Synthesis, structure, antioxidant activity, and water solubility of trolox ion conjugates

The interaction of trolox with ammonia, alkylamines of different classes, and amino derivatives of heterocyclic compounds, including nitroxyl radicals and alkaloids, led to the production of ammonium salts called ion conjugates (ICs). Five ICs were characterised by X-ray diffraction. This is the first time a wide range of ICs were made from trolox with amines, and ESI-MS data demonstrated they have the potential to generate pseudomolecular [(A⁻B⁺) + H]⁺ ions. For all obtained trolox ICs, a significant increase (1–3 orders of magnitude) in water solubility was achieved while retaining high antioxidant activity. ICs synthesised from two biologically active fragments may be used to create polyfunctional agents with varying solubility and bioavailability.

Inhibition of oxidative stress in brain during rat adjuvant arthritis by carnosine, trolox and novel trolox-carnosine

Carnosine (CARN) is an anti-glycating agent able to quench superoxide, and to neutralize 4-hydroxynonenal. Trolox-carnosine (CARN-T) was synthesized because of its resistance against degradation and to improve CARN antioxidant capacity. We evaluated the impact of trolox (TRO), CARN and its derivative CARN-T on oxidative stress (OS) in brain during rat adjuvant arthritis (AA). The experiments were done on healthy, control arthritic and arthritic animals with administration of CARN 150 mg/kg b.w., TRO 41 mg/kg b.w. and CARN-T 75 mg/kg b.w. in a daily dose during 28 days. Antioxidants did not affect the body weight on day 14, but on day 28 TRO enhanced the weight reduction. On day 14 and 28 CARN-T and TRO reduced arthritic score. IL-1beta, MCP-1 and MMP-9 were measured in plasma on day 14. MCP-1 was decreased by CARN-T and TRO. All antioxidants reduced IL-1beta and MMP-9 levels. Malondialdehyde, 4-hydroxynonenal and protein carbonyls were increased in brain. CARN, CARN-T and TRO prevented higher lipid and protein oxidation in brain. CARN and CARN-T caused no weight reduction like TRO that has an advantage in inflammatory arthritis. Moreover the antioxidants administered had a similar therapeutic effects on arthritic score, markers of inflammation in plasma and OS in brain.

Carnosinases, their substrates and diseases

Carnosinases are Xaa-His dipeptidases that play diverse functions throughout all kingdoms of life. Human isoforms of carnosinase (CN1 and CN2) under appropriate conditions catalyze the hydrolysis of the dipeptides carnosine (β-alanyl-l-histidine) and homocarnosine (γ-aminobutyryl-l-histidine). Alterations of serum carnosinase (CN1) activity has been associated with several pathological conditions, such as neurological disorders, chronic diseases and cancer. For this reason the use of carnosinase levels as a biomarker in cerebrospinal fluid (CSF) has been questioned. The hydrolysis of imidazole-related dipeptides in prokaryotes and eukaryotes is also catalyzed by aminoacyl-histidine dipeptidases like PepD (EC 3.4.13.3), PepV (EC 3.4.13.19) and anserinase (EC 3.4.13.5). The review deals with the structure and function of this class of enzymes in physiological and pathological conditions. The main substrates of these enzymes, i.e., carnosine, homocarnosine and anserine (β-alanyl-3-methyl-l-histidine) will also be described.

Supplementation with carnosine decreases plasma triglycerides and modulates atherosclerotic plaque composition in diabetic apo E(-/-) mice

OBJECTIVE

Carnosine has been shown to modulate triglyceride and glycation levels in cell and animal systems. In this study we investigated whether prolonged supplementation with carnosine inhibits atherosclerosis and markers of lesion stability in hyperglycaemic and hyperlipidaemic mice.

METHODS

Streptozotocin-induced diabetic apo E(-/-) mice were maintained for 20 weeks, post-induction of diabetes. Half of the animals received carnosine (2g/L) in their drinking water. Diabetes was confirmed by significant increases in blood glucose and glycated haemoglobin, plasma triglyceride and total cholesterol levels, brachiocephalic artery and aortic sinus plaque area; and lower body mass.

RESULTS

Prolonged carnosine supplementation resulted in a significant (∼20-fold) increase in plasma carnosine levels, and a significant (∼23%) lowering of triglyceride levels in the carnosine-supplemented groups regardless of glycaemic status. Supplementation did not affect glycaemic status, blood cholesterol levels or loss of body mass. In the diabetic mice, carnosine supplementation did not diminish measured plaque area, but reduced the area of plaque occupied by extracellular lipid (∼60%) and increased both macrophage numbers (∼70%) and plaque collagen content (∼50%). The area occupied by α-actin-positive smooth muscle cells was not significantly increased.

CONCLUSIONS

These data indicate that in a well-established model of diabetes-associated atherosclerosis, prolonged carnosine supplementation enhances plasma levels, and has novel and significant effects on atherosclerotic lesion lipid, collagen and macrophage levels. These data are consistent with greater lesion stability, a key goal in treatment of existing cardiovascular disease. Carnosine supplementation may therefore be of benefit in lowering triglyceride levels and suppressing plaque instability in diabetes-associated atherosclerosis.

Carnosine inhibits Aβ(42) aggregation by perturbing the H-bond network in and around the central hydrophobic cluster

Aggregation of the amyloid-β peptide (Aβ) into fibrillar structures is a hallmark of Alzheimer's disease. Thus, preventing self-assembly of the Aβ peptide is an attractive therapeutic strategy. Here, we used experimental techniques and atomistic simulations to investigate the influence of carnosine, a dipeptide naturally occurring in the brain, on Aβ aggregation. Scanning force microscopy, circular dichroism and thioflavin T fluorescence experiments showed that carnosine does not modify the conformational features of Aβ42 but nonetheless inhibits amyloid growth. Molecular dynamics (MD) simulations indicated that carnosine interacts transiently with monomeric Aβ42 by salt bridges with charged side chains, and van der Waals contacts with residues in and around the central hydrophobic cluster ((17)LVFFA(21)). NMR experiments on the nonaggregative fragment Aβ12-28 did not evidence specific intermolecular interactions between the peptide and carnosine, in agreement with MD simulations. However, a close inspection of the spectra revealed that carnosine interferes with the local propensity of the peptide to form backbone hydrogen bonds close to the central hydrophobic cluster (residues E22, S26 and N27). Finally, MD simulations of aggregation-prone Aβ heptapeptide segments show that carnosine reduces the propensity to form intermolecular backbone hydrogen bonds in the region 18-24. Taken together, the experimental and simulation results (cumulative MD sampling of 0.2 ms) suggest that, despite the inability of carnosine to form stable contacts with Aβ, it might block the pathway toward toxic aggregates by perturbing the hydrogen bond network near residues with key roles in fibrillogenesis.

Transforming dietary peptides in promising lead compounds: the case of bioavailable carnosine analogs

The ability of carnosine to prevent advanced glycoxidation end products (AGEs) and advanced lipoxidation end products (ALEs) formation, on the one hand, and the convincing evidence that these compounds act as pathogenetic factors, on the other hand, strongly support carnosine as a promising therapeutic agent for oxidative-based diseases. The mechanism/s by which carnosine inhibits AGEs and ALEs is still under investigation but an emerging hypothesis is that carnosine acts by deactivating the AGEs and ALEs precursors and in particular the reactive carbonyl species (RCS) generated by both lipid and sugar oxidation. The ability of carnosine to inhibit AGEs and ALEs formation and the corresponding biological effects has been demonstrated in several in vitro studies and in some animal models. However, such effects are in line of principle, limited in humans, due to the effect of serum carnosinase (absent in rodents), which catalyzes the carnosine hydrolysis to its constitutive amino acids. Such a limitation has prompted a great interest in the design of carnosine derivatives, which maintaining (or improving) the reactivity with RCS, are more resistant to carnosinase. The present paper intends to critically review the most recent studies oriented to obtaining carnosine derivatives, optimized in terms of reactivity with RCS, selectivity (no reaction with physiological aldehydes) and the pharmacokinetic profile (mainly through an enhanced resistance to carnosinase hydrolysis). The review also includes a brief description of AGEs and ALEs as drug targets and the evidence so far reported regarding the ability of carnosine as inhibitor of AGEs and ALEs formation and the proposed reaction mechanisms.

Protection of prenylated flavonoids from Mori Cortex Radicis (Moraceae) against nitric oxide-induced cell death in neuroblastoma SH-SY5Y cells

Seven prenylated flavanoids, licoflavone C (1), cyclomulberrin (2), neocyclomorusin (3), sanggenon I (4), morusin (5), kuwanon U (6) and kuwanon E (7), and three 2-arylbenzofurans, moracin P (8), moracin O (9), and mulberrofuran Q (10) were isolated from the MeOH extract of Mori Cortex Radicis. Among these, compounds 2-7 enhanced cell viability in a dose-dependent manner against sodium nitroprusside-induced cell death in neuroblastoma SH-SY5Y cells, which was measured by MTT reduction assay (EC(50) values of 4.4, 5.6, 8.0, 6.4, 8.7, and 11.9 μg/mL, respectively). Among 10 compounds, C-3 prenylated flavones (2, 3, and 5) and prenylated flavanones (4, 6, and 7) showed cell protection. However, compound 1 which lacks the prenyl group at C-3 and three 2-arylbenzofurans (8-10) did not show protective effect. The order of cell protection was as follow: C-3 prenylated flavones (2, 3, and 5) > prenylated flavanones (4, 6, and 7) > 2-arylbenzofurans (8-10) and flavone (1). From this result, we show that some prenylated flavones and flavanones might protect neuronal cells against nitrosative stress-mediated cell death. Even though further evaluations are necessary in vitro and in vivo study, we carefully suggest that some prenylated flavonoids from Mori Cortex Radicis might protect neuronal cells from neurodegenerative diseases.

Inhibitory effect of 2-arylbenzofurans from the Mori Cortex Radicis (Moraceae) on oxygen glucose deprivation (OGD)-induced cell death of SH-SY5Y cells

Three known 2-arylbenzofurans, moracin P (1), moracin O (2) and mulberrofuran Q (3) were isolated from the MeOH extract of the Mori Cortex Radicis. These compounds 1-3 enhanced cell viability in dose-dependent manner against oxygen-glucose deprivation (OGD)-induced cell death in neuroblastoma SH-SY5Y cells, which was measured by MTT reduction assay. (EC(50) values of 10.4, 12.6, and 15.9 μM, respectively). In addition, the compounds 1-3 were examined for their inhibitory effect on OGD-induced ROS production by FACS analysis. We observed these compounds reduced ROS production in OGD-induced cell death (IC(50) values of 1.9, 0.3 and 12.1 μM, respectively). Consequently, reactive oxygen species (ROS) were overexpressed in OGD-induced cells and all three compounds reduced ROS induced by OGD in dosedependent manner. Taken together, compounds 1-3 might protect neuronal cell death against the oxidative stress induced by OGD, though further studies in vitro and in vivo models are necessary.

Effect of carnosine and its Trolox-modified derivatives on life span of Drosophila melanogaster

This study investigated the effect of antioxidants, i.e., carnosine and its Trolox- (water-soluble analog of alpha-tocopherol) acylated derivatives (S,S)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carbonyl-beta-alanyl-L-histidine (S,S-Trolox-carnosine, STC) and (R,S)-6-hydroxy-2,5,7,8-tetramethylchroman-2-carbonyl-beta-alanyl-L-histidine (R,S-Trolox-carnosine, RTC) on the life span of the fruit fly Drosophila melanogaster. Adding carnosine to foodstuff was accompanied and followed by a 20% increase in the average life span of males, but it did not influence the average life span of females. At the same time, adding STC to foodstuff prolonged average longevity both in males (by 16%) and females (by 36%), but the addition of RTC to foodstuff had no influence upon the average life span of insects of either gender. The compounds studied have previously been shown to protect neurons of the rat brain from oxidative stress in the descending order of efficiency: RTC > STC > carnosine. The finding obtained in the present study suggests another order of efficacy regarding the effect on life span in male insects: STC > carnosine > RTC (inefficient). No correlation between antioxidant protection of rat neurons and the effect on life span of the fruit fly makes it possible to suppose the presence of additional cellular targets to be acted upon by exposure of D. melanogaster to these compounds.