Free Tryptophan Research Articles

Palladium-Catalyzed Direct C-H Glycosylation of Free (N-H) Indole and Tryptophan by Norbornene-Mediated Regioselective C-H Activation.

We describe the palladium-catalyzed direct C-H glycosylation of free N-H indole or tryptophan for the stereoselective synthesis of 2-glycosylindoles and tryptophan-C-glycosides. This reaction relies on the ortho-directing transient mediator norbornene, which underwent regioselective C-H functionalization at the indole or tryptophan ring, providing high chemoselectivity. This method offers a more straightforward, step-economical, and cost-effective route to construct C-glycosides. The gram-scale amenable building blocks can be further functionalized at C3 and N-H, displaying the robustness of present method.

Neurospecific Molecules Measured in Periphery in Humans: How Do They Correlate with the Brain Levels? A Systematic Review.

Human brain state is usually estimated by brain-specific substances in peripheral tissues, but, for most analytes, a concordance between their content in the brain and periphery is unclear. In this systematic review, we summarized the investigated correlations in humans. PubMed was searched up to June 2022. We included studies measuring the same endogenous neurospecific analytes in the central nervous system and periphery in the same subjects. Not eligible were studies of cerebrospinal fluid, with significant blood–brain barrier disruption, of molecules with well-established blood-periphery concordance or measured in brain tumors. Seventeen studies were eligible. Four studies did not report on correlation and four revealed no significant correlation. Four molecules were examined twice. For BDNF, there was no correlation in both studies. For phenylalanine, glutamine, and glutamate, results were contradictory. Strong correlations were found for free tryptophan (r = 0.97) and translocator protein (r = 0.90). Thus, only for three molecules was there some certainty. BDNF in plasma or serum does not reflect brain content, whereas free tryptophan (in plasma) and translocator protein (in blood cells) can serve as peripheral biomarkers. We expect a breakthrough in the field with advanced in vivo metabolomic analyses, neuroimaging techniques, and blood assays for exosomes of brain origin.

The association between tryptophan levels and postpartum mood disorders: a systematic review and meta-analysis

Over 50% of women experience mood disturbance in the postpartum period, with significant implications for maternal and infant health but identifying those at risk is not easily possible. The essential amino acid, tryptophan (TRP) through its neuroactive metabolites, has been implicated in the pathology of mood disorders. Thus, TRP levels tested in the peripartum period have been proposed as a potential biomarker for subsequent development of postpartum mood disturbances, in particular postpartum depression (PPD). A systematic review and meta-analysis following PROSPERO guidelines [CRD42021252462] was conducted on peer-reviewed, English language studies that measured blood levels of TRP during the postpartum period in women who were also evaluated for postpartum “blues” or PPD. Thirteen studies met the inclusion criteria, of which five studies contained sufficient data to conduct a meta-analysis. Low total TRP levels in postpartum days 1 to 5 were significantly associated with PPD (SMD: -5.39, 95%CI [-7.72, -3.05]). No significant association was found between free TRP levels in the postpartum period and PPD (SMD: -3.43, 95%CI [-7.76, 0.89]). Our findings confirm the necessity for more replicable designed studies regarding TRP and its relationship to postpartum depression. If there were greater clarity regarding TRP metabolism during pregnancy, then the next step would be to consider measuring total plasma TRP levels on postpartum days 1 to 5 to identify women at greater risk of developing PPD.

Dietary Valine/Isoleucine Ratio Impact Carcass Characteristics, Meat Edible Quality and Nutritional Values in Finishing Crossbred Duroc × Landrace × Yorkshire Pigs With Different Slaughter Weights.

The aim of this study was to investigate effects of dietary ratio of valine to isoleucine [R(V/I)] on carcass characteristics and meat quality of finishing pigs and whether slaughter weight influence the effect. We carried out a 2 × 3 factorial trial with two slaughter weight (105 vs. 130 kg) and three R(V/I) (0.58, 1.23, and 2.60 at 75–100 kg body weight, and 0.70, 1.24, and 2.39 at 100–135 kg body weight for L-, N- and H-R (V/I), respectively). Data show that increasing slaughter weight significantly increased meat color (a*45 min and b*45 min), drip loss and shear force (P < 0.05). Meanwhile, increasing slaughter weight reduced sarcomere length, the proportion of protein-bound water, and most kinds of muscular total amino acid contents except for tryptophan and arginine, while increased contents of muscular free lysine, tryptophan, leucine, isoleucine, valine, alanine, and arginine in the M. longissimus thoracis (P < 0.05). Health lipid indices based on fatty acid composition of intramuscular lipid were improved as the slaughter weight increased (P < 0.05). Notably, pigs received N-R (V/I) diet improved carcass traits in terms of thinner backfat thickness and higher fat-free lean index, as well as increased meat flavor-contributing amino acids at the cost of reduced intramuscular fat content and increased shear force of cooked meat compared with the pigs fed L-R (V/I) and H-R(V/I) diets (P < 0.05). H-R (V/I) diet decreased ultimate pH value and sarcomere length of the skeletal muscle but increased the proportion of free water (T23), consequently, increased drip loss and cooking loss of fresh meat in pigs (P < 0.05). In conclusion, both slaughter weight and dietary ratio of valine to isoleucine exerted significant impacts on carcass characteristics, meat quality and nutrition values. In particular, carcass traits and meat color of lighter pigs were more susceptible to the influence of dietary R (V/I) relative to heavier pigs.

Formation of chlorinated halobenzoquinones during chlorination of free aromatic amino acids

Chlorinated halobenzoquinones (HBQs) widely exist in drinking water as emerging disinfection byproducts (DBPs), which have attracted significant attention due to their wide occurrence and high toxicity. In this study, the formation of chlorinated HBQs from the three free aromatic amino acids, tryptophan (Trp), tyrosine (Tyr) and phenylalanine (Phe), during chlorination was investigated, the formation pathways of chlorinated HBQs were explained based on the detected intermediates and influence factors. The results revealed that four chlorinated HBQs, including 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), 2,3,5-trichloro-1,4-benzoquinone, 2,3,5,6-tetrachloro-1,4-benzoquinone and 2,6-dichloro-3-methyl-1,4-benzonquinone, were formed in chlorination of the three free aromatic amino acids, and 2,6-DCBQ was the dominant species among the formed chlorinated HBQs. Of the three free aromatic amino acids, Trp and Tyr presented relatively high yields of chlorinated HBQs than Phe. Moreover, ten intermediates were successfully detected (e.g., N,2-dichloroaniline from Trp, 2,4,6-trichlorophenol from Tyr) according to the isotope and fragment information obtained using high resolution mass spectrometry. The formation pathways of chlorinated HBQs from Trp and Tyr were proposed to include electrophilic addition, electrophilic substitution, oxidation, deacidification and dehydration reaction, and further validated using theoretical calculation. The yields of chlorinated HBQs during chlorination of the free aromatic amino acids were significantly affected by free chlorine dosage, pH and temperature.

Protease‐assisted process for tryptophan release from pumpkin ( Cucurbita maxima ) seed protein extracts

Squash pumpkin (Cucurbita maxima) seeds are currently underused food ingredient, despite being a high tryptophan-rich protein source. In this study, we obtained and characterized a protein hydrolysate from defatted C. maxima seed meal, focusing on the effect of the used protease on tryptophan release. Protein hydrolysates were prepared using five different proteases and compared regarding the degree of hydrolysis (DH), free tryptophan content, hydrolysis kinetics, and potential antioxidant activity over reaction time. Protein hydrolysis using Flavourzyme resulted in the highest DH (35.6%), and free tryptophan concentration (337.9 mg/100 g), whereas hydrolysates obtained using Chymotrypsin showed the highest in vitro antioxidant activity (oxygen radical absorbance capacity [ORAC]) (371.1 mmol TE/100 g DM of protein extract). Our results show that protein hydrolysates from C. maxima seeds are a promising source of free tryptophan, with high antioxidant activity, supporting its potential as a food ingredient or for nutraceutical applications. Practical application C. maxima seeds are a promising source of free tryptophan, and its functionalization through hydrolysis showed a significant effect increasing tryptophan release and antioxidant activity, increasing its potential for ingredient or nutraceutical applications.

Влияние наноалмазов на усиление флуоресценции продуктов реакции фототрансформации триптофана в присутствии галогенуглеводородов

The role of nanodiamonds in the reaction of photochemical transformation of tryptophan in the presence of halogen hydrocarbons has been studied. The photochemical transformation of free tryptophan in a suspension with diamond nanoparticles and in a hybrid complex with them when exposed to UV radiation in the presence of chloroform is investigated. Data from stationary and time-resolved spectroscopic studies show the presence of non-radiative transfer of electron excitation energy between tryptophan molecules and its photodestruction products for the case of a covalent complex with a nanodiamond. It is shown that in the presence of energy transfer, an increase in the intensity of integral fluorescence occurs in the range of ~ 450 nm. Thus, a covalent tryptophan complex with a nanodiamond can serve as a fluorescent marker for the presence of chloroform in solution.

Effect of nanodiamonds on fluorescence enhancement of tryptophan phototransformation reaction products in the presence of halocarbons

The role of nanodiamonds in the reaction of photochemical transformation of tryptophan in the presence of halogen hydrocarbons has been studied. The photochemical transformation of free tryptophan in a suspension with diamond nanoparticles and in a hybrid complex with them when exposed to UV radiation in the presence of chloroform is investigated. Data from stationary and time-resolved spectroscopic studies show the presence of non-radiative transfer of electron excitation energy between tryptophan molecules and its photodestruction products for the case of a covalent complex with a nanodiamond. It is shown that in the presence of energy transfer, an increase in the intensity of integral fluorescence occurs in the range of ~ 450 nm. Thus, a covalent tryptophan complex with a nanodiamond can serve as a fluorescent marker for the presence of chloroform in solution. Keywords: nanoscale diamonds, hybrid complexes, tryptophan phototransformation, spectral-luminescent properties, fluorescence decay kinetics, chloroform.

Linkage of nanosecond protein motion with enzymatic methyl transfer by nicotinamide N-methyltransferase.

Nicotinamide N-methyltransferase (NNMT), a key cytoplasmic protein in the human body, is accountable to catalyze the nicotinamide (NCA) N1-methylation through S-adenosyl-L-methionine (SAM) as a methyl donor, which has been linked to many diseases. Although extensive studies have concerned about the biological aspect, the detailed mechanism study of the enzyme function, especially in the part of protein dynamics is lacking. Here, wild-type nicotinamide N-methyltransferase together with the mutation at position 20 with Y20F, Y20G, and free tryptophan were carried out to explore the connection between protein dynamics and catalysis using time-resolved fluorescence lifetimes. The results show that wild-type nicotinamide N-methyltransferase prefers to adapt a less flexible protein conformation to achieve enzyme catalysis.

Milk fermentation affects amino acid and fatty acid profile of mare milk from Polish Coldblood mares

The aim of this work was to demonstrate the influence of mare milk fermentation type on the amino acid profile, especially the content of tryptophan, water-soluble vitamins and magnesium. Additionally, the atherogenic, thrombogenic and hypercholesterolaemic fatty acid index was analysed. The dominant amino acids of mare milk were glutamic acid, leucine, lysine, and aspartic acid. Fermentation of mares' milk did not affect the riboflavin, cobalamin, and magnesium content. The type of lactic acid bacteria used had no effect on the free tryptophan content of fermented milk. The free tryptophan content of fermented mares' milk was 0.062 mg 100 g−1 (Δ22% compared with unfermented milk). The sum of saturated fatty acid concentration was lower in fermented than in the unfermented mares' milk. Atherogenic index was lower in mare milk than in fermented mares’ milk. The values of fatty acids with a hypocholesterolaemic effect and hypercholesterolaemic fatty acids decreased in fermented milk.

Substrate-Driven Differences in Tryptophan Catabolism by Gut Microbiota and Aryl Hydrocarbon Receptor Activation.

ScopeThis study aims to investigate the effect of tryptophan sources on tryptophan catabolism by gut microbiota and the aryl hydrocarbon receptor (AhR) activation.Methods and ResultsFour substrates (free tryptophan, soybean protein, single and clustered soybean cells) containing an equimolar amount of tryptophan, but with a different bioaccessibility are studied using in vitro batch fermentation. Tryptophan catabolites are identified by LC‐MS/MS. AhR activity is measured by HepG2‐Lucia AhR reporter cells. The total amount of tryptophan‐derived catabolites increases with decreasing level of substrate complexity. Indole is the major catabolite produced from tryptophan and it is the most abundant in the free tryptophan fermentation. Indole‐3‐acetic acid and indole‐3‐aldehyde are abundantly generated in the soybean protein fermentation. The soybean cell fermentation produced high concentrations of tryptamine. Interestingly, large amounts of short‐chain fatty acids (SCFAs) are also found in the soybean cell and protein fermentation. Both tryptophan‐derived catabolites and SCFAs are able to increase AhR reporter activity over time in all four groups.ConclusionThis study illustrates that bacterial catabolism of tryptophan and resulting AhR activation in the gut is modulated by the food matrix, suggesting a role for food design to improve gut health.

ЛЕЙКОЗ КРУПНОГО РОГАТОГО СКОТА — ДИАГНОСТИКА, ОЗДОРОВЛЕНИЕ, АНТРОПОЗООНОЗНЫЙ ПОТЕНЦИАЛ (ИСТОРИЯ ВОПРОСА) (обзор)

Of tumor diseases in the global animal husbandry industry, the greatest danger is bovine leukemia. Since the last century, this neoplastic disease has remained relevant for veterinary medicine and, in addition, more and more questions arise concerning the potential threat of the Bovine leukemia virus (BLV) for humans. The problem is being discussed (G.Yu. Kosovskiy et al., 2016) which additionally stimulates both fundamental research of the pathogen and the pathology, as well as the methods for detection to improve dairy cattle breeding and veterinary safety. A number of publications are devoted to BLV prevalence, peculiarities, the prospects for improving animal health and welfare based on selection and vaccines developed in the world (S.G. Hopkins et al., 1997; M.A. Juliarena et al., 2017). In our report, we retrospectively compare the experience of BLV eradication in the USSR, Russia and abroad, additionally focusing on the possible role of this pathogen in the occurrence of cancer in humans. In veterinary practice, serological tests, i.e., immunodiffusion (ID) assay in agar gel and enzyme-linked immunosorbent assay (ELISA) are mostly used to detect the BLV infection. G.C. Buehring et al. (2019) reported the detection of BLV proviral DNA in blood leukocytes in 38 % of patients examined by PCR and DNA sequencing. IgG antibodies to BLV were detected in 32 %, IgM — in 58 %, and IgA — in 32 % of the samples tested. Accumulated data indicate metabolic changes in the BLV-positive animals, e.g., disorder in the metabolism of tryptophan, a critical essential acid, leading to the accumulation of dangerous endogenous metabolites in the body. Particularly, free tryptophan, indole and anthranilic acid increased in level 4-8-fold are deposited in the organs of the immune and hematopoietic system (lymph nodes, spleen, liver), in the mammary gland, lungs, and kidneys. It has been established that the milk of leukemic animals differs from the milk of healthy cows in terms of physicochemical, bacteriological (lysozyme), technological parameters and mineral composition. In C57 mice fed with pasteurized milk and heat-treated meat from ID-positive cows, the blood cell profile changed. Available data drive to the unambiguous conclusion that the products derived from BLV-infected cattle pose an increased risk to humans. Despite the lack of convincing evidence of the BLV pathogenicity for humans, concerns about the etiological role of this virus in the occurance of cancer in humans additionally necessitates continuing research on the control and eradication of this common oncogenic retro-virus in livestock farms.

Bovine leukemia virus INFECTION — DIAGNOSTICS, ERADICATION, AND ANTHROPOZOONOTIC POTENTIAL (BACKGROUND) (review)

Of tumor diseases in the global animal husbandry industry, the greatest danger is bovine leukemia. Since the last century, this neoplastic disease has remained relevant for veterinary medicine and, in addition, more and more questions arise concerning the potential threat of the Bovine leukemia virus (BLV) for humans. The problem is being discussed (G.Yu. Kosovskiy et al., 2016) which additionally stimulates both fundamental research of the pathogen and the pathology, as well as the methods for detection to improve dairy cattle breeding and veterinary safety. A number of publications are devoted to BLV prevalence, peculiarities, the prospects for improving animal health and welfare based on selection and vaccines developed in the world (S.G. Hopkins et al., 1997; M.A. Juliarena et al., 2017). In our report, we retrospectively compare the experience of BLV eradication in the USSR, Russia and abroad, additionally focusing on the possible role of this pathogen in the occurrence of cancer in humans. In veterinary practice, serological tests, i.e., immunodiffusion (ID) assay in agar gel and enzyme-linked immunosorbent assay (ELISA) are mostly used to detect the BLV infection. G.C. Buehring et al. (2019) reported the detection of BLV proviral DNA in blood leukocytes in 38 % of patients examined by PCR and DNA sequencing. IgG antibodies to BLV were detected in 32 %, IgM — in 58 %, and IgA — in 32 % of the samples tested. Accumulated data indicate metabolic changes in the BLV-positive animals, e.g., disorder in the metabolism of tryptophan, a critical essential acid, leading to the accumulation of dangerous endogenous metabolites in the body. Particularly, free tryptophan, indole and anthranilic acid increased in level 4-8-fold are deposited in the organs of the immune and hematopoietic system (lymph nodes, spleen, liver), in the mammary gland, lungs, and kidneys. It has been established that the milk of leukemic animals differs from the milk of healthy cows in terms of physicochemical, bacteriological (lysozyme), technological parameters and mineral composition. In C57 mice fed with pasteurized milk and heat-treated meat from ID-positive cows, the blood cell profile changed. Available data drive to the unambiguous conclusion that the products derived from BLV-infected cattle pose an increased risk to humans. Despite the lack of convincing evidence of the BLV pathogenicity for humans, concerns about the etiological role of this virus in the occurance of cancer in humans additionally necessitates continuing research on the control and eradication of this common oncogenic retro-virus in livestock farms.

Ozonation Treatment Increases Chlorophenylacetonitrile Formation in Downstream Chlorination or Chloramination.

Chlorophenylacetonitriles (CPANs) are an emerging group of aromatic nitrogenous disinfection byproducts (DBPs). However, their dominant precursors and formation pathways remain unclear, which hinders the further development of effective control strategies. For the first time, CPAN precursors were screened by conducting formation potential (FP) tests on real water samples from six drinking water treatment plants (DWTPs). The average overall removal of CPAN precursors across all six DWTPs was only 10%. Moreover, ozonation increased CPAN precursors by 140% on average. Fluorescence spectroscopy showed a dramatic reduction in aromatic proteins, tyrosine-like proteins, and tryptophan-like proteins following ozonation. Low-apparent-molecular-weight (AMW) (<1 kDa) substances were correlated with the CPAN FP in these samples. We therefore hypothesized that protein fragments with low AMW, such as amino acids, are important CPAN precursors during downstream chlor(am)ination. Two aromatic free amino acids, tyrosine and tryptophan, were selected to investigate the formation of CPANs during chlor(am)ination. Both amino acids were found to act as CPAN precursors for the first time. CPAN formation pathways from these model precursors were proposed based on the frontier molecular orbital theory and intermediate products identified using high-resolution mass spectrometry. This study provides a powerful theoretical foundation for controlling CPAN formation in drinking water.

How Tryptophan Oxidation Arises by "Dark" Photoreactions from Chemiexcited Triplet Acetone.

Dioxetane intermediates readily decompose to chemiluminescent triplet carbonyls, giving rise to what has been paradoxically called photochemistry in the dark. In this issue of Photochemistry and Photobiology, Bechara et al. report on mechanistic advances in such a reaction. With the use of horseradish peroxidase for isobutyraldehyde-derived triplet acetone, light emission from acetone and singlet oxygen can be quenched. The experiments reveal that the reaction depends on oxygen and the amino acid. The analysis reveals that free tryptophan is a target of this form of "carbonyl stress," with the efficient formation of mono-, bi- and tricyclic compounds (N-formylkynurenine, indoline, 1λ2 -indole and 3H-indoles).

Amino acid availability of processed Brassica carinata meals in hybrid striped bass Morone chrysops ♀ x M. saxatilis ♂

An earlier study showed that hybrid striped bass (Morone chrysops ♀ x M. saxatilis ♂) diets containing 20 % animal meals and up to 30 % aerobically fermented (AF) carinata meal (Brassica carinata, CM) followed by a single wash with water (AFCM) or 30 % CM double-washed with water without AF (WCM), resulted in similar growth. However feed utilization and Fulton’s condition factor of 30 % WCM were better. The current study investigated effects of AFCM and WCM on amino acid digestibilities using naive fish. Effects of AFCM and WCM on trypsin activity, and amino acid availability were determined using hybrid striped bass fed experimental diets for 127 and 148 days, respectively (after a growth trial). High (30 %) AFCM reduced all essential amino acids (EAA) and conditionally EAA (CEAA) except histidine, methionine and threonine. However, all EAA and CEAAs except lysine and cysteine were digested better in 30 %WCM than 30 % AFCM. High (30 %) CMs resulted in generally high serum free methionine and tryptophan, but less leucine for the first 9 h. However, 30 % WCM resulted in generally more serum free arginine and valine than 30 % AFCM. High CMs increased muscle free histidine. Generally, WCM resulted in more muscle lysine and valine than AFCM. Muscle methionine was increased by CMs. Both serum and muscle free total EAAs in hybrid striped bass fed 30 % WCM were elevated continuously over a longer period above the baseline levels. Using EAA:lysine, only muscle histidine were adequate for muscle synthesis over the 36-h period. Overall, amino acids were more available in WCM than AFCM.

Supplementation of guanidinoacetic acid and betaine improve growth performance and meat quality of ducks by accelerating energy metabolism

This study was conducted to investigate the effects of guanidinoacetic acid (GAA) and betaine on growth performance, meat quality and metabolism of ducks. A total of 384-one-day-old Cherry Valley meat ducks (55.75 ± 0.55 g) were randomly assigned to four treatments with 6 replicates of 16 ducks. Ducks were fed a basal diet (control) or a test diet supplemented with 0.6 g GAA/kg, 2.0 g betaine/kg, or 0.6 g GAA/kg + 2.0 g betaine/kg. The results showed that compared with the control group, GAA and betaine improved feed conversation ratio from day 1 to 14 and 1 to 35 and body weight at 35 days of age (p < .05). GAA and betaine increased breast muscle percentage while reduced abdominal fat percentage, and drip loss and shear force of breast muscle (p < .05). GAA and betaine lowered free serine, methionine, tryptophan and total amino acid contents in muscles, increased free serine, aspartic acid, phenylalanine and tryptophan contents in plasma (p < .05). There was a synergistic effect on non-esterified fatty acid, lactic acid and uric acid between GAA and betaine. GAA and betaine increased the creatine kinase activity in plasma and creatine and ATP content in breast muscle, decreased the lactate dehydrogenase and L-arginine: glycine amidino transferase activities (p < .05). In conclusion, supplementation of GAA and betaine improved the growth performance and meat quality of ducks by accelerating energy metabolism. There was a synergistic effect on NEFA, LA and UA concentrations in plasma of ducks between GAA and betaine. Highlights Supplementing GAA and betaine improved the growth performance and meat quality of ducks. Adding GAA and betaine accelerated the energy metabolism of ducks. There was a synergistic effect on non-esterified fatty acid, lactic acid and uric acid concentrations in the plasma of ducks between GAA and betaine.

Polydopamine/graphene/MnO2 composite-based electrochemical sensor for in situ determination of free tryptophan in plants

The in vivo detection of small active molecules in plant tissues is essential for the development of precision agriculture. Tryptophan (Trp) is an important precursor material for auxin biosynthesis in plants, and the detection of Trp levels in plants is critical for regulating the plant growth process. In this study, an electrochemical plant sensor was fabricated by electrochemically depositing a polydopamine (PDA)/reduced graphene oxide (RGO)-MnO2 nanocomposite onto a glassy carbon electrode (GCE). PDA/RGO-MnO2/GCE exhibited high electrocatalytic activity for the oxidation of Trp owing to the combined selectivity of PDA and catalytic activity of RGO-MnO2. To address the pH variability of plants, a reliable Trp detection program was proposed for selecting an appropriate quantitative detection model for the pH of the plant or plant tissue of interest. Therefore, a series of linear regression curves was constructed in the pH range of 4.0–7.0 using the PDA/RGO-MnO2/GCE-based sensor. In this pH range, the linear detection range of Trp was 1–300 μM, the sensitivity was 0.39–1.66 μA μM−1, and the detection limit was 0.22–0.39 μM. Moreover, the practical applicability of the PDA/RGO-MnO2/GCE-based sensor was successfully demonstrated by determining Trp in tomato fruit and juice. This sensor stably and reliably detected Trp levels in tomatoes in vitro and in vivo, demonstrating the feasibility of this research strategy for the development of electrochemical sensors for measurements in various plant tissues.

Tryptophan pathway catabolites (serotonin, 5-hydroxyindolacetic acid, kynurenine) and enzymes (monoamine oxidase and indole amine 2,3 dioxygenase) in patients with septic shock: A prospective observational study versus healthy controls.

Septic shock is associated with a strong inflammatory response that induces vasodilation and vascular hyporeactivity. We investigated the role for tryptophan-pathway catabolites of proinflammatory cytokines in septic shock.We prospectively included 30 patients with very recent-onset septic shock and 30 healthy volunteers. The following were assayed once in the controls and on days 1, 2, 3, 7, and 14 in each patient: plasma free and total tryptophan, platelet and plasma serotonin, total blood serotonin, urinary serotonin, plasma and urinary 5-hydroxyindolacetic acid, plasma kynurenine, monoamine oxidase activity, and total indole amine 2,3-dioxygenase activity. Organ-system failure and mortality were recorded.Compared with the healthy controls, the patients with septic shock had 2-fold to 3-fold lower total tryptophan levels throughout the 14-day study period. Platelet serotonin was substantially lower, while monoamine oxidase activity and 5-hydroxyindolacetic acid were markedly higher in the patients than in the controls, consistent with the known conversion of tryptophan to serotonin, which is then promptly and largely degraded to 5-hydroxyindolacetic acid. Plasma kynurenine was moderately increased and indole amine 2,3-dioxygenase activity markedly increased in the patients versus the volunteers, reflecting conversion of tryptophan to kynurenine. Changes over time in tryptophan metabolites were not associated with survival in the patients but were associated with the Sequential Organ Failure Assessment score and hemodynamic variables including hypotension and norepinephrine requirements.Our results demonstrate major tryptophan pathway alterations in septic shock. Marked alterations were found compared with healthy volunteers, and tryptophan metabolite levels were associated with organ failure and hemodynamic alterations. Tryptophan metabolite levels were not associated with surviving septic shock, although this result might be ascribable to the small sample size.Trial registration: ClinicalTrials.gov; No: NCT00684736; URL: www.clinicaltrials.gov.

Effect of cinnamic acid and its derivatives on structure of gluten proteins – A study on model dough with application of FT-Raman spectroscopy

Fourier transform Raman spectroscopy was applied to study interactions between gluten proteins and five phenolic acids during mixing of the model dough. Phenolic acids: cinnamic, p-coumaric, caffeic, ferulic and chlorogenic acids were chosen and added in the amount of 0.05%, 0.1% and 0.2%. These compounds differ in the type of functional groups present at the phenolic aromatic ring, and hence antioxidant activity. Farinographic results show a change in the dough behaviour in the presence of phenolic acids which can be regarded as a dough breakdown. This phenomenon occurs the fastest for caffeic acid, and the slowest for p-coumaric acid that are characterized by the highest and lowest antioxidant activity, respectively. The structural changes observed in gluten proteins also depend on the antioxidant activity of phenolic acids. The largest changes were observed in conformation of disulphide bridges, content of free SH groups and tryptophan environment as a result of caffeic and chlorogenic acids addition. The present results indicate that the studied phenolic acids may incorporate into gluten network or may be closed in hydrophobic pockets without formation of any chemical bonds.