Essential Amino Acids Research Articles

An Experimental Dynamic Investigation of the Influence of Melatonin, Serotonin and Tryptophan on the Stability of the DNA Structure

Background: Small molecules play a crucial role in the exploration of physiological pathways and in drug development by targeting deoxyribonucleic acid (DNA). DNA is a central focus for both endogenous and exogenous ligands, which interact directly or indirectly to regulate transcription and replication processes, thus controlling genetic expression in specific cells. Among these molecules, indole derivatives like tryptophan, serotonin, and melatonin are notable for their widespread presence in nature and significant biological effects. Tryptophan, an essential amino acid, serves as a vital structural element in proteins and a precursor for bioactive compounds like serotonin and melatonin, which impact various physiological functions. Methods: Experimental studies have been conducted to reveal the interaction mechanisms of these endogenous indole derivatives with calf thymus DNA (ct-DNA). These investigations involve viscosity measurements and analysis of double-stranded DNA behavior in the presence of indole molecules, using spectrophotometric UV absorption techniques to assess their impact on DNA stability. Additionally, the influence of calcium and magnesium ions on the resulting complexes of these indole derivatives with ct-DNA has been evaluated. Molecular docking validated our findings, offering additional insights into potential DNA–ligand interactions. Utilizing a crystallographic oligomer with an intercalation gap improved docking accuracy, distinguishing intercalation from groove recognition and enhancing assessment precision. Results: Our study offers detailed insights into the interaction patterns of the indole derivatives with DNA and is highly supported by molecular docking analyses: the indole derivatives were predominantly localized between C and G, interacting via π-π interactions and hydrogen bonds and aligning with known data on conventional intercalators. These findings underscore the importance of small compounds’ planar structure and appropriate size, facilitating tight insertion between adjacent base pairs and disrupting regular DNA stacking. Conclusions: Indoles’ physiological roles and potential as drug candidates targeting specific pathways are highlighted, emphasizing their significance as ubiquitous molecules with the ability to modulate biological effects on DNA structure.

Effects of ultrafine grinding on nutritional, physicochemical and protein composition of Acheta domesticus powder

Acheta domesticus is a new source of high-quality protein, but the accessibility and acceptability of protein is notably limited by the particle size of the house cricket powder, and little information about the effect of particle size on the house cricket powder had been reported. In this study, four kinds of ultrafine cricket powder were obtained by two industrial methods, and compared with the traditional grinding powder. The results illustrated that ultrafine grinding technology could increase the powder properties, such as the thermal stability, crystallinity, color brightness, protein extraction rate and amino acid content, especially the essential amino acid (EAA) content were significantly improved. And the properties and nutrient release of the powder are mainly related to the particle size rather than the method. The results have a certain guiding effect on the development and application of ultrafine house cricket powder as a multifunctional nutrient.

Generation of advanced glycation end products from glycated protein or fructose/glyoxal-protein adducts under in vitro simulated gastrointestinal digestion

Advanced glycation end products (AGEs) are a heterogeneous group of compounds formed both endogenously and exogenously through reactions between reducing sugars and amino acids within the proteins. The digestive tract may also serve as a site for endogenous AGEs generation. This study examined whether additional AGEs are formed during the digestion of glycated protein diets and meal-resembling systems (dietary proteins with fructose or glyoxal). The digestion of glycated protein showed that free AGEs were gradually released, but no additional AGEs were generated. In contrast, co-digestion of dietary proteins with fructose or glyoxal resulted in the formation of additional AGEs, and the reaction substrates (fructose or glyoxal) were depleted during digestion. Additionally, the lysine released from proteins decreased, leading to a loss of nutritional value of the food during co-digestion. The formation of AGEs and the depletion of essential amino acids in the gut may have significant implications for human health.

Upgrading the Bioactive Potential of Hazelnut Oil Cake by Aspergillus oryzae under Solid-State Fermentation.

Hazelnut oil cake (HOC) has the potential to be bioactive component source. Therefore, HOC was processed with a solid-state fermentation (SSF) by Aspergillus oryzae with two steps optimization: Plackett-Burman and Box-Behnken design. The variables were the initial moisture content (X1: 30-50%), incubation temperature (X2: 26-37 °C), and time (X3: 3-5 days), and the response was total peptide content (TPC). The fermented HOC (FHOC) was darker with higher protein, oil, and ash but lower carbohydrate content than HOC. The FHOC had 6.1% more essential amino acid and benzaldehyde comprised 48.8% of determined volatile compounds. Fermentation provided 14 times higher TPC (462.37 mg tryptone/g) and higher phenolic content as 3.5, 48, and 7 times in aqueous, methanolic, and 80% aqueous methanolic extract in FHOC, respectively. FHOC showed higher antioxidant as ABTS+ (75.61 µmol Trolox/g), DPPH (14.09 µmol Trolox/g), and OH (265 mg ascorbic acid/g) radical scavenging, and α-glucosidase inhibition, whereas HOC had more angiotensin converting enzyme inhibition. HOC showed better water absorption while FHOC had better oil absorption activity. Both cakes had similar foaming and emulsifying activity; however, FHOC produced more stable foams and emulsions. SSF at lab-scale yielded more bioactive component with better functionality in FHOC.

A Comprehensive Review of Pests, Pesticides and Residue Detection Techniques in Mushroom

Mushrooms are valued for their dietary benefits and medicinal properties, being rich in proteins, minerals, vitamins, fiber, and essential amino acids. They offer significant health benefits, including the prevention of hypercholesterolemia and cardiovascular diseases, and possess antitumor, antiviral, antihypertensive, anti-inflammatory, and immunomodulating properties. Global mushroom production has seen substantial growth, particularly in Asia. However, mushroom cultivation is challenged by various insect pests, leading to significant crop losses. Pesticides are frequently applied to control pests in mushroom cultivation, but their use can lead to the presence of pesticide residues in the mushrooms, raising concerns about food safety. To detect these low levels of residues, multiresidue analytical methods are crucial. Among these, the QuEChERS method stands out as the most commonly used due to its sensitivity, selectivity, and accuracy in determining multiple pesticide residues simultaneously. These methods are capable of identifying various pesticide compounds in a single analysis, effectively addressing the specific biological characteristics of mushrooms. The maximum residue levels (MRLs) for pesticide residues in mushrooms differ, with strict guidelines enforced by regulatory authorities. This paper provides a comprehensive review of the pests that affect mushroom cultivation, the pesticides utilized, and the analytical techniques developed for the detection of pesticide residues in mushrooms.

Unravelling the Influence of Extraction Techniques on Protein Yield and Nutritional Value in Lesser Mealworm Larvae.

In the present work, chemical and enzymatic assisted techniques were compared for protein extraction from lesser mealworm larvae (LM, Alphitobius diaperinus), recently approved as a novel food in the European Union. All extracts showed appreciable nutritional quality, with quantities of essential amino acids above the reference standard. Conventional alkali extraction allowed the isolation of only 73% of the protein, preserving the amino acid composition but potentially causing denaturation or racemisation. The "stepwise" method, following the Osborne fractionation, improved protein recovery to 91% by isolating four fractions with different solubility properties. Additionally, enzymatic hydrolysis using Bacillus licheniformis proteases was also tested, and it provided hydrolysates with an average degree of hydrolysis of 14%, making them a potential hypoallergenic solution. Overall, these findings indicate the ability to tailor the composition of LM protein to meet specific needs, offering promising prospects for the use of insect protein ingredients in various applications.

Effect of ultrasound treatment on quality parameters and health promoting activity of fish protein hydrolysates extracted from side streams of Atlantic mackerel (Scomber scombrus).

Fish protein hydrolysates (FPH) obtained by enzymatic hydrolysis allows for smart valorization of fish side streams. However, further treatments are normally needed to enhance bioactive and functional properties of the obtained FPH. At present, the commonly used methods to improve functional properties of FPH include chemical and enzymatic modification. Chemical treatments often cause environmental problems, while the enzymatic modification method requires the use of quite expensive enzymes. In recent years, emerging technologies such as ultrasound treatment (US-treatment) have shown great potential in protein modification with high efficiency and safety, low energy consumption, and low nutritional destructiveness. In this study, high-power ultrasound treatments were applied to fish protein hydrolysates (FPH) extracted from Atlantic mackerel (Scomber scombrus) side streams to improve their quality parameters. The effect of three different treatments of 300 W, 450 W and 600 W at the operating frequency of 20 kHz for 10 min on the physicochemical, structural, and functional characteristics of FPH, were examined. The results have shown that with an increase in ultrasound power, the protein solubility of FPH increased linearly, and the changes were significant for all US-treated samples compared to control (untreated) samples. US-treatment significantly increased the degree of hydrolysis of FPH samples treated with 450 W and 600 W compared to control samples. The carbonyl content of FPH increased (significantly for 450 W and 600 W), while thiol groups decreased (significantly for 300 W and 450 W). This indicated that some US-treatments induced oxidation of FPH, however the values of the protein oxidation were low. Amino acid composition of FPH revealed that US-treatment increased the proportion of essential amino acids in the sample treated with 300 W and 450 W, but the increase was not significant. After the US-treatment, all FPH samples became lighter and less yellowish and reddish, which suggest potentially higher attractiveness to consumers. In addition, the in vitro antioxidant activity was assessed using the DPPH, FRAP, and ABTS assays and the cell-free dipeptidyl peptidase IV (DPP-IV) inhibitory activity was also measured. Moreover, these biological activities were measured at cellular level utilizing human intestinal Caco-2 cells. Specifically, the FPH capacity to lower H2O2-induced reactive oxygen species (ROS) and lipid peroxidation levels was used to measure its antioxidant activity. The findings suggest that Scomber scombrus hydrolysates could find use as ingredients for promoting health.

Fabrication and characterization of whey protein isolate-tryptophan nanoparticles by pH-shifting combined with heat treatment

L-Tryptophan (Trp) is an essential amino acid with numerous health benefits. However, incorporating Trp into food products is limited due to its pronounced bitter taste. Encapsulating Trp in nanoparticles by using other natural biopolymers is a potential strategy to mask the bitter taste of Trp in the final products. Whey protein isolate (WPI), composed of alpha-lactalbumin (α-LA), bovine serum albumin (BSA), and beta-lactoglobulin (β-LG), has played a crucial role in delivering bioactive compounds. In order to incorporate Trp within WPI, the present study used a combination of pH-shifting andthermal treatment to fabricatewhey protein isolate-tryptophan nanoparticles (WPI-Trp-NPs). During the pH-shifting technique, WPI unfolds at high pH, such as pH 11, and the dissociated WPI molecules are refolded when pH is shifted back to neutral, creating particles with uniform dispersion and encapsulating smaller particles surrounding them in solution. Further, the well-distributed nanoparticles formed by pH-shifting might encourage the formation of more uniform nanoparticles during subsequent thermal treatment. TheWPI-Trp particles have an average particle size of 110.1 nm and a low average PDI of 0.20. Fluorescence spectroscopy confirmed the encapsulation of Trp by WPI, which shows higher fluorescence when the Trp is encapsulated by the WPI. Surface hydrophobicity, circular dichroism, particle size, free sulfhydryl, and antioxidant activity were used to characterize the WPI-Trp-NPs. WPI-Trp-NPs formed by pH-shifting combined with heating showed a higher surface hydrophobicity and free sulfhydryl content than the untreated WPI-Trp mixture. The conversion of α-helix into random coil in the WPI secondary structure indicated a more disordered structure of the modified whey protein. Molecular docking results indicate the interactions between Trp and WPI, including alpha-lactalbumin (α-LA), bovine serum albumin, and beta-lactoglobulin (β-LG), were mainly driven by hydrophobic interactions and hydrogen bonding. The binding affinity between Trp and these proteins was ranked as α-LA>BSA>β-LG. The combination of pH-shifting and heating improved the functionalityof WPI and was an effective way to fabricate WPI-Trp nanoparticles.

Assessment of Genetic Diversity in Garden Pea (Pisum sativum L.) and Identification of Promising Lines for Hybridization

The current study is being conducted to understand the degree of genetic divergence in order to discover more diversified parents for pea genetic advancement. The creation of high yielding varieties with stable productivity, resistance to diseases and unfavorable environmental conditions, various maturing types, a high rate of organic matter accumulation during the early stages of growth, a sufficiently high intensity of photosynthesis, increases in protein content, essential amino acids, and favorable ratios among them are the most important tasks for pea breeding. The present investigation was carried out at vegetable research farm and laboratory works in the department of Horticulture (Vegetable and Floriculture), BAU, Sabour, Bhagalpur, Bihar during the Rabi season 2020-21. The genotype Kashi Mukti, Kashi Uday, Kashi Nandini and VM-11 of cluster II exhibited superiority for earliness in first flower, days to 50% flowering and days to first picking and significantly better performance as measured by the lowest cluster mean and a substantial improvement in performance while the genotype Haze-02 of cluster IV exhibited superiority for inter-nodal length , plant height , seeds per pod and total sugars (%) based on maximum cluster mean with significantly better performance. It is anticipated that progenies from such diversified crossings will exhibit a broad range of genetic diversity and more potential for transgressive segregant isolation in the later generations. Therefore, a multiple crossing program using these genotypes may be used to retrieve transgressive segregants.

Upcycling of nutrients from kitchen waste: Integration of anaerobic digestion system and microbial protein production system

To upcycle the nutrients from kitchen waste (KW), an integrated system consisting of anaerobic digestion (AD) reactor and microbial protein (MP) production reactor was established in this study. The subsystem I (AD system) demonstrated an efficient bio-energy production (282.37 mL CH4/g VS), with 553.54 mg/L of NH4+-N remained in the digestate. The subsystem II (MP production system) utilized the nitrogenous constituents of the digestate, with 2.04 g/L MP production. In order to further enhance the recovery efficiency, C/N ratio in the subsystem II was studied. NH4+-N recovery efficiency was 23.08% higher after C/N ratio optimization along with 0.24 g/L increment on MP production. Over 0.7 g/L of essential amino acids was obtained, according with the qualitative necessary for the feeds. Also, the key enzyme abundance of CO2 releasing and amino acid biosynthesis was obviously increased with max. 55.21%. Meanwhile, the integrated system was profitable via a simplified economic assessment.

Boerhavia diffusa and Coccinia grandis: Two indigenous vegetables as a source of essential minerals, vitamins, amino acids, and fatty acids

Since the nutritional makeup of many plants is still unknown, people have historically included them in their diets without even being aware of their health advantages. Therefore, the present study aimed to uncover the proximate composition, minerals, vitamins, amino acids, and fatty acids composition of two locally consumed vegetables, namely Boerhavia diffusa and Coccinia grandis. From the analysis, these vegetables had a significant protein, fat, and carbohydrate content. Regarding mineral contents, both plants had a great amount of potassium, calcium, iron, sodium, and zinc. These vegetables had a remarkable content of vitamins such as B1, B2, B3, B5, B6, and C. The leaves of both plants had important essential amino acids such as leucine, lysine, and phenylalanine, as well as non-essential amino acids. Unsaturated fatty acids such as linolenic acid, linoleic acid, and erucic acid were more prominent in Coccinia grandis than Boerhavia diffusa. In addition, both plants had a significant amount of saturated fatty acids such as palmitic acid, stearic acid, and lauric acid. Thus, it can be concluded that these two vegetables have magnificent profiles of nutrients which could make them as important sources of minerals, vitamins, and fatty acids.

Comparative Evaluation of the Proximate Composition and Amino Acid Profile in Fresh and Traditionally Sun-dried Fish Species, Puntius sophore (Hamilton, 1822) and Amblypharyngodon mola (Hamilton, 1822)

Fish is one of the most widely consumed sources of animal protein in the world. However, they are subjected to countless post-harvest changes, so technologies such as sun-drying are employed to preserve fish for a longer time. Currently, sun-dried fish also have a major place in terms of nutrients alongside fresh fish. The present study has been conducted to determine the proximate composition and amino acid content of fish species namely, Puntius sophore (Puthi), and Amblypharyngodon mola (Moa) in fresh and sun-dried conditions to enunciate the nutritional benefits of consuming sun-dried fishes together with fresh fishes. During the study period, fresh fish samples collected were divided into two batches. In one batch all the analyses were carried out under fresh conditions. In the corresponding batch, all the tests were carried out in sun-dried conditions. Proximate composition and amino acid analysis were carried out as per the guidelines of AOAC (2015). The moisture, crude protein, crude fat, ash, and carbohydrate content of the fresh and sun-dried P. sophore and A. mola revealed significantly higher moisture content in the fresh fish samples than in the sun-dried samples. Significantly higher crude protein, crude fat, ash, and carbohydrate contents were obtained in the sun-dried samples compared to the samples in fresh condition. The Essential Amino Acid (EAA) predominant in fresh and sun-dried samples of both the species were found to be Lysine and Histidine respectively. The predominant Non-essential Amino Acid (NEAA) in fresh and sun-dried samples of both species was Glutamic acid. The analysis of nutritional parameters reveals that sun-dried fish can provide comparable nutrition to fresh fish. This study is therefore designed to promote the consumption of sun-dried fish among a broader segment of society, highlighting its dietary significance.

Structural, techno‐functional and nutraceutical properties of lentil proteins – a concise review

SummaryLentil is one of the major pulses consumed in many parts of the world. Lentil proteins comprise primarily three fractions, viz. globulins, albumins and glutelins, each having distinct structural and functional characteristics. The secondary structure of lentil proteins is characterised by a predominance of β‐sheets, which occur in proportions up to 63% in the fractions. Protein isolates, in comparison, have up to 40% random coils, 38% sheets, 36% turns and 33% helix. Lentil proteins contain most essential amino acids, while albumins and glutelins have relatively higher content of lysine, methionine, histidine, threonine and branched‐chain amino acids. Amongst globulin proteins, vicilins have a more balanced amino acid composition than legumins. Lentil proteins also exhibit techno‐functional properties (foaming and emulsification, water and fat absorption and gelation) and may also serve as a potential source of active proteins/peptides, which make them an attractive alternative to conventional protein sources.

MAT1-1 and MAT1-2 Ophiocordyceps xuefengensis and Comparison of Their Chemical Composition.

Many Cordyceps sensu lato species are used as traditional Chinese medicines. However, Cordyceps are entomopathogenic fungi in the family Clavicipitaceae of Ascomycota, and excessive harvesting severely disrupts natural habitat ecosystems. Artificial cultivation of Cordyceps fruiting bodies offers a viable strategy to protect the ecological environment and mitigate the depletion of wild resource. In this study, mononucleate hyphae were selected using DAPI fluorescence staining, the MAT1-1 and MAT1-2 strains of O. xuefengensis were successfully distinguished using loop-mediated isothermal amplification (LAMP). The chemical composition and bioactive components of fruiting bodies produced by these strains were compared. Results showed that the levels of adenosine, thymidine, adenine, guanosine, uridine, total amino acids, and total essential amino acids in the fruiting bodies of MAT1-1 strains were 1.31 mg/g, 0.15 mg/g, 0.26 mg/g, 2.40 mg/g, 2.34 mg/g, 270.3 mg/g, and 102.5 mg/g, respectively, which were significantly higher than those in the MAT1-2 sample. Contrastingly, the fruiting bodies of MAT1-2 strains contained higher levels of mannose and polysaccharides, at 11.7% and 12.2%, respectively. The levels of toxic elements such as Al, Pb, As, and Hg in the MAT1-1 fruiting bodies were 1.862 mg/kg, 0.0848 mg/kg, 0.534 mg/kg, and 0.0054 mg/kg, respectively, which were markedly lower than those in the MAT1-2 fruiting bodies.

Methionine deficiency inhibited pyroptosis in primary hepatocytes of grass carp (Ctenopharyngodon idella): possibly via activating the ROS-AMPK-autophagy axis

BackgroundMethionine (Met) is the only sulfur-containing amino acid among animal essential amino acids, and methionine deficiency (MD) causes tissue damage and cell death in animals. The common modes of cell death include apoptosis, autophagy, pyroptosis, necroptosis. However, the studies about the major modes of cell death caused by MD have not been reported, which worth further study.MethodsPrimary hepatocytes from grass carp were isolated and treated with different doses of Met (0, 0.5, 1, 1.5, 2, 2.5 mmol/L) to examine the expression of apoptosis, pyroptosis, autophagy and necroptosis-related proteins. Based on this, we subsequently modeled pyroptosis using lipopolysaccharides and nigericin sodium salt, then autophagy inhibitors chloroquine (CQ), AMP-activated protein kinase (AMPK) inhibitors compound C (CC) and reactive oxygen species (ROS) scavengers N-acetyl-L-cysteine (NAC) were further used to examine the expression of proteins related to pyroptosis, autophagy and AMPK pathway in MD-treated cells respectively.ResultsMD up-regulated B-cell lymphoma protein 2 (Bax), microtubule-associated protein 1 light chain 3 II (LC3 II), and down-regulated the protein expression levels of B-cell lymphoma-2 (Bcl-2), sequestosome 1 (p62), cleaved-caspase-1, cleaved-interleukin (IL)-1β, and receptor-interacting protein kinase (RIP) 1 in hepatocytes, while it did not significantly affect RIP3. In addition, MD significantly increased the protein expression of liver kinase B1 (LKB1), p-AMPK, and Unc-51-like kinase 1 (ULK1) without significant effect on p-target of rapamycin. Subsequently, the use of CQ increased the protein expression of NOD-like receptor thermal protein domain associated protein 3 (NLRP3), cleaved-caspase-1, and cleaved-IL-1β inhibited by MD; the use of CC significantly decreased the protein expression of MD-induced LC3 II and increased the protein expression of MD-suppressed p62; then the use of NAC decreased the MD-induced p-AMPK protein expression.ConclusionMD promoted autophagy and apoptosis, but inhibited pyroptosis and necroptosis. MD inhibited pyroptosis may be related regarding the promotion of autophagy. MD activated AMPK by inducing ROS production which in turn promoted autophagy. These results could provide partial theoretical basis for the possible mechanisms of Met in ensuring the normal structure and function of animal organs. Furthermore, ferroptosis is closely related to redox states, it is worth investigating whether MD affects ferroptosis in hepatocytes.

Effects of salt and rice flour concentration on microbial diversity and the quality of sour meat, a Chinese traditional meat

This study investigated the effects of salt (3 % and 6 %, m/m) and rice flour (10 % and 20 %, m/m) addition in sour meat, a traditional Chinese fermented meat. It was found that salt has greater effect than rice flour addition in spontaneous fermentation. Low-salt groups had lower pH and higher titratable total acid. In the low-salt groups, the dominant genera were Lactobacillus and Lactococcus, whereas Staphylococcus, Weissella, and Tetragenococcus were dominant in the high-salt groups. Higher total free amino acids and essential amino acids, organic acids, hexanoic acid ethyl ester and octanoic acid ethyl ester were found in the low-salt groups. The RDA analysis revealed that Lactococcus was closely related to product quality, with the S3F10 (3 % salt and 10 % rice flour) group outperforming the others in the sensory evaluation. Therefore, 3 % salt and 10 % rice flour were considered more appropriate for the production of healthy and tasty fermented sour meats.

Role of Peripheral Parenteral Nutrition Composition on Clinical Outcomes in Patients Undergoing Gastrectomy or Colectomy: A Phase III Indian Clinical Trial.

Various types of parenteral nutritional products exist, each with specific formulations designed to meet the diverse nutritional needs of patient's post-abdominal surgery. Here, two different parenteral nutrition (PN) solutions BFLUID and NUTRIFLEX PERI are compared in terms of therapeutic efficacy and safety profile. A prospective, multi-center, randomized, parallel-group, non-inferiority Phase III clinical trial compared two PN solutions namely BFLUID (N = 78) and NUTRIFLEX PERI (N = 72) in 150 patients undergoing gastrectomy or colectomy. Primary endpoints included length of hospital stay while secondary endpoints included assessment and comparison of length of ICU/HDU stay, assessment of incidents of infections and mortality, change in blood levels of vitamin B1, change in nutritional parameters, thrombophlebitis, pain at the injection site, and recording of adverse events (AEs). There was no significant difference in terms of length of hospital stay, length of ICU/HDU stay as well as changes in nutritional parameters from baseline and change in blood levels of vitamin B1 from baseline. Both study groups exhibited comparability in terms of AEs, pain at the injection site, and the incidence of phlebitis. There was no significant difference in the number and severity of adverse events reported in both groups. Additionally, no signs of infection were observed in patients from either group. The trial successfully demonstrated the non-inferiority of BFLUID to NUTRIFLEX PERI. Moreover, the results indicated that PN enriched with high levels of branched-chain amino acids (BCAAs), essential amino acids (EAAs), and thiamine is both safe and efficacious for adult patients undergoing gastrectomy or colectomy. Goyal A, Pathak A, BS Madhu, Soni H, Bhatt K, Raju KVVN, et al. Role of Peripheral Parenteral Nutrition Composition on Clinical Outcomes in Patients Undergoing Gastrectomy or Colectomy: A Phase III Indian Clinical Trial. Indian J Crit Care Med 2024;28(9):871-878.

A turn-off xanthene-based fluorescent probe for detection of cysteine and its practical application in bioimaging and food samples

BackgroundCys, as an essential amino acid that can be ingested from daily food, plays an important role in maintaining the oxidative balance in cells. Abnormal Cys levels in organisms will lead to various diseases. Therefore, it is of great significance to construct a fluorescent probe that can detect Cys levels in food and biological systems. ResultsHere, a turn-off type probe TA had been successfully synthesized, which attached diethylamine as the strong electron donor, acrylate as the weak electron donor, and xanthene as the π-bridge. TA showed wonderful selectivity, low detection limit, good photostability and well live-cell compatibility for Cys by reducing acrylate group to hydroxyl group of TAOH. The reaction mechanism was demonstrated by 1H NMR, ESI-MS spectra, pH-dependent response experiments, and DFT calculations. Importantly, the reason why TAOH exhibited no fluorescence was the disappearance of the ICT effect in the molecule due to the dominant existence of spirocyclic state of TAOH. In addition, the probe can be used not only for the imaging detection of Cys in A549 cells and zebrafish, but also for the detection of Cys levels in food samples. SignificanceThis work provides a new idea for the design of Cys fluorescent probe, which may be beneficial to the comprehension of the potential mechanism of novel fluorescent probe.

Tryptophan production by catalysis of a putative tryptophan synthase protein.

Essential amino acid, tryptophan which intake from food plays a critical role in numerous metabolic functions, exhibiting extensive biological functions and applications. Tryptophan is beneficial for the food sector by enhancing nutritional content and promoting the development of functional foods. A putative gene encoding tryptophan synthase was the first identified in Sphingobacterium soilsilvae Em02, a cellulosic bacterium making it inherently more environmentally friendly. The gene was cloned and expressed in exogenous host Escherichia coli, to elucidate its function. The recombinant tryptophan synthase with a molecular weight 42 KDa was expressed in soluble component. The enzymatic activity to tryptophan synthase in vivo was assessed using indole and L-serine and purified tryptophan synthase. The optimum enzymatic activity for tryptophan synthase was recorded at 50 ºC and pH 7.0, which was improved in the presence of metal ions Mg2+, Sr2+ and Mn2+, whereas Cu2+, Zn2+ and Co2+ proved to be inhibitory. Using site-directed mutagenesis, the consensus pattern HK-S-[GGGSN]-E-S in the tryptophan synthase was demonstrated with K100Q, S202A, G246A, E361A and S385A as the active sites. Tryptophan synthase has been demonstrated to possess the defining characteristics of the β-subunits. The tryptophan synthase may eventually be useful for tryptophan production on a larger scale. Its diverse applications highlight the potential for improving both the quality and health benefits of food products, making it an essential component in advancing food science and technology.

Center-concave nanosheets of core-shell WO3@Prussian blue based handheld microchip-devices for ultrasensitive lysine determination

Lysine is one of the essential amino acids for human body, and its imbalance is a major cause to anemia, aging process, leukemia cell proliferation and tumor growth. Therefore, its monitoring is dominative to the prevention the disease progress and guidance to the clinical treatment. However, traditional in-hospital detection methods, such as colorimetry and fluorometric, often suffer the disadvantages of high cost and long time-consuming. These drawbacks show a difficulty in the home-in and dairy monitoring for the lysine regulation in body. In this study, we have proposed an ultrasensitive microchip-based portable device to achieve the onsite and precise determination of lysine within only 10 s. This microchip was functionalized through constructing a center-concave nanosheet of core-shell WO3@Prussian blue (WO3@PB) to remarkably strengthen the generation and transfer of the detection signal. In this special architecture, the core WO3 nanosheet can be exposed at the center region of this nanocomposite to effectively promote the enzymatic oxidation, while the PB shell enables to strongly reduce the H2O2 produced by the enzymatic reaction. Under above synergetic effects, a handheld device was designed to support the plug-and-play microchip, which performed an outstanding accuracy for the lysine detection in blood.