Addition Of Cysteine Research Articles

Formation of advanced glycation end products in glucose-amino acid models of Maillard reaction under dry- and wet-heating conditions.

Advanced glycation end products (AGEs) are compounds formed by non-enzymatic processes in the Maillard reaction and can cause various chronic diseases. This study explores the AGE formation process in a glucose-amino acid system under both wet- and dry-heating conditions, and analyzes the effect of cysteine in AGE formation. Under wet-heating conditions, Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) concentrations rose for the initial 90 min and subsequently declined after 120 min; after 90 min of heating, the maximum yields in the absence of cysteine were 1151.04 ± 14.01 and 3386.90 ± 26.55 ng mL-1, respectively. The concentration of pyrraline (Pyr) increased after 30 min and then decreased after 60 min with a maximum yield of 777.68 ± 23.36 ng mL-1. However, in dry-heating models, the AGE concentrations consistently increased with increasing heating time; the maximum yields for CML, CEL and Pyr were 468.66 ± 10.96, 1993.57 ± 14.81 and 1085.74 ± 58.06 ng mL-1, respectively. The addition of cysteine showed an inhibitory effect on AGE formation, especially for Pyr in the dry-heating model, with inhibition rates ranging from 17.14% to 95.60%. Although wet-heating models produced more CML and CEL, they produced less Pyr than dry-heating models. The AGE formation in wet-heating models positively correlated with the reaction rate; however, the dry-heating reaction demonstrated a more complex relationship between reaction rate and reaction protocol. Moreover, cysteine exhibited a significant inhibitory effect on AGE production, and the degree of inhibition was proportional to the cysteine concentration. This study provides important insights into the mechanisms for AGE formation under various heating conditions, such as those representing baking (dry-heating) and steaming conditions (wet-heating). © 2024 Society of Chemical Industry.

Proteolytic degradation of seed proteins of vetch species (Vicia L. subgenus Vicia) of section Peregrinae Kupicha during SDS-electrophoresis and its prevention

Background. Due to its simplicity and good reproducibility, SDS-electrophoresis of seed proteins is widely used for investigating the gene pool of legumes and other plants, for species and varietal identification, analyzing the intraspecific variability, and registering collection material. The data obtained by this method agree well with the DNA analysis results complement them. Typically, legume seed proteins, including representatives of the genus Vicia L., show clear informative SDS electrophoretic profiles. When analyzing seed accessions of vetch species of the section Peregrinae Kupicha using standard approaches previously developed at VIR and approved by ISTA (the International Seed Testing Association), clear electrophoretic protein profiles could not be obtained for many accessions. This called into question the applicability of standard approaches to identifying vetch species in the section Peregrinae. The objective of the work was to clarify the nature of seed proteins degradation in representatives of the Peregrinae section and to find ways to prevent it to ensure the possibility of carrying out species identification and registration of all accessions in the vetch collection using a unified approach. Material and methods. Seed proteins of a number of vetch species Vicia L. from sections Bithynicae (B. Fedtsch.) Maxted, Hypechusa (Alef.) Aschers. et Graebner, Microcarinae Maxted and Peregrinae, members of the subgenus Vicia, were analyzed by SDS-electrophoresis using the standard method of protein extraction from flour with 0.025 M Tris-glycine buffer pH 8.3 at room temperature and its modifications, including heating the extract at 80°C or 100°C with or without the addition of 2-mercaptoethanol, as well as the addition of cysteine and serine protease inhibitors. Results and discussion. An analysis of seed proteins of representatives of most sections of the subgenus Vicia yielded informative species-specific protein profiles, whereas species of the section Peregrinae were characterized by the protein profiles, which indicated protein degradation, and species of this section differed in the frequency of such profile occurrence. While such profiles were obtained for all seeds of seven accessions of V. aintabensis Boiss & Hausskn. ex Boiss differing in geographical origin, year and place of regeneration, and 12 out of 13 of V. peregrine L. accessions demonstrated profiles of partially or completely degraded proteins, complete seed protein profiles were obtained for six out of nine V. michauxii Sprengel accessions. A change in conditions for protein isolation, namely replacement of their extraction from flour with Tris-glycine buffer pH 8.3 at room temperature with extraction in the same buffer by a short-term heating at 100°C in the presence of 2-mercaptoethanol, made it possible to obtain complete protein profiles for all accessions representing the section Peregrinae. The protein profiles of representatives of other vetch sections, as well as the profile of soybean proteins used as a standard for legume species identification, did not differ from the original ones under the modified conditions. Conclusions. The obtained results suggest that protein degradation in species of the Peregrinae section is associated with the abnormal activity of endogenous seed proteases under standard protein extraction conditions, and this trait is determined genotypically. A new modification of the method for isolating proteins from seeds makes it possible to apply the generally accepted approaches based on SDS-electrophoresis in the analysis of the gene pool of the Peregrinae section of the subgenus Vicia, as well as other vetch species.

Redox reaction of a RuIII(pic)3 complex with cysteine: Spectral, kinetic and biological studies

The kinetics of the reduction of [RuIII(pic)3] (pic− = picolinate) with cysteine leading to the formation of the corresponding red coloured [RuII(pic)3]− complex (λmax = 466 nm, εmax = 12000 M−1 cm−1) was studied by using stopped-flow and rapid scan spectrophotometry. The time course of the reaction was followed at 466 nm as a function of cysteine concentration, pH and temperature. Kinetic data (k = 291 ± 4 M−1 s−1 at 25 °C and pH 8.4) and activation parameters (ΔH≠ = 36 ± 1 kJ mol−1 and ΔS≠ = −78 ± 3 J mol−1 deg−1) are interpreted in terms of a mechanism involving rate-determining outer-sphere electron transfer between Ru(III) and the cysteine. Inhibition of bacterial growth (Klebsiella pneumonia and Staphylococcus aureus) by the [RuIII(pic)3] complex both in absence and presence of cysteine has been examined, and the results show a positive effect of cysteine addition on the anti-bacterial activity of the complex for S.aureus.

Dual emission BSA-capped bimetallic nanoclusters for detection of acrylamide in certain food matrices based on thiol-ene Michael addition click reaction

Dual-emissive gold and silver nanoclusters stabilized by bovine serum albumin (BSA@Au-Ag NCs) were engineered for the precise and sensitive estimation of acrylamide (ACM). The probe demonstrated emissions at 630 nm and 405 nm upon excitation at 320 nm. Decreasing the fluorescence of the probe at 630 nm was observed upon cysteine (Cys) addition while the emission band at 405 nm experienced a slight increase. The introduction of ACM into the probe led to the recovery of fluorescence at 630 nm, while the fluorescence at 405 nm remained largely unaffected. This selective response provides a ratiometric method for determining ACM. A linear relationship between the response ratio (F630/F405) and ACM concentration was established in the range of 0.12–450 µM, with LOD of 0.03 µM. The fluorescent probe boasts several advantages, including a low LOD, robustness against interference, and reliability. Furthermore, the synthesized probe was deployed for detecting ACM in certain food matrices. The recovery percentages ranged from 96.5 to 102.6 %, with RSD between 2.98 and 4.87 %, thus affirming the potential practical applications of the fluorescent probe.

Investigating the Effects of Pink-Generating Ligands on Enhancing Color Stability and Pigment Properties in Pork Sausage Model Systems Cured with Sodium Nitrite or White Kimchi Powder.

In this study, we investigated the effects of different nitrite sources (sodium nitrite or white kimchi powder) and pink-generating ligands (cysteine, histidine, or nicotinamide) on the development and stability of cured meat color in pork sausage model systems over 30 d of refrigerated storage. The samples were prepared in a 2 × 3 factorial design with two nitrite sources and three ligands, and their physicochemical properties were evaluated on days 0, 15, and 30. Although white kimchi powder induced cured color development similar to that of synthetic sodium nitrite, it resulted in higher cooking loss and lower residual nitrite content in cured pork sausages (p < 0.05). The addition of cysteine resulted in significantly higher CIE a* values, cured meat pigment, and curing efficiency than histidine and nicotinamide (p < 0.05), while yielding lower pH values, residual nitrite content, and total pigment content (p < 0.05). The storage duration significantly reduced the residual nitrite and total pigment contents of the products. These findings suggest that white kimchi powder can serve as a natural alternative to sodium nitrite in pork sausage models and that the incorporation of cysteine has a favorable impact on the development and enhancement of cured meat color.

Chromophoric Keratin‐Cysteine Particle Synthesis Using Factorial Design of Experiment

The quest for novel chromophoric materials with tunable properties to match the natural spectrum of skin tones lacks comprehensive solutions, particularly in harnessing natural proteins for pigment synthesis. This research delved into the synthesis of sub‐micron Keratin‐Cysteine particles inspired by natural pigment production pathways. Adjustment of the initial conditions of the water‐based reaction between keratin, tyrosinase and cysteine, yielded Keratin‐Cysteine particles with colors tunable within the light to intermediate skin tone range. A systematic investigation of the reaction conditions through factorial design of experiment (DOE) identified the sequence of addition of tyrosinase and cysteine as the key determinant of color tone. Ultraviolet‐visible (UV‐Vis) spectroscopy, attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy and color analysis were performed to elucidate the reaction mechanism. This research presents a promising approach to chromophore synthesis for cosmetic and biomedical applications.

Use of the Saccharomycopsis schoenii MET17 promoter for regulated heterologous gene expression

The ability to regulate the expression of genes is a central tool for the characterization of fungal genes. This is of particular interest to study genes required for specific processes or the effect of genes expressed only under specific conditions. Saccharomycopsis species show a unique property of necrotrophic mycoparasitism that is activated upon starvation. Here we describe the use of the MET17 promoter of S. schoenii as a tool to regulate gene expression based on the availability of methionine. Conditional expression was tested using lacZ and GFP reporter genes. Gene expression could be strongly down-regulated by the addition of methionine or cysteine to the growth medium and upregulated by starvation for methionine. We used X-gal (5-bromo-4-chloro-3-indolyl-β-d-galactopyranoside) to detect lacZ-expression in plate assays and ONPG (ortho-nitrophenyl-β-galactopyranoside) as a substrate for β-galactosidase in liquid-phase assays. For in vivo expression analyses we used fluorescence microscopy for the detection and localization of a MET17-driven histone H4-GFP reporter gene. With these assays we demonstrated the usefulness of the MET17 promoter to regulate expression of genes based on methionine availability. In silico analyses revealed similar promoter motifs as found in MET3 genes of Saccharomyces cerevisiae and Ashbya gossypii. This suggests a regulation of the MET17 promoter by CBF1 and MET31/MET32 in conjunction with the transcriptional activator MET4, which were also identified in the S. schoenii genome.

A naphthyl appended ninhydrin based colorimetric chemosensor for Cu2+ ion: Detection of cysteine and ATP

A ninhydrin-based colorimetric chemosensor (LH) was synthesized using 3-hydroxy-2-naphthoic hydrazide and 11H-indeno[1,2-b]quinoxalin-11-one. It was characterized by spectroscopic and single crystal X-ray diffraction techniques. In a semi-aqueous (MeOH/HEPES) system, LH displayed a characteristic chromogenic change from colorless to yellow upon adding Cu2+ ion, with the appearance of a new peak at λmax = 460 nm. A 1:1 binding stoichiometry between LH and Cu2+ ion has been found, with LOD = 2.3 μM (145 ppb) and LOQ = 8 μM (504 ppb). Based on experimental results the formula of [Cu(L)Cl(H2O)2] (1) was assigned and this in-situ generated 1 was found to exhibit a discoloration of upon gradual addition of cysteine (LOD = 60 nM) as well as ATP (LOD = 130 nM) having 1:2 and 1:1 stoichiometry respectively. The LH was useful for recognition of Cu2+ ion in real water samples and on filter paper strips. A two-input-two-output logic gate circuitry was also constructed by employing 1 and cysteine. The DFT/TDDFT calculations performed on LH and 1 were consistent with experimental findings. The binding affinity of LH towards HSA and BSA were determined with HSA having greater affinity than BSA, which was also supported by theoretical calculations.

Structurability of microalgae, soy and pea protein for extruded high-moisture meat analogues

Despite ecological and nutritional benefits, food ingredients derived from microalgae remain a niche market. A contributing factor to this is the lack of knowledge to exploit their techno-functional properties. This research investigated the structurability of Auxenochlorella protothecoides microalgal biomass during high moisture extrusion cooking for meat analogues. The fibrous extrudate structure weakened with increasing A. protothecoides content in the recipe. To scrutinise reasons for this phenomenon, a thorough compositional comparison of microalgal biomass and conventional raw materials from soy and pea was performed. The identified macrocompositional differences were shown to exert only a minor impact on fibrous structure formation. Thus, structurability appears to be predominately influenced by protein composition, protein properties and electrolyte environment. The proteins of the analysed microalgal biomass were 20 % smaller in molecular weight, had 18–68 % higher solubility and contained 15–50 % less hydrophobic sidechains, all of which may impede protein interaction potential and thereby network formation. Additionally, the pH of microalgae suspensions was lower, which has a negative impact on disulfide bridge formation. Moreover, the analysed microalgal biomass contained considerable amounts of kosmotropic ions that stabilise individual proteins. Denaturation, pH shift, addition of cysteine, transglutaminase and polyvalent cations were proposed as measures to improve structurability of the microalgae A. protothecoides.

The potential meat flavoring derived from Maillard reaction products of rice protein isolate hydrolysate-xylose via the regulation of temperature and cysteine

Maillard reaction products (MRPs) derived from rice protein isolate hydrolysate and D-xylose, with or without L-cysteine, were developed as a potential meat flavoring. The combined impact of temperature (80–140 °C) and cysteine on fundamental physicochemical characteristics, antioxidant activity, and flavor of MRPs were investigated through assessments of pH, color, UV–visible spectra, fluorescence spectra, free amino acids, volatile compounds, E-nose, E-tongue, and sensory evaluation. Results suggested that increasing temperature would reduce pH, deepen color, promote volatile compounds formation, and reduce the overall umami and bitterness. Cysteine addition contributed to the color inhibition, enhancement of DPPH radical-scavenging activity and reducing power, improvement in mouthfulness and continuity, reduction of bitterness, and the formation of sulfur compounds responsible for meaty flavor. Overall, MRPs prepared at 120 °C with cysteine addition could be utilized as a potential meat flavoring with the highest antioxidant activity and relatively high mouthfulness, continuity, umami, meaty aroma, and relatively low bitterness.

Smartphone-assisted mobile fluorescence sensor for self-calibrated detection of anthrax biomarker, Cu2+, and cysteine in food analysis

Dipicolinic acid (DPA), as a biomarker for Bacillus anthracis, is highly toxic at trace levels. Rapid and on-site quantitative detection of DPA is essential for maintaining food safety and public health. This work develops a dual-channel self-calibrated fluorescence sensor constructed by the YVO4:Eu and Tb-β-diketone complex for rapid visual detection of DPA. This sensor exhibits high selectivity, fast response time, excellent detection sensitivity, and the detection limit is as low as 4.5 nM in the linear range of 0–16 μM. A smartphone APP and portable ultraviolet lamp can assemble a mobile fluorescence sensor for on-site analysis. Interestingly, adding Cu2+ ions can quench the fluorescence intensity of Tb3+. In contrast, the addition of cysteine can restore the fluorescence, allowing the accurate detection of Cu2+ ions and cysteine in environmental water and food samples. This work provides a portable sensor that facilitates real-time analysis of multiple targets in food and the environment.

Mechanism and Effect of Amino Acids on Lactic Acid Production in Acidic Fermentation of Food Waste

Amino acids, particularly the ones that cannot be synthesised during fermentation, are reportedly to be key nutrients for anaerobic fermentation processes, and some of the acids are also intermediate products of anaerobic fermentation of protein-rich waste. To date, particularly, there is a lack of research on the effects of some amino acids, such as cysteine, glycine, aspartic acid, and valine, on lactic production from the fermentation of food waste and also the mechanisms involved in the process. Thus, this study investigated the effects of the four different amino acids on lactic acid production during the acidic anaerobic fermentation of food waste. Firstly, batch experiments on synthetic food waste at different pHs (4.0, 5.0, and 6.0) were executed. The results harvested in this study showed that higher LA concentrations and yields could be obtained at pH 5.0 and pH 6.0, compared with those at pH 4.0. The yield of lactic acid was slightly lower at pH 5.0 than at pH 6.0. Furthermore, caustic consumption at pH 5.0 was much lower. Therefore, we conducted batch experiments with additions of different amino acids (cysteine, glycine, aspartic acid, and valine) under pH 5.0. The additions of the four different amino acids showed different or even opposite influences on LA production. Glycine and aspartic acids presented no noticeable effects on lactic acid production, but cysteine evidently enhanced the lactic acid yield of food waste by 13%. Cysteine addition increased α-glucosidase activity and hydrolysis rate and simultaneously enhanced the abundance of Lactobacillus at the acidification stage as well as lactate dehydrogenase, which also all favoured lactic acid production. However, the addition of valine evidently reduced lactic acid yield by 18%, and the results implied that valine seemingly inhibited the conversion of carbohydrate. In addition, the low abundance of Lactobacillus was observed in the tests with valine, which appeared to be detrimental to lactic acid production. Overall, this study provides a novel insight into the regulation of lactic acid production from anaerobic fermentation of food waste by adding amino acids under acidic fermentation conditions.

Cysteine and thiosulfate promoted cadmium immobilization in strain G303 by the formation of extracellular CdS

Bacteria have evolved a variety of strategies to defend themselves against cadmium toxicity, however, the specific mechanisms involved in the enhancement of bacterial cadmium resistance by sulfur sources are unclear. In this study, a novel cadmium (Cd)-tolerant bacterium, Stenotrophomonas geniculata G303, was isolated from activated sludge. The growth of strain G303 under diverse Cd concentrations was investigated, and the minimum inhibitory concentration of Cd was found to be 1 mM. Strain G303 effectively remove 94.7 % of Cd after 96 h of culture. Extracellular CdS was detected using multiple methods, with the CdS formed being aggregated in the biofilm. The addition of cysteine and thiosulfate to the medium significantly enhanced the Cd resistance and removal capacity of strain G303. Integrated genomic and proteomic analyses revealed that heavy metal transporters cooperate to resist Cd stress. Cysteine and thiosulfate improved Cd tolerance in strain G303 by upregulating nitrogen and energy metabolism. Proteins associated with nitrate reduction likely played a pivotal role in cysteine and thiosulfate metabolism. Notably, cysteine synthase and the SUF system played crucial roles in CdS formation. This study systematically explored the impact of cysteine and thiosulfate on the Cd resistance of strain G303, deepening our understanding of the microbial response mechanism to heavy metals.

Self-assembled nanovesicles based on chiral bis-H8-BINOL for Fe3+ recognition and secondary recognition of l-cysteine by 1 + 1 complex.

A novel fluorescent "off" sensor, R-β-d-1, was obtained in high yield (91.2%) by using octahydronaphthol as a backbone, introducing an alkyne group at the 2-position, and linking azido-glucose via a click reaction. The sensor was analyzed by scanning electron microscopy and transmission electron microscopy and was found to be a self-assembled vesicle. AFM results showed that the fluorescence burst was extinguished by the addition of Fe3+, and the fluorescence was restored by the addition of cysteine. This is due to charge transfer within the molecular structure, resulting in the ICT effect and phototransfer of electrons (PET), as well as redshifting (from 331 nm to 351 nm) and quenching of the fluorescence. The self-assembled vesicles of the fluorescent sensor R-β-d-1 encapsulated Fe3+, but upon addition of cysteine, the vesicles of R-β-d-1-Fe3+ were also complexed with it, forming the R-β-d-1-Fe3+-l-Cys complex, at which point fluorescence gradually returned. Therefore, the fluorescence test of this probe showed that the lowest detection limit of iron ions was 1.67 × 10-7 mol L-1, and its complexation mode was in the form of 1 + 1. The novel probe formed by R-β-d-1-Fe3+ can be used for the fluorescence detection of cysteine.

ANTIOXIDANTS ENHANCE CHROMIUM (VI) MEDIATED TOXICITY IN NEUROSPORA CRASSA

Chromium can be found in the environment in two main valence states: hexavalent Cr (VI) and trivalent Cr (III). Reduction activation of carcinogenic Cr (VI) is required for the induction of DNA damage and mutations. There is a controversy over antioxidants’ role in Cr (VI) toxicity and cell death in mammalian systems. In the present study we compared the effect of antioxidants and insulin on Cr (VI) induced genotoxicity in wall-less mutant of Neurospora crassa (slime), which contains insulin receptor on its cell surface as a model system. Analysis by comet assay indicated Potassium dichromate (K2 Cr2 O7 ) induced DNA damage in slime cells, as increase in comet tail moment and the effect was dose dependent. Simultaneous addition of N-acetyl cysteine (NAC) &amp; Sodium ascorbate (ASC) increased the extent of DNA damage whereas insulin decreased the extent of DNA damage induced by Cr (VI). The simultaneous exposure of antioxidants and insulin in presence of Cr (VI) showed enhanced cytotoxicity as observed by MTT assay. The results obtained suggest that N-acetyl cysteine and Sodium ascorbate reduce Cr (VI) to Cr (III) enhancing the levels of reactive oxygen species. Absence of protective role of insulin in presence of antioxidants indicate that a differential route may be adopted by the cells in response to metallic stress.

Repurposing of FDA approved kinase inhibitor bosutinib for mitigation of radiation induced damage via inhibition of JNK pathway

Radiotherapy is a common modality for cancer treatment. However, it is often associated with normal tissue toxicity in 20–80% of the patients. Radioprotectors can improve the outcome of radiotherapy by selectively protecting normal cells against radiation toxicity. In the present study, compound libraries containing 54 kinase inhibitors and 80 FDA-approved drugs were screened for radioprotection of lymphocytes using high throughput cell analysis. A second-generation FDA-approved kinase inhibitor, bosutinib, was identified as a potential radioprotector for normal cells. The radioprotective efficacy of bosutinib was evinced from a reduction in radiation induced DNA damage, caspase-3 activation, DNA fragmentation and apoptosis. Oral administration of bosutinib protected mice against whole body irradiation (WBI) induced morbidity and mortality. Bosutinib also reduced radiation induced bone-marrow aplasia and hematopoietic damage in mice exposed to 4 Gy and 6 Gy dose of WBI. Mechanistic studies revealed that the radioprotective action of bosutinib involved interaction with cellular thiols and modulation of JNK pathway. The addition of glutathione and N-acetyl cysteine significantly reduced the radioprotective efficacy of bosutinib. Moreover, bosutinib did not protect cancer cells against radiation induced toxicity. On the contrary, bosutinib per se exhibited anticancer activity against human cancer cell lines. The results highlight possible use of bosutinib as a repurposable radioprotective agent for mitigation of radiation toxicity in cancer patients undergoing radiotherapy.

Flavor improving effects of cysteine in xylose–glycine–fish waste protein hydrolysates (FPHs) Maillard reaction system

A promising way to utilize fish by-products is to develop hydrolysis of fish proteins with enzymes. The obtained fish protein hydrolysates (FPHs) are rich in peptides and amino acids, but bitterness and aroma defects impede further utilization of FPHs. The present study adopted Maillard reaction to improve FPHs’ flavor and illustrated the role of cysteine in this system. We investigated the impact of cysteine (0, 0.25%, 0.5%, 0.75%, and 1%) on the browning intensity, free amino acids (FAAs), molecular weight distribution, structure of MRPs, volatile compounds changes and organoleptic characteristics of xylose–glycine–FPHs Maillard reaction systems. Results showed that the addition of cysteine lowered the browning degree of Maillard reaction products (MRPs) by inhibiting the cross-linking of small peptides and reducing the production of melanin. GC–MS and GC–IMS analysis indicated that cysteine inhibited the formation of furans and nitrogen-containing compounds and facilitated the formation of sulfur-containing compounds contributing to the meaty flavor. Sensory analysis revealed that 0.25–0.75% range of cysteine increased the meaty, caramel, umami, mouthfulness and salty notes, and caused a decrease in bitter taste of the MRPs as confirmed by GC–MS. A highly significant correlation between the organoleptic characteristics and physicochemical indicators of MRPs was found by Mantel test. These results elucidated the influence of cysteine on the formation of Maillard reaction products and will help improve the flavor profile of meat flavorings.Graphical

A H2 S-Generated Supramolecular Photosensitizer for Enhanced Photodynamic Antibacterial Infection and Relieving Inflammation.

Photodynamic therapy (PDT) is a promising treatment against bacteria-caused infections. By producing large amounts of reactive oxygen species (ROS), PDT can effectively eliminate pathogenic bacteria, without causing drug resistance. However, excessive ROS may also impose an oxidative stress on surrounding tissues, resulting in local inflammation. To avoid this major drawback and limit pro-inflammation during PDT, this work prepared a supramolecular photosensitizer (TPP-CN/CP5) based on host-guest interactions between a cysteine-responsive cyano-tetraphenylporphyrin (TPP-CN) and a water-soluble carboxylatopillar[5]arene (CP5). TPP-CN/CP5 not only possesses excellent photodynamic antibacterial properties, but also shows good anti-inflammatory and cell protection capabilities. Under 660nm light irradiation, TPP-CN/CP5 could rapidly produce abundant ROS for sterilization. After the PDT process, the addition of cysteine (Cys) triggers the release of H2 S from TPP-CN. H2 S then stops the induced inflammation by inhibiting the production of related inflammatory factors. Both in vitro and in vivo experiments show the excellent antibacterial effects and anti-inflammatory abilities of TPP-CN/CP5. These results will certainly promote the clinical application of PDT in the treatment of bacterial infectious diseases.

Biofuel production by Candida tropicalis from orange peels waste using response surface methodology

Citrus fruits are widely consumed worldwide due to their nutritional and health benefits. However, the disposal of citrus waste poses significant environmental challenges. Orange peels (OP) are a substantial by-product of fruit processing and hold great potential as a source for bioethanol production, promoting investment in utilizing agricultural waste for biofuel purposes. OP offers a cost-effective substrate for producing value-added compounds, including bioethanol. Autoclaved-water treated OP biomass exhibited the highest release of reducing sugars (68.2%) this results supported by SEM images of that Autoclaving has definite effect on the structure of the OP particles. Among the five tested microbes, Candida tropicalis was selected as a promising bioethanol candidate due to its ethanol tolerance and ability to utilize xylose. Preliminary screening using Plackett-Burman Design (PBD) was conducted to identify six influential factors affecting the fermentation process at three levels, determining the optimum response region for bioethanol production by C. tropicalis. The significant variables were further investigated using Response Surface Methodology-Central Composite Rotatable Design (RSM-CCRD) at five levels, a novel approach in this study. The addition of cysteine and resazurin as reducing agents increased bioethanol production by 2.9 and 2.1 times, respectively, from the treated OP. Under the optimized conditions obtained from RSM-CCRD, bioethanol production reached 16.7 mg/mL per mg/ml reducing sugars. Implementing all the optimized conditions, including an initial pH of 5.75, 3% yeast extract, 2.25 g/L cysteine, 4% inoculum size, 0.6 g/L ZnSO4, 0.29 g/L MgSO4, 0.3 g/L MnSO4, and substrate treatment with active charcoal before fermentation, the bioethanol yield increased by 2.2 times after three days of fermentation using co-cultures of C. tropicalis and Kluyveromyces marxianus. The fermentation process was conducted at 30 °C and 150 rpm. Exploring OP as a low-cost renewable substrate and employing efficient microorganisms open new avenues for bioethanol production.

Purification and Characterization of Alkaline Protease Isolated from Cotton (Gossypium hirsutum) Seeds

Proteases are widely utilized both in physiological and commercial fields such as medicine, food, detergent, and leather. Plant-originated proteases play a significant role in several biomedical fields due to their easy accessibility and activity. Pakistan is an agro-based country and can be an ideal place for the isolation of industrially important proteases from plant sources such as cotton, which is the main crop and frequently available and low cost. Purification of protease was carried out by fractionation with two-fold acetone, ethanol, methanol and various concentrations (40-80%) of ammonium sulphate. The precipitates formed were collected after centrifugation and dialyzed for 24 hours against universal buffer pH 7.0 and was centrifuged in a cooled refrigerated. The dialyzed sample was loaded on Sephadex G–100 gel column. The fractions of the samples were collected and their absorbance of protein was monitored at 280 nm. The homogeneity of the purified enzyme was checked by SDS gel electrophoresis The purified protease enzyme has optimum activity at 30°C and pH 8.0 when casein was used as substrate. The Km and Vmax values of purified cotton seed's alkaline protease activity was recorded as 0.03M and 17 μmol/minute respectively. Protease activity was increased by the addition of cysteine but inhibited by Iodoacetic acid and β-Mercaptoethanol and decreased with some metal ions. These characteristics of the purified enzyme allowed classifying it as a cysteine protease. In conclusion, this study suggests that the alkaline protease enzyme is the best choice for commercial use