Protein is one of the essential macronutrients required by all living things. The breakdown of protein produces monomers known as amino acids. The concept of conjugating natural compounds with amino acids for therapeutic applications emerged from the fact that amino acids are important building blocks of life and are abundantly available; thus, a greater shift can result in structural modification, since amino acids contain a variety of sidechains. This review discusses the data available on amino acid-natural compound conjugates that were reported with respect to their backgrounds, the synthetic approach and their bioactivity. Several amino acid-natural compound conjugates have shown enhanced pharmacokinetic characteristics, including absorption and distribution properties, reduced toxicity and increased physiological effects. This approach could offer a potentially effective system of drug discovery that can enable the development of pharmacologically active and pharmacokinetically acceptable molecules.
Polysulfone (PSF) based mixed matrix membranes (MMMs) are one of the most broadly studied polymeric materials used for CO2/CH4 separation. The performance of existing PSF membranes encounters a bottleneck for widespread expansion in industrial applications due to the trade-off amongst permeability and selectivity. Membrane performance has been postulated to be enhanced via functionalization of filler at different weight percentages. Nonetheless, the preparation of functionalized MMMs without defects and its empirical study that exhibits improved CO2/CH4 separation performance is challenging at an experimental scale that needs prior knowledge of the compatibility between the filler and polymer. Molecular simulation approaches can be used to explore the effect of functionalization on MMM's gas transport properties at an atomic level without the challenges in the experimental study, however, they have received less scrutiny to date. In addition, most of the research has focused on pure gas studies while mixed gas transport properties that reflect real separation in functionalized silica/PSF MMMs are scarcely available. In this work, a molecular simulation computational framework has been developed to investigate the structural, physical properties and gas transport behavior of amine-functionalized silica/PSF-based MMMs. The effect of varying weight percentages (i.e., 15-30 wt.%) of amine-functionalized silica and gas concentrations (i.e., 30% CH4/CO2, 50% CH4/CO2, and 70% CH4/CO2) on physical and gas transport characteristics in amine-functionalized silica/PSF MMMs at 308.15 K and 1 atm has been investigated. Functionalization of silica nanoparticles was found to increase the diffusion and solubility coefficients, leading to an increase in the percentage enhancement of permeability and selectivity for amine-functionalized silica/PSF MMM by 566% and 56%, respectively, compared to silica/PSF-based MMMs at optimal weight percentage of 20 wt.%. The model's permeability differed by 7.1% under mixed gas conditions. The findings of this study could help to improve real CO2/CH4 separation in the future design and concept of functionalized MMMs using molecular simulation and empirical modeling strategies.
Degradation of amines is a significant issue allied to amine-based carbon dioxide (CO2) absorption in post-combustion CO2 capture. It becomes essential to have a detailed understanding of degradation products for advanced post-combustion CO2 capture technology. Identification and quantification of degradation products of amines help in practicability and environmental assessment of amine-based technology. Gas, liquid, and ion chromatographic techniques are the benchmark tools for qualitative and quantitative analyses of the amines and their derivatives. Among others, gas chromatography has been more in use for this specific application, especially for the identification of degradation products of amines. This review focuses on the critical elucidation of gas chromatographic analysis and development of methods to determine the amine degradation products, highlighting preparation methods for samples and selecting columns and detectors. The choice of detector, column, sample preparation, and method development are reviewed in this manuscript, keeping in view the industry and research applications. Furthermore, obtained results on the quantitative and qualitative analyses using gas chromatography are summarized with future perspectives.
We performed quantitative metabolic phenotyping of blood plasma in parallel with cytokine/chemokine analysis from participants who were either SARS-CoV-2 (+) (n = 10) or SARS-CoV-2 (-) (n = 49). SARS-CoV-2 positivity was associated with a unique metabolic phenotype and demonstrated a complex systemic response to infection, including severe perturbations in amino acid and kynurenine metabolic pathways. Nine metabolites were elevated in plasma and strongly associated with infection (quinolinic acid, glutamic acid, nicotinic acid, aspartic acid, neopterin, kynurenine, phenylalanine, 3-hydroxykynurenine, and taurine; p < 0.05), while four metabolites were lower in infection (tryptophan, histidine, indole-3-acetic acid, and citrulline; p < 0.05). This signature supports a systemic metabolic phenoconversion following infection, indicating possible neurotoxicity and neurological disruption (elevations of 3-hydroxykynurenine and quinolinic acid) and liver dysfunction (reduction in Fischer's ratio and elevation of taurine). Finally, we report correlations between the key metabolite changes observed in the disease with concentrations of proinflammatory cytokines and chemokines showing strong immunometabolic disorder in response to SARS-CoV-2 infection.
A rapid and green analytical method based on capillary electrophoresis with capacitively coupled contactless conductivity detection (C⁴D) for the determination of eight environmental pollutants, the biogenic amines (putrescine, cadaverine, spermidine, spermine, tyramine, 2-phenylamine, histamine and tryptamine), is described. The separation was achieved under normal polarity mode at 24 °C and 25 kV with a hydrodynamic injection (50 mbar for 5 s) and using a bare fused-silica capillary (95 cm length × 50 µm i.d.) (detection length of 10.5 cm from the outlet end of the capillary). The optimized background electrolyte consisted of 400 mM malic acid. C⁴D parameters were set at a fixed amplitude (50 V) and frequency (600 kHz). Under the optimum conditions, the method exhibited good linearity over the range of 1.0⁻100 µg mL−1 (R² ≥ 0.981). The limits of detection based on signal to noise (S/N) ratios of 3 and 10 were ≤0.029 µg mL−1. The method was used for the determination of seawater samples that were spiked with biogenic amines. Good recoveries (77⁻93%) were found.
The objective of the study was to determine the effect of different types of soy sauce and marinating time on the formation of heterocyclic amines (HCAs) in roasted chicken. Chicken breast samples were marinated with sweet, salty, light and dark soy sauce at 0, 3, 6 and 12 h (control treatment was the chicken without marinade). The concentrations of free amino acids, sugars and creatinine were determined before roasting while HCA concentrations were determined after roasting. All types of soy sauce significantly increased (p ≤ 0.05) the concentration of HCAs in roasted chicken with increasing marinating time. The highest increment of total concentration of HCAs was found in samples marinated with light soy sauce (887%) followed by dark (375%), salty (193%) and sweet (169%) at 12 h. PhIP (2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine) showed a substantial reduction in samples only momentarily marinated with sweet, salty and dark soy sauce (0 h). Free amino acids were found to be more strongly correlated with the formation of HCAs than reducing sugars or creatinine.
Adsorption performance of chitosan (CS) hydrogel beads was investigated after impregnation of CS with hexadecylamine (HDA) as a cationic surfactant, for the elimination of reactive blue 4 (RB4) from wastewater. The CS/HDA beads formed with 3.8% HDA were the most effective adsorbent. The adsorption capacity was increased by 1.43 times from 317 mg/g (CS) to 454 mg/g (CS/HDA). The RB4 removal increased with decrease in the pH of dye solution from 4 to 9. The isotherm data obtained from RB4 adsorption on CS and CS/HDA are adequately described by Freundlich model (R(2)=0.946 and 0.934, χ(2)=22.414 and 64.761). The kinetic study revealed that the pseudo-second-order rate model (R(2)=0.996 and 0.997) was in better agreement with the experimental data. The negative values of ΔG° (-2.28 and -6.30 kJ/mol) and ΔH° (-172.18 and -101.62 kJ/mol) for CS beads and HDA modified CS beads, respectively; suggested a spontaneous and exothermic process for RB4 adsorption.
The study was carried out to determine the effect of cooking method on Heterocyclic Aromatic Amines (HAs) concentration in grilled chicken and beef (satay). Six common HAs were investigated: 2-amino-3-methylimidazo[4,5-f]quinolone (IQ), 2amino 3,4dimethylimidazo [4,5f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8 trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), 2-amino-3,7,8trimethylimidazo [4,5-f]quinoxaline (7,8-DiMeIQx), and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP). Chicken and beef satay samples were grilled to medium and well done level of doneness. Charcoal grilled (treatment A), microwave pre-treatment prior to grilling (treatment B), and microwave-deep fried (treatment C) were applied to beef and chicken satay samples. The satay samples which were microwaved prior to grilling (B) showed significantly (p<0.05) lower HAs concentration as compared to those charcoal grilled (A). Both medium and well done cooked beef and chicken satay samples that were microwaved and deep fried (C) as an alternative method to grilling were proven to produce significantly lesser HAs as compared to charcoal-grilled (A) and microwaved prior to grilling (B).
There is an increasing concern about the quality and quality assessment procedures of seafood. In the present study, a model to assess fish quality based on biogenic amine contents using fuzzy logic model (FLM) is proposed. The fish used was sardine (Sardinella sp.) where the production of eight biogenic amines was monitored over fifteen days of storage at 0, 3 and 10°C. Based on the results, histamine, putrescine and cadaverine were selected as input variables and twelve quality grades were considered for quality of fish as output variables for the FLM. Input data were processed by rules established in the model and were then defuzzified according to defined output variables. Finally, the quality of fish was evaluated using the designed model and Pearson correlation between storage times with quality of fish showed r=0.97, 0.95 and 1 for fish stored at 0, 3 and 10°C, respectively.
The purpose of this study is to explore the emulsion liquid membrane stability for acetaminophen (ACTP) removal from aqueous solution. In this work, the membrane phase was prepared by dissolving trioctylamine (TOA) with kerosene and Span80. The stability of the emulsion in terms of emulsion size, membrane breakage, and its efficiency in removing ACTP was considered for the optimization of parameters. Investigation on the stability of emulsion was carried out by manipulating the concentration of stripping agent, agitation speed, extraction time, and treat ratio. The best condition to produce a very stable emulsion was achieved at 0.1 M of stripping agent concentration, with 300 rpm of agitation speed for 3 min of extraction time with a treat ratio of 3:1. Eighty-five percent of ACTP successfully stripped into the emulsion with minimum membrane breakage of 0.17% through this experiment.
The key challenge in the synthesis of composite mixed matrix membrane (MMMs) is the incompatible membrane fabrication using porous support in the dry-wet phase inversion technique. The key objective of this research is to synthesize thin composite ternary (amine) mixed matrix membranes on microporous support by incorporating 10 wt% of carbon molecular sieve (CMS) and 5-15 wt% of diethanolamine (DEA) in polyethersulfone (PES) dope solution for the separation of carbon dioxide (CO2) from methane (CH4) at high-pressure applications. The developed membranes were evaluated for their morphological structure, thermal and mechanical stabilities, functional groups, as well as for CO2-CH4 separation performance at high pressure (10-30 bar). The results showed that the developed membranes have asymmetric structure, and they are mechanically strong at 30 bar. This new class of PES/CMS/DEA composite MMMs exhibited improved gas permeance compared to pure PES composite polymeric membrane. CO2-CH4 perm-selectivity enhanced from 8.15 to 16.04 at 15 wt% of DEA at 30 bar pressure. The performance of amine composite MMMs is theoretically predicted using a modified Maxwell model. The predictions were in good agreement with experimental data after applying the optimized values with AARE % = ∼less than 2% and R2 = 0.99.
Azoxystrobin (AZ) is a broad-spectrum synthetic fungicide widely used in agriculture globally. However, there are concerns about its fate and effects in the environment. It is reportedly transformed into azoxystrobin acid as a major metabolite by environmental microorganisms. Bacillus licheniformis strain TAB7 is used as a compost deodorant in commercial compost and has been found to degrade some phenolic and agrochemicals compounds. In this article, we report its ability to degrade azoxystrobin by novel degradation pathway. Biotransformation analysis followed by identification by electrospray ionization-mass spectrometry (MS), high-resolution MS, and nuclear magnetic resonance spectroscopy identified methyl (E)-3-amino-2-(2-((6-(2-cyanophenoxy)pyrimidin-4-yl)oxy)phenyl)acrylate, or (E)-azoxystrobin amine in short, and (Z) isomers of AZ and azoxystrobin amine as the metabolites of (E)-AZ by TAB7. Bioassay testing using Magnaporthe oryzae showed that although 40 μg/mL of (E)-AZ inhibited 59.5 ± 3.5% of the electron transfer activity between mitochondrial Complexes I and III in M. oryzae, the same concentration of (E)-azoxystrobin amine inhibited only 36.7 ± 15.1% of the activity, and a concentration of 80 μg/mL was needed for an inhibition rate of 56.8 ± 7.4%, suggesting that (E)-azoxystrobin amine is less toxic than the parent compound. To our knowledge, this is the first study identifying azoxystrobin amine as a less-toxic metabolite from bacterial AZ degradation and reporting on the enzymatic isomerization of (E)-AZ to (Z)-AZ, to some extent, by TAB7. Although the fate of AZ in the soil microcosm supplemented with TAB7 will be needed, our findings broaden our knowledge of possible AZ biotransformation products.
In the title compound, C15H16N2S3 {systematic name: [({[(4-methyl-phen-yl)meth-yl]sulfan-yl}methane-thio-yl)amino][1-(thio-phen-2-yl)ethyl-idene]amine}, the central CN2S2 residue is almost planar (r.m.s. deviation = 0.0061 Å) and forms dihedral angles of 7.39 (10) and 64.91 (5)° with the thienyl and p-tolyl rings, respectively; the dihedral angle between these rings is 57.52 (6)°. The non-thione S atoms are syn, and with respect to the thione S atom, the benzyl group is anti. In the crystal, centrosymmetrically related mol-ecules self-associate via eight-membered {⋯HNCS}2 synthons. The dimeric aggregates stack along the a axis and are are consolidated into a three-dimensional architecture via methyl-C-H⋯π(benzene) and benzene-C-H⋯π(thien-yl) inter-actions.
The Yb(III) atom in the title complex, [Yb(C27H24Cl3N4O3)] [systematic name: (2,2',2''-{(nitrilo)-tris-[ethane-2,1-di-yl(nitrilo)-methylyl-idene]}tris-(4-chloro-phenolato)ytterbium(III)], is coordinated by a trinegative, hepta-dentate ligand and exists within an N4O3 donor set, which defines a capped octa-hedral geometry whereby the amine N atom caps the triangular face defined by the three imine N atoms. The packing features supra-molecular layers that stack along the a axis, sustained by a combination of aryl-C-H⋯O, imine-C-H⋯O, methyl-ene-C-H⋯π(ar-yl) and end-on C-Cl⋯π(ar-yl) inter-actions. A Hirshfeld surface analysis points to the major contributions of C⋯H/ H⋯C and Cl⋯H/H⋯Cl inter-actions (along with H⋯H) to the overall surface but the Cl⋯H contacts are at distances greater than the sum of their van der Waals radii.
In the solid state, the title compound, C12H16BrNO5 [systematic name: 4-bromo-2-((1E)-{[1,3-dihy-droxy-2-(hy-droxy-meth-yl)propan-2-yl]iminium-yl}meth-yl)-6-meth-oxy-benzen-1-olate], C12H16BrNO5, is found in the keto-amine tautomeric form, with an intra-molecular iminium-N-H⋯O(phenolate) hydrogen bond and an E conformation about the C=N bond. Both gauche (two) and anti relationships are found for the methyl-hydroxy groups. In the crystal, a supra-molecular layer in the bc plane is formed via hy-droxy-O-H⋯O(hy-droxy) and charge-assisted hy-droxy-O-H⋯O(phenolate) hydrogen-bonding inter-actions; various C-H⋯O inter-actions provide additional cohesion to the layers, which stack along the a axis with no directional inter-actions between them. A Hirshfeld surface analysis confirms the lack of specific inter-actions in the inter-layer region.
In the title hydrate, C9H12N4S·H2O (systematic name: 3-methyl-1-{(E)-[(3-methyl-pyridin-2-yl)methyl-idene]amino}-thio-urea monohydrate), a small twist is noted between the pyridine ring and the rest of the organic mol-ecule [dihedral angle = 6.96 (5)°]. The imine and pyridine N atoms are syn, and the amine H atoms are anti. The latter arrangement allows for the formation of an intra-molecular N-H⋯N(imine) hydrogen bond. Both the N-bonded H atoms form hydrogen bonds to symmetry-related water mol-ecules, and the latter forms O-H hydrogen bonds with the pyridine N and thione S atoms. These inter-actions lead to supra-molecular layers that stack along the a-axis direction with no specific inter-actions between them.
In the title di-thio-carbazate ester, C16H17N3S2 (systematic name: (Z)-{[(benzyl-sulfan-yl)methane-thio-yl]amino}[1-(6-methyl-pyridin-2-yl)ethyl-idene]amine), the central methyl-idenehydrazinecarbodi-thio-ate (C2N2S2) core is almost planar (r.m.s. deviation = 0.0111 Å) and forms dihedral angles of 71.67 (3)° with the approximately orthogonally inclined thio-ester phenyl ring, and 7.16 (7)° with the approximately coplanar substituted pyridyl ring. The latter arrangement and the Z configuration about the imine-C=N bond allows for the formation of an intra-molecular hydrazine-N-H⋯N(pyrid-yl) hydrogen bond that closes an S(6) loop. In the crystal, phenyl-C-H⋯S(thione), methyl-ene-C-H⋯π(pyrid-yl), methyl-ene- and phenyl-C-H⋯π(phen-yl) contacts connect mol-ecules into supra-molecular layers propagating in the bc plane; the layers stack along the a axis with no directional inter-actions between them. The analysis of the Hirshfeld surface indicates the relative importance of an intra-layer phenyl-H⋯H(pyrid-yl) contact upon the mol-ecular packing.
Among wide range of membrane-based operations, membrane contactors, as they reify comparatively modern membrane-based mechanism are gaining quite an attention in both pilot and industrial scales. In recent literature, carbon capture is one of the most researched applications of membrane contactors. Membrane contactors have the potential to minimize the energy consumption and capital cost of traditional CO2 absorptions columns. In a membrane contactor, CO2 regeneration can take place below the solvent boiling point, resulting into lower consumption of energy. Various polymeric as well as ceramic membrane materials have been employed in gas liquid membrane contactors along with several solvents including amino acids, ammonia, amines etc. This review article provides detailed introduction of membrane contactors in terms of CO2 removal. It also discusses that the main challenge that is faced by membrane contactors is membrane pore wetting caused by solvent that in turn can reduce the mass transfer coefficient. Other potential challenges such as selection of suitable solvent and membrane pair as well as fouling are also discussed in this review and are followed by potential ways to reduce them. Furthermore, both membrane gas separation and membrane contactor technologies are analysed and compared in this study on the basis of their characteristics, CO2 separation performances and techno economical transvaluation. Consequently, this review provides an opportunity to thoroughly understand the working principle of membrane contactors along its comparison with membrane-based gas separation technology. It also provides a clear understanding of latest innovations in membrane contactor module designs as well as challenges encountered by membrane contactors along with possible solutions to overcome these challenges. Finally, semi commercial and commercial implementation of membrane contactors has been highlighted.
The development of advanced multifunctional wound dressings remains a major challenge. Herein, a novel multilayer (ML) electrospun nanofibers (NFs) wound dressing based on diethylenetriamine (DETA) functionalized polyacrylonitrile (PAN), TiO2 nanoparticles (NPs) coating (Ct), and bioderived gelatin (Gel) was developed for potential applications in wound healing. The ML PAN-DETA-Ct-Gel membrane was developed by combining electrospinning, chemical functionalization, synthesis, and electrospray techniques, using a layer-by-layer method. The ML PAN-DETA-Ct-Gel membrane is comprised of an outer layer of PAN-DETA as a barrier to external microorganisms and structural support, an interlayer TiO2 NPs (Ct) as antibacterial function, and a contact layer (Gel) to improve biocompatibility and cell viability. The NFs membranes were characterized by scanning electron microscopy (SEM), surface profilometry, BET analysis, and water contact angle techniques to investigate their morphology, surface roughness, porosity, and wettability. The ML PAN-DETA-Ct-Gel wound dressing exhibited good surface roughness, porosity, and better wettability. Cell morphology, proliferation, and viability were determined using fibroblasts (3T3), and antibacterial assays were performed against six pathogens. The ML PAN-DETA-Ct-Gel NFs membrane showed good cell morphology, proliferation, viability, and antibacterial activity compared with other membranes. This new class of ML NFs membranes offers a multifunctional architecture with adequate biocompatibility, cell viability, and antibacterial activity.
Ikan pekasam is a fermented fish product produced in Malaysia and is usually made from freshwater fish with ground roasted uncooked rice as the main source of carbohydrate. In this study, the amino acid, biogenic amine, and trans- and cis-urocanic acid (UCA) contents of fifteen commercial samples of Ikan pekasam made from Javanese carp and black tilapia, that had undergone either natural or acid-assisted fermentation, were quantified. The latter includes either tamarind (Tamarindus indica) pulp or dried slices of Garcinia atroviridis fruit in the fermentation process. Results showed that there are no significant differences in most of the biogenic amines including histamine, while there are significant differences in total UCA content, and trans- and cis-UCA contents between the two samples. Differences in the amino acid contents were largely fish-dependent.