Main Binding Force Research Articles

In vitro and in silico DNA interaction studies of a series of 3-carboxamide-4-quinolone derivatives prepared from an one-pot stepwise synthesis (OPSS) method

The 3-carboxamide-4-quinolone framework is highly regarded in the fields of Medicinal and Bioorganic Chemistry mainly due to its widespread bioactive properties. This versatile scaffold allows for the development of compounds with various pharmacological effects. In this sense, the present work explores a novel one-pot stepwise (OPPS) method for synthesizing fifteen 3-carboxamide-4-quinolone derivatives, some of which exhibit antitumor profiles in previous works. These compounds were synthesized using the OPPS methodology with yields ranging from 35 % to 88 %, streamlining the synthetic process and reducing solvent usage. Furthermore, interaction studies with calf-thymus DNA were done by UV–Vis absorption and steady-state fluorescence measurements combined with molecular docking calculations. Compounds 10a-b, 10d-g, 10k, and 10n were selected for the CT-DNA interaction assays, from which it was possible to demonstrate their DNA-binding property through peripheral secondary interactions. Molecular docking results suggested van der Waals and hydrogen bonds as the main binding forces responsible for the interactive profile between the nucleobases and the 3-carboxamide-4-quinolone derivatives. All these results unveiled promising insights into their role as DNA replication inhibitors, highlighting their potential in developing antiproliferative drugs.

Exploring the effects of whey protein components on the interaction and stability of cyanidin-3-O-glucoside.

Anthocyanins are susceptible to degradation due to external factors. Despite the potential for improved anthocyanin stability with whey protein isolate (WPI), the specific effects of individual components within WPI on the stability of anthocyanins have yet to be studied extensively. This study investigated the interaction of WPI, β-lactoglobulin (β-Lg), bovine serum albumin (BSA), and lactoferrin (LF) with cyanidin-3-O-glucoside (C3G), and also considered their effects on stability. Fluorescence analysis revealed static quenching effects between C3G and WPI, β-Lg, BSA, and LF. The binding constants were 1.923 × 103 L · mol⁻¹ for WPI, 24.55 × 103 L · mol⁻¹ for β-Lg, 57.25 × 103 L · mol⁻¹ for BSA, and 1.280 × 103 L · mol⁻¹ for LF. Hydrogen bonds, van der Waals forces, and electrostatic attraction were the predominant forces in the interactions between C3G and WPI and between C3G and BSA. Hydrophobic interaction was the main binding force in the interaction between C3G and β-Lg and between C3G and LF. The binding of C3G with WPI, β-Lg, BSA, and LF was driven by different thermodynamic parameters. Enthalpy changes (∆H) were -38.76 kJ · mol⁻¹ for WPI, -17.59 kJ · mol⁻¹ for β-Lg, -16.09 kJ · mol⁻¹ for BSA, and 39.50 kJ · mol⁻¹ for LF. Entropy changes (∆S) were -67.21 J · mol⁻¹·K⁻¹ for WPI, 3.72 J · mol⁻¹·K⁻¹ for β-Lg, 37.09 J · mol⁻¹·K⁻¹ for BSA, and 192.04 J · mol⁻¹·K⁻¹ for LF. The addition of C3G influenced the secondary structure of the proteins. The decrease in the α-helix content suggested a disruption and loosening of the hydrogen bond network structure. The presence of proteins enhanced the light stability and thermal stability (stability in the presence of light and heat) of C3G. In vitro simulated digestion experiments demonstrated that the addition of proteins led to a delayed degradation of C3G and to improved antioxidant capacity. The presence of WPI and its components enhanced the thermal stability, light stability, and oxidation stability of C3G. Preheated proteins exhibited a more pronounced effect than unheated proteins. These findings highlight the potential of preheating protein at appropriate temperatures to preserve C3G stability and bioactivity during food processing. © 2024 Society of Chemical Industry.

Identification of salty peptides from enzymolysis extract of oyster by peptidomics and virtual screening

Salty peptide as an important sodium substitute, which could reduce the risk of cardiovascular disease caused by excessive sodium intake. In this study, novel salty peptides were prepared and identified from enzymolysis extract of oysters by peptitomic identification, virtual screening and solid phase synthesis. Additionally, molecular simulation was used to study the taste mechanism of salty peptides. 316 peptides were identified in the enzymatic hydrolysates of oysters. 6 peptides, selected through virtual screening, were synthesized using solid-phase synthesis, and EK, LFE, LEY and DR were confirmed to possess a pleasing salty taste through electronic tongue evaluation. Molecular docking results indicated that these 4 peptides could enter the binding pocket within the transmembrane channel-like 4 (TMC4) cavity, wherein salt bridges, hydrogen bonds and attractive charges were the main binding forces. This study provides a rapid screening method for salty peptides in sea food products but possibly applied for other sources.

Multi-spectroscopic analysis and molecular simulations provide insights into the noncovalent interactions between the novel antimicrobial peptide Pup2 and Epigallocatechin-3-gallate (EGCG)

Antimicrobial peptide Pup2, due to high cost, shows restricted application value in food preservative, which may be improved by interacting with EGCG, characterized by good functional properties. This study aims to characterize a novel antimicrobial peptide-phenolic complex with activity against Staphylococcus aureus and investigate their interaction mechanism. Pup2 and Epigallocatechin-3-gallate (EGCG) exhibited synergistic effects, resulting in a 4-fold and 8-fold decrease in the minimum inhibitory concentration, respectively. Furthermore, the Pup2/EGCG showed a synergistic damaging effect on the bacterial cell wall and membranes. Multi-spectroscopic analyses, which included UV, fluorescence, FTIR, and Raman spectroscopy, showed that Pup2 and EGCG were non-covalently bound through hydrophobic interactions predominantly and assisted by hydrogen bonding. These interactions led to changes in the amino acid microenvironment of Pup2 and alterations in its secondary structure, with the α-helix content increasing from 3% to 26%. DSC similarly confirmed the occurrence of interactions and increased peptide stability. Additionally, molecular simulations further demonstrated hydrophobic interaction and hydrogen bonding were the main binding forces between Pup2 and EGCG, resulting in the formation of a stable complex. This study helps to elucidate the interaction mechanism between antimicrobial peptide Pup2 and EGCG at the molecular level, while highlights the potential application of this complex as a more economical and effective natural antimicrobial preservative.

Revealing the potential effects of oil phase on the stability and bioavailability of astaxanthin contained in Pickering emulsions: In vivo, in vitro and molecular dynamics simulation analysis

This study investigated the effects of oil phases on the encapsulation rate, storage stability, and bioavailability of astaxanthin (ASTA) in Pickering emulsions (PEs). Results showed PEs of mixed oils (olive oil/edible tea oil) had excellent encapsulation efficiency (about 96.0%) and storage stability of ASTA. In vitro simulated gastrointestinal digestion results showed the mixed oil PE with a smaller interfacial area and higher monounsaturated fatty acid content may play a better role in improving ASTA retention and bioaccessibility. In vivo absorption results confirmed the mixed oil PE with an olive oil/edible tea oil of 7:3 was more favorable for ASTA absorption. Molecular dynamics simulation showed ASTA bound more strongly and stably to fatty acid molecules in the system of olive oil/edible tea oil of 7:3; and van der Waals force was the main binding force. NMR further proved there really were interactions between ASTA and four main fatty acids.

Study on the molecular interactions between givosiran and theophylline by surface-enhanced Raman spectroscopy, biolayer interferometry, and visible/fluorescence spectroscopy

Givosiran is a small-interfering ribonucleic acid (siRNA) drug used to treat acute hepatic porphyria. As an exogenous double-stranded RNA, givosiran has a specific spatial conformation. When they coexist, givosiran and small-molecule drugs may interact through non-covalent bonds, which may affect their efficacies. This study aimed to evaluate the molecular interaction between givosiran and three structurally-related small-molecule drugs. We combined surface-enhanced Raman spectroscopy, biolayer interferometry, and visible/fluorescence spectroscopy with a methylene blue probe to study the molecular interaction between givosiran and theophylline, caffeine, and theobromine. Molecular interactions were observed only between theophylline and givosiran, with an affinity constant (KD) of 64.2 μM. The main binding forces were hydrogen bonds and van der Waals forces, and the equilibrium binding constant (KA) was 1.855 × 104 L·mol−1. This study focused on the 5 W (Whether, Where, Why, hoW about the tendency, hoW strong) issues of the molecular interaction between givosiran and small-molecule chemical drugs. Our findings contradict the previous perception that the probability of drug–drug interactions (DDI) between nucleic acid and small-molecular drugs is low. Our study illustrates that a combination of direct and indirect analytical methods will pave a new way for future siRNA-related unknown interactions studies.

Sulfate glycosaminoglycan from swim bladder exerts immunomodulatory potential on macrophages via toll-like receptor 4 mediated NF-κB signaling pathways

This study explored the immunomodulatory impact and potential mechanisms on macrophages RAW264.7 using a purified macromolecular sulfate glycosaminoglycan (SBSG) from the swim bladder, whose structure was similar to chondroitin sulfate A. The results showed that SBSG at 0.25–1 mg/mL increased the viability and phagocytosis of RAW264.7 cells. Meanwhile, SBSG promoted the secretion of tumor necrosis factor α (TNF-α), interleukin 10 (IL-10), and nitric oxide (NO), as well as the production of reactive oxygen species (ROS). According to the RT-PCR and Western blot data, SBSG activated TLR4-nuclear factor kappa B (NF-κB) signaling pathways, which decreased the relative mRNA and protein levels of Toll-like receptor 4 (TLR4), IκB kinase β (IKKβ), NF-κB p65, and p-NF-κB p65. The molecular docking and molecular dynamic simulation findings revealed that the main binding force between TLR4 and SBSG was conventional hydrogen bond interaction, resulting in more stable ligand receptor complexes. In summary, SBSG exhibits significant immunomodulatory potential, similar to chondroitin sulfate C. The underlying molecular mechanism involved the binding of SBSG through hydrogen bonding to TLR4 receptors, triggering the NF-κB signaling pathway to downregulate the expression of related genes and proteins. This, in turn, regulated the secretion of various cytokines that were mediated by macrophages to exert the immunity of the body.

Conformational changes induced by selected flavor compounds from spices regulate the binding ability of myofibrillar proteins to aldehyde compounds

Interactions among flavor compounds from spices (FCS) and myofibrillar proteins (MP) were investigated. Fluorescence and Fourier transform infrared spectroscopy showed that hydrogen bonding and hydrophobic interactions were the main binding forces between FCS and MP. The FCS increased the particle size and SH content of MP and caused a reduction of zeta potential from −5.23 to −6.50 mV. Furthermore, FCS could modify the binding ability of MP and aldehydes. Eugenol reduced the ability of MP to bond with aldehydes by 22.70–47.87 %. Molecular dynamics simulations demonstrated that eugenol may combat nonanal to attain binding site of amino acid residue (PHE165) and induce protein conformational changes. Electrostatic interactions and van der Waals forces within myosin-nonanal may be disrupted by these alterations, which could reduce stability of complex and cause release of nonanal. This study could provide new insights into regulating the ability of proteins to release and hold flavors.

Investigation of the Interaction of Monoamine Oxidase (MAO) Inhibitor Biscoumarins with Hemoglobin and Albumin Using Multi-Spectroscopic Techniques and Molecular Docking

Coumarin and their derivatives, such as biscoumarins, which are found as active ingredients in a variety of drugs, possess a wide range of biological activities. In this paper, the inhibitory effects of biscoumarin derivatives B1 and B2 on monoamine oxidase (MAO) enzyme activity were studied. Their binding mechanism to bovine serum hemoglobin (BHb) and bovine serum albumin (BSA) was investigated using molecular docking and multi-spectroscopic methods such as absorption, fluorescence, and synchronized fluorescence spectroscopy. The fluorescence quenching processes were analyzed using the Stern-Volmer, Lineweaver-Burk, and Hill methods. In this regard, Stern-Volmer quenching constants (Ksv), Lineweaver-Burk constants (KLB), and binding constants (Ka) were calculated at three temperatures (298, 310 and 322 K). The fluorescence studies showed that the binding of biscoumarins to BHb or BSA was a driven by static quenching. The Ka values of B2 to BHb and BSA (2179.11 and 18453.98 x 105 M-1) was larger than B1 at corresponding temperature (62.75 and 599.90 x105 M-1 for BHb and BSA, respectively), which indicates that the affinity of B2 toward the proteins were higher than that of B1. Moreover, thermodynamic parameters explained that hydrogen bonds were the main binding force stabilizing the protein-ligand complexes. Additionally, molecular docking studies have revealed binding energies, ligand efficiency values, and interactions with amino acid residues of proteins. The results of these investigations may be helpful in analyzing drug-protein binding of biscoumarins for potential future applications.

Effects of different oil fractions and tannic acid concentrations on konjac glucomannan-stabilized emulsions

Polysaccharide-stabilized emulsions have received extensive attention, but emulsifying activity of polysaccharides is poor. In this study, konjac glucomannan (KGM) and tannic acid (TA) complex (KGM-TA) was prepared via non-covalent binding to increase the polysaccharide interfacial stability. The emulsifying stabilities of KGM-TA complex-stabilized emulsions were analyzed under different TA concentrations and oil fractions. The results indicated that hydrogen bonds and hydrophobic bonds were the main binding forces for KGM-TA complex, which were closely related to TA concentrations. The interfacial tension of KGM-TA complex decreased from 20.0 mN/m to 13.4 mN/m with TA concentration increasing from 0 % to 0.3 %, indicating that TA improved the interfacial activity of KGM. Meanwhile, the contact angle of KGM-TA complex was closer to 90° with the increasing TA concentrations. The emulsifying stability of KGM-TA complex-stabilized emulsions increased in an oil mass fraction-dependent manner, reaching the maximum at 75 % oil mass fraction. Moreover, the droplet sizes of KGM-TA complex-stabilized high-internal-phase emulsions (HIPEs) decreased from 82.7 μm to 44.7 μm with TA concentration increasing from 0 to 0.3 %. Therefore, high TA concentrations were conducive to the improvement of the emulsifying stability of KGM-TA complex-stabilized HIPEs. High oil mass fraction promoted the interfacial contact of adjacent droplets, thus enhancing the non-covalent binding of KGM molecules at the interfaces with TA as bridges. Additionally, the high TA concentrations increased the gel network density in the aqueous phase, thus enhancing the emulsifying stability of emulsions. Our findings reveal the mechanisms by which polysaccharide-polyphenol complex stabilized HIPEs. Therefore, this study provides theoretical basis and references for the developments of polysaccharide emulsifier with high emulsifying capability and high-stability emulsions.

Increasing the polarity of β-lapachone does not affect its binding capacity with bovine plasma protein

Despite ortho-quinones showing several biological and pharmacological activities, there is still a lack of biophysical characterization of their interaction with albumin - the main carrier of different endogenous and exogenous compounds in the bloodstream. Thus, the interactive profile between bovine serum albumin (BSA) with β-lapachone (1) and its corresponding synthetic 3-sulfonic acid (2, under physiological pH in the sulphonate form) was performed. There is one main binding site of albumin for both β-lapachones (n ≈ 1) and a static fluorescence quenching mechanism was proposed. The Stern-Volmer constant (KSV) values are 104 M−1, indicating a moderate binding affinity. The enthalpy (−3.41 ± 0.45 and − 8.47 ± 0.37 kJ mol−1, for BSA:1 and BSA:2, respectively) and the corresponding entropy (0.0707 ± 0.0015 and 0.0542 ± 0.0012 kJ mol−1 K−1) values indicate an enthalpically and entropically binding driven. Hydrophobic interactions and hydrogen bonding are the main binding forces. The differences in the polarity of 1 and 2 did not change significantly the affinity to albumin. In addition, the 1,2-naphthoquinones showed a similar binding trend compared with 1,4-naphthoquinones.

Multiple spectroscopic and computational studies on binding interaction of 2-phenylamino-4-phenoxyquinoline derivatives with bovine serum albumin

Binding characteristics of potent non-nucleoside HIV-1 reverse transcriptase inhibitors, 4-(2′,6′-dimethyl-4′-formylphenoxy)-2-(5″-cyanopyridin-2″ylamino) quinoline (1) and 4-(2′,6′-dimethyl-4′-cyanophenoxy)-2-(5″-cyanopyridin-2″ylamino) quinoline (2), to bovine serum albumin (BSA) under simulative physiological conditions were investigated by multiple spectroscopic and computational methods. The experimental results demonstrated that (1) and (2) bound to BSA at site III (subdomain IB), and quenched BSA fluorescence through a static quenching process. The binding interaction of (1) or (2) to BSA forms stable complexes with the binding constants (Kb) at the level of 104 L/mol and the number of binding site was determined to be 1 for both systems, indicating that new synthesized compounds occupied one site in BSA with moderate binding affinities. Based on the analysis of the thermodynamic parameters, it can be indicated that the main binding forces for interaction between BSA and both compounds were hydrogen bonding and van der Waals force. Synchronous fluorescence results revealed that the interaction of two compounds with BSA led to modifications in the microenvironment surrounding tryptophan residue of BSA. Circular dichroism spectra demonstrated alterations in the secondary structure of BSA induced by (1) and (2). Moreover, the experimental data of molecular docking and molecular dynamics (MD) simulations supported the results obtained from multiple spectroscopic techniques, confirming the binding interactions between both compounds and BSA.

Sensitive detection of furazolidone and nitrofurantoin by fluorescent nanoprobe coated with 3-mercaptopropionic acid on CdS quantum dots

Cadmium sulfide quantum dots (CdS QDs) were synthesized with 3-mercaptopropionic acid (MPA) as protective agent, which were characterized by TEM, UV–vis, fluorescence, XRD and TGA. Based on the fluorescence quenching of 3-MPA-CdS QDs, the indirect methods for the determination of furazolidone (FZD) and nitrofurantoin (NFT) were established. The interaction between FZD/NFT and CdS QDs was investigated by using fluorescence, resonance light scattering, UV–vis and FT-IR. The analyses of Stern-Volmer and fluorescence lifetime indicated that the two quenching systems were all static. The binding constant (Ka) of FZD/NFT-CdS QDs was 1.20 × 104/1.81 × 104 L/mol at 293 K, respectively. Hydrogen bond or van der Waals force was the main binding force between CdS QDs and drugs. Under optimum experimental conditions, the concentration of FZD/NFT was respectively highly correlated with the fluorescence intensity ratio in the range of 0.27 – 36.03/0.57 – 28.58 μg mL−1. The interference experiments showed that the methods had good selectivity. The limit of detection (LOD) for FZD/NFT was 0.02/0.01 μg mL−1. The contents of FZD and NFT in fish samples were determined, and the recoveries were 97.41–99.52 % and 96.64–100.49 %, respectively.

Synthetic dimethoxyxanthones bind similarly to human serum albumin compared with highly oxygenated xanthones

Spectroscopic studies were carried out for the interaction of the bioactive compounds 2,3-dimethoxyxanthone (1) and 3,4-dimethoxyxanthone (2) with human serum albumin (HSA). The UV absorption, steady-state, and time-resolved fluorescence spectroscopy studies showed that 1 and 2 interact with HSA through a ground-state association. The decrease in the Stern-Volmer constant (KSV) values with increasing temperature, and the bimolecular quenching rate constant (kq) values in the order of 1012 M−1s−1 indicated a static fluorescence quenching mechanism, corroborating with time-resolved fluorescence decays. The association constant (Ka) values in the order of 104 M−1 indicated a moderate interaction between these xanthones and HSA. Circular dichroism experiments showed weak perturbation on the secondary structure of albumin after the interaction with 1 and 2. Thermodynamic parameters suggested that the binding is entropically (for HSA:1, ΔS° 0.012 ± 0.003 and for HSA:2 0.008 ± 0.002 J/molK) and enthalpically (for HSA:1, ΔH° -24.0 ± 0.99 and for HSA:2 -25.6 ± 0.67 kJ/mol) controlled, with a Gibbs free energy change (ΔG°) close to -28.0 kJ/mol in both cases. Competitive drug-displacement and molecular docking results showed that 1 and 2 could interact not only with subdomain IIA, where Trp-214 residue can be found, but also with subdomains IIIA and IB. Hydrogen bonding, electrostatic, and hydrophobic interactions were detected as the main binding forces to stabilize the association HSA:1 and HSA:2. Overall, the dimethoxyxanthones have similar binding affinity compared with highly oxygenated xanthones, e.g., mangiferin, gentiacaulein, and norswertianin.

Regulation Mechanism of Phenolic Hydroxyl Number on Self-Assembly and Interaction between Edible Dock Protein and Hydrophobic Flavonoids.

In this study, galangin (Gal), kaempferol (Kae), quercetin (Que), and myricetin (Myr) were chosen as the representative flavonoids with different phenolic hydroxyl numbers in the B-ring. The edible dock protein (EDP) was chosen as the new plant protein. Based on this, the regulation mechanism of the phenolic hydroxyl number on the self-assembly behavior and molecular interaction between EDP and flavonoid components were investigated. Results indicated that the loading capacity order of flavonoids within the EDP nanomicelles was Myr (10.92%) > Que (9.56%) > Kae (6.63%) > Gal (5.55%). Moreover, this order was consistent with the order of the hydroxyl number in the flavonoid's B ring: Myr (3) > Que (2) > Kae (1) > Gal (0). The micro morphology exhibited that four flavonoid-EDP nanomicelles had a core-shell structure. In the meantime, the EDP encapsulation remarkably improved the flavonoids' water solubility, storage stability, and sustained release characteristics. During the interaction of EDP and flavonoids, the noncovalent interactions including van der Waals forces, hydrophobic interaction, and hydrogen bonding were the main binding forces. All of the results demonstrated that the hydroxyl number of bioactive compounds is a critical factor for developing a delivery system with high loading ability and stability.

Tracking the binding site of anticancer drug fluxoridin with Fe-related proteins to achieve intelligent drug delivery

In cancer cells that need a lot of iron for growth and metastasis, halo-transferrin (TF-containing iron) enters the cell with the help of the transferrin receptor 1 (TFR1) protein. If the anticancer drug can bind to the iron site by interacting with apo-transferrin (iron-free FT), it can enter the cancer cell by the same mechanism. Two iron-related proteins, Bovine liver catalase (BLC) and apo-Transferrin (TF), that are important in cancer patients were selected and their interaction with the anti-cancer drug Floxuridine (FUDR) was investigated. Here, the protective role of FUDR was evaluated by several variables such as drug concentration, interaction time, and temperature-induced degradation of enzyme function. The results showed that the protective effect of the FUDR is greater in high concentrations (in 5 × 10-5 M:1.78 % and 2.59 % after 24 and 48 h). The interaction of the FUDR with both proteins can reduce the intensity of the fluorescence emission by a static mechanism. The binding strength of the FUDR with both proteins was almost similar and with the order of 104 M−1 (Kb = 3.90 ± 0.41 × 104 M−1 for BLC-FUDR and 5.01 ± 0.36 × 104 M−1 for TF-FUDR at 310 K). The thermodynamic calculations (in agreement with the docking results) indicated that FUDR-protein complex formation was exothermic and the main binding forces in the binding process were van der Waals interactions and hydrogen bonds. Both fluorophores tryptophan (Trp) and tyrosine (Tyr) of both proteins had significant roles in fluorescence quenching and the interaction process, the polarity of their microenvironment changed. CD results showed that the secondary structure changes of TF are slightly more than BLC. Molecular docking showed that the binding of the FUDR to TF is very close to the Fe-specific site and is placed in the cavity among the wrapping domain, N-Terminal arm, and β-barrel in BLC.

In Vitro Characterization of the Interactions of Human Serum Albumin with Rosuvastatin and Atorvastatin Using Fluorescence Spectroscopy and Molecular Modeling

Human serum albumin (HSA) is one of the most important transporters for drugs in the systemic circulation. In this study, we investigated the interaction of rosuvastatin (ROS) and atorvastatin (ATO) with HSA. Binding of a drug molecule to HSA significantly affects the pharmacokinetics of the drug as it increases drug solubility in plasma, decreases toxicity and protects molecules from oxidation. This study was made using fluorescence spectroscopy and molecular modeling approach. Fluorescence spectra were recorded for two different statins brands at seven different concentrations. The results revealed that both statins (ROS and ATO) cause the fluorescence quenching of the HSA solution. ROS and ATO binds strongly to HSA with the binding constant (Kb) of 1.0246×106 and 0,9018×106, respectively. In addition, it was observed that high concentrations of ATO cause a shift of the emission maximum towards longer wavelengths (red-shift), which may be due to the unfolding of protein chains or denaturation. Furthermore, it was calculated that HSA possesses one binding site for ROS and ATO. Results from molecular docking showed that ROS has a higher affinity for Sudlow site I compared to Sudlow site II and the main binding forces are hydrogen bonds. ATO has nearly equal affinity for both binding sites on HSA, and the main binding forces are hydrophobic interactions.

Insights into the enzymatic degradation of DNA expedited by typical perfluoroalkyl acids

Perfluoroalkyl acids (PFAAs) are considered forever chemicals, gaining increasing attention for their hazardous impacts. However, the ecological effects of PFAAs remain unclear. Environmental DNA (eDNA), as the environmental gene pool, is often collected for evaluating the ecotoxicological effects of pollutants. In this study, we found that all PFAAs investigated, including perfluorohexanoic acid, perfluorooctanoic acid, perfluorononanoic acid, and perfluorooctane sulfonate, even at low concentrations (0.02 and 0.05 mg/L), expedited the enzymatic degradation of DNA in a nonlinear dose–effect relationship, with DNA degradation fragment sizes being lower than 1,000 bp and 200 bp after 15 and 30 min of degradation, respectively. This phenomenon was attributed to the binding interaction between PFAAs and AT bases in DNA via groove binding. van der Waals force (especially dispersion force) and hydrogen bonding are the main binding forces. DNA binding with PFAAs led to decreased base stacking and right-handed helicity, resulting in loose DNA structure exposing more digestion sites for degrading enzymes, and accelerating the enzymatic degradation of DNA. The global ecological risk evaluation results indicated that PFAA contamination could cause medium and high molecular ecological risk in 497 samples from 11 contamination-hot countries (such as the USA, Canada, and China). The findings of this study show new insights into the influence of PFAAs on the environmental fates of biomacromolecules and reveal the hidden molecular ecological effects of PFAAs in the environment.

Interaction of curcumin with four types of gelatins in nanoparticles: Mechanism and application for emulsion stabilization

The research of the interaction between proteins and functional active substances in the protein nanoparticles is a research hotspot in the field of food science. Gelatin type had a significant effect on the structural and functional properties of gelatins. Herein, the interaction mechanism of curcumin with four types of gelatins (bovine bone gelatin, BBG; cold water fish skin gelatin, CFG; fish gelatin, FG; and porcine skin gelatin, PSG) and the structural and functional properties of gelatin/curcumin nanoparticles were explored. All four types of gelatins could be applied to prepare gelatin/curcumin nanoparticles with an amorphous state of curcumin. The nanoparticle sizes were not dependent on the molecular weight of gelatins. The stability of gelatin/curcumin nanoparticle solutions was dependent not on the nanoparticle size but on the gelatin type. The binding affinity between gelatins and curcumin was dependent on gelatin type and the number of binding sites was nearly 1. The main binding forces to form gelatin-curcumin nanoparticles were hydrogen bonds, Pi-alkyl interaction, and Pi-anion interaction. The nanoparticulation increased the surface hydrophobicity of BBG, FG, and PSG, whereas it decreased the surface hydrophobicity of CFG. The nanoparticulation increased the surface tension of gelatins and decreased the dynamic interfacial tension of gelatins. The functional properties were dependent on both gelatin type and nanoparticulation. CFG/Cur nanoparticulation could not change the creaming stability, whereas other gelatins/curcumin nanoparticulation significantly increased creaming stability than the corresponding gelatins. This work provided the basic knowledge to illustrate the interaction and application of protein nanoparticles for Pickering emulsion stabilization.

An intelligent chitosan/gelatin film via improving the anthocyanin-induced color recognition accuracy for beef sub-freshness differentiation monitoring

A novel volatile amine-responsive food freshness smart film, CG-BAE, has been developed utilizing chitosan (CS) and gelatin (GL) as film substrates and butterfly pea flower anthocyanin extract (BAE) as the indicator. The pH value of the film-forming solution was found to significantly impact the physical properties, biogenic amine response sensitivity, and initial color of the film. The hydrogen bonding interaction between anthocyanins and the film matrix was identified as the main binding force, as confirmed by FT-IR spectroscopy and molecular docking simulation analysis. Notably, CG-BAE-2.0 films have demonstrated excellent color stability, antioxidant activity, and color responsiveness. The performance of the film in monitoring beef freshness was evaluated and proved clear differentiation between four stages: freshness, sub-freshness, onset of spoilage, and complete spoilage. The color change of the film was assessed using RGB values obtained from a smartphone App, reducing the difference in color recognition by individual naked eyes. Therefore, this work addresses the limitation that BAE-based intelligent films cannot be distinguished at the starting point of meat spoilage, and presents a promising approach to sub-freshness indication, opening new possibilities for food freshness differentiation monitoring.