Identification differential behavior of Gd@C82(OH)22 upon interaction with serum albumin using spectroscopic analysis

Effect of epigallocatechin-3-gallate modification on the structure and emulsion stability of rice bran protein in the presence of soybean protein isolate

For improving the emulsion stability of rice bran protein (RBP), RBP was modified by different concentrations of epigallocatechin-3-gallate (EGCG) in the presence of soybean protein isolate (SPI), and RBP-EGCG-SPI conjugate was prepared by alkaline pH-shifting. The results showed that the addition of EGCG led to an increase in the bound phenol content and the flexibility of the secondary structure, a decrease in the free sulfhydryl and disulfide bond content of the RBP-EGCG-SPI conjugate. EGCG covalently bound to RBP and SPI through non-disulfide bonds. When the concentration of EGCG was 10 % (w/v), the emulsifying activity index and emulsion stability index of conjugate reached the maximum value (36.61 m2/g and 255.61 min, respectively), and the conjugate had the best emulsion stability. However, an EGCG concentration above 10 % (w/v) negatively affected the emulsion stability, with increasing particle size due to protein aggregation. Summarily, the modification of EGCG improved the emulsion stability of conjugate by regulating the spatial structure of RBP-EGCG-SPI conjugate. The work provided an important guide to further improve the emulsion stability of RBP.

The inhibitory effect and mechanism of small molecules on acetic anhydride-induced BSA acetylation and aggregation

Protein acetylation is a significant post-translational modification, and hyperacetylation results in amyloid aggregation, which is closely related to neurodegenerative diseases (Alzheimer's disease, Huntington's disease, and so on). Therefore, it is significant to inhibit the hyperacetylation of proteins and their induced aggregation. In the present study, we aimed to explore the anti-acetylation and anti-amyloid properties of five small molecules (gallic acid, menadione, resveratrol, apigenin, and quercetin) in the process of acetic anhydride-induced protein hyperacetylation and its aggregation. Optical detection methods, such as SDS-PAGE, inverted fluorescence microscopy, and endogenous fluorescence spectroscopy, were used to investigate the effects of small molecules on protein acetylation, aggregation, and structure. In addition, fluorescence quenching and molecular docking techniques were used to explore the relationship between small molecules and acetylation. The results showed that gallic acid (200 μM), menadione (100 μM), quercetin (40 μM), resveratrol (5 μM), and apigenin (20 μM) (unmodified rates were 61.12 %, 67.76 %, 65.11 %, 62.66 %, and 67.81 %, respectively) had strong inhibitory effects on acetylation, and there was no significant difference (P < 0.05). In addition, gallic acid (200 μM), menadione (100 μM), and resveratrol (5 μM) (inhibition rates of 29.89 %, 26.53 %, and 26.09 %, respectively) had more substantial inhibitory effects on protein aggregation, indicating that the five small molecules could inhibit acetic anhydride-induced hyperacetylation and protein aggregation. The underlying mechanism might be that it could inhibit hyperacetylation and resist amyloid aggregation by interacting with proteins to occupy acetylation sites. Collectively, our findings showed that gallic acid, menadione, and resveratrol could potentially prevent and treat neurodegenerative diseases, such as Alzheimer's disease, by inhibiting acetylation and acetylation-induced aggregation.

Effects of Zinc Adaptation on Histological Morphology, Antioxidant Responses, and Expression of Immune-Related Genes of Grass Carp (Ctenopharyngodon idella)

The study was conducted to evaluate the effect of zinc adaptation on histological morphology and antioxidant and immune responses of grass carp(Ctenopharyngodon idella). A total of 180 young grass carp (20.0 ± 2.0 g) was equally distributed into 9 groups, and triplicate groups were subjected to 0 μg/L Zn²⁺ (control group), 200 μg/L Zn²⁺, and 300 μg/L Zn²⁺ solution for 42 days, respectively. The results indicated that the liver and gill have obvious pathological changes after long-term adaptation to zinc except the intestine; the zinc adaptation can positively influence intestinal morphology. The activities of GPX (glutathione peroxidase activity), SOD (superoxide dismutase), and CAT (Catalase) were significantly increased in zinc treatment groups (P < 0.05). The genes expression levels of CuZnSOD (copper zinc superoxide dismutase), CAT, Hsp70 (heat shock protein-70), IL-1b (interleukin-1-b), and TGF-β1 (transforming growth factor-β1) were upregulated in the gill and intestine of grass carp following waterborne adaptation to zinc solution for 42 days (P < 0.05). In conclusion, zinc adaptation has different effects on organs of grass carp and may reduce the inflammatory response of the body's gills and intestines by improving the body's antioxidant and anti-stress defense capabilities.

Metallofullerenols in biomedical applications

Metallofullerenols (MFs) are functionalized endohedral fullerenes connecting at least three levels of organization of matter: atomic, molecular, and supramolecular, resulting in their unique activity at the nanoscale. Biomedical applications of MFs started from gadolinium-containing contrasting agents, but today their potential medical applications go far beyond diagnostics and magnetic resonance imaging. In many cases, preclinical studies have shown a great therapeutic value of MFs, and here we provide an overview of interactions of MFs with high-energy radiation and with reactive oxygen species generated during radiation as a ground for potential applications in modern therapy of cancer patients. We also present the current knowledge on interactions of MFs with proteins and with other components of cells and tissues. Due to their antioxidant properties, as well as their ability to regulate the expression of genes involved in apoptosis, angiogenesis, and stimulation of the immune response, MFs can contribute to inhibition of tumor growth and protection of normal cells. MFs with enclosed gadolinium act as inhibitors of tumor growth in targeted therapy along with imaging techniques, but we hope that the data gathered in this review will help to accelerate further progress in the implementation of MFs, also the ones containing rare earth metals other than gadolinium, in a broad range of bioapplications covering not only diagnostics and bioimaging but also radiation therapy and cancer treatment by not-cytotoxic agents.

Comparison of the interactions of flupyrimin and nitenpyram with serum albumins via multiple analysis methods

Flupyrimin and nitenpyram are emerging neonicotinoid insecticides that may cause potential harm to the human body. In the present work, the interactions of flupyrimin/nitenpyram with serum albumins under normal physiological conditions were thoroughly studied by using multiple spectroscopic techniques, DFT calculations and molecular docking. Flupyrimin/nitenpyram can quench the endogenous fluorescence of HSA/BSA and form a complex with HSA/BSA through a static process, causing conformational and secondary structure changes of HSA/BSA. Thermodynamic analysis shows that the combination of flupyrimin/nitenpyram with HSA/BSA is a spontaneous process, mainly driven by hydrogen bonds and hydrophobic forces. Site marking and molecular docking experiments indicated that flupyrimin/nitenpyram binds with HSA/BSA at site II (subdomain IIIA). The binding constant K_a in HSA-flupyrimin, HSA-nitenpyram, BSA-flupyrimin and BSA-nitenpyram systems at 298 K was 2.11 × 10⁵ M^-1, 2.35 × 10⁵ M^-1, 1.91 × 10⁵ M^-1 and 2.11 × 10⁵ M^-1, respectively. The binding constant K_a of nitenpyram with HSA/BSA was greater than flupyrimin, indicating that nitenpyram binds HSA/BSA was more stable than that of flupyrimin, which was consistent with the DFT calculation. In addition, the acute toxicity bioassay showed that flupyrimin and nitenpyram exhibited low toxicity to zebrafish, with 96 h LC₅₀ values of 181.662 and 250.658 mg a. i. L^-1, respectively. These results can help understand the interactions of flupyrimin/nitenpyram with HSA/BSA.

Immunopotentiators improve the antioxidant defense, apoptosis, and immune response in Shaoxing ducklings

The abuse of antibiotics for agricultural purposes has been under scrutiny. Therefore, there is an urgent need to find antibiotic substitutes in animal production. The effects of chlorogenic acid, β-D-Glucan, astragalus flavone, CpG-DNA, and chicken IgG on spleen antioxidant capacity, apoptosis, and the immune response in Shaoxing ducklings were investigated in this study. The ducklings treated with β-D-Glucan, astragalus flavone, CpG-DNA, and chicken IgG showed significant reduction in catalase and superoxide dismutase activities. The five immunopotentiators facilitated caspase 3 expression and reduced Bcl2 expression in the spleen. Compared to the control group, the protein level of COX2 was significantly upregulated in the chlorogenic acid, CpG-DNA, and chicken IgG groups. The protein level of iNOS expression was significantly improved in all immunopotentiator groups, except for the astragalus flavone group. The five immunopotentiators induced IL-1β, IFN-α, IFN-β, TNF-α, RIG-I, TLR3, and TLR7 gene expression. In summary, chlorogenic acid, β-D-Glucan, astragalus flavone, CpG-DNA, and chicken IgG, as immunopotentiators, improved the innate immune response in the ducklings, which not only provides a new avenue for the development of efficient approaches to prevent pathogen infections, but also offers an alternative to antibiotics in animal production.

Vibrational spectra of La@C60 and Ce@C60 endohedral fullerenes: Influence of spin state multiplicity

Endohedral fullerenes with paramagnetic encapsulated atoms are new magnetic materials of interest for numerous applications from medicine to quantum computers. An important phenomenon with endohedral fullerenes is the appearance of new vibrational frequencies not associated with empty fullerenes. The vibrational spectra of the lanthanide endohedral fullerenes La@C₆₀ and Ce@C₆₀ in various spin states are calculated using the density functional method. Most of the spectral lines lie in the 300-1600 cm^-1range, and their intensities change dramatically depending on the molecule's symmetry and spin state, which are determined by the encapsulated lanthanide atom. The average frequency shift of the carbon cage vibrations caused by spin transition is only 5 cm^-1. The calculated frequencies of the coupled "metal-carbon cage" vibrations of the lanthanide endohedral fullerenes La@C₆₀ and Ce@C₆₀ in various spin states lie in the 10-170 cm^-1range. The computational results for both the frequencies and intensities of the metal-cage modes depend considerably on the spin state. The changes in these vibrational modes are due to the changes in the molecular symmetry and the metal-carbon bond lengths. Such dependence can be used as a basis for controlling the spin state of metallofullerenes by measuring the vibration frequencies in the far-infrared zone, which could be important for nanoelectronics and quantum informatics.

Antioxidant Potential of Aqueous Dispersions of Fullerenes C60, C70, and Gd@C82

The antioxidant potential (capacity and activity) of aqueous fullerene dispersions (AFD) of non-functionalized C60, C70, and Gd@C82 endofullerene (in micromolar concentration range) was estimated based on chemiluminescence measurements of the model of luminol and generation of organic radicals by 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP). The antioxidant capacity was estimated by the TRAP method, from the concentration of half-suppression, and from the suppression area in the initial period. All three approaches agree and show that the antioxidant capacity of AFDs increased in the order Gd@C82 < C70 < C60. Mathematical modeling of the long-term kinetics data was used for antioxidant activity estimation. The effect of C60 and C70 is found to be quenching of the excited product of luminol with ABAP-generated radical and not an actual antioxidant effect; quenching constants differ insignificantly. Apart from quenching with a similar constant, the AFD of Gd@C82 exhibits actual antioxidant action. The antioxidant activity in Gd@C82 is 300-fold higher than quenching constants.

Effects of immunopotentiators on biochemical parameters, proinflammatory cytokine, and nonspecific immune responses in Shaoxing ducklings

Antibiotics are one of the most important medical discoveries of the 20th century and will remain an essential tool for treating animal and human diseases in the 21st century. However, misuse of antibiotics imperils the development of animal husbandry and human health all over the world, and it is important to find reliable alternatives to antibiotics to reduce the use of antibiotics. In this study, 22 potential immunopotentiators were screened on the levels of apoptosis and inflammatory factor in duck embryo fibroblast cells (DEFs). The results indicated that interferon (IFN)-β and tumor necrosis factor-α gene transcriptions were significantly upregulated, while interleukin (IL)-2 and Bcl2 mRNA levels were significantly decreased during 22 immunopotentiators treatment. Besides, the expression level of IL-1β mRNA showed significant increase during dihydromyricetin, chlorogenic acid, naringin, imiquimod, thymopentin, β-D-Glucan, astragalus polysacharin, astragalus saponin I, astragalus flavone, curcumin, CpG-DNA-2, and LPS treatment. And the level of caspase 3 protein was significantly upregulated with treating chlorogenic acid, β-D-Glucan, astragalus polysacharin, astragalus flavone, curcumin, CpG-DNA-2, chicken IgG, LPS, and poly(I:C). These results indicated that chlorogenic acid, β-D-Glucan, astragalus flavone, CpG-DNA-2, and chicken IgG have the positive immune regulation effects on duck DEFs. Thus, the 5 immunopotentiators were chosen to further verify their immunomodulatory function in vivo. The results showed that the activity of serum AST was significantly downregulated during all immunopotentiators treatments excepting for β-D-Glucan, and the activities of serum IL12p40, IL-1β, IFN-α, and IFN-β were significantly increased compared with the control group. Five immunopotentiators also induced the duck's pattern recognition receptors and inflammatory factor gene expression. In addition, 5 immunopotentiators could facilitate the contents of serum caspase 3, iNOSm and COX2 and reduce the Bcl2. These results suggested that these 5 immunopotentiators could enhance duck innate immune responses. Taken together, our study not only screened out 5 kinds of duck innate immune immunopotentiators but also initially clarified their underlying mechanism of action, which provide a new insight for the development of efficient approaches to prevent the duck disease from pathogen infections.

Interactive effect of thermal and hypoxia on largemouth bass (Micropterus salmoides) gill and liver: Aggravation of oxidative stress, inhibition of immunity and promotion of cell apoptosis

High temperatures and low oxygen in aquatic environments, such as intensive aquaculture or in natural watersheds, inevitably cause stress in fish. Fish are exposed to high temperatures during the summer, which exacerbates hypoxia. Hypoxia (1.2 ± 0.2 mg/L) under 20 °C (20 HG) and 26 °C (26 HG) was simulated to induce stress in largemouth bass (Micropterus salmoides). Related enzymes and genes involved in antioxidant, immune, and apoptotic responses were selected to explore the interactive effects of temperature and hypoxia on largemouth bass. The results showed that malondialdehyde (MDA) levels in plasma, gill, and liver increased in the 26 HG (p < 0.05). Liver superoxide dismutase (SOD) activity increased in the 26 HG. Peak SOD (SOD1, SOD2, SOD3a, and SOD3b), CAT, and GSH-Px mRNA levels in the gill and liver were observed at 12-24 h of stress. The levels of gill and liver total antioxidant capacity, catalase (CAT), glutathione peroxidase (GSH-Px) activities and other enzyme activities and genes in the 26 HG were higher than those in the 20 HG (p < 0.05). The gill and liver acid phosphatase and alkaline phosphatase activities increased with time in the 26 HG (p < 0.05), while gill and liver lysozyme activities in the 26 HG were lower than those in the 20 HG (p < 0.05). Tumor necrosis factor-α mRNA level was upregulated in the gill and downregulated in the liver at 24 h in the 26 HG. Interleukin (IL)-1β and IL-8 mRNA levels were upregulated in the gill and liver in the 26 HG at 24 h, whereas IL-15 mRNA level was downregulated in the 26 HG at 12 h. Transforming growth factor-β1 mRNA level was upregulated in the gill in the 20 HG at 24 h, but downregulated in gill and liver in the 26 HG at 24 h. Similarly, IL-10, Hepcidin-1, and Hepcidin-2 showed lower expression levels in the 26 HG. Gill and liver caspase-3 activities were higher in the 26 HG (p < 0.05), and gill caspase-3 activity was higher than that in the liver. The mRNA levels of proapoptotic genes (caspase-3, caspase-8, and caspase-9) were higher in the 26 HG. The present study demonstrates the interactive effects of temperature and hypoxia on stress in largemouth bass gill and liver. These results will be helpful to understand the mechanisms of stress induced by temperature and hypoxia in fish and provide a theoretical basis for aquaculture management.

Multi-spectroscopic measurements, molecular modeling and density functional theory calculations for interactions of 2,7-dibromocarbazole and 3,6-dibromocarbazole with serum albumin

2,7-Dibromocarbazole (2,7-DBCB) and 3,6-dibromocarbazole (3,6-DBCB) are emerging environmental pollutants, being potentially high risks to human health. In this study, interactions of the two compounds with human serum albumin (HSA) and bovine serum albumin (BSA) were investigated by molecular modeling, density functional theory calculations (DFT) and multispectral techniques. The static quenching interaction deduced in the fluorescence quenching experiment is confirmed by the time-resolved analyses. The interactions of the two compounds with HSA/BSA induce molecular microenvironment and conformation changes, as assessed by synchronous and 3D fluorescence spectra, together with a destruction of polypeptide carbonyl hydrogen bond network by circular dichroism and Fourier transform infrared analyses. The thermodynamic analysis indicated that the spontaneous interaction was hydrogen bonding and hydrophobic forces. The binding constant Ka at 298 K was 3.54 × 10⁵ M^-1 in HSA-2,7-DBCB, 6.63 × 10⁵ M^-1 in HSA-3,6-DBCB, 1.32 × 10⁵ M^-1 in BSA-2,7-DBCB and 2.17 × 10⁵ M^-1 in BSA-3,6-DBCB. These results indicates that 3,6-DBCB binds HSA/BSA more strongly than 2,7-DBCB, which was estimated with DFT calculations. Site marker competition experiments coupled with molecular modeling studies confirmed that both compounds bind HSA/BSA at site I (subdomain IIA). The results suggest that interactions between 2,7-DBCB and 3,6-DBCB with HSA and BSA may affect the normal physiological activities in human and animals.

A Novel Drug Design Strategy: An Inspiration from Encaging Tumor by Metallofullerenol Gd@C82(OH)22

Cancer remains a major threat to human health worldwide. Cytotoxicity has imposed restrictions on the conventional cytotoxic drug-based chemotherapy. The rapidly-developing nanomedicine has shown great promise in revolutionizing chemotherapy with improved efficiency and reduced toxicity. Gd@C₈₂(OH)₂₂, a novel endohedral metallofullerenol, was first reported by our research group to suppress tumor growth and metastasis efficiently without obvious toxicity. Gd@C₈₂(OH)₂₂ imprisons tumors by facilitating the formation of surrounding fibrous layers which is different from chemotherapeutics that poison tumor cells. In this review, the authors first reported the antineoplastic activity of metallofullerenol Gd@C₈₂(OH)₂₂ followed by further discussions on its new anti-cancer molecular mechanism—tumor encaging. On this basis, the unparalleled advantages of nanomedicine in the future drug design are discussed. The unique interaction modes of Gd@C₈₂(OH)₂₂ with specific targeted biomolecules may shed light on a new avenue for drug design. Depending on the surface characteristics of target biomolecules, nanomedicine, just like a transformable and dynamic key, can self-assemble into suitable shapes to match several locks for the thermodynamic stability, suggesting the target-tailoring ability of nanomedicine.

The interaction between human serum albumin and antidiabetic agent - exenatide: determination of the mechanism binding and effect on the protein conformation by fluorescence and circular dichroism techniques - Part I

The interactions between transport proteins and drugs are very important from the pharmacological point of view. In this study, using fluorescence and circular dichroism (CD) techniques, we investigated the interaction between human serum albumin (HSA) and incretin antidiabetic drug - exenatide. Moreover, the effect of common metal ions (Ca²⁺, Zn²⁺, Cr³⁺) on the exenatide-HSA binding - was also described. Based on the experimental data under pseudophysiological conditions, the calculated binding constant values are on the order of 10⁴ M^-1, and the constants are lower in the presence of metal ions. We observed the increase of the hydrophobicity near the tryptophan-214 residue in subdomain IIA, but almost no change in the hydrophobicity surrounding tyrosine residues. A similar effect on the tryptophan microenvironment is influenced by metal ions. The calculated thermodynamic parameters indicated that the characteristic electrostatic and hydrophobic interactions play an important role in the albumin-exenatide complexes. The CD studies showed that exenatide does not change the secondary structure of the protein but used metal ions have some impact on albumin α-helical content.Communicated by Ramaswamy H. Sarma.

Effects of antimicrobial peptides on serum biochemical parameters, antioxidant activity and non-specific immune responses in Epinephelus coioides

Antimicrobial peptides (AMPs) are small proteins showing broad-spectrum antimicrobial activity that have been known to be powerful agents against a variety of pathogens (bacteria, fungi and viruses). In this study, the effects of AMPs from Bacillus subtilis on Epinephelus coioides were examined. E. coioides were fed with diets containing AMPs (0, 100, 200, 400 or 800 mg/kg) for four weeks. Results showed that the levels of total protein (TP), albumin (ALB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and blood glucose (GLU) and lipopolysaccharide (LPS) in the serum of E. coioides changed than those of the control group; compared to the control group, the levels of total antioxidant capacity (T-AOC), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and lysozyme (LZM) levels in E. coioides fed with different dosages AMP diets were also different; in addition, the mRNA expression of tumor necrosis factor alpha (TNF-α), interleukin-1-beta (IL-1β), and heat shock protein 90 (Hsp90) in the tissues of E. coioides were measured, the three genes in the tissues examined were significantly upregulated. The results demonstrated that diets containing AMPs can enhance the antioxidant capacity and innate immune ability of E. coioides, indicating that AMPs might be a potential alternative to antibiotics in E. coioides.