Molecular characterization of the effects of Ganoderma Lucidum polysaccharides on the structure and activity of bovine serum albumin

Investigation on the binding behavior of human α1-acid glycoprotein with Janus Kinase inhibitor baricitinib: Multi-spectroscopic and molecular simulation methodologies

Baricitinib is a Janus Kinase (JAK) inhibitor that is primarily used to treat moderately to severely active rheumatoid arthritis in adults and has recently been reported for the treatment of patients with severe COVID-19. This paper describes the investigation of the binding behavior of baricitinib to human α1-acid glycoprotein (HAG) employing a variety of spectroscopic techniques, molecular docking and dynamics simulations. Baricitinib can quench the fluorescence from amino acids in HAG through a mix of dynamic and static quenching, according to steady-state fluorescence and UV spectra observations, but it is mainly static quenching at low concentration. The binding constant (K_b) of baricitinib to HAG at 298 K was at the level of 10⁴ M^-1, indicating a moderate affinity of baricitinib to HAG. Hydrogen bonding and hydrophobic interactions conducted the main effect, according to thermodynamic characteristics, competition studies between ANS and sucrose, and molecular dynamics simulations. For the change in HAG conformation, the results of multiple spectra showed that baricitinib was able to alter the secondary structure of HAG as well as increase the polarity of the microenvironment around the Trp amino acid. Furthermore, the binding behavior of baricitinib to HAG was investigated by molecular docking and molecular dynamics simulations, which validated experimental results. Also explored is the influence of K⁺, Co²⁺, Ni²⁺, Ca²⁺, Fe³⁺, Zn²⁺, Mg²⁺ and Cu²⁺plasma on binding affinity.

Application of Molecular Simulation Methods in Food Science: Status and Prospects

Molecular simulation methods, such as molecular docking, molecular dynamic (MD) simulation, and quantum chemical (QC) calculation, have become popular as characterization and/or virtual screening tools because they can visually display interaction details that in vitro experiments can not capture and quickly screen bioactive compounds from large databases with millions of molecules. Currently, interdisciplinary research has expanded molecular simulation technology from computer aided drug design (CADD) to food science. More food scientists are supporting their hypotheses/results with this technology. To understand better the use of molecular simulation methods, it is necessary to systematically summarize the latest applications and usage trends of molecular simulation methods in the research field of food science. However, this type of review article is rare. To bridge this gap, we have comprehensively summarized the principle, combination usage, and application of molecular simulation methods in food science. We also analyzed the limitations and future trends and offered valuable strategies with the latest technologies to help food scientists use molecular simulation methods.

An updated review on the stability of anthocyanins regarding the interaction with food proteins and polysaccharides

The health benefits of anthocyanins are compromised by their chemical instability and susceptibility to external stress. Researchers found that the interaction between anthocyanins and macromolecular components such as proteins and polysaccharides substantially determines the stability of anthocyanins during food processing and storage. The topic thus has attracted much attention in recent years. This review underlines the new insights gained in our current study of physical and chemical properties and functional properties in complex food systems. It examines the interaction between anthocyanins and food proteins or polysaccharides by focusing on the "structure-stability" relationship. Furthermore, multispectral and molecular computing simulations are used as the chief instruments to explore the interaction's mechanism. During processing and storage, the stability of anthocyanins is generally influenced by the adverse characteristics of food and beverage, including temperature, light, oxygen, enzymes, pH. While the action modes and types between protein/polysaccharide and anthocyanins mainly depend on their structures, the noncovalent interaction between them is the key intermolecular force that increases the stability of anthocyanins. Our goal is to provide the latest understanding of the stability of anthocyanins under food processing conditions and further improve their utilization in food industries. Practical Application: This review provides support for the steady-state protection of active substances.

Polysaccharides in Selenium-Enriched Tea: Extraction Performance under Innovative Technologies and Antioxidant Activities

Pulsed electric fields (PEF) and ultrasonic-assisted extraction (UE) were applied to improve the extraction performance of selenium-enriched tea polysaccharides (Se−TPSs) in mild conditions. Two combined extraction processes were investigated: (1) PEF strength at 10 kV/cm followed by conventional extraction (CE) at 50 °C for 60 min and (2) PEF+UE (PEF strength at 10 kV/cm followed by UE at 400 W for 60 min). The optimal extraction yields, and energy consumption rates were obtained at 36.86% and 41.53% and 78.78 kJ/mg and 133.91 kJ/mg, respectively. The Se−TPSs were analyzed and characterized by GPC, UV, and FT-IR, which evidenced the structural stability of the Se−TPSs during the extraction processes. It was found that PEF and UE could reduce the particle size diameter of the Se−TPS extract, as well as the proportion of uronic acid. Moreover, PEF could increase the selenium content in the Se−TPS extract by 160.14% due to a lower extraction temperature compared to conventional extraction. The antioxidant activities of the Se−TPSs in vitro were investigated using OH, O2−, and ABTS+ scavenging experiments, as well as a total antioxidant ability evaluation. It was found that the antioxidant activity of the Se−TPSs obtained using PEF₂+CE₂ was relatively high due to the potential synergistic effect between the selenium and polysaccharides. Based on these results, we speculate that PEF₂+CE₂ was the best extraction process for the Se−TPSs. Furthermore, this research indicates the application of selenium-enriched tea for functional food production.

Effects of guar gum or xanthan gum addition in conjunction with pasteurization on liquid egg white

In this study, effects of varying levels of xanthan or guar gum (XG/GG, 0.05%, 0.1%, 0.2%, 0.4% and 0.8%, w/v) on the spatial structure and functional properties of egg white (EW) proteins under different pasteurization conditions of the liquid egg was evaluated. Results showed that XG could bury the aromatic ring residues and reduce the hydrophobicity of protein in EW, whereas GG could only increase the hydrophobicity. With 0.8% GG addition and pasteurization under 60℃/3.5 min, the emulsifying stability of EW was improved by nearly 100%, while with 0.8% XG addition the gel structure of EWwould become porousandloosen under each pasteurization condition. The hardness of EW gels was decreased by 90% when the concentration of XG was 0.4% or 0.8%. According to the results, the concentration of gums and the pasteurization parameters should be considered together when adding gums into the liquid egg products for pasteurization simultaneously.

Effects of ultra-high pressure treatment on structure and bioactivity of polysaccharides from large leaf yellow tea

In this study, the changes of structure and bioactivity of polysaccharides from large leaf yellow tea (LYTP) were investigated under ultra-high pressure (UHP). Native yellow tea polysaccharide were treatmented with ultra-high pressure (200, 400 and 600 MPa) for 5 min to yield yellow tea polysaccharide including 200 MPa-LYTP, 400 MPa-LYTP and 600 MPa-LYTP. It was found that the monosaccharide composition of LYTP changed significantly after the ultra-high pressure treatment. The molecular weight (Mw) of 200 MPa-LYTP (from 563.6 to 11.7 kDa), 400 MPa-LYTP (from 372.2 to 11.8 kDa) and 600 MPa-LYTP (from 344 to 11.6 kDa) sharply decreased upon ultra-high pressure treatment compared with LYTP (771.5 kDa), coincidentally particle size was also significantly reduced for 200 MPa-LYTP (23.2 %), 400 MPa-LYTP (40.2 %) and 600 MPa-LYTP (25.9 %). The results of the scanning electron microscope showed that ultra-high pressure also changed the surface and spatial morphology of LYTP. LYTP after ultra-high pressure treatment (UHP-LYTP) could further ameliorate alcohol-induced liver injury in mice. In addition, UHP treatment can more efficiently remove protein than the Sevages method. With the gradual removal of protein, its hepatoprotective effect increased. These findings demonstrated that UHP treatment could change the primary structure and spatial structure of LYTP, increase the content of acidic polysaccharides, and improve its bioactivity.

Preparation and characterization of soybean protein isolate-dextran conjugate-based nanogels

Soybean protein isolate (SPI)-dextran conjugate-based nanogels were prepared via the Maillard reaction combined with protein self-assembly in this study. The dextran molecular weight (40 kDa), SPI/dextran mass ratio (1:1.75), and incubation time (3.3 d) for preparing SPI-dextran conjugate (SDC) were firstly optimized. The SDC was confirmed by analyzing the changes in protein composition and infrared absorption bands and showed loosened tertiary conformation, reduced surface hydrophobicity, decreased Z-average hydrodynamic diameter (D_h) and zeta potential, and improved emulsifying properties compared to the native SPI. Effects of conjugate concentration, pH, heating temperature, and time on D_h and polydispersity index were also evaluated. The SDC-based nanogels were translucent in aqueous solution and exhibited a spherical core-shell structure with a D_h of ∼104.4 nm and a good stability against thermal treatment, ionic strength, and storage. Results demonstrated the SDC-based nanogels possessed a potential to be used as desirable nanocarriers for encapsulating hydrophobic bioactive compounds.

Effects of isolation conditions on structural and functional properties of the seed gum from Chinese quince (Chaenomeles sinensis)

Chinese quince seed gum (CQSG) extracted under water-, alkali- and acid- conditions at 25, 50, and 80 °C, were evaluated in terms of yield, monosaccharide composition, molecular distribution, thermal gravimetry, emulsifying stability, rheological properties, and free radical scavenging ability. The results showed that the yield of CQSG increased to 3.9% after water extraction at 80 °C. Alkali and acid treatments promoted the conversion of neutral sugars to the uronic acid branch. Regardless of the extraction temperature, the xylose chain was the main component (35%-40%); however, a reduction was observed as the extraction temperature increased to 80 °C. All CQSG solutions extracted under these isolation conditions exhibited non-Newtonian rheological behavior. Compared to water-extracted samples, the alkali-extracted samples showed the worst thermal stability, while the acid-treated samples showed the worst emulsifying stability. This study provides theoretical support for the potential application of CQSG polysaccharides in the food and pharmaceutical industries.

The interaction of folate-modified Bletilla striata polysaccharide-based micelle with bovine serum albumin

We fabricated an amphiphilic folate-modified Bletilla striata polysaccharide (FA-BSP-SA) copolymer that exhibited good biocompatibility and superior antitumor effects. This study investigated the affinity between FA-BSP-SA and bovine serum albumin (BSA) via multispetroscopic approaches. Changes in the morphology and particle size showed that FA-BSP-SA formed a blurry "protein corona". Stern-Volmer equation demonstrated that FA-BSP-SA micelles decreased the fluorescence of BSA via static quenching. The measurement results of thermodynamic parameters (entropy change, enthalpy change, and Gibbs free energy) suggested that the binding between FA-BSP-SA and BSA was spontaneous in which Van der Waals forces and hydrogen bonding played major roles. The results from synchronous fluorescence, circular dichroism, and UV spectra also revealed that BSA conformation was slightly altered by decreasing α-helical contents. In addition, the antitumor effects in vitro of Dox@FA-BSP-SA micelles and the cellular uptake behavior of micelles in 4T1 cells were decreased after incubating with BSA.

Ultrasound irradiation alters the spatial structure and improves the antioxidant activity of the yellow tea polysaccharide

In this study, the impact of ultrasound irradiation on the structural characteristics and antioxidant properties of yellow tea polysaccharides with different molecular weights (Mw) were investigated. Native yellow tea polysaccharide containing YTPS-3N, YTPS-5N and YTPS-7N were prepared through precipitation with ethanol at various concentrations of 30%, 50%, and 70%, respectively, and irradiated with high intensity ultrasound (20 kHz) for 55 min to yield yellow tea polysaccharide including YTPS-3U, YTPS-5U and YTPS-7U. The molecular weight (Mw) of YTPS-3N (from 37.7 to 15.1 kDa) and YTPS-5N (from 14.6 to 5.2 kDa) sharply decreased upon ultrasound irradiation, coincidentally particle size (Zavg) was also significantly reduced for YTPS-3N (40%), YTPS-5N (48%) and YTPS-7N (54%). The high-performance liquid chromatography and Fourier transform-infrared spectroscopy analysis revealed a partial degradation of native yellow tea polysaccharide treated with ultrasound, though the monosaccharide composition was not altered. Furthermore, changes in morphology and the breakdown of native yellow tea polysaccharide upon irradiation was confirmed with the circular dichroism spectrum, atomic force and scanning electron microscopy. As a consequence, irradiation of yellow tea polysaccharide increased free radical scavenging activity with YTPS-7U exhibiting the highest levels of 2, 2-diphenyl-1-picrylhydrazyl free radical, superoxide and hydroxyl radicals scavenging activity. These results suggest that the alteration of the spatial structure of yellow tea polysaccharide can enhance its antioxidant activity which is an important property for functional foods or medicines.

Evaluation of the interaction of novel tyrosine kinase inhibitor apatinib mesylate with bovine serum albumin using spectroscopies and theoretical calculation approaches

Apatinib mesylate (APM), a novel tyrosine kinase inhibitor, has been applied in treating various cancers. In the present study, the binding mechanism of APM with bovine serum albumin (BSA) was studied by making use of various spectroscopic and theoretical calculation approaches to provide theoretical support for further studying its pharmacokinetics and metabolism. The results from fluorescence experiments showed that the quenching mechanism of BSA induced by APM was static quenching and the APM-BSA complex with the stoichiometry of 1:1 was formed during binding reaction. Moreover, the findings also showed that the binding process of APM to BSA was spontaneous and enthalpy-driven, and the mainly driving forces were hydrogen bonding, van der Waals as well as hydrophobic interactions. From the outcomes of the competitive experiments, it can be found that the binding site was primarily nestled in sub-domain IIIA of BSA (site II) which was in line with the results of molecular docking. An appreciable decline in α-helix content of BSA can be observed from the FT-IR data, meaning that the conformational change of BSA occurred after binding with APM, this phenomenon can be corroborated by the results of UV-vis, synchronous fluorescence and 3D fluorescence studies. Furthermore, the effect of some metal ions (e.g. K⁺, Co²⁺, Ni²⁺, Fe³⁺) on the binding constant of APM to BSA was explored.Communicated by Ramaswamy H. Sarma.

Biotransformation of 5-hydroxymethylfurfural into 2,5-dihydroxymethylfuran by Ganoderma sessile and toxicological assessment of both compounds

Biotransformation has the advantages of low cost and environmental protection and is a preferred method for production of compounds. At present, most 2,5-dihydroxymethylfuran (DHMF) is synthesized by chemical methods. In this study, 12.008 μg/mL DHMF was produced from 9.045 μg/mL 5-hydroxymethylfurfural (5-HMF) with a yield of 1.33 g/g using the crude enzymes from fungus Ganoderma sessile. To elucidate the toxic potential for both compounds, cytotoxicity tests and acute toxicity were evaluated respectively. 5-HMF induced weak cytotoxicity in HCT-8, A549 and SGC-7901 cells and DHMF exerted no cytotoxicity on HCT-8 while induced inhibition proliferation of A549 and SGC-7901 cells. The acute toxicity study showed no mortality happened in any group even at the single dose of 2000 mg/kg body weight. These results suggest it is feasible to convert 5-HMF to DHMF via crude enzymes from fungus G. sessile under mild condition, and that DHMF displays a potential effect of antitumor in vitro with little acute toxicity.

Fabrication of Oleogels via a Facile Method by Oil Absorption in the Aerogel Templates of Protein-Polysaccharide Conjugates

In this study, a novel and facile method was developed to fabricate oleogels. The alginate/soy protein conjugates with excellent emulsifying activity and emulsion stability were prepared via Maillard reaction and freeze-dried to form the aerogel templates, which were then immersed in corn oil within 6 h to induce the oleogels. Compared with the alginate and soy protein solutions, the viscosity and elastic modulus G' of the conjugate solutions increased, indicating the formation of a new macromolecule and strengthened gel network from Maillard reaction. The conjugate aerogels presented the morphology of serious aggregation and conglutination but the higher elastic modulus and better thermal stability, due to the increasing covalent interactions. These aerogel templates showed a good oil absorption of up to 10.89 g/g aerogel and holding capacity of 40%. The resulting oleogels loaded with thymol showed excellent antimicrobial activities against Staphylococcus aureus and Escherichia coli. This work suggests that the fabrication of oleogels is not limited to the choice of existing oleogelators but from a wide variety of protein-polysaccharide conjugates to form the aerogel templates for oil absorption.

Chemical and rheological properties of proteoglycans from Sarcandra glabra (Thunb.) Nakai

Two proteoglycans (HPP and LPP) with different ratios of protein/polysaccharide were extracted from S. glabra. The chemical compositions, relative average molecular weights, monosaccharide compositions, FT-IR spectra, and rheological properties of the two proteoglycans were determined. The results exhibited that the two proteoglycans had pseudoplastic fluids properties and displayed shear-thinning behavior. The apparent viscosity of the two proteoglycans both increased with increasing concentrations. The temperature had different effects on the viscosity of the two proteoglycans. As temperature increased from 25 to 85 °C, the viscosity of LPP descended while the HPP's viscosity rose first and then dropped slightly. The effects of CaCl₂ addition on the two samples were like that of the temperature. The viscosities of HPP and LPP had different tolerances to acidity and alkalinity. HPP solution was more sensitive to pH changes due to its high protein content. The addition of sucrose increased the viscosities of samples. The modulus G' and G″ of HPP and LPP were increased with the increase of oscillation frequency, while the crossover points of G' and G″ values decreased with the increasing concentrations of HPP and LPP. The above data presented that the two proteoglycans could be promising candidates for food industries and pharmacological applications.

An overview of fungal glycan-based therapeutics

Edible medicinal mushrooms have been traditionally used for health promotion and longevity in China and other East Asian countries for centuries. Structural and pharmacological studies revealed that fungal glycans show multiple physiological and healthy promoting effects including immunomodulation, anti-tumor, anti-aging, anti-oxidation, hypoglycemic, hypolipidemic, anti-radiation, and other effects. Fungal glycans isolated from different kinds of medicinal mushrooms are partially purified and clinically tested. Without serious safety concerns of mostly glycans from edible mushrooms and/or the cultured mycelium, eight of them are approved by Chinese Food and Drug Administration (SFDA) and used clinically in China since 1980s. In this chapter, 185 independent studies involving in biochemical, pharmacological and clinical studies of fungal glycans during the past four decades (1977-2019) from PubMed, CNKI (China National Knowledge Infrastructure) and Wanfang databases are summarized. In future, understanding the fungal glycan-based drugs at molecular biological level would be needed to comprehend the clinical efficacy of glycan-based drugs.