muramidase and naringenin

The present study applied steady-state fluorescence, UV-Vis spectrophotometry, molecular docking studies, and circular dichroism (CD) to investigate the interaction of naringenin with lysozyme in an aqueous medium. The UV-Vis measurement indicated the changes in lysozyme secondary and tertiary structure change as a function of the concentration of naringenin. Naringenin could be used to turn the static quenching mechanism into the intrinsic fluorescence of lysozyme. The negative amount of Gibbs free energy (ΔG°) suggested that the binding operation was spontaneous. Fluorescence studies also demonstrated the changes occurring in the Trp microenvironment upon the concatenation into lysozyme. Analysis of thermodynamic parameters also revealed that hydrophobic forces played a fundamental role in determining the complex stability; this was consistent with the previous modeling studies. Circular dichroism also suggested that the alpha-helicity of lysozyme was enhanced as ligand was bound. Naringenin inhibited lysozyme enzymatic activity, displaying its affinity with the lysozyme active site. Further, molecular docking studies demonstrated that naringenin could bind to both residues essential for catalytic activity in the proximity of Trp 62 and Trp 63.

Topics: Binding Sites; Circular Dichroism; Flavanones; Molecular Docking Simulation; Muramidase; Protein Binding; Spectrometry, Fluorescence; Thermodynamics

The main scope of the present study was to analyze the membrane interaction of members of different classes of polyphenols, i.e. resveratrol, naringenin, epigallocatechin gallate and enterodiol, in model systems of different compositions and phase states. In addition, the possible association between membrane affinity and membrane protection against both lipid oxidation and bilayer-disruptive compounds was studied. Gibbs monolayer experiments indicated that even though polyphenols showed poor surface activity, it readily interacted with lipid films. Actually, a preferential interaction with expanded monolayers was observed, while condensed and cholesterol-containing monolayers decreased the affinity of these phenolic compounds. On the other hand, fluorescence anisotropy studies showed that polyphenols were able to modulate membrane order degree, but again this effect was dependent on the cholesterol concentration and membrane phase state. In fact, cholesterol induced a surface rather than deep into the hydrophobic core localization of phenolic compounds in the membranes. In general, the polyphenolic molecules tested had a better antioxidant activity when they were allowed to get inserted into the bilayers, i.e. in cholesterol-free membranes. On the other hand, a membrane-protective effect against bilayer permeabilizing activity of lysozyme, particularly in the presence of cholesterol, could be assessed. It can be hypothesized that phenolic compounds may protect membrane integrity by loosely covering the surface of lipid vesicles, once cholesterol push them off from the membrane hydrophobic core. However, this cholesterol-driven distribution may lead to a reduced antioxidant activity of linoleic acid double bonds.

Topics: 1,2-Dipalmitoylphosphatidylcholine; Antioxidants; Catechin; Cholesterol; Dimyristoylphosphatidylcholine; Flavanones; Fluorescence Polarization; Hydrophobic and Hydrophilic Interactions; Lignans; Linoleic Acid; Lipid Bilayers; Lipid Peroxidation; Liposomes; Muramidase; Reactive Oxygen Species; Resveratrol; Stilbenes; Surface Properties

The expectorant activity of naringenin was studied. Mucus secretion was evaluated in mice by measuring the tracheal output of phenol red. Mucociliary movement function was investigated using a migration method of carbon granules in unanesthetized pigeons. And the effect of naringenin on the secretion of mucin and lysozyme was performed in the rat tracheal ring explants. Naringenin could significantly increase the secretion of phenol red from mouse tracheas at the doses of 30-67 mg/kg (i.g.) (P<0.05). Naringenin, at the dose of 90 mg/kg, increased the tracheal mucociliary velocity (TMV) to 144.4% of control (P<0.01). 100 microM naringenin could enhance the basal lysozyme secretion, but had no effect on the basal mucin secretion from the rat tracheal ring explants. Treatment with naringenin at higher concentration (10 micromol/l) could inhibit the 100 ng/ml lipopolysaccharide (LPS)-induced mucin increase. These data suggest, therefore, that naringenin has the expectorant activity.

Topics: Animals; Columbidae; Dose-Response Relationship, Drug; Expectorants; Female; Flavanones; In Vitro Techniques; Male; Mice; Mucins; Mucociliary Clearance; Muramidase; Rats; Trachea