morin and Hemolysis

Streptococcus pneumoniae (pneumococcus) is an important causative agent of acute invasive and non-invasive infections. Pneumolysin is one of a considerable number of virulence traits produced by pneumococcus that exhibits a variety of biological activities, thus making it a target of small molecule drug development. In this study, we aimed to evaluate the effect of morin, a natural compound that has no antimicrobial activity against S. pneumonia, is a potent neutralizer of pneumolysin-mediated cytotoxicity and genotoxicity by impairing oligomer formation, and possesses the capability of mitigating tissue damage caused by pneumococcus. These findings indicate that morin could be a potent candidate for a novel therapeutic or auxiliary substance to treat infections for which there are inadequate vaccines and that are resistant to traditional antibiotics.

Topics: A549 Cells; Animals; Bacterial Proteins; Biopolymers; Female; Flavonoids; Hemolysis; Humans; Mice; Mice, Inbred C57BL; Microbial Sensitivity Tests; Streptococcus pneumoniae; Streptolysins

To investigate the mechanism by which morin hydrate inhibits the haemolytic activity of α-hemolysin (Hla), a channel-forming toxin that is important for the pathogenesis of disease in experimental animals, and its therapeutic effect against Staphylococcus aureus pneumonia in a mouse model.. The results from the in vitro (haemolysis, western blot and cytotoxicity assays) and in vivo (mouse model of intranasal lung infection) experiments indicated that morin hydrate, a natural compound with little anti-Staph. aureus activity, could effectively antagonize the cytolytic activity of Hla, alleviate human lung cell injury, and protect against mortality of Staph. aureus pneumonia in a mouse model of infection. Molecular dynamics simulations, free energy calculations and mutagenesis assays were further employed to determine the catalytic mechanism of inhibition, which indicated that a direct binding of morin to the 'Stem' domain of Hla (residues I107 and T109) and the concomitant change in conformation led to the inhibition of the self-assembly of the heptameric transmembrane pore, thus inhibiting the biological activity of Hla for cell lysis.. Morin inhibited Staph. aureus virulence via inhibiting the haemolytic activity of α-hemolysin.. These findings suggested that morin is a promising candidate for the development of anti-virulence therapeutic agents for the treatment of Staph. aureus infections.

Topics: Animals; Anti-Bacterial Agents; Bacterial Toxins; Flavonoids; Hemolysin Proteins; Hemolysis; Humans; Lung; Mice; Pneumonia, Staphylococcal; Staphylococcus aureus; Virulence

The influence of novel synthetic and plant origin flavonoids on activity of multidrug resistance-associated protein (MRP1) was investigated in human erythrocytes used as a cell model expressing MRP1 in plasma membrane. The fluorescent probe, BCPCF (2', 7'-bis-(3-carboxy-propyl)-5-(and-6)-carboxyfluorescein), was applied as a substrate for MRP1 multidrug resistance transporter. The effect of compounds belonging to different classes of natural flavonoids: flavone, flavonol, isoflavones and flavanolignan was compared with action of new synthetic derivatives of genistein. Most of the flavonoids showed strong or moderate ability to inhibit transport carried out by MRP1. Inhibitory properties of flavonoids were compared to the effects of indomethacin, probenecid and MK-571 known as MRP1 inhibitors. Studying the influence of new synthetic genistein derivatives on BCPCF transport we have found that the presence of hydrophobic groups substituting hydrogen of hydroxyl group at the position 4' in ring B of isoflavone is more important for inhibitory properties than hydrophobic substitution at the position 7 in ring A. In case of naturally occurring isoflavones the replacement of hydrogen at position 4' by hydrophobic ring structure seems also to be favourable for inhibition potency.

Topics: Dose-Response Relationship, Drug; Erythrocytes; Flavonoids; Fluoresceins; Genistein; Hemolysis; Humans; Indomethacin; Multidrug Resistance-Associated Proteins; Plants; Propionates; Protein Transport; Quinolines; Silybin; Silymarin

To investigate the effects of flavonoids on free radical-mediated biological membrane damage and the interaction of flavonoids with heme proteins, we studied the effects of quercetin, its glycosides (rutin and quercetin-3-O-glucoside), morin and (-)epicatechin on the hemolysis of the bovine erythrocytes induced by the hydrophilic free radical initiator, 2,2'-azobis(2-amidinopropane)dihydrochloride (AAPH), and their interaction with hemoglobin. These flavonoids retarded the onset of the hemolysis dose-dependently. The effects of quercetin and other flavonoids were much greater than those of dihydric-phenols studied previously. The inhibitory effects of quercetin and its glycosides were stronger than those of morin and (-)epicatechin. In the absence of AAPH, the relatively hydrophobic flavonoids quercetin and morin induced the oxidation of oxyhemoglobin to methemoglobin. Oxidation by quercetin was especially marked. However, this oxidation did not induce hemolysis. These findings indicate that relatively hydrophobic flavonoids penetrate the cytoplasm of erythrocytes, interact with hemoglobin, and oxidize the heme iron.

Topics: Enzyme Inhibitors; Erythrocytes; Flavonoids; Free Radical Scavengers; Glycosides; Hemoglobins; Hemolysis; Hydrophobic and Hydrophilic Interactions; Methemoglobin; Oxidation-Reduction; Oxyhemoglobins; Quercetin; Spectrophotometry, Ultraviolet; Time Factors