betadex and fluorexon

OSW-1 is a structurally unique steroidal saponin isolated from the bulbs of Ornithogalum saundersiae, and has exhibited highly potent and selective cytotoxicity in tumor cell lines. This study aimed to investigate the molecular mechanism for the membrane-permeabilizing activity of OSW-1 in comparison with those of other saponins by using various spectroscopic approaches. The membrane effects and hemolytic activity of OSW-1 were markedly enhanced in the presence of membrane cholesterol. Binding affinity measurements using fluorescent cholestatrienol and solid-state NMR spectroscopy of a 3-d-cholesterol probe suggested that OSW-1 interacts with membrane cholesterol without forming large aggregates while 3-O-glycosyl saponin, digitonin, forms cholesterol-containing aggregates. The results suggest that OSW-1/cholesterol interaction is likely to cause membrane permeabilization and pore formation without destroying the whole membrane integrity, which could partly be responsible for its highly potent cell toxicity.

Topics: Antineoplastic Agents, Phytogenic; beta-Cyclodextrins; Biological Transport; Cholestenones; Cholesterol; Digitonin; Dimyristoylphosphatidylcholine; Erythrocyte Membrane; Fluoresceins; Glycyrrhizic Acid; Hemolysis; Humans; Membrane Lipids; Oleanolic Acid; Ornithogalum; Phosphatidylcholines; Saponins; Unilamellar Liposomes

Topics: Adamantane; beta-Cyclodextrins; Biomimetics; Cell Membrane; Fluoresceins; Fluorescent Dyes; Imines; Models, Molecular; Molecular Structure; Particle Size; Polyethylenes; Surface Properties

pH-sensitive microgels were prepared by crosslinking carboxymethylcellulose (CMC) and polymeric beta-cyclodextrin (PbetaCD) using (2-hydroxyethyl)trimethylammonium chloride benzoate (TMACB) as a crosslinker. PbetaCD was prepared by reacting epichlorohydrin and beta-CD in an aqueous phase (NaOH solution, 30% (w/w)). TMACB will interact with CMC by an electrostatic interaction and it will also interact with PbetaCD by a hydrophobic interaction. The size of microgel was tens of nanometers to several micrometers. The degree of calcein release in 24h from the microgels was as low as 23% at pH 8.0. The degree of release at pH 3.0 was almost 100%. The carboxyl groups of CMC will lose their charge in an acidic condition and they would lose their ability to form salt bridges with TMACB, leading to the disintegration of microgels. The degree of release at pH 11, about 47%, was less than the value at pH 3.0 but it was greater than the value at pH 8.0. The CMC will be strongly electrostatically charged in the alkali condition, so the microgels would swell due to the electrostatic repulsion among CMC molecules, which could promote the release of their contents.

Topics: beta-Cyclodextrins; Carboxymethylcellulose Sodium; Chemistry, Pharmaceutical; Cross-Linking Reagents; Drug Carriers; Fluoresceins; Gels; Hydrogen-Ion Concentration; Hydrophobic and Hydrophilic Interactions; Particle Size; Quaternary Ammonium Compounds; Salts; Static Electricity

Adhesion is an important virulence function for Entamoeba histolytica, the causative agent of amoebic dysentery. Lipid rafts, cholesterol-rich domains, function in compartmentalization of cellular processes. In E. histolytica, rafts participate in parasite-host cell interactions; however, their role in parasite-host extracellular matrix (ECM) interactions has not been explored. Disruption of rafts with a cholesterol extracting agent, methyl-beta-cyclodextrin (MbetaCD), resulted in inhibition of adhesion to collagen, and to a lesser extent, to fibronectin. Replenishment of cholesterol in MbetaCD-treated cells, using a lipoprotein-cholesterol concentrate, restored adhesion to collagen. Confocal microscopy revealed enrichment of rafts at parasite-ECM interfaces. A raft-resident adhesin, the galactose/N-acetylgalactosamine-inhibitable lectin, mediates interaction to host cells by binding to galactose or N-acetylgalactosamine moieties on host glycoproteins. In this study, galactose inhibited adhesion to collagen, but not to fibronectin. Together these data suggest that rafts participate in E. histolytica-ECM interactions and that raft-associated Gal/GalNAc lectin may serve as a collagen receptor.

Topics: Animals; beta-Cyclodextrins; Cell Adhesion; Cholesterol; Collagen; Dose-Response Relationship, Drug; Entamoeba histolytica; Epithelial Cells; Extracellular Matrix; Fibronectins; Fluoresceins; Fluorescent Dyes; Galactose; Humans; Lectins; Lectins, C-Type; Membrane Microdomains; Membrane Proteins; Microscopy, Confocal; Receptors, Cell Surface

Liposome stability during incubation in presence of cyclodextrins (CDs) is studied. Dried-rehydrated vesicle (DRV), multilamellar vesicle (MLV) and small unilamellar vesicle (SUV) calcein-encapsulating liposomes, composed of different lipids are formulated, and retention of calcein is followed during vesicle incubation in hydroxypropyl-beta-CD (HP beta-CD), HP gamma-CD or methyl-beta-CD (Me beta-CD), for 24h. Results demonstrate that liposome integrity in cyclodextrins is affected by lipid composition and type. For the same lipid composition calcein release from vesicles is faster in the order: MLV > DRV > SUV. Me beta-CD influences liposome stability most, compared to the other CD's studied. Vesicles composed of saturated phospholipids were found more stable compared to phosphatidyl-choline (PC) liposomes, suggesting that phospholipid saturation and membrane rigidity influences the interaction between liposomal-lipids and CD molecules. Chol (cholesterol) addition in lipid membrane improves PC-liposome integrity, but has opposite or no effect on liposomes consisting of saturated lipids. Decrease of vesicle dispersion turbidity and size distribution in presence of CD, implies that Me beta-CD induces vesicle disruption and solubilization (to micelles). Turbidity measurements confirm that DRV liposomes are affected more than SUV.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; beta-Cyclodextrins; Chemistry, Pharmaceutical; Cholesterol; Cyclodextrins; Drug Compounding; Excipients; Fluoresceins; Fluorescent Dyes; gamma-Cyclodextrins; Lipids; Liposomes; Membrane Fluidity; Nanotechnology; Nephelometry and Turbidimetry; Particle Size; Phosphatidylcholines; Solubility; Technology, Pharmaceutical; Time Factors