Glycolipids from a colloid chemical point of view

Polymeric chitosan-glycolipid nanocarriers for an effective delivery of marine carotenoid fucoxanthin for induction of apoptosis in human colon cancer cells (Caco-2 cells)

Fucoxanthin (FUCO), a marine carotenoid is photo-, and thermo-labile and poorly bioavailable due to its lipophilicity. Hence, we developed a chitosan (CS) + glycolipid (GL) nanogels (NGs) to increase cellular uptake and anticancer efficacy of FUCO (10 μM) in human colon cells (Caco-2). Effect of FUCO loaded in NGs with/with no GL was studied in comparison with micellar FUCO. Results showed that the cell viability was lower (p < 0.05) in NGs + GL (50.5%) compared to NGs (-GL) (66.5%) and the mixed micelles (72.5%) groups over 48 h exposure. An enhanced reactive oxygen species (ROS) generation was evident in NGs + GL (379.2%) group compared to NGs (-GL) and mixed micelles groups. Further, induction of apoptosis with an increased chromatin condensation and DNA fragmentation as evidenced in DAPI staining and DNA ladder assay were higher in NGs + GL group than other groups. Down-regulation of Bcl-2 (6.6 folds) was higher in NGs + GL group compared to NGs (-GL) (1.94 fold) and mixed micelles (1.19 fold) groups. Higher Bax up-regulation in NGs + GL compared to other groups supports the Bcl-2 down regulation. Mitochondrial membrane polarisation (ΔΨ_m) was higher in NGs + GL group (2.46 fold) compared to NGs (-GL) (1.91 fold) and mixed micelles (1.26 fold) groups. The cellular FUCO uptake illustrated a positive correlation between its level (pmol/10⁶ cells) in NGs + GL (758.3) and enhanced caspase-3 activity (25.8 folds). This could be the reason for an increased apoptotic activity in NGs + GL group than other groups. Results demonstrate that delivery of FUCO in NGs + GL carrier aids cellular uptake and chemotherapeutic potential of FUCO. Results further demonstrate, for the first time, higher anti-cancer activity of FUCO loaded in NGs + GL and the effect was through ROS generation via a caspase dependent mechanism in Caco-2 cells.

Exploring the meaning of sugar configuration in a supramolecular environment: comparison of six octyl glycoside micelles by ITC and NMR spectroscopy

To promote understanding of sugar configuration in a supramolecular context, glycomicelles were compared and a “trinity projection” of glycosides proposed.

Bis-triazologlycolipid mimetics – low molecular weight organogelators

A facile regioselective synthesis of bis-triazologlycolipids, a class of organogelators, has been accomplished by “Click reaction”. The morphology and self-assembly of the gelators were examined by FESEM and HRTEM analysis.

Establishing the feasibility of using β-glucosidase entrapped in Lentikats and in sol-gel supports for cellobiose hydrolysis

β-Glucosidases represent an important group of enzymes due to their pivotal role in various biotechnological processes. One of the most prominent is biomass degradation for the production of fuel ethanol from cellulosic agricultural residues and wastes, where the use of immobilized biocatalysts may prove advantageous. Within such scope, the present work aimed to evaluate the feasibility of entrapping β-glucosidase in either sol-gel or in Lentikats supports for application in cellobiose hydrolysis, and to perform the characterization of the resulting bioconversion systems. The activity and stability of the immobilized biocatalyst over given ranges of temperature and pH values were assessed, as well as kinetic data, and compared to the free form, and the operational stability was evaluated. Immobilization increased the thermal stability of the enzyme, with a 10 °C shift to an optimal temperature in the case of sol-gel support. Mass transfer hindrances as a result of immobilization were not significant, for sol-gel support. Lentikats-entrapped glucosidase was used in 19 consecutive batch runs for cellobiose hydrolysis, without noticeable decrease in product yield. Moreover, encouraging results were obtained for continuous operation. In the overall, the feasibility of using immobilized biocatalysts for cellobiose hydrolysis was established.

Antioxidant properties of ganglioside micelles

Antioxidant activity of gangliosides GM1 and GT1b in the Fenton type of reaction was investigated by EPR spectroscopy using DMPO as a spin trap. Hydroxyl radical spin adduct signal intensity was significantly reduced in the presence of gangliosides at their micellar concentrations. Mean micellar hydrodynamic diameter was not changed, whereas significant changes in negative Zeta potential values were observed as evidenced by Zetasizer Nano ZS. This study showed that the primary mode of ganglioside action was not due to direct scavenging of OH., but rather to the inhibition of hydroxyl radical formation. This phenomenon is related to the ability of ganglioside micelles to bind oppositely charged ferrous ions, thus reducing their concentration and consequently inhibiting OH. formation.

Integration of ganglioside GT1b receptor into DPPE and DPPC phospholipid monolayers: an X-ray reflectivity and grazing-incidence diffraction study

Using synchrotron grazing-incidence x-ray diffraction (GIXD) and reflectivity, the in-plane and out-of-plane structures of mixed-ganglioside GT(1b)-phospholipid monolayers were investigated at the air-liquid interface and compared with monolayers of the pure components. The receptor GT(1b) is involved in the binding of lectins and toxins, including botulinum neurotoxin, to cell membranes. Monolayers composed of 20 mol % ganglioside GT(1b), the phospholipid dipalmitoyl phosphatidylethanolamine (DPPE), and the phospholipid dipalmitoyl phosphatidylcholine (DPPC) were studied in the gel phase at 23 degrees C and at surface pressures of 20 and 40 mN/m, and at pH 7.4 and 5. Under these conditions, the two components did not phase-separate, and no evidence of domain formation was observed. The x-ray scattering measurements revealed that GT(1b) was intercalated within the host DPPE/DPPC monolayers, and slightly expanded DPPE but condensed the DPPC matrix. The oligosaccharide headgroups extended normally from the monolayer surfaces into the subphase. This study demonstrated that these monolayers can serve as platforms for investigating toxin membrane binding and penetration.

Simultaneous analysis of glycolipids and phospholids molecular species in avocado (Persea americana Mill) fruit

The molecular species of phospholipids (PLs) and glycolipids (GLs) were simultaneously characterized in the pulp and almond of the avocado fruit (Persea americana Mill) of four varieties by means of high performance liquid chromatography-electrospray ionisation ion-trap tandem mass spectrometry. In the pulp, the predominant species of monoglycosyldiglycerides (MGD) were m/z 796.6 (oleic/linolenic and linoleic/linoleic acids) and m/z 800.4 (stearic/linoleic and oleic/oleic acids). One of the main diglycosyldiglycerides (DGD) both in the pulp and almond was m/z 958.5 (oleic/linolenic); however, the pulp was also rich of m/z 962.4 (oleic/oleic), whereas in the almond, m/z 934.5 (palmitic/linoleic and palmitoleic/oleic) and m/z 960.5 (oleic/linoleic and stearic/linolenic) were more abundant. In the almond, the main PL classes (phosphatidic acid (PA), phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI)) contained always palmitic/linoleic acids. Alpha-linolenic acid was contained as MGD (linolenic/linolenic) and DGD (linolenic/linolenic), more present in the pulp than in the almond. The major molecular species of glycocerebrosides (GCer) in the pulp and almond carried hydroxy-palmitic acid (C(16h:0))/4,8-sphyngadienine (d(18:2)).