Orcinol Glucoside Loaded Polymer - Lipid Hybrid Nanostructured Lipid Carriers: Potential Cytotoxic Agents against Gastric, Colon and Hepatoma Carcinoma Cell Lines.

PURPOSE: Orcinol glucoside (OG) - loaded nanostructured lipid carrier (NLC), coated with polyethylene glycol-25/55-stearate (PEG-25/55-SA), were explored for delivering OG to improve in vitro cytotoxicity against gastrointestinal tract (GIT), colon and hepatoma carcinoma cell lines. It is being expected that the PEGylated formulations would possess the sustainability in withstanding the adverse physiological extremities like the most significant metabolic activities and phase I / II enzymatic activities in the intestines. METHODS: NLCs were prepared using tristearin, oleic acid and PEG-25/55-stearate by hot homogenization-ultrasonic dispersion; characterized by DLS, TEM, SEM, AFM, entrapment efficiency and drug loading capacity studies. RESULTS: NLC diameter ranged from 160 to 230 nm with negative zeta potential of -8 to -20 mV. TEM/SEM and AFM studies suggest spherical and smooth surface morphologies. Differential scanning calorimetry studies reveal the loss of crystallinity when OG was incorporated into the NLC. NLCs showed initial burst release, followed by sustained release of OG. PEG-NLC exhibited superior anticancer activity against GIT and also in hepatoma cancer cell lines. CONCLUSIONS: This is the first report demonstrating a practical approach for possible oral delivery of OG in GIT and targeting hepatoma cancer, warranting further in vivo studies for superior management of GIT cancer.

Effect of cationic dendrimer on membrane mimetic systems in the form of monolayer and bilayer.

Interactions between a zwitterionic phospholipid, 1, 2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) and four anionic phospholipids dihexadecyl phosphate (DHP), 1, 2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG), 1, 2-dipalmitoyl-sn-glycero-3-phosphate (DPP) and 1, 2-dipalmitoyl-sn-glycero-3-phospho ethanol (DPPEth) in combination with an additional amount of 30 mol% cholesterol were separately investigated at air-buffer interface through surface pressure (π) - area (A) measurements. π-A isotherm derived parameters revealed maximum negative deviation from ideality for the mixtures comprising 30 mol% anionic lipids. Besides the film functionality, structural changes of the monomolecular films at different surface pressures in the absence and presence of polyamidoamine (PAMAM, generation 4), a cationic dendrimer, were visualised through Brewster angle microscopy and fluorescence microscopic studies. Fluidity/rigidity of monolayers were assessed by surface dilatational rheology studies. Effect of PAMAM on the formation of adsorbed monolayer, due to bilayer disintegration of liposomes (DPPC:anionic lipids= 7:3 M/M, and 30 mol% cholesterol) were monitored by surface pressure (π) - time (t) isotherms. Bilayer disintegration kinetics were dependent on lipid head group and chain length, besides dendrimer concentration. Such studies are considered to be an in vitro cell membrane model where the alteration of molecular orientation play important roles in understanding the nature of interaction between the dendrimer and cell membrane. Liposome-dendrimer aggregates were nontoxic to breast cancer cell line as well as in doxorubicin treated MDA-MB-468 cell line suggesting their potential as drug delivery systems.

Dendrimer Induced Bilayer Disintegration of Hybrid Vesicles.

Physicochemical investigations on the inclusion of anionic polyamidoaminesuccinamic acid dendrimer, generation 5 (PAMAM-SA, G5) with positively charged hybrid vesicles (HCV), prepared using soylecithin, ion pair amphiphile (IPA), cholesterol and dihexadecyldimethylammonium bromide, were investigated by dynamic light scattering, transmission electron/atomic force microscopy (TEM/AFM), differential scanning calorimetry, fluorescence spectroscopy and surface pressure-time isotherm studies. Adsorption of dendrimer onto vesicle surface and subsequent bilayer disruption strongly depends on the bilayer composition and dendrimer concentration. Change in the zeta potential value with increasing dendrimer concentration suggests the dendrimer-vesicle interaction to be electrostatic in nature. AFM studies also confirm the adsorption of dendrimer as well as hole formation in the bilayer. Impact of the inclusion of dendrimer into the bilayer were further investigated through differential scanning calorimetry by monitoring the chain melting temperature and enthalpy of the chain melting processes. Dendrimer at low concentration does not alter bilayer integrity, while hole formations are noted at higher dendrimer concentration. Fluorescence anisotropy studies confirm the adsorption and subsequent bilayer disruption due to dendrimer inclusion. Dendrimer induced vesicle disintegration kinetics conclusively illustrate the transformation of cationic bilayer to monolayer and thereby exposing the role of IPA. In vitro cytotoxicity studies on PAMAM-SA, G5 and HCVs mixtures against human breast cancer cell line suggest that dendrimer-liposome aggregates (dendriosomes) exhibit substantial anticancer activities with insignificant side effects. It is expected that the dendriosomes may have application to host and deliver anticancer drug in the field of targeted drug delivery.

Influence of Lipid Composition, pH, and Temperature on Physicochemical Properties of Liposomes with Curcumin as Model Drug.

The physicochemical properties of large unilamellar vesicles (LUVs) were assessed with respect to lipid composition, pH, time, and temperature by monitoring their size, zeta potential, drug payload, and thermal behavior. A conventional thin film hydration technique was employed to prepare liposomes from soy phosphatidylcholine (SPC), dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylglycerol (DPPG), and a 7:3 (M/M) mixture of DPPC+DPPG along with 30 mole% cholesterol in each combination. While the size of liposomes depended on lipid composition, pH and temperature, the zeta potential was found to be independent of the pH of the medium, although it varied with liposome type. Spherical morphology and bilayer were observed by electron microscopy. The phase transition temperature increased with decreasing pH. Membrane micro-viscosity showed the highest value for SPC, and membrane rigidity increased with increasing pH. The entrapment efficiency of liposomes with reference to curcumin was as follows: DPPC>DPPC+DPPG>DPPG>SPC. Sustained release of curcumin was observed for all liposomes. Curcumin-loaded liposomes exhibited substantial antibacterial activity against the gram-positive bacteria Bacillus amyloliquefaciens. Additional studies are needed to improve the understanding of the effect of formulation variables on the physicochemical stability of liposomes.

Effects of Fatty Acids on the Interfacial and Solution Behavior of Mixed Lipidic Aggregates Called Solid Lipid Nanoparticles.

Mutual miscibility of soylecithin, tristearin, fatty acids (FAs), and curcumin was assessed by means of surface pressure-area isotherms at the air-solution interface in order to formulate modified solid lipid nanoparticles (SLN). Appearance of minima in the excess area (Aex) and changes in free energy of mixing (∆G(0)ex) were recorded for systems with 20 mole% FAs. Modified SLNs, promising as topical drug delivery systems, were formulated using the lipids in combination with curcumin, stabilized by an aqueous Tween 60 solution. Optimal formulations were assessed by judiciously varying the FA chain length and composition. Physicochemical properties of SLNs were studied such as the size, zeta potential (by dynamic light scattering), morphology (by freeze fracture transmission electron microscopy), and thermal behavior (by differential scanning calorimetry). The size and zeta potential of the formulations were in the range 300-500 nm and -10 to -20 mV, respectively. Absorption and emission spectroscopic analyses supported the dynamic light scattering and differential scanning calorimetry data and confirmed localization of curcumin to the palisade layer of SLNs. These nanoparticles showed a sustained release of incorporated curcumin. Curcumin-loaded SLNs were effective against a gram-positive bacterial species, Bacillus amyloliquefaciens. Our results on the physicochemical properties of curcumin-loaded SLNs, the sustained release, and on antibacterial activity suggest that SLNs are promising delivery agents for topical drugs.

Ion-pair amphiphile: a neoteric substitute that modulates the physicochemical properties of biomimetic membranes.

Ion-pair amphiphiles (IPAs) are neoteric pseudo-double-tailed compounds with potential as a novel substitute of phospholipid. IPA, synthesized by stoichiometric/equimolar mixing of aqueous solution of hexadecyltrimethylammonium bromide (HTMAB) and sodium dodecyl sulfate (SDS), was used as a potential substituent of naturally occurring phospholipid, soylecithin (SLC). Vesicles were prepared using SLC and IPA in different ratios along with cholesterol. The impact of IPA on SLC was examined by way of surface pressure (π)-area (A) measurements. Associated thermodynamic parameters were evaluated; interfacial miscibility between the components was found to depend on SLC/IPA ratio. Solution behavior of the bilayers, in the form of vesicles, was investigated by monitoring the hydrodynamic diameter, zeta potential, and polydispersity index over a period of 100 days. Size and morphology of the vesicles were also investigated by electron microscopic studies. Systems comprising 20 and 40 mol % IPA exhibited anomalous behavior. Thermal behavior of the vesicles, as scrutinized by differential scanning calorimetry, was correlated with the hydrocarbon chain as well as the headgroup packing. Entrapment efficiency (EE) of the vesicles toward the cationic dye methylene blue (MB) was also evaluated. Vesicles were smart enough to entrap the dye, and the efficiency was found to vary with IPA concentration. EE was found to be well above 80% for some stable dispersions. Such formulations thus could be considered to have potential as novel drug delivery systems.