Lipid nanoparticles coated with chitosan using a one-step association method to target rifampicin to alveolar macrophages.

This work proposes the development and characterization of solid lipid nanoparticles (SLNs) loaded with rifampicin (RIF) aiming to enhance mucoadhesion of the SLNs and consequently internalization by the alveolar macrophages (AMs). The lipid nanoparticles (NPs) were characterized and the results showed that the NPs obtained present a spherical or a starry shape with diameter around 250-500 nm, a monodisperse population, with zeta potential between -31 mV for uncoated SLNs and +33 mV for coated SLNs. The drug EE was approximately 90 % and the loading capacity (LC) 4.5 %. The SLNs coated with chitosan by the association method (aC-SLNs) show an effective mucoadhesive profile, verified by the turdimetry and surface loading method, corroborated with the cellular assays. The presence of chitosan in the aC-SLNs promotes higher mucoadhesive properties to the NPs and permeability in A549, suggesting that the safe aC-SLNs-RIF can be used as a promising drug delivery system for improving tuberculosis treatment.

pH-responsive chitosan based hydrogels affect the release of dapsone: Design, set-up, and physicochemical characterization.

Dapsone (DAP) is a bactericidal agent used in the treatment of leprosy, caused by Mycobacterium leprae. Despite its therapeutic potential, DAP has low solubility, which results in allow therapeutic index and a high microbial resistance. Recently, new approaches were used to increase the DAP solubility. In particular, the use of interpenetrating polymer network (IPN)-hydrogels based chitosan (CS) for the controlled release of DAP provides some advantages because they can modify their swelling properties and network structures as a response to environmental stimuli. The aim of this study was to synthesize and physicochemically characterize pH-responsive chitosan/polymer hydrogels to control the release of DAP. For this reason, different combination of polymers, such as polyvinyl pyrrolidone, polyethylene glycol and hydroxypropyl methylcellulose, and concentrations of the cross-linking agents (glutaraldehyde) were used and then blended to the CS. The resulting hydrogels were evaluated in terms of physicochemical and swelling properties, rheological analysis and in vitro release of DAP at different pHs (1.2-6.8). Hydrogels were further characterized by Fourier transformed infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM) analysis. pH-responsive DAP-loaded hydrogels may represent the set-up for developing potential oral formulations for the treatment of leprosy caused by Mycobacterium leprae.

Mucoadhesive chitosan-coated solid lipid nanoparticles for better management of tuberculosis.

Taking into consideration the potential mucoadhesion properties of systems in lung delivery, this paper describes the preparation and characterization of chitosan-coated solid lipid nanoparticles (C-SLNs) loaded with rifampicin (RIF) as anti-tuberculosis (anti-TB) drug. The process of development and characterization of the NPs in terms of size, surface charge, encapsulation efficiency (EE), morphology, in vitro drug release, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), in vitro assessment of mucoadhesive property, cell viability and permeability studies are documented. Results showed that the SLNs had a smooth spherical shape with a size of ca. 245-344 nm and with a zeta potential around -30 mV for SLNs and +40 mV for C-SLNs. The surface charge variation from negative to positive charge and FTIR analysis demonstrated the successful process of coating the nanoparticles (NPs) surface with chitosan. The DSC thermograms were in agreement with the nanostructure of the SLNs. The EE of drug was found to be higher than 90% and the loading capacity (LC) around 4.5%. C-SLNs show higher in vitro muchoadesive properties and a higher permeability in alveolar epithelial cells A549 than uncoated SLNs, indicating that the developed C-SLNs can be used as a promising carrier for sasfer and efficient management of TB.

Synthesis and anti-parasitic activity of a novel quinolinone-chalcone series.

A series of novel quinolinone-chalcone hybrids and analogues were designed, synthesized and their biological activity against the mammalian stages of Trypanosoma brucei and Leishmania infantum evaluated. Promising molecular scaffolds with significant microbicidal activity and low cytotoxicity were identified. Quinolinone-chalcone 10 exhibited anti-parasitic properties against both organisms, being the most potent anti-L. infantum agent of the entire series (IC50 value of 1.3±0.1 µM). Compounds 4 and 11 showed potency toward the intracellular, amastigote stage of L. infantum (IC50 values of 2.1±0.6 and 3.1±1.05 µM, respectively). Promising trypanocidal compounds include 5 and 10 (IC50 values of 2.6±0.1 and 3.3±0.1 µM, respectively) as well as 6 and 9 (both having IC50 values of <5 µM). Chemical modifications on the quinolinone-chalcone scaffold were performed on selected compounds in order to investigate the influence of these structural features on antiparasitic activity.

P-glycoprotein activity in human Caucasian male lymphocytes does not follow its increased expression during aging.

P-glycoprotein (P-gp) is a transmembrane protein that mediates the efflux of innumerous structurally unrelated compounds. It was initially found over-expressed in tumor cells, associated to a multidrug resistance phenotype (MDR). Then, P-gp was found constitutively expressed in excretory cells/tissues and in circulating cells, such as lymphocytes. Considering the importance of this transporter in the establishment of therapeutic protocols and the existence of contradictory results, this study aimed at evaluating the influence of aging in the expression and function of P-gp in human lymphocytes, comparing two different methodologies to assess both parameters. P-gp activity and expression were evaluated in lymphocytes isolated from whole blood samples of 65 healthy caucasian male donors, divided into two groups according to age (group 1: under 30-years old; group 2: above 60-years old). P-gp expression was assessed using the anti-P-gp monoclonal antibody, UIC2, in the presence and in absence of vinblastine (Vbl). P-gp activity was evaluated measuring the efflux rate of the fluorescent P-gp substrate rhodamine 123 (Rho 123) and also using UIC2 shift assay. Flow cytometric analysis was performed to assess all the proceedings. Furthermore, P-gp expression and each of the P-gp activity determination methods were compared, through correlation analysis and linear regression models. We observed a significant age-dependent increase in mean P-gp expression (p = 0.029), which was not reflected in the transporter's activity (p > 0.050). Statistical analysis allowed selection of UIC2 shift assay over Rho 123 efflux assay as a more selective method to assess P-gp activity. Despite the significant correlation between P-gp expression and P-gp activity found in lymphocytes (Gp1(group 1)-r = 0.609, p < 0.001; Gp2-r = 0.461, p = 0.012), using UIC2 shift assay, these data reinforce the need for P-gp activity assessment, rather than P-gp expression determination alone, when starting new therapeutic regimens with P-gp substrates, especially in men older than 60 years of age.

In vitro study of P-glycoprotein induction as an antidotal pathway to prevent cytotoxicity in Caco-2 cells.

The Caco-2 cell line is a reliable in vitro model for predicting drug intestinal absorption and P-glycoprotein (P-gp)-mediated excretion in humans. Recent in vivo studies suggested the induction of P-gp as a cellular protection tool against paraquat poisoning, through the increase in its pulmonary and intestinal excretion. Thus, the aim of the present work was to evaluate P-gp expression and activity in Caco-2 cells exposed to doxorubicin (a known P-gp inducer) and to correlate these changes with paraquat toxic effects. Cytotoxicity of doxorubicin (0-100 µM) and paraquat (0-1,000 µM) was evaluated for a maximum period of 96 h. In doxorubicin-exposed cells, P-gp expression and transport activity were evaluated by flow cytometry, using a fluorescein isothiocyanate-conjugated antibody and the P-gp fluorescent subtract rhodamine 123, respectively. A significant increase in P-gp expression was observed as soon as 6 h after exposure to 5 µM doxorubicin. P-gp activity also increased after 6 h, but only at higher doxorubicin concentrations (over 50 µM). Paraquat (0-5,000 µM) cytotoxicity was then evaluated with or without previous exposure of the cells to doxorubicin (5-100 µM, a concentration range causing both an increase in P-gp expression and activity). Under P-gp induction, a significant reduction in paraquat cytotoxicity was observed. Furthermore, when these cells were incubated with a specific P-gp inhibitor (UIC2 antibody) the doxorubicin protective effects were blocked, confirming the involvement of P-gp in the reduction in paraquat cytotoxicity. In conclusion, the human Caco-2 cell line model can be used for the study of P-gp induction as an antidotal pathway against substrates of this transporter system.

In vitro and in vivo anticancer activity of a novel nano-sized formulation based on self-assembling polymers against pancreatic cancer.

PURPOSE: To evaluate the in vitro and in vivo pancreatic anticancer activity of a nano-sized formulation based on novel polyallylamine grafted with 5% mole cholesteryl pendant groups (CH(5)-PAA). METHODS: Insoluble novel anticancer drug, Bisnaphthalimidopropyldiaaminooctane (BNIPDaoct), was loaded into CH(5)-PAA polymeric self-assemblies by probe sonication. Hydrodynamic diameters and polydispersity index measurements were determined by photon correlation spectroscopy. The in vitro cytotoxicity evaluation of the formulation was carried out by the sulforhodamine B dye assay with human pancreatic adenocarcinoma BxPC-3 cells, while for the in vivo study, Xenograff mice were used. In vitro apoptotic cell death from the drug formulation was confirmed by flow cytometric analysis. RESULTS: The aqueous polymer-drug formulation had a mean hydrodynamic size of 183 nm. The drug aqueous solubility was increased from negligible concentration to 0.3 mg mL(-1). CH(5)-PAA polymer alone did not exhibit cytotoxicity, but the new polymer-drug formulation showed potent in vitro and in vivo anticancer activity. The mode of cell death in the in vitro study was confirmed to be apoptotic. The in vivo results revealed that the CH(5)-PAA alone did not have any anti-proliferative effect, but the CH(5)-PAA-drug formulation exhibited similar tumour reduction efficacy as the commercial drug, gemcitabine. CONCLUSIONS: The proposed formulation shows potential as pancreatic cancer therapeutics.