Antimicrobial evaluation of the polyisoprenylated benzophenones nemorosone and guttiferone A.

Polyisoprenylated benzophenones have been isolated from plants, particularly in the Clusiaceae family, and their biological properties recently have received considerable attention from a pharmacological point of view. The aim of the study was to investigate the polyisoprenylated benzophenones, nemorosone and guttiferone A, for their antimicrobial effect against a panel of bacteria, fungi and protozoan parasites. They showed a moderate activity against the Gram-positive bacterium Staphylococcus aureus, while no activity was demonstrated against Escherichia coli and the fungi Trichophyton rubrum and Candida albicans. An interesting activity was found for Plasmodium falciparum with IC50 values lower than 1 µm, while cytotoxicity on MRC-5 cells revealed CC50 values of 15.5 and 12.0 µm, respectively, for nemorosone and guttiferone A.

PLGA nanoparticles and nanosuspensions with amphotericin B: Potent in vitro and in vivo alternatives to Fungizone and AmBisome.

This paper describes the development of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) and nanosuspensions with the polyene antibiotic amphotericin B (AmB). The nanoformulations were prepared using nanoprecipitation and were characterised with respect to size, zeta potential, morphology, drug crystallinity and content. Standard in vitro sensitivity tests were performed on MRC-5 cells, red blood cells, Leishmania infantum promastigotes and intracellular amastigotes and the fungal species Candida albicans, Aspergillus fumigatus and Trichophyton rubrum. The in vivo efficacy was assessed and compared to that of Fungizone and AmBisome in the acute A. fumigatus mouse model at a dose of 2.5 and 5.0mg/kg AmB equivalents. The developed AmB nanoformulations were equivalently or more effective against the different Leishmania stages and axenic fungi in comparison with the free drug. The in vitro biological activity, and especially hemolytic activity, clearly depended on the preparation parameters of the different nanoformulations. Further, we demonstrated that the superior in vitro antifungal activity could be extrapolated to the in vivo situation. At equivalent dose, the optimal AmB-loaded PLGA NP was about two times and the AmB nanosuspension about four times more efficacious in reducing the total burden than AmBisome. The developed AmB nanomedicines could represent potent and cost-effective alternatives to Fungizone and AmBisome.

Intracellular drug delivery in Leishmania-infected macrophages: Evaluation of saponin-loaded PLGA nanoparticles.

Drug delivery systems present an opportunity to potentiate the therapeutic effect of antileishmanial drugs. Colloidal carriers are rapidly cleared by the phagocytic cells of the reticuloendothelial system (RES), rendering them ideal vehicles for passive targeting of antileishmanials. This paper describes the development of poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) for the antileishmanial saponin ß-aescin. NPs were prepared using the combined emulsification solvent evaporation/salting-out technique. Confocal microscopy was used to visualise the internalisation and intracellular trafficking of fluorescein- and nile red-labelled PLGA NPs in J774A.1 macrophages infected with GFP-transfected Leishmania donovani. The in vitro activity of aescin and aescin-loaded NPs on L. infantum was determined in the axenic model as well as in the ex vivo model. The developed PLGA NPs were monodispersed with Z(ave)<300 nm, exhibited negative zeta potentials and had relatively high drug loadings ranging from 5.80 to 8.68% w/w PLGA. The fluorescent NPs were internalised by the macrophages and trafficked towards the lysosomes after 2 h in vitro incubation. Co-localisation of the NPs and the parasite was not shown. A two-fold increase in activity was observed in the ex vivo macrophage model by encapsulating ß-aescin in PLGA NPs (IC(50), 0.48-0.76 µg/mL vs. 1.55 ± 0.32 µg/mL for the free drug).

PLGA nanoparticles loaded with the antileishmanial saponin ß-aescin: factor influence study and in vitro efficacy evaluation.

Colloidal carriers are known to improve the therapeutic index of the conventional drugs in the treatment of visceral leishmaniasis (VL) by decreasing their toxicity whilst maintaining or increasing therapeutic efficacy. This paper describes the development of poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles (NPs) for the antileishmanial saponin ß-aescin. NPs were prepared by the W/O/W emulsification solvent evaporation technique and the influence of five preparation parameters on the NPs' size (Z(ave)), zeta potential and entrapment efficiency (EE%) was investigated using a 2(5-2) fractional factorial design. Cytotoxicity of aescin, aescin-loaded and blank PLGA NPs was evaluated in J774 macrophages and non-phagocytic MRC-5 cells, whereas antileishmanial activity was determined in the Leishmania infantum ex vivo model. The developed PLGA NPs were monodispersed with Z(ave)<500 nm and exhibited negative zeta potentials. The process variables 'surfactant primary emulsion', 'concentration aescin' and 'solvent evaporation rate' had a positive effect on EE%. Addition of Tween 80 to the inner aqueous phase rendered the primary emulsion more stable, which in its turn led to better saponin entrapment. The selectivity index (SI) towards the supporting host macrophages increased from 4 to 18 by treating the cells with aescin-loaded NPs instead of free ß-aescin. In conclusion, the in vitro results confirmed our hypothesis.