Vanessa Carla Furtado Mosqueira

Nanotechnology applied to the treatment of malaria

Despite the fact that we live in an era of advanced technology and innovation, infectious diseases, like malaria, continue to be one of the greatest health challenges worldwide. The main drawbacks of conventional malaria chemotherapy are the development of multiple drug resistance and the non-specific targeting to intracellular parasites, resulting in high dose requirements and subsequent intolerable toxicity. Nanosized carriers have been receiving special attention with the aim of minimizing the side effects of drug therapy, such as poor bioavailability and the selectivity of drugs. Several nanosized delivery systems have already proved their effectiveness in animal models for the treatment and prophylaxis of malaria. A number of strategies to deliver antimalarials using nanocarriers and the mechanisms that facilitate their targeting to Plasmodium spp.-infected cells are discussed in this review. Taking into account the peculiarities of malaria parasites, the focus is placed particularly on lipid-based (e.g., liposomes, solid lipid nanoparticles and nano and microemulsions) and polymer-based nanocarriers (nanocapsules and nanospheres). This review emphasizes the main requirements for developing new nanotechnology-based carriers as a promising choice in malaria treatment, especially in the case of severe cerebral malaria.

Poly(D,L‐Lactide) Nanocapsules Prepared by a Solvent Displacement Process: Influence of the Composition on Physicochemical and Structural Properties

Nanocapsules (NC) were prepared by interfacial deposition of preformed biodegradable polymer (PLA(50)) after a solvent displacement process. The influence of the composition used for the preparation of NC was evaluated in terms of particle size, polydispersity, zeta potential, homogeneity, and structural characteristics of the systems. The nature of the oil phase, polymer molecular weight, type and concentration of different surfactants were investigated to optimize the formulation to obtain NC suitable for intravenous administration. The influence of the physicochemical properties of the different oils used in NC preparation on the NC size was evaluated. The interfacial tension between the oil and water phases seems to have a greater effect on NC size than the oil viscosity. Miglyol 810 and ethyl oleate lead to the formation of smaller NC, probably because of the reduced interfacial tension. The polymer molecular weight plays only a small role in NC surface charge in the presence of lecithin, whereas NC surface charge, size, polydispersity, and short-term stability were highly influenced by lecithin purity. It appears that the absence of poloxamer 188 leads to smaller polydispersity, less contamination with nanospheres, and reduced formation of structures other than NC. Furthermore, electron microscopy and density gradient density techniques were used to examine the structure of the particles formed and their homogeneity. NC formation was evidenced by the bands with intermediate density between nanoemulsion and nanospheres; however, other bands of low intensity were observed. The presence of liposomes and multilayers in NC preparation was confirmed by electron microscopy. The percentage of carboxyfluorescein entrapped in different NC formulations allowed us to estimate the contamination by liposomes. It has been show that, under our experimental conditions, an excess of lecithin is an essential prerequisite for a stable preparation of PLA NC.

Interactions between a macrophage cell line (J774A1) and surface-modified poly (D,L-lactide) nanocapsules bearing poly(ethylene glycol).

The interactions of naked and surface-modified poly(D,L-lactic acid) (PLA) nanocapsules (NC), where polyethyleneglycol (PEG) was adsorbed or covalently attached, have been studied with a macrophage-like cell line. The fluorescent oil marker, DiD, was successfully encapsulated in NCs in order to follow their interactions with cells. The cell-associated fluorescence obtained with PEG-PLA NC was about 3- to 13-fold lower than that obtained with naked-PLA NC. The effects of PEG chain length, its content as a percentage of total polymer and NC concentration in the culture medium were evaluated. PEG-PLA NC showed dramatically reduced fluorescence association with cells during an 18 h incubation compared with naked-PLA NC, showing that covalent attachment of PEG is important for the persistence of low uptake. The best results in reducing cell-associated fluorescence were obtained with a surface-modified PEG-PLA NC bearing a chain with 20000 MW. Increasing the percentage of PEG produced a reduction in marker association for a given PEG chain length. Moreover, when the PEG-containing poloxamer was simply adsorbed, marker association was dependent on the extent of dilution and the type of serum in the culture medium. Serum proteins, especially immunoglobulins, increased cell-associated fluorescence for PEG-adsorbed NC, but had very little effect on PEG-PLA NC. Marker association was only partially inhibited in the presence of cytochalasin B. The mechanisms of cell-NC interaction depended on the characteristics of the NC surface in each formulation. When the NC was physically separated from cells no diffusion of fluorescent marker in aqueous medium occurred. Nevertheless, collision-mediated transfer of DiD from NC to J774 cells was a non-negligible route of marker transfer, mainly for naked NC. However, this collision-mediated transfer was reduced for the PEG-PLA NC probably due to the restricted contact between NC and cells afforded by PEG steric hindrance at the surface.

Efficacy and Pharmacokinetics of Intravenous Nanocapsule Formulations of Halofantrine in Plasmodium berghei-Infected Mice

ABSTRACT The efficacy and pharmacokinetics of a new parenteral formulation of halofantrine were studied in mice infected with Plasmodium berghei. The formulation consisted of nanocapsules with an oily core, prepared from either poly(d,l-lactide) (PLA) homopolymer or PLA that was surface modified with grafted polyethylene glycol chains. They were compared with a previously described intravenous halofantrine preparation. No toxic effects were observed with halofantrine in form of nanocapsules after intravenous administration for doses of up to 100 mg/kg, whereas the solubilized form in polyethylene glycol-dimethylacetamide was toxic at this dose. The halofantrine-loaded nanocapsules showed activity that was similar to or better than that of the solution in the 4-day test and as a single dose in severely infected mice, with only minimal differences between the two nanocapsule formulations. Halofantrine pharmacokinetics were determined in parallel with parasite development in severely infected mice. Nanocapsules increased the area under the curve for halofantrine in plasma more than sixfold compared with the solution throughout the experimental period of 70 h. Furthermore, nanocapsules induced a significantly faster control of parasite development than the solution in the first 48 h posttreatment. While the parasitemia fell more rapidly with PLA nanocapsules, the effect was more sustained with the surface-modified ones. This is consistent with surface-modified nanocapsules remaining longer in the circulation. These results suggest that nanocapsule formulations could provide a more favorable halofantrine profile in the plasma and reduce the intravenous dose necessary and therefore the toxicity, thus suggesting the use of halofantrine by a parenteral route in severe malaria.

Chloroaluminium phthalocyanine polymeric nanoparticles as photosensitisers: Photophysical and physicochemical characterisation, release and phototoxicity in vitro

Nanoparticles of poly(d,l-lactide-co-glycolide), poly(d,l-lactide) and polyethylene glycol-block-poly(d,l-lactide) were developed to encapsulate chloroaluminium phthalocyanine (AlClPc), a new hydrophobic photosensitiser used in photodynamic therapy (PDT). The mean nanoparticle size varied from 115 to 274 nm, and the encapsulation efficiency ranged from 57% to 96% due to drug precipitation induced by different types of polymer. All nanoparticle formulations presented negative zeta potential values (-37 mV to -59 mV), explaining their colloidal stability. The characteristic photophysical parameters were analysed: the absorption spectrum profile, fluorescence quantum yield and transient absorbance decay, with similar values for free and nanoparticles of AlClPc. The time-resolved spectroscopy measurements for AlClPc triplet excited state lifetimes indicate that encapsulation in nanocapsules increases triplet lifetime, which is advantageous for PDT efficiency. A sustained release profile over 168 h was obtained using external sink method. An in vitro phototoxic effect higher than 80% was observed in human fibroblasts at low laser light doses (3 J/cm(2)) with 10 μM of AlClPc. The AlClPc loaded within polymeric nanocapsules presented suitable physical stability, improved photophysical properties, sustained released profile and suitable activity in vitro to be considered a promising formulation for PDT.

HPLC-FLD methods to quantify chloroaluminum phthalocyanine in nanoparticles, plasma and tissue: application in pharmacokinetic and biodistribution studies

Analytical and bioanalytical methods of high-performance liquid chromatography with fluorescence detection (HPLC-FLD) were developed and validated for the determination of chloroaluminum phthalocyanine in different formulations of polymeric nanocapsules, plasma and livers of mice. Plasma and homogenized liver samples were extracted with ethyl acetate, and zinc phthalocyanine was used as internal standard. The results indicated that the methods were linear and selective for all matrices studied. Analysis of accuracy and precision showed adequate values, with variations lower than 10% in biological samples and lower than 2% in analytical samples. The recoveries were as high as 96% and 99% in the plasma and livers, respectively. The quantification limit of the analytical method was 1.12 ng/ml, and the limits of quantification of the bioanalytical method were 15 ng/ml and 75 ng/g for plasma and liver samples, respectively. The bioanalytical method developed was sensitive in the ranges of 15-100 ng/ml in plasma and 75-500 ng/g in liver samples and was applied to studies of biodistribution and pharmacokinetics of AlClPc.

Profile of wound healing process induced by allantoin

PURPOSE To evaluate and characterize the wound healing process profile induced by allantoin incorporated in soft lotion oil/water emulsion using the planimetric and histological methods. METHODS Female Wistar rats (n=60) were randomly assigned to 3 experimental groups: (C) control group-without treatment; (E) group treated with soft lotion O/W emulsion excipients; (EA) group treated with soft lotion O/W emulsion containing allantoin 5%. The emulsions either containing or not allantoin were topically administered for 14 days and the wound area was evaluated by planimetry and by qualitative and quantitative histological analysis of open wound model. RESULTS The data which were obtained and analyzed innovate by demonstrating, qualitatively and quantitatively, by histological analysis, the profile of healing process induced by allantoin. The results suggest that the wound healing mechanism induced by allantoin occurs via the regulation of inflammatory response and stimulus to fibroblastic proliferation and extracellular matrix synthesis. CONCLUSION This work show, for the first time, the histological wound healing profile induced by allantoin in rats and demonstrated that it is able to ameliorate and fasten the reestablishment of the normal skin.

Therapeutical approaches under investigation for treatment of Chagas disease

Introduction: A century after its discovery, American trypanosomiasis or Chagas disease remains a serious health problem in Latin America, where it affects around 7 – 8 million people. The prevalence of Chagas disease in the poorer parts of the world has meant that it has largely been neglected with limited progress that made in identifying new drugs for the treatment. The nitroheterocyclic drugs nifurtimox and benznidazole are first-line drugs available for Chagas disease with limitations that include variable efficacy, long treatment courses and toxicity. Areas covered: This review focuses on different therapeutic strategies that have been used for the discovery of new treatments for Chagas disease. These include combination chemotherapy, drug repositioning, re-dosing regimens for current drugs and the identification of new drugs with specified target profiles. Expert opinion: There are currently several reasons for a more optimistic view about chemotherapy with Chagas disease. However, despite some progress being made in preclinical studies, there is yet to be an ideal drug or formulation for human treatment. One major drawback in the evaluation of potential Chagas disease therapeutics is the lack of tools available to perform the said evaluation. Indeed, there is a great need to discover a better biomarker that could determine the efficacy of potential chemotherapeutics in treated patients.

Nanotecnologia farmacêutica aplicada ao tratamento da malária

Apesar do desenvolvimento tecnologico e cientifico, a malaria permanece como um dos maiores problemas de saude a serem combatidos. As estrategias modernas para o controle da doenca preveem acoes conjuntas, como o combate do inseto vetor, diagnostico rapido e preciso, garantia de terapeutica adequada, reducao dos casos de resistencia, alem do desenvolvimento de novos agentes terapeuticos e vacina e atraves da otimizacao da acao de farmacos utilizados na atualidade. Os sistemas de liberacao controlada de farmacos vem recebendo atencao especial nesta area de pesquisa, com o desenvolvimento de estrategias para a veiculacao de agentes bioativos e vacinas na forma de nanodispositivos tais como lipossomas, nanoparticulas e microparticulas. Diversos nanossistemas ja demonstraram eficacia na otimizacao de vacinas e quimioterapicos destinados ao controle da malaria. Este artigo de revisao tem por objetivo avaliar o estado da arte na terapeutica da malaria e demonstrar o potencial da nanotecnologia farmaceutica como ferramenta destinada ao combate da doenca.

Sesquiterpene Lactone in Nanostructured Parenteral Dosage Form Is Efficacious in Experimental Chagas Disease

ABSTRACT The drugs available for Chagas disease treatment are toxic and ineffective. We studied the in vivo activity of a new drug, lychnopholide (LYC). LYC was loaded in nanocapsules (NC), and its effects were compared to free LYC and benznidazole against Trypanosoma cruzi. Infected mice were treated in the acute phase at 2.0 mg/kg/day with free LYC, LYC-poly-ε-caprolactone NC (LYC-PCL), and LYC-poly(lactic acid)-co-polyethylene glycol NC (LYC-PLA-PEG) or at 50 mg/kg/day with benznidazole solution by the intravenous route. Animals infected with the CL strain, treated 24 h after infection for 10 days, evaluated by hemoculture, PCR, and enzyme-linked immunosorbent assay exhibited a 50% parasitological cure when treated with LYC-PCL NC and 100% cure when treated with benznidazole, but 100% of the animals treated during the prepatent period for 20 days with these formulations or LYC-PLA-PEG NC were cured. In animals with the Y strain treated 24 h after infection for 10 days, only mice treated by LYC-PCL NC were cured, but animals treated in the prepatent period for 20 days exhibited 100, 75, and 62.5% cure when treated with LYC-PLA-PEG NC, benznidazole, and LYC-PCL NC, respectively. Free LYC reduced the parasitemia and improved mice survival, but no mice were cured. LYC-loaded NC showed higher cure rates, reduced parasitemia, and increased survival when used in doses 2five times lower than those used for benznidazole. This study confirms that LYC is a potential new treatment for Chagas disease. Furthermore, the long-circulating property of PLA-PEG NC and its ability to improve LYC efficacy showed that this formulation is more effective in reaching the parasite in vivo.