In vitro evaluation of bisnaphthalimidopropyl derivatives loaded into pegylated nanoparticles against Leishmania infantum protozoa

Encapsulation of Citrus sinensis essential oil and R-limonene in lipid nanocarriers: A potential strategy for the treatment of leishmaniasis

Leishmaniases, a group of neglected tropical diseases caused by an intracellular parasite of the genus Leishmania, have significant impacts on global health. Current treatment options are limited due to drug resistance, toxicity, and high cost. This study aimed to develop nanostructured lipid carriers (NLCs) for delivering Citrus sinensis essential oil (CSEO) and its main constituent, R-limonene, against leishmaniasis. The influence of surface-modified NLCs using chitosan was also examined. The NLCs were prepared using a warm microemulsion method, and surface modification with chitosan was achieved through electrostatic interaction. These nanocarriers were characterized by differential scanning calorimetry (DSC), X-ray diffraction (XRD), transmission electron microscopy, and dynamic light scattering (DLS). In vitro cytotoxicity was assessed in L929 and RAW 264.7 cells, and leishmanicidal activity was evaluated against promastigote and amastigote forms. The NLCs were spherical, with particle sizes ranging from 97.9 nm to 111.3 nm. Chitosan-coated NLCs had a positive surface charge, with zeta potential values ranging from 45.8 mV to 59.0 mV. Exposure of L929 cells to NLCs resulted in over 70 % cell viability. Conversely, surface modification significantly reduced the viability of promastigotes (93 %) compared to free compounds. Moreover, chitosan-coated NLCs presented a better IC50 against the amastigote forms than uncoated NLCs. Taken together, these findings demonstrate the feasibility of using NLCs to overcome the limitations of current leishmaniasis treatments, warranting further research.

Antileishmanial Activity of BNIPDaoct- and BNIPDanon-loaded Emulsomes on Leishmania infantum Parasites

Among bisnaphthalimidopropyl (BNIP) derivatives, BNIPDaoct and BNIPDanon recently came forward with antileishmanial activities beyond the standard, commercialized antileishmanial therapies. However, high-level toxicity on macrophages plus poor aqueous solubility and poor bioavailability of the compounds limit their application in therapies. Addressing these limitations, the present study introduces BNIPDaoct- and BNIPDanon-loaded emulsomes as lipid-based nanocarrier systems. Accordingly, emulsome formulations were prepared with the presence of BNIP compounds. The average diameters of BNIPDaoct- and BNIPDanon-loaded emulsomes were found as 363.1 and 337.4 nm, respectively; while empty emulsomes differed with a smaller average particle diameter, i.e., 239.1 nm. All formulations exhibited a negative zeta potential value. The formulations achieved the encapsulation of BNIPDaoct and BNIPDanon at approximately 0.31 mg/ml (501 µM) and 0.24 mg/ml (387 µM), respectively. The delivery of BNIP within the emulsomes improved the antileishmanial activity of the compounds. BNIPDaoct-loaded emulsome with 50% inhibitory concentration (IC50) value of 0.59 ± 0.08 µM was in particular effective against Leishmania infantum promastigotes compared to free BNIPDaoct (0.84 ± 0.09 µM), free BNIPDanon (1.85 ± 0.01 µM), and BNIPDanon-loaded emulsome (1.73 ± 0.02 µM). Indicated by at least ≥ 2-fold higher 50% cytotoxic concentration (CC50) values, the incorporation of BNIP into emulsomes significantly reduced the toxicity of BNIPs against macrophages, corresponding to up to 16-fold improvement in selectivity index (CC50/IC50) for L. infantum promastigotes. The infection rates of macrophages were determined using dual-fluorescent flow cytometry as 68.6%. Both BNIP formulations at concentration of 1.87 µM reduced the parasitic load nearly to 40%, whereas BNIPDaoct-loaded emulosmes could further decrease the parasitic load below 20% at 7.5 µM and above. In conclusion, the incorporation of BNIPDaoct and BNIPDanon into emulsomes results in water-soluble dispersed emulsome formulations that do not only successfully facilitate the delivery of BNIP compounds into the parasites and the Leishmania-infected macrophages in vitro but also enhance antileishmanial efficacy as proven by the decline in IC50 values. The selectivity of the formulation for L. infantum parasites further contributes to the challenging safety profile of the compounds. The promising in vitro antileishmanial efficacy of BNIP-loaded emulsomes highlights the potential of the system for the future in vivo studies.

Oral administration of buparvaquone nanostructured lipid carrier enables in vivo activity against Leishmania infantum

Leishmaniasis, a neglected tropical disease, is prevalent in 98 countries with the occurrence of 1.3 million new cases annually. The conventional therapy for visceral leishmaniasis requires hospitalization due to the severe adverse effects of the drugs, which are administered parenterally. Buparvaquone (BPQ) showed in vitro activity against leishmania parasites; nevertheless, it has failed in vivo tests due to its low aqueous solubility. Though, lipid nanoparticles can overcome this holdback. In this study we tested the hypothesis whether BPQ-NLC shows in vivo activity against L. infantum. Two optimized formulations were prepared (V1: 173.9 ± 1.6 nm, 0.5 mg of BPQ/mL; V2: 232.4 ± 1.6 nm, 1.3 mg of BPQ/mL), both showed increased solubility up to 73.00-fold, and dissolution up to 83.29%, while for the free drug it was only 2.89%. Cytotoxicity test showed their biocompatibility (CC50 >554.4 µM). Besides, the V1 dose of 0.3 mg/kg/day for 10 days reduced the parasite burden in 83.4% ±18.2% (p <0.05) in the liver. BPQ-NLC showed similar leishmanicidal activity compared to miltefosine. Therefore, BPQ-NLC is a promising addition to the limited therapeutic arsenal suitable for leishmaniasis oral administration treatment.

Nanotechnology-aided diagnosis, treatment and prevention of leishmaniasis

Leishmaniasis is a prevalent parasitic infection belonging to neglected tropical diseases. It is caused by Leishmania protozoan parasites transmitted by sandflies and it is responsible for increased morbidity/mortality especially in low- and middle-income countries. The lack of cheap, portable, easy to use diagnostic tools exhibiting high efficiency and specificity impede the early diagnosis of the disease. Furthermore, the typical anti-leishmanial agents are cytotoxic, characterized by low patient compliance and require long-term regimen and usually hospitalization. In addition, due to the intracellular nature of the disease, the existing treatments exhibit low bioavailability resulting in low therapeutic efficacy. The above, combined with the common development of resistance against the anti-leishmanial agents, denote the urgent need for novel therapeutic strategies. Furthermore, the lack of effective prophylactic vaccines hinders the control of the disease. The development of nanoparticle-based biosensors and nanocarrier-aided treatment and vaccination strategies could advance the diagnosis, therapy and prevention of leishmaniasis. The present review intends to highlight the various nanotechnology-based approaches pursued until now to improve the detection of Leishmania species in biological samples, decrease the side effects and increase the efficacy of anti-leishmanial drugs, and induce enhanced immune responses, specifically focusing on the outcome of their preclinical and clinical evaluation.

Intracellular adenosine released from THP-1 differentiated human macrophages is involved in an autocrine control of Leishmania parasitic burden, mediated by adenosine A2A and A2B receptors

Leishmania infected macrophages have conditions to produce adenosine. Despite its known immunosuppressive effects, no studies have yet established whether adenosine alter Leishmania parasitic burden upon macrophage infection. This work aimed at investigating whether endogenous adenosine exerts an autocrine modulation of macrophage response towards Leishmania infection, identifying its origin and potential pharmacological targets for visceral leishmaniasis (VL), using THP-1 differentiated macrophages. Adenosine deaminase treatment of infected THP-1 cells reduced the parasitic burden (29.1 ± 2.2%, P < 0.05). Adenosine A_2A and A_2B receptor subtypes expression was confirmed by RT-qPCR and by immunocytochemistry and their blockade with selective adenosine A_2A and A_2B antagonists reduced the parasitic burden [14.5 ± 3.1% (P < 0.05) and 12.3 ± 3.1% (P < 0.05), respectively; and 24.9 ± 2.8% (P < 0.05), by the combination of the two antagonists)], suggesting that adenosine A₂ receptors are tonically activated in infected THP-1 differentiated macrophages. The tonic activation of adenosine A₂ receptors was dependent on the release of intracellular adenosine through equilibrative nucleoside transporters (ENT1/ENT2): NBTI or dipyridamole reduced (~25%) whereas, when ENTs were blocked, adenosine A₂ receptor antagonists failed to reduce and A₂ agonists increase parasitic burden. Effects of adenosine A₂ receptors antagonists and ENT1/2 inhibitor were prevented by L-NAME, indicating that nitric oxide production inhibition prevents adenosine from increasing parasitic burden. Results suggest that intracellular adenosine, released through ENTs, elicits an autocrine increase in parasitic burden in THP-1 macrophages, through adenosine A₂ receptors activation. These observations open the possibility to use well-established ENT inhibitors or adenosine A₂ receptor antagonists as new therapeutic approaches in VL.

Microspheres of essential oil in polylactic acid and poly(methyl methacrylate) matrices and their blends

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains. The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5-9.5 µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10 ± 10.0 wt. % for PLA system and 76.0 ± 3.3 wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.

Co-delivery of buparvaquone and polymyxin B in a nanostructured lipid carrier for leishmaniasis treatment

OBJECTIVES

This study aimed to describe the preparation and in vitro evaluation of a surface-modified nanostructured lipid carrier (NLC) using chitosan and dextran for co-delivery of buparvaquone (BPQ) and polymyxin B (PB) against leishmaniasis.

METHODS

The NLC was prepared using high-pressure homogenisation. Polymyxin B binding and surface modification with biopolymers were achieved by electrostatic interaction. In vitro cytotoxicity was assessed in mouse peritoneal macrophages, and leishmanicidal activity in amastigotes of Leishmania infantum.

RESULTS

The performance attributes of BPQ-NLC, BPQ-NLC-PB[A^-] (anionic) and BPQ-NLC-PB[C⁺] (cationic) were respectively: Z-average 173.9 ± 1.6, 183.8 ± 4.5 and 208.8 ± 2.6 nm; zeta potential -19.6 ± 1.5, -20.1 ± 1.1 and 31.1 ± 0.8 mV; CC₅₀ 583.4 ± 0.10, 203.1 ± 0.04 and 5.7 ± 0.06 μM; IC₅₀ 229.0 ± 0.04, 145.7 ± 0.04 and 150.5 ± 0.02 nM. The NLC in vitro leishmanicidal activity showed up to 3.1-fold increase when compared with free BPQ (P <  0.05, α = 0.05).

CONCLUSIONS

The developed NLC proved to be a promising formulation with which to overcome the drawbacks of current leishmaniasis treatment by the co-delivery of two alternative drugs and a macrophage targeting modified surface.

Antileishmanial Activity of Amphotericin B-loaded-PLGA Nanoparticles: An Overview

In recent decades, nanotechnology has made phenomenal strides in the pharmaceutical field, favouring the improvement of the biopharmaceutical properties of many active compounds. Many liposome-based formulations containing antitumor, antioxidant and antifungal compounds are presently on the market and are used daily (for example Doxil^®/Caelyx^® and Ambisome^®). Polymeric nanoparticles have also been used to entrap many active compounds with the aim of improving their pharmacological activity, bioavailability and plasmatic half-life while decreasing their side effects. The modulation of the structural/morphological properties of nanoparticles allows us to influence various technological parameters, such as the loading capacity and/or the release profile of the encapsulated drug(s). Amongst the biocompatible polymers, poly(D,L-lactide) (PLA), poly(D,L-glycolide) (PLG) and their co-polymers poly(lactide-co-glycolide) (PLGA) are the most frequently employed due to their approval by the FDA for human use. The aim of this review is to provide a description of the foremost recent investigations based on the encapsulation of amphotericin B in PLGA nanoparticles, in order to furnish an overview of the technological properties of novel colloidal formulations useful in the treatment of Leishmaniasis. The pharmacological efficacy of the drug after nanoencapsulation will be compared to the commercial formulations of the drug (i.e., Fungizone^®, Ambisome^®, Amphocil^® and Abelcet^®).

Comparing the therapeutic efficacy of different amphotericin B-carrying delivery systems against visceral leishmaniasis

Amphotericin B (Amp) has been well-successfully used to treat against Leishmania infection, although high toxicity has been found in patients. In the present study, Amp was administered in Leishmania infantum-infected BALB/c mice by three distinct delivery systems aiming to compare their efficacy against challenge infection, as well as their side effects in a murine visceral leishmaniasis (VL) model. This product was administered in a Poloxamer P407 (Pluronic^® F127)-based polymeric micelle system (Amp/M), in the Ambisome^® formulation (Lip-Amp) or in a free format (free Amp). Glucantime^® (Gluc) was used as a comparative drug. Aiming to evaluate different endpoints of the treatments, the efficacy of the compounds was investigated one and 15-days after the therapeutic regimens, determining the parasite load by a limiting dilution assay and a quantitative PCR (qPCR) technique, as well as evaluating the immune response generated in the infected and treated animals. In the results, Amp/M or Lip-Amp-treated mice presented the best outcomes, since significant parasite load reductions were found in the evaluated organs, as well as a parasite-specific Th1 immune response was observed in the animals. In addition, no hepatic or renal damage was found in these mice. On the other hand, free Amp or Gluc induced toxicity in the animals, which was associated with a low Th1 immune response. Comparatively, Amp/M was the most effective drug in our experimental model, and results showed that the Amp-carrying system could be considered as a future alternative in studies against VL.

Multifunctional nanospheres for co-delivery of methotrexate and mild hyperthermia to colon cancer cells

A multifunctional nanomedicine platform was designed and evaluated for efficient colon cancer therapy by a combinatorial therapeutic approach based on a chemotherapeutic drug and mild hyperthermia. Advantage was taken from the dual role of methotrexate (MTX), as folate receptor-targeting, overexpressed in tumor cells, and as anticancer drug. Incorporation of superparamagnetic iron oxide nanoparticles (SPIONs) allows to heat cancer cells externally through an alternating magnetic field. The developed nanocarrier was based on polyethylene glycol-polylactic acid (PEG-PLA) nanospheres to improve biocompatibility, enhancing their targeting by prolonging blood circulation time. By an emulsion-evaporation method the nanospheres were produced and then characterized for size distribution, zeta-potential, in vitro drug release profile and cellular studies. The co-delivery of MTX and SPIONs on PEG-PLA nanospheres resulted in nanocarriers with a size of 160nm in diameter, a polydispersity index below 0.2 and a zeta potential of ca. -18mV. Multifunctional nanospheres were monodisperse and stable up to 3months. MTX was released preferentially under mild hyperthermia conditions. The multifunctional nanospheres were able to increase the cytotoxicity of MTX towards Caco-2 and SW-480 colon cancer cells, in comparison to free drug. Also, the nanospheres allowed the incorporated MTX to induce greater cell cycle arrest and apoptotic effects than the free MTX. This study provides evidences that MTX-SPIONs-PEG-PLA nanospheres are a promising solution to address colorectal cancer over-expressing folate receptors, by a combinatory approach.

Activity of Bisnaphthalimidopropyl Derivatives against Trypanosoma brucei

Current treatments for African trypanosomiasis are either toxic, costly, difficult to administer, or prone to elicit resistance. This study evaluated the activity of bisnaphthalimidopropyl (BNIP) derivatives againstTrypanosoma brucei BNIPDiaminobutane (BNIPDabut), the most active of these compounds, showedin vitroinhibition in the single-unit nanomolar range, similar to the activity in the reference drug pentamidine, and presented low toxicity and adequate metabolic stability. Additionally, using a murine model of acute infection and live imaging, a significant decrease in parasite load in BNIPDabut-treated mice was observed. However, cure was not achieved. BNIPDabut constitutes a new scaffold for antitrypanosomal drugs that deserves further consideration.

Nanobody conjugated PLGA nanoparticles for active targeting of African Trypanosomiasis

Targeted delivery of therapeutics is an alternative approach for the selective treatment of infectious diseases. The surface of African trypanosomes, the causative agents of African trypanosomiasis, is covered by a surface coat consisting of a single variant surface glycoprotein, termed VSG. This coat is recycled by endocytosis at a very high speed, making the trypanosome surface an excellent target for the delivery of trypanocidal drugs. Here, we report the design of a drug nanocarrier based on poly ethylen glycol (PEG) covalently attached (PEGylated) to poly(D,L-lactide-co-glycolide acid) (PLGA) to generate PEGylated PLGA nanoparticles. This nanocarrier was coupled to a single domain heavy chain antibody fragment (nanobody) that specifically recognizes the surface of the protozoan pathogen Trypanosoma brucei. Nanoparticles were loaded with pentamidine, the first-line drug for T. b. gambiense acute infection. An in vitro effectiveness assay showed a 7-fold decrease in the half-inhibitory concentration (IC50) of the formulation relative to free drug. Furthermore, in vivo therapy using a murine model of African trypanosomiasis demonstrated that the formulation cured all infected mice at a 10-fold lower dose than the minimal full curative dose of free pentamidine and 60% of mice at a 100-fold lower dose. This nanocarrier has been designed with components approved for use in humans and loaded with a drug that is currently in use to treat the disease. Moreover, this flexible nanobody-based system can be adapted to load any compound, opening a range of new potential therapies with application to other diseases.

Polymeric colloidal particulate systems: intelligent tools for intracellular targeting of antileishmanial cargos

INTRODUCTION

Targeted cargo delivery systems can overcome drawbacks associated with antileishmanials delivery, by defeating challenges of physiological barriers. Various colloidal particulate systems have been developed in the past; few of them even achieved success in the market, but still are limited in some ways.

AREAS COVERED

This review is focused on the pathobiology of leishmaniasis, interactions of particulate systems with biological environment, targeting strategies along with current conventional and vaccine therapies with special emphasis on polymeric nanotechnology for effective antileishmanial cargo delivery.

EXPERT OPINION

The problems concerned with limited accessibility of chemotherapeutic cargos in conventional modes to Leishmania-harboring macrophages, their toxicity, and resistant parasitic strain development can be sorted out through target-specific delivery of cargos. Vaccination is another therapeutic approach employing antigen alone or adjuvant combinations delivered by means of a carrier, and can provide preventive measures against human leishmaniasis (HL). Therefore, there is an urgent need of designing site-specific antileishmanial cargo carriers for safe and effective management of HL. Among various colloidal carriers, polymeric particulate systems hold tremendous potential as an effective delivery tool by providing control over spatial and temporal distribution of cargos after systemic or localized administration along with enhancing their stability profile at a comparatively cost-effective price leading to improved chances of commercial applicability.