Heparosan as a potential alternative to hyaluronic acid for the design of biopolymer-based nanovectors for anticancer therapy.

Glycosaminoglycans (GAGs) are important components of the extracellular matrix that have attracted great interest for drug delivery and pharmaceutical applications due to their diverse biological functions. Among GAGs, heparosan (Hep), a biosynthetic precursor of heparin, has recently emerged as a promising building block for the design of nanoparticles with stealth properties. Though this non-sulfated polysaccharide has a chemical structure very close to that of hyaluronic acid (HA), it distinguishes from HA in that it is biologically inert in the extracellular spaces in the body. In this study, we designed Hep- and HA-based nanogels (NGs) that differ only in the chemical nature of the hydrophilic shell. The nanogels were prepared in a very straightforward way from Hep and HA modified with a thermoresponsive copolymer properly designed to induce self-assembly below room temperature. This versatile synthetic approach also enabled further shell-crosslinking allowing an increase in the colloidal stability. After careful characterization of the un-crosslinked and crosslinked Hep and HA NGs in terms of size (Z-average diameters of un-crosslinked and crosslinked NGs ∼110 and 150 nm) and morphology, they were injected intravenously into tumor-bearing mice for biodistribution experiments. Interestingly, these show that the liver uptake of Hep nanogels is remarkably reduced and tumor accumulation significantly improved as compared to HA nanogels (intensity ratios of tumor-to-liver of 2.2 and 1.4 for the un-crosslinked and crosslinked Hep NGs versus 0.11 for the un-crosslinked and crosslinked HA ones). These results highlight the key role played by the shell-forming GAGs on the in vivo fate of nanogels, which correlates with the specific biological properties of Hep and HA.

VOSalophen: a vanadium complex with a stilbene derivative-induction of apoptosis, autophagy, and efficiency in experimental cutaneous leishmaniasis.

In our previous work, we demonstrated the promising in vitro effect of VOSalophen, a vanadium complex with a stilbene derivative, against Leishmania amazonensis. Its antileishmanial activity has been associated with oxidative stress in L. amazonensis promastigotes and L. amazonensis-infected macrophages. In the present study, the mechanism involved in the death of parasites after treatment with VOSalophen, as well as in vivo effect in the murine model cutaneous leishmaniasis, has been investigated. Promastigotes of L. amazonensis treated with VOSalophen presented apoptotic cells features, such as cell volume decrease, phosphatidylserine externalization, and DNA fragmentation. An increase in autophagic vacuoles formation in treated promastigotes was also observed, showing that autophagy also may be involved in the death of these parasites. In intracellular amastigotes, DNA fragmentation was observed after treatment with VOSalophen, but this effect was not observed in host cells, highlighting the selective effect of this vanadium complex. In addition, VOSalophen showed activity in the murine model of cutaneous leishmaniasis, without hepatic and renal damages. The outcome described here points out that VOSalophen had promising antileishmanial properties and these data also contribute to the understanding of the mechanisms involved in the death of protozoa induced by metal complexes.

Induction of Early Autophagic Process on Leishmania amazonensis by Synergistic Effect of Miltefosine and Innovative Semi-synthetic Thiosemicarbazone.

Drug combination therapy is a current trend to treat complex diseases. Many benefits are expected from this strategy, such as cytotoxicity decrease, retardation of resistant strains development, and activity increment. This study evaluated in vitro combination between an innovative thiosemicarbazone molecule - BZTS with miltefosine, a drug already consolidated in the leishmaniasis treatment, against Leishmania amazonensis. Cytotoxicity effects were also evaluated on macrophages and erythrocytes. Synergistic antileishmania effect and antagonist cytotoxicity were revealed from this combination therapy. Mechanisms of action assays were performed in order to investigate the main cell pathways induced by this treatment. Mitochondrial dysfunction generated a significant increase of reactive oxygen and nitrogen species production, causing severe cell injuries and promoting intense autophagy process and consequent apoptosis cell death. However, this phenomenon was not strong enough to promote dead in mammalian cell, providing the potential selective effect of the tested combination for the protozoa. Thus, the results confirmed that drugs involved in distinct metabolic routes are promising agents for drug combination therapy, promoting a synergistic effect.

Sulfated glycosaminoglycan-based block copolymer: preparation of biocompatible chondroitin sulfate-b-poly(lactic acid) micelles.

Despite a growing interest in amphiphilic polysaccharide-based diblock copolymers as functional polymeric drug delivery nanosystems, biologically relevant sulfated glycosaminoglycan systems were not yet investigated. Here, we report the synthesis and the self-assembly properties in water of chondroitin sulfate-b-poly(lactic acid) (CS-b-PLA(n)). The CS-b-PLA(n) were synthesized using click-grafting onto method implying reducing-end alkynation of low-molecular weight depolymerized CS (M(w) = 5000 g·mol(-1)) and azide-terminated functionalization of PLAn (M(w) = 6500 g·mol(-1) (n = 46) and M(w) = 1700 g·mol(-1) (n = 20)). The diblock copolymer self-assembled in water giving rise to spherical micelles that were characterized in solution using dynamic/static light scattering and at dry state by TEM technique. In vitro assays on healthy cells showed that at high concentrations, up to 10 µg·mL(-1), CS-b-PLA(n) were noncytotoxic. Those preliminary studies are promising in the perspective to use them as biocompatible nanovehicles for anticancer drug delivery.

Silver sulfadiazine loaded chitosan/chondroitin sulfate films for a potential wound dressing application.

Silver sulfadiazine (AgSD) loaded chitosan/chondroitin sulfate (CHI/CS) films were formed to be applied as a potential wound dressing material. The liquid uptake capacity of both, CHI/CS and CHI/CS/AgSD, films exhibited a pH-dependent behavior. Tensile tests showed that the amount of CS used to form the films and the further incorporation of AgSD affect the mechanical properties of the films. In vitro AgSD-release assays showed that the CHI/CS mass ratio influences the AgSD release rate. All the investigated CHI/CS/AgSD films sustain the AgSD release up to 96h at physiological pH. Antibacterial activity and cell viability assays showed that all the CHI/CS/AgSD films have activity against Pseudomonas aeruginosa and Staphylococcus aureus but they were not toxic to Vero cells. The results presented in this work indicate that the CHI/CS/AgSD exhibits potential to be applied as a wound dressing material.

Antimicrobial and cytotoxic activities of medicinal plants of the Brazilian cerrado, using Brazilian cachaça as extractor liquid.

ETHNOPHARMACOLOGICAL IMPORTANCE: Many species of plants in the Brazilian cerrado (savanna) are widely used in ethnomedicine. However, the safety and effectiveness of medicinal plants used in communities with little or no access to manufactured drugs should be evaluated. AIM OF THE STUDY: Evaluate the antimicrobial and cytotoxic activities of extracts from eight plant species, obtained using Brazilian cachaça as the extractor liquid. MATERIALS AND METHODS: The extracts were tested against Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Candida albicans, Candida parapsilosis, promastigote forms of Leishmania amazonensis, and poliovirus. In addition, cytotoxic activity was assayed in Vero cells and in human erythrocytes. RESULTS: The plant species Curatella americana, Sclerolobium aureum, and Plathymenia reticulata showed the best activity against yeasts, especially the crude extract of C. americana and its ethyl-acetate fraction. Kielmeyera lathrophyton showed a minimum inhibitory concentration of 250 µg/ml against S. aureus, and was inactive against gram-negative bacteria. The extract obtained from Annona coriacea showed the best activity against the promastigote forms of Leishmania amazonensis (IC(50)=175 µg/ml). Only C. americana showed potential for antipoliovirus activity. The concentrations of the crude extracts that showed toxicity to VERO cells had CC(50) between 31 and 470 µg/ml, and the lyophilized Brazilian cachaça showed a CC(50) of 307 µg/ml. None of the extracts showed toxicity against human erythrocytes. CONCLUSIONS: Among the plant species studied, C. americana proved to be effective against microorganisms, especially as an antifungal. The results will help in the search for alternative drugs to be used in pharmacotherapy, and will contribute to establish safe and effective use of phytomedicines in the treatment of infectious diseases.