Lipid-based nanoformulations of trifluralin analogs in the management of Leishmania infantum infections.

AIM: To improve the potential of trifluralin (TFL) in the management of Leishmania infantum infections through the synthesis of analogs (TFLA) and incorporation in nanoparticulate drug delivery systems (NanoDDS), liposomes and solid lipid nanoparticles, for selective targeting to leishmania infection sites. MATERIAL & METHODS: In vitro screening of 18 TFLA was performed by flow cytometry. NanoDDS were loaded with active TFLA and evaluated for antileishmanial efficacy in mice through determination of parasite burden in liver and spleen. RESULTS: The in vitro testing revealed the most active and nontoxic TFLAs, which were selected for the in vivo studies based on high incorporation in liposomes and lipid nanoparticles (>90%). Selected TFLA nanoformulations showed superior antileishmanial activity in mice (parasite burden >80%), over free TFLA and Glucantime. CONCLUSION: The modification of TFL structure to obtain active TFLA, together with their incorporation in NanoDDS, improved their in vivo performance against L. infantum infection.

Hemisynthetic trifluralin analogues incorporated in liposomes for the treatment of leishmanial infections.

Leishmaniasis, a vector-borne parasitic disease caused by Leishmania protozoa, is one of the most neglected tropical diseases in terms of drug discovery and development. Current treatment is based on a limited number of chemotherapeutic agents all of which present either/or resistance issues, severe toxicities and adverse reactions associated with extended treatment regimens, and high cost of therapy. Dinitroanilines are a new class of drugs with proven in vitro antileishmanial activity. In previous work a liposomal formulation of one dinitroaniline (TFL) was found to be active against Leishmania parasites in a murine model of visceral leishmaniasis (VL) and in the treatment of experimental canine leishmaniasis. In this study we have investigated the use of dinitroaniline analogues (TFL-A) associated to liposomes, as means to further improve TFL antileishmanial activity. The potential of the liposomal formulations was assessed in vitro against Leishmania infantum promastigotes and intracellular amastigotes and in vivo in a murine model of zoonotic VL. Free and liposomal TFL-A were active in vitro against Leishmania parasites, and they also exhibited reduced cytotoxicity and haemolytic activity. Treatment of infected mice with liposomal TFL-A reduced the amastigote loads in the spleen up to 97%, compared with the loads for untreated controls. These findings illustrate that chemical synthesis of new molecules associated with the use of Nano Drug Delivery Systems that naturally target the diseased organs could be a promising strategy for effective management of VL.

A novel tripodal tris-hydroxypyrimidinone sequestering agent for trivalent hard metal ions: synthesis, complexation and in vivo studies.

A new tripodal hexadentate ligand, NTP(PrHPM)(3), having three hydroxypyrimidinone (HPM) chelating units attached to a nitrilotripropionic acid (NTP) has been prepared and studied in terms of thermodynamic stability of the complexes with iron, aluminium and gallium and it has been subsequently in vivo assayed for its capacity to remove hard metal ions from an animal model overloaded with (67)Ga. The anchoring of the HPM units to the NTP scaffold revealed to be an interesting alternative to the reported hexadentate tris(3-hydroxy-4-pyridinone) analogue, NTP(PrHP)(3), because the new tris-HPM ligand still keeps high chelating capacity for hard metal ions and presents better water-solubility (log P = -1.51). The in vivo studies show that NTP(PrHPM)(3) induces a faster clearance from main organs and an enhancement of overall excretion, as compared with the commercial drug, DFP, or the bidentate HPM compound (HOPY-PrN), albeit slightly lower than the tris-hydroxypyridinone analogue, NTP(PrHP)(3). The solution and in vivo results herein presented encourage further studies envisaging the potential clinical applications of hexadentate HPM derivatives as metal sequestering agents.

Evaluation of the growth-inhibitory effect of trifluralin analogues on in vitro cultured Babesia bovis parasites.

Bovine babesiosis, caused by Babesia bovis, is a global tick borne hemoprotozoan parasite disease characterized by fever, anemia, weight losses and ultimately death. Several babesicidal drugs that have been in use in cattle for years have proven to be only partially effective and the development of alternative chemotherapeutics that are highly specific and have low toxicity against babesiosis is needed. Trifluralin derivatives specifically bind alpha-tubulin in plants and protozoa parasites causing growth inhibition. A set of 12 trifluralin analogues (TFLA) has previously been shown to be inhibitory for the growth of Leishmania species. The conservation of several key amino acids involved in the trifluralin binding site of alpha-tubulin among Leishmania sp. and B. bovis provides rationale for testing these compounds also as babesiacides. The previously tested Leishmania inhibitory, TFLA 1-12 minus TFLA 5, in addition to three novel TFLA (termed TFLA 13-15), were tested against in vitro cultured B. bovis parasites. While all of the TFLA tested in the study showed inhibition of B. bovis growth in vitro TFLA 7, TFLA 10 and TFLA 13, were the most effective inhibitors with estimated IC50 (µM) at 72 h of 8.5 ± 0.3; 9.2 ± 0.2; 8.9 ± 0.7, respectively for the biologically attenuated cloned B. bovis Mo7 strain, and 13.6 ± 1.5; 18.7 ± 1.6; 10.6 ± 1.9, respectively for the virulent B. bovis T3Bo strain. The differences found between the two strains were not statistically significant. Importantly, these drugs displayed low levels of toxicity for the host erythrocytes and bovine renal arterial endothelial cells at the doses tested. The demonstrated ability of trifluralin analogues to inhibit in vitro growth of B. bovis parasites combined with their low toxicity for host cells suggests that these compounds may be further developed as novel alternatives for the treatment of bovine babesiosis.

New hydroxypyrimidinone-containing sulfonamides as carbonic anhydrase inhibitors also acting as MMP inhibitors.

A set of benzenesulfonamide (BSA) derivatives bearing a hydroxypyrimidinone (HPM) moiety were synthesized and investigated for their inhibitory activity against several carbonic anhydrase (CA, EC 4.2.1.1) isozymes. They all revealed to be very potent inhibitors (nanomolar order) of the cytosolic CA I and II isozymes, but especially of the transmembrane, tumor-associated CA IX isozyme, a beneficial feature for a potential antitumor effect of these compounds. Further structure optimization aimed at improving the specificity of CA inhibition and enhancing their matrix metalloproteinase (MMP) inhibitory activity may also lead to new compounds with an attractive dual mechanism of action as antitumor agents.

New silica-immobilized hydroxypyrimidinone as sorbent of hard metal ions from aqueous fluids.

The chemical modification of solid supports with chelators for the sorption of residual amounts of specific metal ions is of environmental and biological current interest. The present work describes the preparation and chelating properties of a new hydroxypyrimidinone-functionalized silica, (HOPY-PrN)-Si, with high affinity for hard metal ions. The new chelating matrix was obtained by coupling a 1-hydroxy-2-(1H)-pyrimidinone derivative, HOPY-PrN, to an epoxy-activated silica. It showed good stability at neutral and acidic conditions and high sequestering capacity for hard metal ions, namely Fe3+ and Al3+, as previously found for the corresponding sepharosic derivative. However, the fact that the present silica-gel derivative is considerably less expensive gives support to its potential interest as a sorbent of traces of toxic hard metal ions from water streams or even from physiological fluids, aided by extracorporeal devices containing the immobilized chelator.