Single-dose treatment for cutaneous leishmaniasis with an easily synthesized chalcone entrapped in polymeric microparticles

Synthesis and evaluation of hybrid sulfonamide-chalcones with potential antileishmanial activity

Leishmaniasis is an emerging tropical infectious disease caused by a protozoan parasite of the genus Leishmania. In this work, the molecular hybridization between a trimethoxy chalcone and a sulfonamide group was used to generate a series of sulfonamide-chalcones. A series of eight sulfonamide-chalcone hybrids were made with good yields (up to 95%). These sulfonamide-chalcones were tested against promastigotes of Leishmania amazonensis and cytotoxicity against mouse macrophages, which showed good antileishmanial activity with IC50  = 1.72-3.19 µM. Three of them (10c, 10g, and 10h) were also highly active against intracellular amastigotes and had a good selectivity index (SI > 9). Thus, those three compounds were docked in the cytosolic tryparedoxin peroxidase (cTXNPx) enzyme of the parasite, and molecular dynamics simulations were carried out. This enzyme was selected as a target protein for the sulfonamide-chalcones due to the fact of the anterior report, which identified a strong and stable interaction between the chalcone NAT22 (6) and the cTXNPx. In addition, a prediction of the drug-likeness, and the pharmacokinetic profile of all compounds were made, demonstrating a good profile of those chalcones.

Microparticles in the Development and Improvement of Pharmaceutical Formulations: An Analysis of In Vitro and In Vivo Studies

Microparticulate systems such as microparticles, microspheres, microcapsules or any particle in a micrometer scale (usually of 1–1000 µm) are widely used as drug delivery systems, because they offer higher therapeutic and diagnostic performance compared to conventional drug delivery forms. These systems can be manufactured with many raw materials, especially polymers, most of which have been effective in improving the physicochemical properties and biological activities of active compounds. This review will focus on the in vivo and in vitro application in the last decade (2012 to 2022) of different active pharmaceutical ingredients microencapsulated in polymeric or lipid matrices, the main formulation factors (excipients and techniques) and mostly their biological activities, with the aim of introducing and discussing the potential applicability of microparticulate systems in the pharmaceutical field.

Structure and interaction roles in the release profile of chalcone-loaded liposomes

The structures and molecular interactions of established synthetic chalcones were correlated with their release profiles from asolectin liposomes. The effects of chalcones on the properties of liposomes were evaluated by dynamic light scattering (DLS), ultraviolet-visible spectroscopy (UV-VIS), horizontal attenuated total reflection Fourier transform infrared (HATR-FTIR), ³¹P nuclear magnetic resonance (³¹P NMR), zeta (ζ) potential and differential scanning calorimetry (DSC). The profiles and mechanisms of release were accessed according to the Korsmeyer-Peppas model. Results obtained allowed the establishment of a relationship between the chalcone release profile and 1) the ordering effects of chalcones in different membrane regions, 2) their polar or interfacial location in the lipid layer, 3) the influence of hydroxy and methoxy substituents, 4) their effect on reorientation of lipid choline-phosphate regions. The obtained data may improve the development of chalcone-based systems to be used in the therapy of chronic and acute diseases.

Chalcones identify cTXNPx as a potential antileishmanial drug target

With current drug treatments failing due to toxicity, low efficacy and resistance; leishmaniasis is a major global health challenge that desperately needs new validated drug targets. Inspired by activity of the natural chalcone 2’,6’-dihydroxy-4’-methoxychalcone (DMC), the nitro-analogue, 3-nitro-2’,4’,6’- trimethoxychalcone (NAT22, 1c) was identified as potent broad spectrum antileishmanial drug lead. Structural modification provided an alkyne containing chemical probe that labelled a protein within the parasite that was confirmed as cytosolic tryparedoxin peroxidase (cTXNPx). Crucially, labelling is observed in both promastigote and intramacrophage amastigote life forms, with no evidence of host macrophage toxicity. Incubation of the chalcone in the parasite leads to ROS accumulation and parasite death. Deletion of cTXNPx, by CRISPR-Cas9, dramatically impacts upon the parasite phenotype and reduces the antileishmanial activity of the chalcone analogue. Molecular docking studies with a homology model of in-silico cTXNPx suggest that the chalcone is able to bind in the putative active site hindering access to the crucial cysteine residue. Collectively, this work identifies cTXNPx as an important target for antileishmanial chalcones.

Leishmaniasis is an insect vector-borne parasitic disease. With >350 million people world wide considered at risk, 12 million people currently infected and an economic cost that can be estimated in terms of >3.3 million working life years lost, leishmaniasis is a major global health challenge. The disease is of particular importance in Brazil. Current treatment of leishmaniasis is difficult requiring a long, costly course of drug treatment using old drugs with poor safety indications requiring close medical supervision. Moreover, resistance to current antileishmanials is growing, emphasising a major need for new drug targets. In earlier work we had identified a naturally inspired chalcone which had promising antileishmanial activity but with no known mode of action. In this work we use an analogue of this molecule as an activity based probe to identify a protein target of the chalcone. This protein, cTXNPx, has a major role in protecting the parasite against attack by reactive oxygen species in the host cell. By inhibiting this protein the parasite can no longer survive in the host. Collectively this work validates cTXNPx as a drug target with the chalcone as a lead structure for future drug discovery programmes.