Enhanced Solubility of Albendazole in Cyclodextrin Inclusion Complex: A Molecular Modeling Approach and Physicochemical Evaluation.

BACKGROUND: Albendazole (ABZ) is the drug of choice for the treatment of a variety of human and veterinary parasites. However, it has low aqueous solubility and low bioavailability. Cyclodextrins (CD) are pharmaceutical excipients with the ability to modulate the solubilization property of hydrophobic molecules. OBJECTIVE: The aim of the study was to analyze through in vitro and in silico studies (Autodock Vina software and CycloMolder platform) the formation of inclusion complexes between ABZ, ß-cyclodextrin (ß-CD) and its derivatives Methyl-ß-cyclodextrin (M-ß-CD) and Hydroxypropyl-ß-cyclodextrin (HP-ß-CD). METHODS: The most stable inclusion complexes were produced by the kneading method and characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-Ray Diffraction (XRD), determination of the ABZ content and in vitro dissolution profile. RESULTS: Molecular modeling revealed that inclusion complexes between HP-ß-CD:ABZ (in the proportion 1:1 and 2:1) presented the lowest formation energy and the highest number of intermolecular interactions, showing that the use of more cyclodextrins does not generate gains in the stability of the complex. On the characterization tests, the complexes experimentally obtained by the kneading method demonstrated highly suggestive parameters, including ABZ in HP-ß-CD in both molar proportions, suppression of bands in the infrared spectrum, displacement of the drug's melting temperature in DSC, crystallinity halos instead of the characteristic peaks of ABZ crystals in the XRD and a release of more than 80% of ABZ in less than 5 minutes, dissolution efficiency of up to 92%. CONCLUSION: In silico studies provided a rational selection of the appropriate complexes of cyclodextrin, enabling the elaboration of more targeted complexes, decreasing time and costs for elaboration of new formulations, thereby increasing the oral biodisponibility of ABZ.

Studies toward the structural optimization of novel thiazolylhydrazone-based potent antitrypanosomal agents.

In previous studies, we identified promising anti-Trypanosoma cruzi cruzain inhibitors based on thiazolylhydrazones. To optimize this series, a number of medicinal chemistry directions were explored and new thiazolylhydrazones and thiosemicarbazones were thus synthesized. Potent cruzain inhibitors were identified, such as thiazolylhydrazones 3b and 3j, which exhibited IC(50) of 200-400nM. Furthermore, molecular docking studies showed concordance with experimentally derived structure-activity relationships (SAR) data. In the course of this work, lead compounds exhibiting in vitro activity against both the epimastigote and trypomastigote forms of T. cruzi were identified and in vivo general toxicity analysis was subsequently performed. Novel SAR were documented, including the importance of the thiocarbonyl carbon attached to the thiazolyl ring and the direct comparison between thiosemicarbazones and thiazolylhydrazones.

Development of inclusion complex based on cyclodextrin and oxazolidine derivative

Abstract Oxazolidine derivatives (OxD) have been described as third-line antibiotics and antitumoral agents. The inclusion complexes based on cyclodextrin could improve the solubility and bioavailability of these compounds. A novel synthetic OxD was used, and its inclusion complexes were based on 2-hydroxy-beta-cyclodextrin (2-HPßCD). We conducted an in silico study to evaluate the interaction capacity between OxD and 2-HPßCD. Characterization studies were performed through scanning electron microscopy (SEM), Fourier-transformed infrared (FTIR), nuclear magnetic resonance spectroscopy (1H-NMR), X-ray diffraction (XRD), and thermal analyses. A kinetic study of the OxD was performed, including a cytotoxicity assay using peripheral blood mononuclear cells (PBMCs). The maximum increment of solubility was obtained at 70 mM OxD using 400 mM 2-HPßCD. SEM analyses and FTIR spectra indicated the formation of inclusion complexes. 1H-NMR presented chemical shifts that indicated 1:1 stoichiometry. Different thermal behaviors were obtained. The pharmacokinetic profile showed a short release time. Pure OxD and its inclusion complex did not exhibit cytotoxicity in PBMCs. In silico studies provided a foremost insight into the interactions between OxD and 2-HPßCD, including a higher solubility in water and an average releasing profile without toxicity in normal cells

Design, synthesis and structure-activity relationship of phthalimides endowed with dual antiproliferative and immunomodulatory activities.

The present work reports the synthesis and evaluation of the antitumour and immunomodulatory properties of new phthalimides derivatives designed to explore molecular hybridization and bioisosterism approaches between thalidomide, thiosemicarbazone, thiazolidinone and thiazole series. Twenty-seven new molecules were assessed for their immunosuppressive effect toward TNFα, IFNγ, IL-2 and IL-6 production and antiproliferative activity. The best activity profile was observed for the (6a-f) series, which presents phthalyl and thiazolidinone groups.

2-Pyridyl thiazoles as novel anti-Trypanosoma cruzi agents: structural design, synthesis and pharmacological evaluation.

The present work reports on the synthesis, anti-Trypanosoma cruzi activities and docking studies of a novel series of 2-(pyridin-2-yl)-1,3-thiazoles derived from 2-pyridine thiosemicarbazone. The majority of these compounds are potent cruzain inhibitors and showed excellent inhibition on the trypomastigote form of the parasite, and the resulting structure-activity relationships are discussed. Together, these data present a novel series of thiazolyl hydrazones with potential effects against Chagas disease and they could be important leads in continuing development against Chagas disease.

Structural design, synthesis and structure-activity relationships of thiazolidinones with enhanced anti-Trypanosoma cruzi activity.

Pharmacological treatment of Chagas disease is based on benznidazole, which displays poor efficacy when administered during the chronic phase of infection. Therefore, the development of new therapeutic options is needed. This study reports on the structural design and synthesis of a new class of anti-Trypanosoma cruzi thiazolidinones (4 a-p). (2-[2-Phenoxy-1-(4-bromophenyl)ethylidene)hydrazono]-5-ethylthiazolidin-4-one (4 h) and (2-[2-phenoxy-1-(4-phenylphenyl)ethylidene)hydrazono]-5-ethylthiazolidin-4-one (4 l) were the most potent compounds, resulting in reduced epimastigote proliferation and were toxic for trypomastigotes at concentrations below 10 µM, while they did not display host cell toxicity up to 200 µM. Thiazolidinone 4 h was able to reduce the in vitro parasite burden and the blood parasitemia in mice with similar potency to benznidazole. More importantly, T. cruzi infection reduction was achieved without exhibiting mouse toxicity. Regarding the molecular mechanism of action, these thiazolidinones did not inhibit cruzain activity, which is the major trypanosomal protease. However, investigating the cellular mechanism of action, thiazolidinones altered Golgi complex and endoplasmic reticulum (ER) morphology, produced atypical cytosolic vacuoles, as well as induced necrotic parasite death. This structural design employed for the new anti-T. cruzi thiazolidinones (4 a-p) led to the identification of compounds with enhanced potency and selectivity compared to first-generation thiazolidinones. These compounds did not inhibit cruzain activity, but exhibited strong antiparasitic activity by acting as parasiticidal agents and inducing a necrotic parasite cell death.

Structural investigation of anti-Trypanosoma cruzi 2-iminothiazolidin-4-ones allows the identification of agents with efficacy in infected mice.

We modified the thiazolidinic ring at positions N3, C4, and C5, yielding compounds 6-24. Compounds with a phenyl at position N3, 15-19, 22-24, exhibited better inhibitory properties for cruzain and against the parasite than 2-iminothiazolidin-4-one 5. We were able to identify one high-efficacy trypanocidal compound, 2-minothiazolidin-4-one 18, which inhibited the activity of cruzain and the proliferation of epimastigotes and was cidal for trypomastigotes but was not toxic for splenocytes. Having located some of the structural determinants of the trypanocidal properties, we subsequently wished to determine if the exchange of the thiazolidine for a thiazole ring leaves the functional properties unaffected. We therefore tested thiazoles 26-45 and observed that they did not inhibit cruzain, but they exhibited trypanocidal effects. Parasite development was severely impaired when treated with 18, thus reinforcing the notion that this class of heterocycles can lead to useful cidal agents for Chagas disease.

Quercetin as an inhibitor of snake venom secretory phospholipase A2.

As polyphenolic compounds isolated from plants extracts, flavonoids have been applied to various pharmaceutical uses in recent decades due to their anti-inflammatory, cancer preventive, and cardiovascular protective activities. In this study, we evaluated the effects of the flavonoid quercetin on Crotalus durissus terrificus secretory phospholipase A2 (sPLA2), an important protein involved in the release of arachidonic acid from phospholipid membranes. The protein was chemically modified by treatment with quercetin, which resulted in modifications in the secondary structure as evidenced through circular dichroism. In addition, quercetin was able to inhibit the enzymatic activity and some pharmacological activities of sPLA2, including its antibacterial activity, its ability to induce platelet aggregation, and its myotoxicity by approximately 40%, but was not able to reduce the inflammatory and neurotoxic activities of sPLA2. These results suggest the existence of two pharmacological sites in the protein, one that is correlated with the enzymatic site and another that is distinct from it. We also performed molecular docking to better understand the possible interactions between quercetin and sPLA2. Our docking data showed the existence of hydrogen-bonded, polar interactions and hydrophobic interactions, suggesting that other flavonoids with similar structures could bind to sPLA2. Further research is warranted to investigate the potential use of flavonoids as sPLA2 inhibitors.