Enhancing Giardicidal Activity and Aqueous Solubility through the Development of "RetroABZ", a Regioisomer of Albendazole: In Vitro, In Vivo, and In Silico Studies.

Parasitic diseases, including giardiasis caused by Giardia lamblia (G. lamblia), present a considerable global health burden. The limited effectiveness and adverse effects of current treatment options underscore the necessity for novel therapeutic compounds. In this study, we employed a rational design strategy to synthesize retroalbendazole (RetroABZ), aiming to address the limitations associated with albendazole, a commonly used drug for giardiasis treatment. RetroABZ exhibited enhanced in vitro activity against G. lamblia trophozoites, demonstrating nanomolar potency (IC50 = 83 nM), outperforming albendazole (189 nM). Moreover, our in vivo murine model of giardiasis displayed a strong correlation, supporting the efficacy of RetroABZ, which exhibited an eleven-fold increase in potency compared to albendazole, with median effective dose (ED50) values of 5 µg/kg and 55 µg/kg, respectively. A notable finding was RetroABZ's significantly improved water solubility (245.74 µg/mL), representing a 23-fold increase compared to albendazole, thereby offering potential opportunities for developing derivatives that effectively target invasive parasites. The molecular docking study revealed that RetroABZ displays an interaction profile with tubulin similar to albendazole, forming hydrogen bonds with Glu198 and Cys236 of the ß-tubulin. Additionally, molecular dynamics studies demonstrated that RetroABZ has a greater number of hydrophobic interactions with the binding site in the ß-tubulin, due to the orientation of the propylthio substituent. Consequently, RetroABZ exhibited a higher affinity compared to albendazole. Overall, our findings underscore RetroABZ's potential as a promising therapeutic candidate not only for giardiasis but also for other parasitic diseases.

Giardia lamblia G6PD::6PGL Fused Protein Inhibitors Decrease Trophozoite Viability: A New Alternative against Giardiasis.

Treatments to combat giardiasis have been reported to have several drawbacks, partly due to the drug resistance and toxicity of current antiparasitic agents. These constraints have prompted many researchers to investigate new drugs that act against protozoan parasites. Enzyme inhibition is an important means of regulating pathogen metabolism and has recently been identified as a significant alternative target in the search for new treatments. Glucose-6-phosphate dehydrogenase and 6-phosphogluconolactonase (G6PD::6PGL) is a bifunctional enzyme involved in the pentose phosphate pathway (PPP) in Giardia lamblia (G. lamblia). The G. lamblia enzyme is unusual since, unlike the human enzyme, it is a fused enzyme. Here, we show, through inhibition assays, that an in-house chemical library of 120 compounds and four target compounds, named CNZ-7, CNZ-8, CMC-1, and FLP-2, are potent inhibitors of the G. lamblia G6PD::6PGL fused enzyme. With a constant (k2) of 2.3, 3.2, and 2.8 M−1 s−1, respectively, they provoke alterations in the secondary and tertiary protein structure and global stability. As a novel approach, target compounds show antigiardial activity, with IC50 values of 8.7, 15.2, 15.3, and 24.1 µM in trophozoites from G. lamblia. Moreover, these compounds show selectivity against G. lamblia, since, through counter-screening in Caco-2 and HT29 human cells, they were found to have low toxicity. This finding positions these compounds as a potential and attractive starting point for new antigiardial drugs.

Kinetic and Molecular Docking Studies to Determine the Effect of Inhibitors on the Activity and Structure of Fused G6PD::6PGL Protein from Trichomonas vaginalis.

Trichomoniasis is a sexually transmitted disease with a high incidence worldwide, affecting 270 million people. Despite the existence of a catalog of available drugs to combat this infection, their extensive use promotes the appearance of resistant Trichomonas vaginalis (T. vaginalis), and some side effects in treated people, which are reasons why it is necessary to find new alternatives to combat this infection. In this study, we investigated the impact of an in-house library comprising 55 compounds on the activity of the fused T. vaginalis G6PD::6PGL (TvG6PD::6PGL) protein, a protein mediating the first reaction step of the pentose phosphate pathway (PPP), a crucial pathway involved in the parasite's energy production. We found four compounds: JMM-3, CNZ-3, CNZ-17, and MCC-7, which inhibited the TvG6PD::6PGL protein by more than 50%. Furthermore, we determined the IC50, the inactivation constants, and the type of inhibition. Our results showed that these inhibitors induced catalytic function loss of the TvG6PD::6PGL enzyme by altering its secondary and tertiary structures. Finally, molecular docking was performed for the best inhibitors, JMM-3 and MCC-7. All our findings demonstrate the potential role of these selected hit compounds as TvG6PD::6PGL enzyme selective inhibitors.

Neumotórax bilateral en un paciente con nódulos reumatoideos colonizados por Aspergillus fumigatus / No disponible

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