Molecular Dynamics of a N-Cyclohexyl-1,2,4-Oxadiazole Derivative as a Reversible Cruzain Inhibitor in Trypanosoma cruzi.

BACKGROUND: Chagas disease kills around 10,000 people yearly, primarily in Latin America, where it is prevalent. Current treatment has limited chronic effectiveness, is unsafe, and has substantial side effects. As a result, the use of oxadiazole derivatives and similar heterocyclic compounds as bioisosteres are well known, and they are prospective candidates in the hunt for novel anti-Trypanosoma cruzi chemicals. Recent research has revealed that the cysteine protease cruzain from T. cruzi is a validated target for disease treatment. OBJECTIVE: Thus, using a molecular dynamics simulation, the current study attempted to determine if a significant interaction occurred between the enzyme cruzain and its ligand. RESULTS: Interactions with the catalytic site and other critical locations were observed. Also, the RMSD values suggested that the molecule under research had stable interactions with its target. CONCLUSION: Finally, the findings indicate that the investigated molecule 2b can interfere enzymatic activity of cruzain, indicating that it might be a promising antichagasic drug.

Biological activity of 1,2,3-triazole-2-amino-1,4-naphthoquinone derivatives and their evaluation as therapeutic strategy for malaria control.

Malaria can be caused by several Plasmodium species and the development of an effective vaccine is challenging. Currently, the most effective tool to control the disease is the administration of specific chemotherapy; however, resistance to the frontline antimalarials is one of the major problems in malaria control and thus the development of new drugs becomes urgent. The study presented here sought to evaluate the antimalarial activities of compounds derived from 2-amino-1,4-naphthoquinones containing 1,2,3-triazole using in vivo and in vitro models. 1H-1,2,3-Triazole 2-amino-1,4-naphthoquinone derivatives were synthesized and evaluated for antimalarial activity in vitro, using P. falciparum W2 chloroquine (CQ) resistant strain and in vivo using the murine-P. berghei ANKA strain. Acute toxicity was determined as established by the OECD (2001). Cytotoxicity was evaluated against HepG2 and Vero mammalian cell lines. Transmission electron microscopy of the Plasmodium falciparum trophozoite (early and late stages) was used to evaluate the action of compounds derived at ultra-structural level. The compounds displayed low cytotoxicity CC50 > 100 µM, neither did they cause hemolysis at the tested doses and nor the signs of toxicity in the in vivo acute toxicity test. Among the five compounds tested, one showed IC50 values in submicromolar range of 0.8 µM. Compounds 7, 8 and 11 showed IC50 values < 5 µM, and selectivity index (SI) ranging from 6.8 to 343 for HepG2, and from 13.7 to 494.8 for Vero cells. Compounds 8 and 11 were partially active against P. berghei induced parasitemia in vivo. Analysis of the ultrastructural changes associated with the treatment of these two compounds, showed trophozoites with completely degraded cytoplasm, loss of membrane integrity, organelles in the decomposition stage and possible food vacuole deterioration. Our results indicated that compounds 8 and 11 may be considered hit molecules for antimalarial drug discovery platform and deserve further optimization studies.

Antiviral activity of ouabain against a Brazilian Zika virus strain.

Zika virus (ZIKV) is an emerging arbovirus associated with neurological disorders. Currently, no specific vaccines or antivirals are available to treat the ZIKV infection. Ouabain, a cardiotonic steroid known as Na+/K+-ATPase inhibitor, has been previously described as an immunomodulatory substance by our group. Here, we evaluated for the first time the antiviral activity of this promising substance against a Brazilian ZIKV strain. Vero cells were treated with different concentrations of ouabain before and after the infection with ZIKV. The antiviral effect was evaluated by the TCID50 method and RT-qPCR. Ouabain presented a dose-dependent inhibitory effect against ZIKV, mainly when added post infection. The reduction of infectious virus was accompanied by a decrease in ZIKV RNA levels, suggesting that the mechanism of ZIKV inhibition by ouabain occurred at the replication step. In addition, our in silico data demonstrated a conformational stability and favorable binding free energy of ouabain in the biding sites of the NS5-RdRp and NS3-helicase proteins, which could be related to its mechanism of action. Taken together, these data demonstrate the antiviral activity of ouabain against a Brazilian ZIKV strain and evidence the potential of cardiotonic steroids as promising antiviral agents.

Anti-Leishmania infantum in vitro effect of n-cyclohexyl-1,2,4-oxadiazole and its ADME/TOX parameters.

Leishmaniasis is a disease that represents a serious global health problem with a potentially fatal outcome in some cases. Leishmania spp. is transmitted by the bite of a sandfly and the disease is endemic in 98 countries. Treatment is carried out with toxic drugs and not consistently effective, so there is a need for new treatments. Oxadiazoles are five-membered heterocyclic compounds, and their antileishmanial activity is well documented in the literature. Specifically, n-cyclohexyl-1,2,4-oxadiazole (2b) was designed to obtain the simplified molecular data line entry system (SMILES). The approach for predicting pharmacokinetic properties used was pkCSM-Pharmacokinetics and ADME/TOX parameters were achieved. SMILES of 2b and Amphotericin B (ANF B) were submitted to the server and the results were compared. The cytotoxic action of 2b on host cells (LLC-MK2) was also evaluated, using MTT salt and antileishmanial activity against Leishmania infantum promastigotes at different concentrations for 24 h. The molecule 2b studied here demonstrated low toxicity in LLC-MK2 cells even at the highest concentration (1000 µM) with cell viability of 69%. Furthermore, it demonstrated anti-L. infantum action with cell viability of 13% at the highest concentration (1000 µM), while (ANF B) (16 µg/mL) demonstrated cell viability of 7%, justifying the need for further studies with n-cyclohexyl-1.2,4-oxadiazole employing experimental models of leishmaniasis.

Ivermectin: an award-winning drug with expected antiviral activity against COVID-19.

Ivermectin is an FDA-approved broad-spectrum antiparasitic agent with demonstrated antiviral activity against a number of DNA and RNA viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Despite this promise, the antiviral activity of ivermectin has not been consistently proven in vivo. While ivermectin's activity against SARS-CoV-2 is currently under investigation in patients, insufficient emphasis has been placed on formulation challenges. Here, we discuss challenges surrounding the use of ivermectin in the context of coronavirus disease-19 (COVID-19) and how novel formulations employing micro- and nanotechnologies may address these concerns.

Glycerol carbonate in Ferrier reaction: Access to new enantiopure building blocks to develop glycoglycerolipid analogues.

Glycerol carbonate and tri-O-acetyl-D-glucal were used for the synthesis of glycero-functionalized carbohydrates. Ferrier reaction between the two partners afforded the O-glucoside in 84% yield. Spontaneous crystallization yielded 28% of a pure diastereoisomer with the S configuration as determined by X-ray crystallography. Then, the azido-glycerosugar was prepared in two steps: ring opening of the cyclic carbonate with sodium azide and per-acetylation with an excellent yield of 94%. A library of glycoconjugates were prepared using a 1,3-dipolar cycloaddition in yields ranging from 64 to 99%.

Synthesis and anti-inflammatory activity of new alkyl-substituted phthalimide 1H-1,2,3-triazole derivatives.

Four new 1,2,3-triazole phthalimide derivatives with a potent anti-inflammatory activity have been synthesized in the good yields by the 1,3-dipolar cycloaddition reaction from N-(azido-alkyl)phthalimides and terminal alkynes. The anti-inflammatory activity was determined by injecting carrageenan through the plantar tissue of the right hind paw of Swiss white mice to produce inflammation. All the compounds 3a-c and 5a-c exhibited an important anti-inflammatory activity; the best activity was found for the compounds 3b and 5c, which showed to be able to decrease by 69% and 56.2% carrageenan-induced edema in mice. These compounds may also offer a future promise as a new anti-inflammatory agent.