Esters of Quinoxaline-7-Carboxylate 1,4-di-N-Oxide as Potential Inhibitors of Glycolytic Enzymes of Entamoeba histolytica: In silico Approach

BACKGROUND

Esters of quinoxaline-7-carboxylate 1,4-di-N-oxide (7-carboxylate QdNOs) derivatives are compounds that inhibit the growth of Entamoeba histolytica, the causative agent of amebiasis. Although these compounds cause changes in the redistribution of glycogen deposits within the parasite, it is unknown whether these compounds interact with enzymes of the glycolytic pathway.

OBJECTIVE

The aim of this study was to test the binding affinity of these compounds to pyrophosphate- dependent phosphofructokinase (PPi-PFK), triosephosphate isomerase (TIM), and pyruvate phosphate dikinase (PPDK) from E. histolytica as a possible mechanism of action.

METHODS

The molecular docking study of the 7-carboxylate QdNOs derivatives and the proteins was performed using AutoDock/Vina software. Molecular dynamics simulation was performed for 100 ns.

RESULTS

Among all the selected compounds, T-072 exhibited the best binding affinity to EhPPi- PFK and EhTIM proteins, while T-006 interacted best with EhPPDK. ADMET analysis revealed that T-072 was non-toxic, while T-006 could become harmful to the host. In addition, molecular dynamics showed that T-072 has stable interaction with EhPPi-PFK and EhTIM.

CONCLUSION

Including all aspects, these data indicated that these compounds might inhibit the activity of key enzymes in energy metabolism leading to parasite death. Furthermore, these compounds may be a good starting point for the future development of new potent antiamebic agents.

Serum levels of anti-inflammatory/proinflammatory adipocytokines, and copper levels in overweight and obese women in an adult Mexican population

BACKGROUND

An imbalance between adipokines and micronutrient concentrations, such as those of copper (Cu), has been linked to dysregulation of energy homeostasis leading to weight gain and the development of other comorbidities; however, information on this issue remains limited. Our aim was to investigate the correlation between Cu status and serum adipokine levels and their relationship in normal-weight, overweight, and obese adult women.

METHODS

Sixty patients were evaluated and classified according to their body mass index (BMI) and biochemical parameters; adipokines and Cu were measured at fasting.

RESULTS

Leptin (Lep) and resistin (Res) levels were elevated, whereas adiponectin (Adpn) and ghrelin (Ghr) values were decreased in overweight and obese women (p = 0.001). The mean Adpn/Lep ratio was <0.5 in overweight and obese subjects, while the Lep/Ghr ratio increased significantly in relation to weight gain, suggesting an inverse link between the ratios of these hormones in the regulation of obesity. The analysis revealed a positive association between BMI and Cu levels in obese women. Moreover, a negative association between Cu and Res in normal-weight subjects was found.

CONCLUSIONS

Circulating fasting Res levels are negatively associated with serum Cu concentration in normal-weight adult women. We also observed a close relationship between Adpn/Lep and Lep/Ghr ratios with obesity. However, more observational studies are required to confirm these results in future research.

Proteomic and Functional Analysis of the Effects of Quinoxaline Derivatives on Entamoeba histolytica

Quinoxalines are heterocyclic compounds that contain a benzene ring and a pyrazine ring. The oxidation of both nitrogen of the pyrazine ring results in quinoxaline derivatives (QdNO), which exhibit a variety of biological properties, including antiparasitic activity. However, its activity against Entamoeba histolytica, the protozoan that causes human amebiasis, is poorly understood. Recently, our group reported that various QdNOs produce morphological changes in E. histolytica trophozoites, increase reactive oxygen species, and inhibit thioredoxin reductase activity. Notably, T-001 and T-017 derivatives were among the QdNOs with the best activity. In order to contribute to the characterization of the antiamebic effect of QdNOs, in this work we analyzed the proteomic profile of E. histolytica trophozoites treated with the QdNOs T-001 and T-017, and the results were correlated with functional assays. A total number of 163 deregulated proteins were found in trophozoites treated with T-001, and 131 in those treated with T-017. A set of 21 overexpressed and 24 under-expressed proteins was identified, which were mainly related to cytoskeleton and intracellular traffic, nucleic acid transcription, translation and binding, and redox homeostasis. Furthermore, T-001 and T-017 modified the virulence of trophozoites, since they altered their erythrophagocytosis, migration, adhesion and cytolytic capacity. Our results show that in addition to alter reactive oxygen species, and thioredoxin reductase activity, T-001 and T-017 affect essential functions related to the actin cytoskeleton, which eventually affects E. histolytica virulence and survival.

Bioactivity of Natural Polyphenols as Antiparasitic Agents and their Biochemical Targets

BACKGROUND

Leishmaniasis and trypanosomiasis are diseases that affect public health worldwide due to their high incidence, morbidity, and mortality. Available treatments are costly, prolonged, and toxic, not to mention the problem of parasite resistance. The development of alternative treatments is justified and polyphenols show promising activity.

OBJECTIVE

The main aim of this mini-review was to analyze the most promising phenolic compounds with reported antileishmanial and antitrypanosomal activity as well as their mechanisms of action.

RESULTS

We found that the mode of action of these natural compounds mainly lignans, neolignans, and flavonoids depends on the organism they act on and includes, macrophage activation, induction of morphological changes such as chromatin condensation, DNA fragmentation, accumulation of acidocalcisomes, and glycosomes, Golgi damage and mitochondrial dysfunction as well as negative regulation of mitochondrial enzymes and other essential enzymes for parasite survival such as arginase. This gives a wide scope for future research towards the rational development of anti-kinetoplastid drugs.

CONCLUSION

Although the specific molecular targets, bioavailability, route of administration, and dosages of some of these natural compounds need to be determined, polyphenols and their combinations represent a very promising and safe strategy to be considered for use against Leishmania spp and Trypanosoma spp. In addition, these compounds may provide a scaffold for developing new, more potent, and more selective antiprotozoal agents.

Efficacy of Individualized Homeopathy in Treatment-Resistant Depression

Treatment-resistant major depression (TRD), defined as an insufficient response to at least two antidepressant treatments, is usually treated with antidepressants, psychotherapy, electroconvulsive therapy, repetitive transcranial magnetic stimulation, and vagus nerve stimulation or combinations of these. However, the response rate is modest and, on many occasions, insufficient or nonexistent. Here, we describe the case of a 19-year-old woman with a history of TRD, treated for depression since the age of five years. Her symptoms were resistant to fluoxetine, escitalopram, atomoxetine, and psychotherapy. Individualized homeopathic treatment with Staphisagria, Nux vomica, Arsenicum album, and Lachesis trigonocephalus was started. Posology was carried out in 200CH dynamizations. Treatment was prescribed for four months. This led to an immediate improvement in mood and a sustained and gradual reduction of depressive symptoms and, consequently, a reduction and then cessation of medication with antidepressants and psychotherapy. At follow-up eight months later, the patient is free of depression and medication. This case study reconfirms the usefulness of homeopathy in the treatment of depression. It also suggests that individualized homeopathic treatment may be useful in cases of treatment-resistant depression.

Current status of quinoxaline and quinoxaline 1,4-di-N-oxides derivatives as potential antiparasitic agents

Parasitic diseases are a public health problem, especially in developing countries where millions of people are affected every year. Current treatments have several drawbacks: emerging resistance to the existing drugs, lack of efficacy, and toxic side effects. Therefore, new antiparasitic drugs are urgently needed to treat and control diseases that affect human health, such as malaria, Chagas disease, leishmaniasis, amebiasis, giardiasis schistosomiasis, and filariasis, among others. Quinoxaline is a compound containing a benzene ring and a pyrazine ring. The oxidation of both pyrazine ring nitrogens allows the obtention of quinoxaline 1,4-di-N-oxides (QdNOs) derivatives. By modifying the chemical structure of these compounds, it is possible to obtain a wide variety of biological properties. This review investigated the activity of quinoxaline derivatives and QdNOs against different protozoan parasites and helminths. We also cover the structure-activity relationship (SAR) and summarize the main findings related to their mechanisms of action from published works in recent years. However, further studies are needed to determine specific molecular targets. This review aims to highlight the new development of antiparasitic drugs with better pharmacological profiles than current treatments.

mRNA Polyadenylation Machineries in Intestinal Protozoan Parasites

In humans, mRNA polyadenylation involves the participation of about 20 factors in four main complexes that recognize specific RNA sequences. Notably, CFIm25, CPSF73, and PAP have essential roles for poly(A) site selection, mRNA cleavage, and adenosine residues polymerization. Besides the relevance of polyadenylation for gene expression, information is scarce in intestinal protozoan parasites that threaten human health. To better understand polyadenylation in Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum, which represent leading causes of diarrhea worldwide, genomes were screened for orthologs of human factors. Results showed that Entamoeba histolytica and C. parvum have 16 and 12 proteins out of the 19 human proteins used as queries, respectively, while G. lamblia seems to have the smallest polyadenylation machinery with only six factors. Remarkably, CPSF30, CPSF73, CstF77, PABP2, and PAP, which were found in all parasites, could represent the core polyadenylation machinery. Multiple genes were detected for several proteins in Entamoeba, while gene redundancy is lower in Giardia and Cryptosporidium. Congruently with their relevance in the polyadenylation process, CPSF73 and PAP are present in all parasites, and CFIm25 is only missing in Giardia. They conserve the functional domains and predicted folding of human proteins, suggesting they may have the same roles in polyadenylation.

The 25 kDa subunit of cleavage factor Im Is a RNA-binding protein that interacts with the poly(A) polymerase in Entamoeba histolytica

In eukaryotes, polyadenylation of pre-mRNA 3´ end is essential for mRNA export, stability and translation. Taking advantage of the knowledge of genomic sequences of Entamoeba histolytica, the protozoan responsible for human amoebiasis, we previously reported the putative polyadenylation machinery of this parasite. Here, we focused on the predicted protein that has the molecular features of the 25 kDa subunit of the Cleavage Factor Im (CFIm25) from other organisms, including the Nudix (nucleoside diphosphate linked to another moiety X) domain, as well as the RNA binding domain and the PAP/PAB interacting region. The recombinant EhCFIm25 protein (rEhCFIm25) was expressed in bacteria and used to generate specific antibodies in rabbit. Subcellular localization assays showed the presence of the endogenous protein in nuclear and cytoplasmic fractions. In RNA electrophoretic mobility shift assays, rEhCFIm25 was able to form specific RNA-protein complexes with the EhPgp5 mRNA 3´ UTR used as probe. In addition, Pull-Down and LC/ESI-MS/MS tandem mass spectrometry assays evidenced that the putative EhCFIm25 was able to interact with the poly(A) polymerase (EhPAP) that is responsible for the synthesis of the poly(A) tail in other eukaryotic cells. By Far-Western experiments, we confirmed the interaction between the putative EhCFIm25 and EhPAP in E. histolytica. Taken altogether, our results showed that the putative EhCFIm25 is a conserved RNA binding protein that interacts with the poly(A) polymerase, another member of the pre-mRNA 3´ end processing machinery in this protozoan parasite.

[Prevalence of Barrett's esophagus in patients with colorectal carcinoma]

OBJECTIVE

To determine Barrett's esophagus (BO) prevalence in patients diagnosed with colorectal carcinoma (CC) and feasibility-associated factors in a 10 week period from March 1st to June 15, 1999.

PLACE

Endoscopy Department, Oncology Hospital, Centro Médico Nacional Siglo XXI, IMSS.

METHOD

A prospective, transversal, observational and comparative assay of 48 patients with histologically confirmed diagnosis of colorectal carcinoma in whom high endoscopy with biopsy harvest was performed; otherwise, colonoscopy was performed in eight patients with confirmed BO.

RESULTS

Thirty men and 18 women were studied with an average age of 53 years of age. In 100%, colon cancer was determined as adenocarcinoma and location were rectal in 43.7%. Prevalence of BO was 22.9% in addition to 0.74 to 2% in the general population. This implies an odds ratio calculated at 36.43 (p = 0.00000) and 3.09 p = 0.00007), respectively, for risk to present BO concomitant with CC. There was no statistical significance in relation to age, smoking habit, and/or alcoholism. Among eight patients with BO without CCR, only one had a tubulovellous polypus (12.5%) identified.

CONCLUSIONS

Although the results were not to conclusive to affirm the association of BA with CCR, the high prevalence found justifies the performance of routine endoscopy in CCR carrier patients with reflux symptoms.